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Diffstat (limited to 'src/replication.c')
| -rw-r--r-- | src/replication.c | 2654 |
1 files changed, 2654 insertions, 0 deletions
diff --git a/src/replication.c b/src/replication.c new file mode 100644 index 0000000..bde37bc --- /dev/null +++ b/src/replication.c @@ -0,0 +1,2654 @@ +/* Asynchronous replication implementation. + * + * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * * Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of Redis nor the names of its contributors may be used + * to endorse or promote products derived from this software without + * specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + + +#include "server.h" + +#include <sys/time.h> +#include <unistd.h> +#include <fcntl.h> +#include <sys/socket.h> +#include <sys/stat.h> + +void replicationDiscardCachedMaster(void); +void replicationResurrectCachedMaster(int newfd); +void replicationSendAck(void); +void putSlaveOnline(client *slave); +int cancelReplicationHandshake(void); + +/* --------------------------- Utility functions ---------------------------- */ + +/* Return the pointer to a string representing the slave ip:listening_port + * pair. Mostly useful for logging, since we want to log a slave using its + * IP address and its listening port which is more clear for the user, for + * example: "Closing connection with slave 10.1.2.3:6380". */ +char *replicationGetSlaveName(client *c) { + static char buf[NET_PEER_ID_LEN]; + char ip[NET_IP_STR_LEN]; + + ip[0] = '\0'; + buf[0] = '\0'; + if (c->slave_ip[0] != '\0' || + anetPeerToString(c->fd,ip,sizeof(ip),NULL) != -1) + { + /* Note that the 'ip' buffer is always larger than 'c->slave_ip' */ + if (c->slave_ip[0] != '\0') memcpy(ip,c->slave_ip,sizeof(c->slave_ip)); + + if (c->slave_listening_port) + anetFormatAddr(buf,sizeof(buf),ip,c->slave_listening_port); + else + snprintf(buf,sizeof(buf),"%s:<unknown-slave-port>",ip); + } else { + snprintf(buf,sizeof(buf),"client id #%llu", + (unsigned long long) c->id); + } + return buf; +} + +/* ---------------------------------- MASTER -------------------------------- */ + +void createReplicationBacklog(void) { + serverAssert(server.repl_backlog == NULL); + server.repl_backlog = zmalloc(server.repl_backlog_size); + server.repl_backlog_histlen = 0; + server.repl_backlog_idx = 0; + + /* We don't have any data inside our buffer, but virtually the first + * byte we have is the next byte that will be generated for the + * replication stream. */ + server.repl_backlog_off = server.master_repl_offset+1; +} + +/* This function is called when the user modifies the replication backlog + * size at runtime. It is up to the function to both update the + * server.repl_backlog_size and to resize the buffer and setup it so that + * it contains the same data as the previous one (possibly less data, but + * the most recent bytes, or the same data and more free space in case the + * buffer is enlarged). */ +void resizeReplicationBacklog(long long newsize) { + if (newsize < CONFIG_REPL_BACKLOG_MIN_SIZE) + newsize = CONFIG_REPL_BACKLOG_MIN_SIZE; + if (server.repl_backlog_size == newsize) return; + + server.repl_backlog_size = newsize; + if (server.repl_backlog != NULL) { + /* What we actually do is to flush the old buffer and realloc a new + * empty one. It will refill with new data incrementally. + * The reason is that copying a few gigabytes adds latency and even + * worse often we need to alloc additional space before freeing the + * old buffer. */ + zfree(server.repl_backlog); + server.repl_backlog = zmalloc(server.repl_backlog_size); + server.repl_backlog_histlen = 0; + server.repl_backlog_idx = 0; + /* Next byte we have is... the next since the buffer is empty. */ + server.repl_backlog_off = server.master_repl_offset+1; + } +} + +void freeReplicationBacklog(void) { + serverAssert(listLength(server.slaves) == 0); + zfree(server.repl_backlog); + server.repl_backlog = NULL; +} + +/* Add data to the replication backlog. + * This function also increments the global replication offset stored at + * server.master_repl_offset, because there is no case where we want to feed + * the backlog without incrementing the buffer. */ +void feedReplicationBacklog(void *ptr, size_t len) { + unsigned char *p = ptr; + + server.master_repl_offset += len; + + /* This is a circular buffer, so write as much data we can at every + * iteration and rewind the "idx" index if we reach the limit. */ + while(len) { + size_t thislen = server.repl_backlog_size - server.repl_backlog_idx; + if (thislen > len) thislen = len; + memcpy(server.repl_backlog+server.repl_backlog_idx,p,thislen); + server.repl_backlog_idx += thislen; + if (server.repl_backlog_idx == server.repl_backlog_size) + server.repl_backlog_idx = 0; + len -= thislen; + p += thislen; + server.repl_backlog_histlen += thislen; + } + if (server.repl_backlog_histlen > server.repl_backlog_size) + server.repl_backlog_histlen = server.repl_backlog_size; + /* Set the offset of the first byte we have in the backlog. */ + server.repl_backlog_off = server.master_repl_offset - + server.repl_backlog_histlen + 1; +} + +/* Wrapper for feedReplicationBacklog() that takes Redis string objects + * as input. */ +void feedReplicationBacklogWithObject(robj *o) { + char llstr[LONG_STR_SIZE]; + void *p; + size_t len; + + if (o->encoding == OBJ_ENCODING_INT) { + len = ll2string(llstr,sizeof(llstr),(long)o->ptr); + p = llstr; + } else { + len = sdslen(o->ptr); + p = o->ptr; + } + feedReplicationBacklog(p,len); +} + +/* Propagate write commands to slaves, and populate the replication backlog + * as well. This function is used if the instance is a master: we use + * the commands received by our clients in order to create the replication + * stream. Instead if the instance is a slave and has sub-slaves attached, + * we use replicationFeedSlavesFromMaster() */ +void replicationFeedSlaves(list *slaves, int dictid, robj **argv, int argc) { + listNode *ln; + listIter li; + int j, len; + char llstr[LONG_STR_SIZE]; + + /* If the instance is not a top level master, return ASAP: we'll just proxy + * the stream of data we receive from our master instead, in order to + * propagate *identical* replication stream. In this way this slave can + * advertise the same replication ID as the master (since it shares the + * master replication history and has the same backlog and offsets). */ + if (server.masterhost != NULL) return; + + /* If there aren't slaves, and there is no backlog buffer to populate, + * we can return ASAP. */ + if (server.repl_backlog == NULL && listLength(slaves) == 0) return; + + /* We can't have slaves attached and no backlog. */ + serverAssert(!(listLength(slaves) != 0 && server.repl_backlog == NULL)); + + /* Send SELECT command to every slave if needed. */ + if (server.slaveseldb != dictid) { + robj *selectcmd; + + /* For a few DBs we have pre-computed SELECT command. */ + if (dictid >= 0 && dictid < PROTO_SHARED_SELECT_CMDS) { + selectcmd = shared.select[dictid]; + } else { + int dictid_len; + + dictid_len = ll2string(llstr,sizeof(llstr),dictid); + selectcmd = createObject(OBJ_STRING, + sdscatprintf(sdsempty(), + "*2\r\n$6\r\nSELECT\r\n$%d\r\n%s\r\n", + dictid_len, llstr)); + } + + /* Add the SELECT command into the backlog. */ + if (server.repl_backlog) feedReplicationBacklogWithObject(selectcmd); + + /* Send it to slaves. */ + listRewind(slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) continue; + addReply(slave,selectcmd); + } + + if (dictid < 0 || dictid >= PROTO_SHARED_SELECT_CMDS) + decrRefCount(selectcmd); + } + server.slaveseldb = dictid; + + /* Write the command to the replication backlog if any. */ + if (server.repl_backlog) { + char aux[LONG_STR_SIZE+3]; + + /* Add the multi bulk reply length. */ + aux[0] = '*'; + len = ll2string(aux+1,sizeof(aux)-1,argc); + aux[len+1] = '\r'; + aux[len+2] = '\n'; + feedReplicationBacklog(aux,len+3); + + for (j = 0; j < argc; j++) { + long objlen = stringObjectLen(argv[j]); + + /* We need to feed the buffer with the object as a bulk reply + * not just as a plain string, so create the $..CRLF payload len + * and add the final CRLF */ + aux[0] = '$'; + len = ll2string(aux+1,sizeof(aux)-1,objlen); + aux[len+1] = '\r'; + aux[len+2] = '\n'; + feedReplicationBacklog(aux,len+3); + feedReplicationBacklogWithObject(argv[j]); + feedReplicationBacklog(aux+len+1,2); + } + } + + /* Write the command to every slave. */ + listRewind(slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + /* Don't feed slaves that are still waiting for BGSAVE to start */ + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) continue; + + /* Feed slaves that are waiting for the initial SYNC (so these commands + * are queued in the output buffer until the initial SYNC completes), + * or are already in sync with the master. */ + + /* Add the multi bulk length. */ + addReplyMultiBulkLen(slave,argc); + + /* Finally any additional argument that was not stored inside the + * static buffer if any (from j to argc). */ + for (j = 0; j < argc; j++) + addReplyBulk(slave,argv[j]); + } +} + +/* This function is used in order to proxy what we receive from our master + * to our sub-slaves. */ +#include <ctype.h> +void replicationFeedSlavesFromMasterStream(list *slaves, char *buf, size_t buflen) { + listNode *ln; + listIter li; + + /* Debugging: this is handy to see the stream sent from master + * to slaves. Disabled with if(0). */ + if (0) { + printf("%zu:",buflen); + for (size_t j = 0; j < buflen; j++) { + printf("%c", isprint(buf[j]) ? buf[j] : '.'); + } + printf("\n"); + } + + if (server.repl_backlog) feedReplicationBacklog(buf,buflen); + listRewind(slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + /* Don't feed slaves that are still waiting for BGSAVE to start */ + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) continue; + addReplyString(slave,buf,buflen); + } +} + +void replicationFeedMonitors(client *c, list *monitors, int dictid, robj **argv, int argc) { + listNode *ln; + listIter li; + int j; + sds cmdrepr = sdsnew("+"); + robj *cmdobj; + struct timeval tv; + + gettimeofday(&tv,NULL); + cmdrepr = sdscatprintf(cmdrepr,"%ld.%06ld ",(long)tv.tv_sec,(long)tv.tv_usec); + if (c->flags & CLIENT_LUA) { + cmdrepr = sdscatprintf(cmdrepr,"[%d lua] ",dictid); + } else if (c->flags & CLIENT_UNIX_SOCKET) { + cmdrepr = sdscatprintf(cmdrepr,"[%d unix:%s] ",dictid,server.unixsocket); + } else { + cmdrepr = sdscatprintf(cmdrepr,"[%d %s] ",dictid,getClientPeerId(c)); + } + + for (j = 0; j < argc; j++) { + if (argv[j]->encoding == OBJ_ENCODING_INT) { + cmdrepr = sdscatprintf(cmdrepr, "\"%ld\"", (long)argv[j]->ptr); + } else { + cmdrepr = sdscatrepr(cmdrepr,(char*)argv[j]->ptr, + sdslen(argv[j]->ptr)); + } + if (j != argc-1) + cmdrepr = sdscatlen(cmdrepr," ",1); + } + cmdrepr = sdscatlen(cmdrepr,"\r\n",2); + cmdobj = createObject(OBJ_STRING,cmdrepr); + + listRewind(monitors,&li); + while((ln = listNext(&li))) { + client *monitor = ln->value; + addReply(monitor,cmdobj); + } + decrRefCount(cmdobj); +} + +/* Feed the slave 'c' with the replication backlog starting from the + * specified 'offset' up to the end of the backlog. */ +long long addReplyReplicationBacklog(client *c, long long offset) { + long long j, skip, len; + + serverLog(LL_DEBUG, "[PSYNC] Slave request offset: %lld", offset); + + if (server.repl_backlog_histlen == 0) { + serverLog(LL_DEBUG, "[PSYNC] Backlog history len is zero"); + return 0; + } + + serverLog(LL_DEBUG, "[PSYNC] Backlog size: %lld", + server.repl_backlog_size); + serverLog(LL_DEBUG, "[PSYNC] First byte: %lld", + server.repl_backlog_off); + serverLog(LL_DEBUG, "[PSYNC] History len: %lld", + server.repl_backlog_histlen); + serverLog(LL_DEBUG, "[PSYNC] Current index: %lld", + server.repl_backlog_idx); + + /* Compute the amount of bytes we need to discard. */ + skip = offset - server.repl_backlog_off; + serverLog(LL_DEBUG, "[PSYNC] Skipping: %lld", skip); + + /* Point j to the oldest byte, that is actually our + * server.repl_backlog_off byte. */ + j = (server.repl_backlog_idx + + (server.repl_backlog_size-server.repl_backlog_histlen)) % + server.repl_backlog_size; + serverLog(LL_DEBUG, "[PSYNC] Index of first byte: %lld", j); + + /* Discard the amount of data to seek to the specified 'offset'. */ + j = (j + skip) % server.repl_backlog_size; + + /* Feed slave with data. Since it is a circular buffer we have to + * split the reply in two parts if we are cross-boundary. */ + len = server.repl_backlog_histlen - skip; + serverLog(LL_DEBUG, "[PSYNC] Reply total length: %lld", len); + while(len) { + long long thislen = + ((server.repl_backlog_size - j) < len) ? + (server.repl_backlog_size - j) : len; + + serverLog(LL_DEBUG, "[PSYNC] addReply() length: %lld", thislen); + addReplySds(c,sdsnewlen(server.repl_backlog + j, thislen)); + len -= thislen; + j = 0; + } + return server.repl_backlog_histlen - skip; +} + +/* Return the offset to provide as reply to the PSYNC command received + * from the slave. The returned value is only valid immediately after + * the BGSAVE process started and before executing any other command + * from clients. */ +long long getPsyncInitialOffset(void) { + return server.master_repl_offset; +} + +/* Send a FULLRESYNC reply in the specific case of a full resynchronization, + * as a side effect setup the slave for a full sync in different ways: + * + * 1) Remember, into the slave client structure, the replication offset + * we sent here, so that if new slaves will later attach to the same + * background RDB saving process (by duplicating this client output + * buffer), we can get the right offset from this slave. + * 2) Set the replication state of the slave to WAIT_BGSAVE_END so that + * we start accumulating differences from this point. + * 3) Force the replication stream to re-emit a SELECT statement so + * the new slave incremental differences will start selecting the + * right database number. + * + * Normally this function should be called immediately after a successful + * BGSAVE for replication was started, or when there is one already in + * progress that we attached our slave to. */ +int replicationSetupSlaveForFullResync(client *slave, long long offset) { + char buf[128]; + int buflen; + + slave->psync_initial_offset = offset; + slave->replstate = SLAVE_STATE_WAIT_BGSAVE_END; + /* We are going to accumulate the incremental changes for this + * slave as well. Set slaveseldb to -1 in order to force to re-emit + * a SELECT statement in the replication stream. */ + server.slaveseldb = -1; + + /* Don't send this reply to slaves that approached us with + * the old SYNC command. */ + if (!(slave->flags & CLIENT_PRE_PSYNC)) { + buflen = snprintf(buf,sizeof(buf),"+FULLRESYNC %s %lld\r\n", + server.replid,offset); + if (write(slave->fd,buf,buflen) != buflen) { + freeClientAsync(slave); + return C_ERR; + } + } + return C_OK; +} + +/* This function handles the PSYNC command from the point of view of a + * master receiving a request for partial resynchronization. + * + * On success return C_OK, otherwise C_ERR is returned and we proceed + * with the usual full resync. */ +int masterTryPartialResynchronization(client *c) { + long long psync_offset, psync_len; + char *master_replid = c->argv[1]->ptr; + char buf[128]; + int buflen; + + /* Parse the replication offset asked by the slave. Go to full sync + * on parse error: this should never happen but we try to handle + * it in a robust way compared to aborting. */ + if (getLongLongFromObjectOrReply(c,c->argv[2],&psync_offset,NULL) != + C_OK) goto need_full_resync; + + /* Is the replication ID of this master the same advertised by the wannabe + * slave via PSYNC? If the replication ID changed this master has a + * different replication history, and there is no way to continue. + * + * Note that there are two potentially valid replication IDs: the ID1 + * and the ID2. The ID2 however is only valid up to a specific offset. */ + if (strcasecmp(master_replid, server.replid) && + (strcasecmp(master_replid, server.replid2) || + psync_offset > server.second_replid_offset)) + { + /* Run id "?" is used by slaves that want to force a full resync. */ + if (master_replid[0] != '?') { + if (strcasecmp(master_replid, server.replid) && + strcasecmp(master_replid, server.replid2)) + { + serverLog(LL_NOTICE,"Partial resynchronization not accepted: " + "Replication ID mismatch (Slave asked for '%s', my " + "replication IDs are '%s' and '%s')", + master_replid, server.replid, server.replid2); + } else { + serverLog(LL_NOTICE,"Partial resynchronization not accepted: " + "Requested offset for second ID was %lld, but I can reply " + "up to %lld", psync_offset, server.second_replid_offset); + } + } else { + serverLog(LL_NOTICE,"Full resync requested by slave %s", + replicationGetSlaveName(c)); + } + goto need_full_resync; + } + + /* We still have the data our slave is asking for? */ + if (!server.repl_backlog || + psync_offset < server.repl_backlog_off || + psync_offset > (server.repl_backlog_off + server.repl_backlog_histlen)) + { + serverLog(LL_NOTICE, + "Unable to partial resync with slave %s for lack of backlog (Slave request was: %lld).", replicationGetSlaveName(c), psync_offset); + if (psync_offset > server.master_repl_offset) { + serverLog(LL_WARNING, + "Warning: slave %s tried to PSYNC with an offset that is greater than the master replication offset.", replicationGetSlaveName(c)); + } + goto need_full_resync; + } + + /* If we reached this point, we are able to perform a partial resync: + * 1) Set client state to make it a slave. + * 2) Inform the client we can continue with +CONTINUE + * 3) Send the backlog data (from the offset to the end) to the slave. */ + c->flags |= CLIENT_SLAVE; + c->replstate = SLAVE_STATE_ONLINE; + c->repl_ack_time = server.unixtime; + c->repl_put_online_on_ack = 0; + listAddNodeTail(server.slaves,c); + /* We can't use the connection buffers since they are used to accumulate + * new commands at this stage. But we are sure the socket send buffer is + * empty so this write will never fail actually. */ + if (c->slave_capa & SLAVE_CAPA_PSYNC2) { + buflen = snprintf(buf,sizeof(buf),"+CONTINUE %s\r\n", server.replid); + } else { + buflen = snprintf(buf,sizeof(buf),"+CONTINUE\r\n"); + } + if (write(c->fd,buf,buflen) != buflen) { + freeClientAsync(c); + return C_OK; + } + psync_len = addReplyReplicationBacklog(c,psync_offset); + serverLog(LL_NOTICE, + "Partial resynchronization request from %s accepted. Sending %lld bytes of backlog starting from offset %lld.", + replicationGetSlaveName(c), + psync_len, psync_offset); + /* Note that we don't need to set the selected DB at server.slaveseldb + * to -1 to force the master to emit SELECT, since the slave already + * has this state from the previous connection with the master. */ + + refreshGoodSlavesCount(); + return C_OK; /* The caller can return, no full resync needed. */ + +need_full_resync: + /* We need a full resync for some reason... Note that we can't + * reply to PSYNC right now if a full SYNC is needed. The reply + * must include the master offset at the time the RDB file we transfer + * is generated, so we need to delay the reply to that moment. */ + return C_ERR; +} + +/* Start a BGSAVE for replication goals, which is, selecting the disk or + * socket target depending on the configuration, and making sure that + * the script cache is flushed before to start. + * + * The mincapa argument is the bitwise AND among all the slaves capabilities + * of the slaves waiting for this BGSAVE, so represents the slave capabilities + * all the slaves support. Can be tested via SLAVE_CAPA_* macros. + * + * Side effects, other than starting a BGSAVE: + * + * 1) Handle the slaves in WAIT_START state, by preparing them for a full + * sync if the BGSAVE was succesfully started, or sending them an error + * and dropping them from the list of slaves. + * + * 2) Flush the Lua scripting script cache if the BGSAVE was actually + * started. + * + * Returns C_OK on success or C_ERR otherwise. */ +int startBgsaveForReplication(int mincapa) { + int retval; + int socket_target = server.repl_diskless_sync && (mincapa & SLAVE_CAPA_EOF); + listIter li; + listNode *ln; + + serverLog(LL_NOTICE,"Starting BGSAVE for SYNC with target: %s", + socket_target ? "slaves sockets" : "disk"); + + rdbSaveInfo rsi = RDB_SAVE_INFO_INIT; + /* If we are saving for a chained slave (that is, if we are, + * in turn, a slave of another instance), make sure after + * loadig the RDB, our slaves select the right DB: we'll just + * send the replication stream we receive from our master, so + * no way to send SELECT commands. */ + if (server.master) rsi.repl_stream_db = server.master->db->id; + + if (socket_target) + retval = rdbSaveToSlavesSockets(&rsi); + else + retval = rdbSaveBackground(server.rdb_filename,&rsi); + + /* If we failed to BGSAVE, remove the slaves waiting for a full + * resynchorinization from the list of salves, inform them with + * an error about what happened, close the connection ASAP. */ + if (retval == C_ERR) { + serverLog(LL_WARNING,"BGSAVE for replication failed"); + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) { + slave->flags &= ~CLIENT_SLAVE; + listDelNode(server.slaves,ln); + addReplyError(slave, + "BGSAVE failed, replication can't continue"); + slave->flags |= CLIENT_CLOSE_AFTER_REPLY; + } + } + return retval; + } + + /* If the target is socket, rdbSaveToSlavesSockets() already setup + * the salves for a full resync. Otherwise for disk target do it now.*/ + if (!socket_target) { + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) { + replicationSetupSlaveForFullResync(slave, + getPsyncInitialOffset()); + } + } + } + + /* Flush the script cache, since we need that slave differences are + * accumulated without requiring slaves to match our cached scripts. */ + if (retval == C_OK) replicationScriptCacheFlush(); + return retval; +} + +/* SYNC and PSYNC command implemenation. */ +void syncCommand(client *c) { + /* ignore SYNC if already slave or in monitor mode */ + if (c->flags & CLIENT_SLAVE) return; + + /* Refuse SYNC requests if we are a slave but the link with our master + * is not ok... */ + if (server.masterhost && server.repl_state != REPL_STATE_CONNECTED) { + addReplySds(c,sdsnew("-NOMASTERLINK Can't SYNC while not connected with my master\r\n")); + return; + } + + /* SYNC can't be issued when the server has pending data to send to + * the client about already issued commands. We need a fresh reply + * buffer registering the differences between the BGSAVE and the current + * dataset, so that we can copy to other slaves if needed. */ + if (clientHasPendingReplies(c)) { + addReplyError(c,"SYNC and PSYNC are invalid with pending output"); + return; + } + + serverLog(LL_NOTICE,"Slave %s asks for synchronization", + replicationGetSlaveName(c)); + + /* Try a partial resynchronization if this is a PSYNC command. + * If it fails, we continue with usual full resynchronization, however + * when this happens masterTryPartialResynchronization() already + * replied with: + * + * +FULLRESYNC <replid> <offset> + * + * So the slave knows the new replid and offset to try a PSYNC later + * if the connection with the master is lost. */ + if (!strcasecmp(c->argv[0]->ptr,"psync")) { + if (masterTryPartialResynchronization(c) == C_OK) { + server.stat_sync_partial_ok++; + return; /* No full resync needed, return. */ + } else { + char *master_replid = c->argv[1]->ptr; + + /* Increment stats for failed PSYNCs, but only if the + * replid is not "?", as this is used by slaves to force a full + * resync on purpose when they are not albe to partially + * resync. */ + if (master_replid[0] != '?') server.stat_sync_partial_err++; + } + } else { + /* If a slave uses SYNC, we are dealing with an old implementation + * of the replication protocol (like redis-cli --slave). Flag the client + * so that we don't expect to receive REPLCONF ACK feedbacks. */ + c->flags |= CLIENT_PRE_PSYNC; + } + + /* Full resynchronization. */ + server.stat_sync_full++; + + /* Setup the slave as one waiting for BGSAVE to start. The following code + * paths will change the state if we handle the slave differently. */ + c->replstate = SLAVE_STATE_WAIT_BGSAVE_START; + if (server.repl_disable_tcp_nodelay) + anetDisableTcpNoDelay(NULL, c->fd); /* Non critical if it fails. */ + c->repldbfd = -1; + c->flags |= CLIENT_SLAVE; + listAddNodeTail(server.slaves,c); + + /* Create the replication backlog if needed. */ + if (listLength(server.slaves) == 1 && server.repl_backlog == NULL) { + /* When we create the backlog from scratch, we always use a new + * replication ID and clear the ID2, since there is no valid + * past history. */ + changeReplicationId(); + clearReplicationId2(); + createReplicationBacklog(); + } + + /* CASE 1: BGSAVE is in progress, with disk target. */ + if (server.rdb_child_pid != -1 && + server.rdb_child_type == RDB_CHILD_TYPE_DISK) + { + /* Ok a background save is in progress. Let's check if it is a good + * one for replication, i.e. if there is another slave that is + * registering differences since the server forked to save. */ + client *slave; + listNode *ln; + listIter li; + + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + slave = ln->value; + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_END) break; + } + /* To attach this slave, we check that it has at least all the + * capabilities of the slave that triggered the current BGSAVE. */ + if (ln && ((c->slave_capa & slave->slave_capa) == slave->slave_capa)) { + /* Perfect, the server is already registering differences for + * another slave. Set the right state, and copy the buffer. */ + copyClientOutputBuffer(c,slave); + replicationSetupSlaveForFullResync(c,slave->psync_initial_offset); + serverLog(LL_NOTICE,"Waiting for end of BGSAVE for SYNC"); + } else { + /* No way, we need to wait for the next BGSAVE in order to + * register differences. */ + serverLog(LL_NOTICE,"Can't attach the slave to the current BGSAVE. Waiting for next BGSAVE for SYNC"); + } + + /* CASE 2: BGSAVE is in progress, with socket target. */ + } else if (server.rdb_child_pid != -1 && + server.rdb_child_type == RDB_CHILD_TYPE_SOCKET) + { + /* There is an RDB child process but it is writing directly to + * children sockets. We need to wait for the next BGSAVE + * in order to synchronize. */ + serverLog(LL_NOTICE,"Current BGSAVE has socket target. Waiting for next BGSAVE for SYNC"); + + /* CASE 3: There is no BGSAVE is progress. */ + } else { + if (server.repl_diskless_sync && (c->slave_capa & SLAVE_CAPA_EOF)) { + /* Diskless replication RDB child is created inside + * replicationCron() since we want to delay its start a + * few seconds to wait for more slaves to arrive. */ + if (server.repl_diskless_sync_delay) + serverLog(LL_NOTICE,"Delay next BGSAVE for diskless SYNC"); + } else { + /* Target is disk (or the slave is not capable of supporting + * diskless replication) and we don't have a BGSAVE in progress, + * let's start one. */ + if (server.aof_child_pid == -1) { + startBgsaveForReplication(c->slave_capa); + } else { + serverLog(LL_NOTICE, + "No BGSAVE in progress, but an AOF rewrite is active. " + "BGSAVE for replication delayed"); + } + } + } + return; +} + +/* REPLCONF <option> <value> <option> <value> ... + * This command is used by a slave in order to configure the replication + * process before starting it with the SYNC command. + * + * Currently the only use of this command is to communicate to the master + * what is the listening port of the Slave redis instance, so that the + * master can accurately list slaves and their listening ports in + * the INFO output. + * + * In the future the same command can be used in order to configure + * the replication to initiate an incremental replication instead of a + * full resync. */ +void replconfCommand(client *c) { + int j; + + if ((c->argc % 2) == 0) { + /* Number of arguments must be odd to make sure that every + * option has a corresponding value. */ + addReply(c,shared.syntaxerr); + return; + } + + /* Process every option-value pair. */ + for (j = 1; j < c->argc; j+=2) { + if (!strcasecmp(c->argv[j]->ptr,"listening-port")) { + long port; + + if ((getLongFromObjectOrReply(c,c->argv[j+1], + &port,NULL) != C_OK)) + return; + c->slave_listening_port = port; + } else if (!strcasecmp(c->argv[j]->ptr,"ip-address")) { + sds ip = c->argv[j+1]->ptr; + if (sdslen(ip) < sizeof(c->slave_ip)) { + memcpy(c->slave_ip,ip,sdslen(ip)+1); + } else { + addReplyErrorFormat(c,"REPLCONF ip-address provided by " + "slave instance is too long: %zd bytes", sdslen(ip)); + return; + } + } else if (!strcasecmp(c->argv[j]->ptr,"capa")) { + /* Ignore capabilities not understood by this master. */ + if (!strcasecmp(c->argv[j+1]->ptr,"eof")) + c->slave_capa |= SLAVE_CAPA_EOF; + else if (!strcasecmp(c->argv[j+1]->ptr,"psync2")) + c->slave_capa |= SLAVE_CAPA_PSYNC2; + } else if (!strcasecmp(c->argv[j]->ptr,"ack")) { + /* REPLCONF ACK is used by slave to inform the master the amount + * of replication stream that it processed so far. It is an + * internal only command that normal clients should never use. */ + long long offset; + + if (!(c->flags & CLIENT_SLAVE)) return; + if ((getLongLongFromObject(c->argv[j+1], &offset) != C_OK)) + return; + if (offset > c->repl_ack_off) + c->repl_ack_off = offset; + c->repl_ack_time = server.unixtime; + /* If this was a diskless replication, we need to really put + * the slave online when the first ACK is received (which + * confirms slave is online and ready to get more data). */ + if (c->repl_put_online_on_ack && c->replstate == SLAVE_STATE_ONLINE) + putSlaveOnline(c); + /* Note: this command does not reply anything! */ + return; + } else if (!strcasecmp(c->argv[j]->ptr,"getack")) { + /* REPLCONF GETACK is used in order to request an ACK ASAP + * to the slave. */ + if (server.masterhost && server.master) replicationSendAck(); + return; + } else { + addReplyErrorFormat(c,"Unrecognized REPLCONF option: %s", + (char*)c->argv[j]->ptr); + return; + } + } + addReply(c,shared.ok); +} + +/* This function puts a slave in the online state, and should be called just + * after a slave received the RDB file for the initial synchronization, and + * we are finally ready to send the incremental stream of commands. + * + * It does a few things: + * + * 1) Put the slave in ONLINE state (useless when the function is called + * because state is already ONLINE but repl_put_online_on_ack is true). + * 2) Make sure the writable event is re-installed, since calling the SYNC + * command disables it, so that we can accumulate output buffer without + * sending it to the slave. + * 3) Update the count of good slaves. */ +void putSlaveOnline(client *slave) { + slave->replstate = SLAVE_STATE_ONLINE; + slave->repl_put_online_on_ack = 0; + slave->repl_ack_time = server.unixtime; /* Prevent false timeout. */ + if (aeCreateFileEvent(server.el, slave->fd, AE_WRITABLE, + sendReplyToClient, slave) == AE_ERR) { + serverLog(LL_WARNING,"Unable to register writable event for slave bulk transfer: %s", strerror(errno)); + freeClient(slave); + return; + } + refreshGoodSlavesCount(); + serverLog(LL_NOTICE,"Synchronization with slave %s succeeded", + replicationGetSlaveName(slave)); +} + +void sendBulkToSlave(aeEventLoop *el, int fd, void *privdata, int mask) { + client *slave = privdata; + UNUSED(el); + UNUSED(mask); + char buf[PROTO_IOBUF_LEN]; + ssize_t nwritten, buflen; + + /* Before sending the RDB file, we send the preamble as configured by the + * replication process. Currently the preamble is just the bulk count of + * the file in the form "$<length>\r\n". */ + if (slave->replpreamble) { + nwritten = write(fd,slave->replpreamble,sdslen(slave->replpreamble)); + if (nwritten == -1) { + serverLog(LL_VERBOSE,"Write error sending RDB preamble to slave: %s", + strerror(errno)); + freeClient(slave); + return; + } + server.stat_net_output_bytes += nwritten; + sdsrange(slave->replpreamble,nwritten,-1); + if (sdslen(slave->replpreamble) == 0) { + sdsfree(slave->replpreamble); + slave->replpreamble = NULL; + /* fall through sending data. */ + } else { + return; + } + } + + /* If the preamble was already transfered, send the RDB bulk data. */ + lseek(slave->repldbfd,slave->repldboff,SEEK_SET); + buflen = read(slave->repldbfd,buf,PROTO_IOBUF_LEN); + if (buflen <= 0) { + serverLog(LL_WARNING,"Read error sending DB to slave: %s", + (buflen == 0) ? "premature EOF" : strerror(errno)); + freeClient(slave); + return; + } + if ((nwritten = write(fd,buf,buflen)) == -1) { + if (errno != EAGAIN) { + serverLog(LL_WARNING,"Write error sending DB to slave: %s", + strerror(errno)); + freeClient(slave); + } + return; + } + slave->repldboff += nwritten; + server.stat_net_output_bytes += nwritten; + if (slave->repldboff == slave->repldbsize) { + close(slave->repldbfd); + slave->repldbfd = -1; + aeDeleteFileEvent(server.el,slave->fd,AE_WRITABLE); + putSlaveOnline(slave); + } +} + +/* This function is called at the end of every background saving, + * or when the replication RDB transfer strategy is modified from + * disk to socket or the other way around. + * + * The goal of this function is to handle slaves waiting for a successful + * background saving in order to perform non-blocking synchronization, and + * to schedule a new BGSAVE if there are slaves that attached while a + * BGSAVE was in progress, but it was not a good one for replication (no + * other slave was accumulating differences). + * + * The argument bgsaveerr is C_OK if the background saving succeeded + * otherwise C_ERR is passed to the function. + * The 'type' argument is the type of the child that terminated + * (if it had a disk or socket target). */ +void updateSlavesWaitingBgsave(int bgsaveerr, int type) { + listNode *ln; + int startbgsave = 0; + int mincapa = -1; + listIter li; + + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) { + startbgsave = 1; + mincapa = (mincapa == -1) ? slave->slave_capa : + (mincapa & slave->slave_capa); + } else if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_END) { + struct redis_stat buf; + + /* If this was an RDB on disk save, we have to prepare to send + * the RDB from disk to the slave socket. Otherwise if this was + * already an RDB -> Slaves socket transfer, used in the case of + * diskless replication, our work is trivial, we can just put + * the slave online. */ + if (type == RDB_CHILD_TYPE_SOCKET) { + serverLog(LL_NOTICE, + "Streamed RDB transfer with slave %s succeeded (socket). Waiting for REPLCONF ACK from slave to enable streaming", + replicationGetSlaveName(slave)); + /* Note: we wait for a REPLCONF ACK message from slave in + * order to really put it online (install the write handler + * so that the accumulated data can be transfered). However + * we change the replication state ASAP, since our slave + * is technically online now. */ + slave->replstate = SLAVE_STATE_ONLINE; + slave->repl_put_online_on_ack = 1; + slave->repl_ack_time = server.unixtime; /* Timeout otherwise. */ + } else { + if (bgsaveerr != C_OK) { + freeClient(slave); + serverLog(LL_WARNING,"SYNC failed. BGSAVE child returned an error"); + continue; + } + if ((slave->repldbfd = open(server.rdb_filename,O_RDONLY)) == -1 || + redis_fstat(slave->repldbfd,&buf) == -1) { + freeClient(slave); + serverLog(LL_WARNING,"SYNC failed. Can't open/stat DB after BGSAVE: %s", strerror(errno)); + continue; + } + slave->repldboff = 0; + slave->repldbsize = buf.st_size; + slave->replstate = SLAVE_STATE_SEND_BULK; + slave->replpreamble = sdscatprintf(sdsempty(),"$%lld\r\n", + (unsigned long long) slave->repldbsize); + + aeDeleteFileEvent(server.el,slave->fd,AE_WRITABLE); + if (aeCreateFileEvent(server.el, slave->fd, AE_WRITABLE, sendBulkToSlave, slave) == AE_ERR) { + freeClient(slave); + continue; + } + } + } + } + if (startbgsave) startBgsaveForReplication(mincapa); +} + +/* Change the current instance replication ID with a new, random one. + * This will prevent successful PSYNCs between this master and other + * slaves, so the command should be called when something happens that + * alters the current story of the dataset. */ +void changeReplicationId(void) { + getRandomHexChars(server.replid,CONFIG_RUN_ID_SIZE); + server.replid[CONFIG_RUN_ID_SIZE] = '\0'; +} + +/* Clear (invalidate) the secondary replication ID. This happens, for + * example, after a full resynchronization, when we start a new replication + * history. */ +void clearReplicationId2(void) { + memset(server.replid2,'0',sizeof(server.replid)); + server.replid2[CONFIG_RUN_ID_SIZE] = '\0'; + server.second_replid_offset = -1; +} + +/* Use the current replication ID / offset as secondary replication + * ID, and change the current one in order to start a new history. + * This should be used when an instance is switched from slave to master + * so that it can serve PSYNC requests performed using the master + * replication ID. */ +void shiftReplicationId(void) { + memcpy(server.replid2,server.replid,sizeof(server.replid)); + /* We set the second replid offset to the master offset + 1, since + * the slave will ask for the first byte it has not yet received, so + * we need to add one to the offset: for example if, as a slave, we are + * sure we have the same history as the master for 50 bytes, after we + * are turned into a master, we can accept a PSYNC request with offset + * 51, since the slave asking has the same history up to the 50th + * byte, and is asking for the new bytes starting at offset 51. */ + server.second_replid_offset = server.master_repl_offset+1; + changeReplicationId(); + serverLog(LL_WARNING,"Setting secondary replication ID to %s, valid up to offset: %lld. New replication ID is %s", server.replid2, server.second_replid_offset, server.replid); +} + +/* ----------------------------------- SLAVE -------------------------------- */ + +/* Returns 1 if the given replication state is a handshake state, + * 0 otherwise. */ +int slaveIsInHandshakeState(void) { + return server.repl_state >= REPL_STATE_RECEIVE_PONG && + server.repl_state <= REPL_STATE_RECEIVE_PSYNC; +} + +/* Avoid the master to detect the slave is timing out while loading the + * RDB file in initial synchronization. We send a single newline character + * that is valid protocol but is guaranteed to either be sent entierly or + * not, since the byte is indivisible. + * + * The function is called in two contexts: while we flush the current + * data with emptyDb(), and while we load the new data received as an + * RDB file from the master. */ +void replicationSendNewlineToMaster(void) { + static time_t newline_sent; + if (time(NULL) != newline_sent) { + newline_sent = time(NULL); + if (write(server.repl_transfer_s,"\n",1) == -1) { + /* Pinging back in this stage is best-effort. */ + } + } +} + +/* Callback used by emptyDb() while flushing away old data to load + * the new dataset received by the master. */ +void replicationEmptyDbCallback(void *privdata) { + UNUSED(privdata); + replicationSendNewlineToMaster(); +} + +/* Once we have a link with the master and the synchroniziation was + * performed, this function materializes the master client we store + * at server.master, starting from the specified file descriptor. */ +void replicationCreateMasterClient(int fd, int dbid) { + server.master = createClient(fd); + server.master->flags |= CLIENT_MASTER; + server.master->authenticated = 1; + server.master->reploff = server.master_initial_offset; + memcpy(server.master->replid, server.master_replid, + sizeof(server.master_replid)); + /* If master offset is set to -1, this master is old and is not + * PSYNC capable, so we flag it accordingly. */ + if (server.master->reploff == -1) + server.master->flags |= CLIENT_PRE_PSYNC; + if (dbid != -1) selectDb(server.master,dbid); +} + +void restartAOF() { + int retry = 10; + while (retry-- && startAppendOnly() == C_ERR) { + serverLog(LL_WARNING,"Failed enabling the AOF after successful master synchronization! Trying it again in one second."); + sleep(1); + } + if (!retry) { + serverLog(LL_WARNING,"FATAL: this slave instance finished the synchronization with its master, but the AOF can't be turned on. Exiting now."); + exit(1); + } +} + +/* Asynchronously read the SYNC payload we receive from a master */ +#define REPL_MAX_WRITTEN_BEFORE_FSYNC (1024*1024*8) /* 8 MB */ +void readSyncBulkPayload(aeEventLoop *el, int fd, void *privdata, int mask) { + char buf[4096]; + ssize_t nread, readlen; + off_t left; + UNUSED(el); + UNUSED(privdata); + UNUSED(mask); + + /* Static vars used to hold the EOF mark, and the last bytes received + * form the server: when they match, we reached the end of the transfer. */ + static char eofmark[CONFIG_RUN_ID_SIZE]; + static char lastbytes[CONFIG_RUN_ID_SIZE]; + static int usemark = 0; + + /* If repl_transfer_size == -1 we still have to read the bulk length + * from the master reply. */ + if (server.repl_transfer_size == -1) { + if (syncReadLine(fd,buf,1024,server.repl_syncio_timeout*1000) == -1) { + serverLog(LL_WARNING, + "I/O error reading bulk count from MASTER: %s", + strerror(errno)); + goto error; + } + + if (buf[0] == '-') { + serverLog(LL_WARNING, + "MASTER aborted replication with an error: %s", + buf+1); + goto error; + } else if (buf[0] == '\0') { + /* At this stage just a newline works as a PING in order to take + * the connection live. So we refresh our last interaction + * timestamp. */ + server.repl_transfer_lastio = server.unixtime; + return; + } else if (buf[0] != '$') { + serverLog(LL_WARNING,"Bad protocol from MASTER, the first byte is not '$' (we received '%s'), are you sure the host and port are right?", buf); + goto error; + } + + /* There are two possible forms for the bulk payload. One is the + * usual $<count> bulk format. The other is used for diskless transfers + * when the master does not know beforehand the size of the file to + * transfer. In the latter case, the following format is used: + * + * $EOF:<40 bytes delimiter> + * + * At the end of the file the announced delimiter is transmitted. The + * delimiter is long and random enough that the probability of a + * collision with the actual file content can be ignored. */ + if (strncmp(buf+1,"EOF:",4) == 0 && strlen(buf+5) >= CONFIG_RUN_ID_SIZE) { + usemark = 1; + memcpy(eofmark,buf+5,CONFIG_RUN_ID_SIZE); + memset(lastbytes,0,CONFIG_RUN_ID_SIZE); + /* Set any repl_transfer_size to avoid entering this code path + * at the next call. */ + server.repl_transfer_size = 0; + serverLog(LL_NOTICE, + "MASTER <-> SLAVE sync: receiving streamed RDB from master"); + } else { + usemark = 0; + server.repl_transfer_size = strtol(buf+1,NULL,10); + serverLog(LL_NOTICE, + "MASTER <-> SLAVE sync: receiving %lld bytes from master", + (long long) server.repl_transfer_size); + } + return; + } + + /* Read bulk data */ + if (usemark) { + readlen = sizeof(buf); + } else { + left = server.repl_transfer_size - server.repl_transfer_read; + readlen = (left < (signed)sizeof(buf)) ? left : (signed)sizeof(buf); + } + + nread = read(fd,buf,readlen); + if (nread <= 0) { + serverLog(LL_WARNING,"I/O error trying to sync with MASTER: %s", + (nread == -1) ? strerror(errno) : "connection lost"); + cancelReplicationHandshake(); + return; + } + server.stat_net_input_bytes += nread; + + /* When a mark is used, we want to detect EOF asap in order to avoid + * writing the EOF mark into the file... */ + int eof_reached = 0; + + if (usemark) { + /* Update the last bytes array, and check if it matches our delimiter.*/ + if (nread >= CONFIG_RUN_ID_SIZE) { + memcpy(lastbytes,buf+nread-CONFIG_RUN_ID_SIZE,CONFIG_RUN_ID_SIZE); + } else { + int rem = CONFIG_RUN_ID_SIZE-nread; + memmove(lastbytes,lastbytes+nread,rem); + memcpy(lastbytes+rem,buf,nread); + } + if (memcmp(lastbytes,eofmark,CONFIG_RUN_ID_SIZE) == 0) eof_reached = 1; + } + + server.repl_transfer_lastio = server.unixtime; + if (write(server.repl_transfer_fd,buf,nread) != nread) { + serverLog(LL_WARNING,"Write error or short write writing to the DB dump file needed for MASTER <-> SLAVE synchronization: %s", strerror(errno)); + goto error; + } + server.repl_transfer_read += nread; + + /* Delete the last 40 bytes from the file if we reached EOF. */ + if (usemark && eof_reached) { + if (ftruncate(server.repl_transfer_fd, + server.repl_transfer_read - CONFIG_RUN_ID_SIZE) == -1) + { + serverLog(LL_WARNING,"Error truncating the RDB file received from the master for SYNC: %s", strerror(errno)); + goto error; + } + } + + /* Sync data on disk from time to time, otherwise at the end of the transfer + * we may suffer a big delay as the memory buffers are copied into the + * actual disk. */ + if (server.repl_transfer_read >= + server.repl_transfer_last_fsync_off + REPL_MAX_WRITTEN_BEFORE_FSYNC) + { + off_t sync_size = server.repl_transfer_read - + server.repl_transfer_last_fsync_off; + rdb_fsync_range(server.repl_transfer_fd, + server.repl_transfer_last_fsync_off, sync_size); + server.repl_transfer_last_fsync_off += sync_size; + } + + /* Check if the transfer is now complete */ + if (!usemark) { + if (server.repl_transfer_read == server.repl_transfer_size) + eof_reached = 1; + } + + if (eof_reached) { + int aof_is_enabled = server.aof_state != AOF_OFF; + + if (rename(server.repl_transfer_tmpfile,server.rdb_filename) == -1) { + serverLog(LL_WARNING,"Failed trying to rename the temp DB into dump.rdb in MASTER <-> SLAVE synchronization: %s", strerror(errno)); + cancelReplicationHandshake(); + return; + } + serverLog(LL_NOTICE, "MASTER <-> SLAVE sync: Flushing old data"); + /* We need to stop any AOFRW fork before flusing and parsing + * RDB, otherwise we'll create a copy-on-write disaster. */ + if(aof_is_enabled) stopAppendOnly(); + signalFlushedDb(-1); + emptyDb( + -1, + server.repl_slave_lazy_flush ? EMPTYDB_ASYNC : EMPTYDB_NO_FLAGS, + replicationEmptyDbCallback); + /* Before loading the DB into memory we need to delete the readable + * handler, otherwise it will get called recursively since + * rdbLoad() will call the event loop to process events from time to + * time for non blocking loading. */ + aeDeleteFileEvent(server.el,server.repl_transfer_s,AE_READABLE); + serverLog(LL_NOTICE, "MASTER <-> SLAVE sync: Loading DB in memory"); + rdbSaveInfo rsi = RDB_SAVE_INFO_INIT; + if (rdbLoad(server.rdb_filename,&rsi) != C_OK) { + serverLog(LL_WARNING,"Failed trying to load the MASTER synchronization DB from disk"); + cancelReplicationHandshake(); + /* Re-enable the AOF if we disabled it earlier, in order to restore + * the original configuration. */ + if (aof_is_enabled) restartAOF(); + return; + } + /* Final setup of the connected slave <- master link */ + zfree(server.repl_transfer_tmpfile); + close(server.repl_transfer_fd); + replicationCreateMasterClient(server.repl_transfer_s,rsi.repl_stream_db); + server.repl_state = REPL_STATE_CONNECTED; + /* After a full resynchroniziation we use the replication ID and + * offset of the master. The secondary ID / offset are cleared since + * we are starting a new history. */ + memcpy(server.replid,server.master->replid,sizeof(server.replid)); + server.master_repl_offset = server.master->reploff; + clearReplicationId2(); + /* Let's create the replication backlog if needed. Slaves need to + * accumulate the backlog regardless of the fact they have sub-slaves + * or not, in order to behave correctly if they are promoted to + * masters after a failover. */ + if (server.repl_backlog == NULL) createReplicationBacklog(); + + serverLog(LL_NOTICE, "MASTER <-> SLAVE sync: Finished with success"); + /* Restart the AOF subsystem now that we finished the sync. This + * will trigger an AOF rewrite, and when done will start appending + * to the new file. */ + if (aof_is_enabled) restartAOF(); + } + return; + +error: + cancelReplicationHandshake(); + return; +} + +/* Send a synchronous command to the master. Used to send AUTH and + * REPLCONF commands before starting the replication with SYNC. + * + * The command returns an sds string representing the result of the + * operation. On error the first byte is a "-". + */ +#define SYNC_CMD_READ (1<<0) +#define SYNC_CMD_WRITE (1<<1) +#define SYNC_CMD_FULL (SYNC_CMD_READ|SYNC_CMD_WRITE) +char *sendSynchronousCommand(int flags, int fd, ...) { + + /* Create the command to send to the master, we use simple inline + * protocol for simplicity as currently we only send simple strings. */ + if (flags & SYNC_CMD_WRITE) { + char *arg; + va_list ap; + sds cmd = sdsempty(); + va_start(ap,fd); + + while(1) { + arg = va_arg(ap, char*); + if (arg == NULL) break; + + if (sdslen(cmd) != 0) cmd = sdscatlen(cmd," ",1); + cmd = sdscat(cmd,arg); + } + cmd = sdscatlen(cmd,"\r\n",2); + + /* Transfer command to the server. */ + if (syncWrite(fd,cmd,sdslen(cmd),server.repl_syncio_timeout*1000) + == -1) + { + sdsfree(cmd); + return sdscatprintf(sdsempty(),"-Writing to master: %s", + strerror(errno)); + } + sdsfree(cmd); + va_end(ap); + } + + /* Read the reply from the server. */ + if (flags & SYNC_CMD_READ) { + char buf[256]; + + if (syncReadLine(fd,buf,sizeof(buf),server.repl_syncio_timeout*1000) + == -1) + { + return sdscatprintf(sdsempty(),"-Reading from master: %s", + strerror(errno)); + } + server.repl_transfer_lastio = server.unixtime; + return sdsnew(buf); + } + return NULL; +} + +/* Try a partial resynchronization with the master if we are about to reconnect. + * If there is no cached master structure, at least try to issue a + * "PSYNC ? -1" command in order to trigger a full resync using the PSYNC + * command in order to obtain the master run id and the master replication + * global offset. + * + * This function is designed to be called from syncWithMaster(), so the + * following assumptions are made: + * + * 1) We pass the function an already connected socket "fd". + * 2) This function does not close the file descriptor "fd". However in case + * of successful partial resynchronization, the function will reuse + * 'fd' as file descriptor of the server.master client structure. + * + * The function is split in two halves: if read_reply is 0, the function + * writes the PSYNC command on the socket, and a new function call is + * needed, with read_reply set to 1, in order to read the reply of the + * command. This is useful in order to support non blocking operations, so + * that we write, return into the event loop, and read when there are data. + * + * When read_reply is 0 the function returns PSYNC_WRITE_ERR if there + * was a write error, or PSYNC_WAIT_REPLY to signal we need another call + * with read_reply set to 1. However even when read_reply is set to 1 + * the function may return PSYNC_WAIT_REPLY again to signal there were + * insufficient data to read to complete its work. We should re-enter + * into the event loop and wait in such a case. + * + * The function returns: + * + * PSYNC_CONTINUE: If the PSYNC command succeded and we can continue. + * PSYNC_FULLRESYNC: If PSYNC is supported but a full resync is needed. + * In this case the master run_id and global replication + * offset is saved. + * PSYNC_NOT_SUPPORTED: If the server does not understand PSYNC at all and + * the caller should fall back to SYNC. + * PSYNC_WRITE_ERROR: There was an error writing the command to the socket. + * PSYNC_WAIT_REPLY: Call again the function with read_reply set to 1. + * PSYNC_TRY_LATER: Master is currently in a transient error condition. + * + * Notable side effects: + * + * 1) As a side effect of the function call the function removes the readable + * event handler from "fd", unless the return value is PSYNC_WAIT_REPLY. + * 2) server.master_initial_offset is set to the right value according + * to the master reply. This will be used to populate the 'server.master' + * structure replication offset. + */ + +#define PSYNC_WRITE_ERROR 0 +#define PSYNC_WAIT_REPLY 1 +#define PSYNC_CONTINUE 2 +#define PSYNC_FULLRESYNC 3 +#define PSYNC_NOT_SUPPORTED 4 +#define PSYNC_TRY_LATER 5 +int slaveTryPartialResynchronization(int fd, int read_reply) { + char *psync_replid; + char psync_offset[32]; + sds reply; + + /* Writing half */ + if (!read_reply) { + /* Initially set master_initial_offset to -1 to mark the current + * master run_id and offset as not valid. Later if we'll be able to do + * a FULL resync using the PSYNC command we'll set the offset at the + * right value, so that this information will be propagated to the + * client structure representing the master into server.master. */ + server.master_initial_offset = -1; + + if (server.cached_master) { + psync_replid = server.cached_master->replid; + snprintf(psync_offset,sizeof(psync_offset),"%lld", server.cached_master->reploff+1); + serverLog(LL_NOTICE,"Trying a partial resynchronization (request %s:%s).", psync_replid, psync_offset); + } else { + serverLog(LL_NOTICE,"Partial resynchronization not possible (no cached master)"); + psync_replid = "?"; + memcpy(psync_offset,"-1",3); + } + + /* Issue the PSYNC command */ + reply = sendSynchronousCommand(SYNC_CMD_WRITE,fd,"PSYNC",psync_replid,psync_offset,NULL); + if (reply != NULL) { + serverLog(LL_WARNING,"Unable to send PSYNC to master: %s",reply); + sdsfree(reply); + aeDeleteFileEvent(server.el,fd,AE_READABLE); + return PSYNC_WRITE_ERROR; + } + return PSYNC_WAIT_REPLY; + } + + /* Reading half */ + reply = sendSynchronousCommand(SYNC_CMD_READ,fd,NULL); + if (sdslen(reply) == 0) { + /* The master may send empty newlines after it receives PSYNC + * and before to reply, just to keep the connection alive. */ + sdsfree(reply); + return PSYNC_WAIT_REPLY; + } + + aeDeleteFileEvent(server.el,fd,AE_READABLE); + + if (!strncmp(reply,"+FULLRESYNC",11)) { + char *replid = NULL, *offset = NULL; + + /* FULL RESYNC, parse the reply in order to extract the run id + * and the replication offset. */ + replid = strchr(reply,' '); + if (replid) { + replid++; + offset = strchr(replid,' '); + if (offset) offset++; + } + if (!replid || !offset || (offset-replid-1) != CONFIG_RUN_ID_SIZE) { + serverLog(LL_WARNING, + "Master replied with wrong +FULLRESYNC syntax."); + /* This is an unexpected condition, actually the +FULLRESYNC + * reply means that the master supports PSYNC, but the reply + * format seems wrong. To stay safe we blank the master + * replid to make sure next PSYNCs will fail. */ + memset(server.master_replid,0,CONFIG_RUN_ID_SIZE+1); + } else { + memcpy(server.master_replid, replid, offset-replid-1); + server.master_replid[CONFIG_RUN_ID_SIZE] = '\0'; + server.master_initial_offset = strtoll(offset,NULL,10); + serverLog(LL_NOTICE,"Full resync from master: %s:%lld", + server.master_replid, + server.master_initial_offset); + } + /* We are going to full resync, discard the cached master structure. */ + replicationDiscardCachedMaster(); + sdsfree(reply); + return PSYNC_FULLRESYNC; + } + + if (!strncmp(reply,"+CONTINUE",9)) { + /* Partial resync was accepted. */ + serverLog(LL_NOTICE, + "Successful partial resynchronization with master."); + + /* Check the new replication ID advertised by the master. If it + * changed, we need to set the new ID as primary ID, and set or + * secondary ID as the old master ID up to the current offset, so + * that our sub-slaves will be able to PSYNC with us after a + * disconnection. */ + char *start = reply+10; + char *end = reply+9; + while(end[0] != '\r' && end[0] != '\n' && end[0] != '\0') end++; + if (end-start == CONFIG_RUN_ID_SIZE) { + char new[CONFIG_RUN_ID_SIZE+1]; + memcpy(new,start,CONFIG_RUN_ID_SIZE); + new[CONFIG_RUN_ID_SIZE] = '\0'; + + if (strcmp(new,server.cached_master->replid)) { + /* Master ID changed. */ + serverLog(LL_WARNING,"Master replication ID changed to %s",new); + + /* Set the old ID as our ID2, up to the current offset+1. */ + memcpy(server.replid2,server.cached_master->replid, + sizeof(server.replid2)); + server.second_replid_offset = server.master_repl_offset+1; + + /* Update the cached master ID and our own primary ID to the + * new one. */ + memcpy(server.replid,new,sizeof(server.replid)); + memcpy(server.cached_master->replid,new,sizeof(server.replid)); + + /* Disconnect all the sub-slaves: they need to be notified. */ + disconnectSlaves(); + } + } + + /* Setup the replication to continue. */ + sdsfree(reply); + replicationResurrectCachedMaster(fd); + return PSYNC_CONTINUE; + } + + /* If we reach this point we received either an error (since the master does + * not understand PSYNC or because it is in a special state and cannot + * serve our request), or an unexpected reply from the master. + * + * Return PSYNC_NOT_SUPPORTED on errors we don't understand, otherwise + * return PSYNC_TRY_LATER if we believe this is a transient error. */ + + if (!strncmp(reply,"-NOMASTERLINK",13) || + !strncmp(reply,"-LOADING",8)) + { + serverLog(LL_NOTICE, + "Master is currently unable to PSYNC " + "but should be in the future: %s", reply); + sdsfree(reply); + return PSYNC_TRY_LATER; + } + + if (strncmp(reply,"-ERR",4)) { + /* If it's not an error, log the unexpected event. */ + serverLog(LL_WARNING, + "Unexpected reply to PSYNC from master: %s", reply); + } else { + serverLog(LL_NOTICE, + "Master does not support PSYNC or is in " + "error state (reply: %s)", reply); + } + sdsfree(reply); + replicationDiscardCachedMaster(); + return PSYNC_NOT_SUPPORTED; +} + +/* This handler fires when the non blocking connect was able to + * establish a connection with the master. */ +void syncWithMaster(aeEventLoop *el, int fd, void *privdata, int mask) { + char tmpfile[256], *err = NULL; + int dfd = -1, maxtries = 5; + int sockerr = 0, psync_result; + socklen_t errlen = sizeof(sockerr); + UNUSED(el); + UNUSED(privdata); + UNUSED(mask); + + /* If this event fired after the user turned the instance into a master + * with SLAVEOF NO ONE we must just return ASAP. */ + if (server.repl_state == REPL_STATE_NONE) { + close(fd); + return; + } + + /* Check for errors in the socket: after a non blocking connect() we + * may find that the socket is in error state. */ + if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &sockerr, &errlen) == -1) + sockerr = errno; + if (sockerr) { + serverLog(LL_WARNING,"Error condition on socket for SYNC: %s", + strerror(sockerr)); + goto error; + } + + /* Send a PING to check the master is able to reply without errors. */ + if (server.repl_state == REPL_STATE_CONNECTING) { + serverLog(LL_NOTICE,"Non blocking connect for SYNC fired the event."); + /* Delete the writable event so that the readable event remains + * registered and we can wait for the PONG reply. */ + aeDeleteFileEvent(server.el,fd,AE_WRITABLE); + server.repl_state = REPL_STATE_RECEIVE_PONG; + /* Send the PING, don't check for errors at all, we have the timeout + * that will take care about this. */ + err = sendSynchronousCommand(SYNC_CMD_WRITE,fd,"PING",NULL); + if (err) goto write_error; + return; + } + + /* Receive the PONG command. */ + if (server.repl_state == REPL_STATE_RECEIVE_PONG) { + err = sendSynchronousCommand(SYNC_CMD_READ,fd,NULL); + + /* We accept only two replies as valid, a positive +PONG reply + * (we just check for "+") or an authentication error. + * Note that older versions of Redis replied with "operation not + * permitted" instead of using a proper error code, so we test + * both. */ + if (err[0] != '+' && + strncmp(err,"-NOAUTH",7) != 0 && + strncmp(err,"-ERR operation not permitted",28) != 0) + { + serverLog(LL_WARNING,"Error reply to PING from master: '%s'",err); + sdsfree(err); + goto error; + } else { + serverLog(LL_NOTICE, + "Master replied to PING, replication can continue..."); + } + sdsfree(err); + server.repl_state = REPL_STATE_SEND_AUTH; + } + + /* AUTH with the master if required. */ + if (server.repl_state == REPL_STATE_SEND_AUTH) { + if (server.masterauth) { + err = sendSynchronousCommand(SYNC_CMD_WRITE,fd,"AUTH",server.masterauth,NULL); + if (err) goto write_error; + server.repl_state = REPL_STATE_RECEIVE_AUTH; + return; + } else { + server.repl_state = REPL_STATE_SEND_PORT; + } + } + + /* Receive AUTH reply. */ + if (server.repl_state == REPL_STATE_RECEIVE_AUTH) { + err = sendSynchronousCommand(SYNC_CMD_READ,fd,NULL); + if (err[0] == '-') { + serverLog(LL_WARNING,"Unable to AUTH to MASTER: %s",err); + sdsfree(err); + goto error; + } + sdsfree(err); + server.repl_state = REPL_STATE_SEND_PORT; + } + + /* Set the slave port, so that Master's INFO command can list the + * slave listening port correctly. */ + if (server.repl_state == REPL_STATE_SEND_PORT) { + sds port = sdsfromlonglong(server.slave_announce_port ? + server.slave_announce_port : server.port); + err = sendSynchronousCommand(SYNC_CMD_WRITE,fd,"REPLCONF", + "listening-port",port, NULL); + sdsfree(port); + if (err) goto write_error; + sdsfree(err); + server.repl_state = REPL_STATE_RECEIVE_PORT; + return; + } + + /* Receive REPLCONF listening-port reply. */ + if (server.repl_state == REPL_STATE_RECEIVE_PORT) { + err = sendSynchronousCommand(SYNC_CMD_READ,fd,NULL); + /* Ignore the error if any, not all the Redis versions support + * REPLCONF listening-port. */ + if (err[0] == '-') { + serverLog(LL_NOTICE,"(Non critical) Master does not understand " + "REPLCONF listening-port: %s", err); + } + sdsfree(err); + server.repl_state = REPL_STATE_SEND_IP; + } + + /* Skip REPLCONF ip-address if there is no slave-announce-ip option set. */ + if (server.repl_state == REPL_STATE_SEND_IP && + server.slave_announce_ip == NULL) + { + server.repl_state = REPL_STATE_SEND_CAPA; + } + + /* Set the slave ip, so that Master's INFO command can list the + * slave IP address port correctly in case of port forwarding or NAT. */ + if (server.repl_state == REPL_STATE_SEND_IP) { + err = sendSynchronousCommand(SYNC_CMD_WRITE,fd,"REPLCONF", + "ip-address",server.slave_announce_ip, NULL); + if (err) goto write_error; + sdsfree(err); + server.repl_state = REPL_STATE_RECEIVE_IP; + return; + } + + /* Receive REPLCONF ip-address reply. */ + if (server.repl_state == REPL_STATE_RECEIVE_IP) { + err = sendSynchronousCommand(SYNC_CMD_READ,fd,NULL); + /* Ignore the error if any, not all the Redis versions support + * REPLCONF listening-port. */ + if (err[0] == '-') { + serverLog(LL_NOTICE,"(Non critical) Master does not understand " + "REPLCONF ip-address: %s", err); + } + sdsfree(err); + server.repl_state = REPL_STATE_SEND_CAPA; + } + + /* Inform the master of our (slave) capabilities. + * + * EOF: supports EOF-style RDB transfer for diskless replication. + * PSYNC2: supports PSYNC v2, so understands +CONTINUE <new repl ID>. + * + * The master will ignore capabilities it does not understand. */ + if (server.repl_state == REPL_STATE_SEND_CAPA) { + err = sendSynchronousCommand(SYNC_CMD_WRITE,fd,"REPLCONF", + "capa","eof","capa","psync2",NULL); + if (err) goto write_error; + sdsfree(err); + server.repl_state = REPL_STATE_RECEIVE_CAPA; + return; + } + + /* Receive CAPA reply. */ + if (server.repl_state == REPL_STATE_RECEIVE_CAPA) { + err = sendSynchronousCommand(SYNC_CMD_READ,fd,NULL); + /* Ignore the error if any, not all the Redis versions support + * REPLCONF capa. */ + if (err[0] == '-') { + serverLog(LL_NOTICE,"(Non critical) Master does not understand " + "REPLCONF capa: %s", err); + } + sdsfree(err); + server.repl_state = REPL_STATE_SEND_PSYNC; + } + + /* Try a partial resynchonization. If we don't have a cached master + * slaveTryPartialResynchronization() will at least try to use PSYNC + * to start a full resynchronization so that we get the master run id + * and the global offset, to try a partial resync at the next + * reconnection attempt. */ + if (server.repl_state == REPL_STATE_SEND_PSYNC) { + if (slaveTryPartialResynchronization(fd,0) == PSYNC_WRITE_ERROR) { + err = sdsnew("Write error sending the PSYNC command."); + goto write_error; + } + server.repl_state = REPL_STATE_RECEIVE_PSYNC; + return; + } + + /* If reached this point, we should be in REPL_STATE_RECEIVE_PSYNC. */ + if (server.repl_state != REPL_STATE_RECEIVE_PSYNC) { + serverLog(LL_WARNING,"syncWithMaster(): state machine error, " + "state should be RECEIVE_PSYNC but is %d", + server.repl_state); + goto error; + } + + psync_result = slaveTryPartialResynchronization(fd,1); + if (psync_result == PSYNC_WAIT_REPLY) return; /* Try again later... */ + + /* If the master is in an transient error, we should try to PSYNC + * from scratch later, so go to the error path. This happens when + * the server is loading the dataset or is not connected with its + * master and so forth. */ + if (psync_result == PSYNC_TRY_LATER) goto error; + + /* Note: if PSYNC does not return WAIT_REPLY, it will take care of + * uninstalling the read handler from the file descriptor. */ + + if (psync_result == PSYNC_CONTINUE) { + serverLog(LL_NOTICE, "MASTER <-> SLAVE sync: Master accepted a Partial Resynchronization."); + return; + } + + /* PSYNC failed or is not supported: we want our slaves to resync with us + * as well, if we have any sub-slaves. The master may transfer us an + * entirely different data set and we have no way to incrementally feed + * our slaves after that. */ + disconnectSlaves(); /* Force our slaves to resync with us as well. */ + freeReplicationBacklog(); /* Don't allow our chained slaves to PSYNC. */ + + /* Fall back to SYNC if needed. Otherwise psync_result == PSYNC_FULLRESYNC + * and the server.master_replid and master_initial_offset are + * already populated. */ + if (psync_result == PSYNC_NOT_SUPPORTED) { + serverLog(LL_NOTICE,"Retrying with SYNC..."); + if (syncWrite(fd,"SYNC\r\n",6,server.repl_syncio_timeout*1000) == -1) { + serverLog(LL_WARNING,"I/O error writing to MASTER: %s", + strerror(errno)); + goto error; + } + } + + /* Prepare a suitable temp file for bulk transfer */ + while(maxtries--) { + snprintf(tmpfile,256, + "temp-%d.%ld.rdb",(int)server.unixtime,(long int)getpid()); + dfd = open(tmpfile,O_CREAT|O_WRONLY|O_EXCL,0644); + if (dfd != -1) break; + sleep(1); + } + if (dfd == -1) { + serverLog(LL_WARNING,"Opening the temp file needed for MASTER <-> SLAVE synchronization: %s",strerror(errno)); + goto error; + } + + /* Setup the non blocking download of the bulk file. */ + if (aeCreateFileEvent(server.el,fd, AE_READABLE,readSyncBulkPayload,NULL) + == AE_ERR) + { + serverLog(LL_WARNING, + "Can't create readable event for SYNC: %s (fd=%d)", + strerror(errno),fd); + goto error; + } + + server.repl_state = REPL_STATE_TRANSFER; + server.repl_transfer_size = -1; + server.repl_transfer_read = 0; + server.repl_transfer_last_fsync_off = 0; + server.repl_transfer_fd = dfd; + server.repl_transfer_lastio = server.unixtime; + server.repl_transfer_tmpfile = zstrdup(tmpfile); + return; + +error: + aeDeleteFileEvent(server.el,fd,AE_READABLE|AE_WRITABLE); + if (dfd != -1) close(dfd); + close(fd); + server.repl_transfer_s = -1; + server.repl_state = REPL_STATE_CONNECT; + return; + +write_error: /* Handle sendSynchronousCommand(SYNC_CMD_WRITE) errors. */ + serverLog(LL_WARNING,"Sending command to master in replication handshake: %s", err); + sdsfree(err); + goto error; +} + +int connectWithMaster(void) { + int fd; + + fd = anetTcpNonBlockBestEffortBindConnect(NULL, + server.masterhost,server.masterport,NET_FIRST_BIND_ADDR); + if (fd == -1) { + serverLog(LL_WARNING,"Unable to connect to MASTER: %s", + strerror(errno)); + return C_ERR; + } + + if (aeCreateFileEvent(server.el,fd,AE_READABLE|AE_WRITABLE,syncWithMaster,NULL) == + AE_ERR) + { + close(fd); + serverLog(LL_WARNING,"Can't create readable event for SYNC"); + return C_ERR; + } + + server.repl_transfer_lastio = server.unixtime; + server.repl_transfer_s = fd; + server.repl_state = REPL_STATE_CONNECTING; + return C_OK; +} + +/* This function can be called when a non blocking connection is currently + * in progress to undo it. + * Never call this function directly, use cancelReplicationHandshake() instead. + */ +void undoConnectWithMaster(void) { + int fd = server.repl_transfer_s; + + aeDeleteFileEvent(server.el,fd,AE_READABLE|AE_WRITABLE); + close(fd); + server.repl_transfer_s = -1; +} + +/* Abort the async download of the bulk dataset while SYNC-ing with master. + * Never call this function directly, use cancelReplicationHandshake() instead. + */ +void replicationAbortSyncTransfer(void) { + serverAssert(server.repl_state == REPL_STATE_TRANSFER); + undoConnectWithMaster(); + close(server.repl_transfer_fd); + unlink(server.repl_transfer_tmpfile); + zfree(server.repl_transfer_tmpfile); +} + +/* This function aborts a non blocking replication attempt if there is one + * in progress, by canceling the non-blocking connect attempt or + * the initial bulk transfer. + * + * If there was a replication handshake in progress 1 is returned and + * the replication state (server.repl_state) set to REPL_STATE_CONNECT. + * + * Otherwise zero is returned and no operation is perforemd at all. */ +int cancelReplicationHandshake(void) { + if (server.repl_state == REPL_STATE_TRANSFER) { + replicationAbortSyncTransfer(); + server.repl_state = REPL_STATE_CONNECT; + } else if (server.repl_state == REPL_STATE_CONNECTING || + slaveIsInHandshakeState()) + { + undoConnectWithMaster(); + server.repl_state = REPL_STATE_CONNECT; + } else { + return 0; + } + return 1; +} + +/* Set replication to the specified master address and port. */ +void replicationSetMaster(char *ip, int port) { + int was_master = server.masterhost == NULL; + + sdsfree(server.masterhost); + server.masterhost = sdsnew(ip); + server.masterport = port; + if (server.master) { + freeClient(server.master); + } + disconnectAllBlockedClients(); /* Clients blocked in master, now slave. */ + + /* Force our slaves to resync with us as well. They may hopefully be able + * to partially resync with us, but we can notify the replid change. */ + disconnectSlaves(); + cancelReplicationHandshake(); + /* Before destroying our master state, create a cached master using + * our own parameters, to later PSYNC with the new master. */ + if (was_master) replicationCacheMasterUsingMyself(); + server.repl_state = REPL_STATE_CONNECT; + server.repl_down_since = 0; +} + +/* Cancel replication, setting the instance as a master itself. */ +void replicationUnsetMaster(void) { + if (server.masterhost == NULL) return; /* Nothing to do. */ + sdsfree(server.masterhost); + server.masterhost = NULL; + /* When a slave is turned into a master, the current replication ID + * (that was inherited from the master at synchronization time) is + * used as secondary ID up to the current offset, and a new replication + * ID is created to continue with a new replication history. */ + shiftReplicationId(); + if (server.master) freeClient(server.master); + replicationDiscardCachedMaster(); + cancelReplicationHandshake(); + /* Disconnecting all the slaves is required: we need to inform slaves + * of the replication ID change (see shiftReplicationId() call). However + * the slaves will be able to partially resync with us, so it will be + * a very fast reconnection. */ + disconnectSlaves(); + server.repl_state = REPL_STATE_NONE; + + /* We need to make sure the new master will start the replication stream + * with a SELECT statement. This is forced after a full resync, but + * with PSYNC version 2, there is no need for full resync after a + * master switch. */ + server.slaveseldb = -1; +} + +/* This function is called when the slave lose the connection with the + * master into an unexpected way. */ +void replicationHandleMasterDisconnection(void) { + server.master = NULL; + server.repl_state = REPL_STATE_CONNECT; + server.repl_down_since = server.unixtime; + /* We lost connection with our master, don't disconnect slaves yet, + * maybe we'll be able to PSYNC with our master later. We'll disconnect + * the slaves only if we'll have to do a full resync with our master. */ +} + +void slaveofCommand(client *c) { + /* SLAVEOF is not allowed in cluster mode as replication is automatically + * configured using the current address of the master node. */ + if (server.cluster_enabled) { + addReplyError(c,"SLAVEOF not allowed in cluster mode."); + return; + } + + /* The special host/port combination "NO" "ONE" turns the instance + * into a master. Otherwise the new master address is set. */ + if (!strcasecmp(c->argv[1]->ptr,"no") && + !strcasecmp(c->argv[2]->ptr,"one")) { + if (server.masterhost) { + replicationUnsetMaster(); + sds client = catClientInfoString(sdsempty(),c); + serverLog(LL_NOTICE,"MASTER MODE enabled (user request from '%s')", + client); + sdsfree(client); + } + } else { + long port; + + if ((getLongFromObjectOrReply(c, c->argv[2], &port, NULL) != C_OK)) + return; + + /* Check if we are already attached to the specified slave */ + if (server.masterhost && !strcasecmp(server.masterhost,c->argv[1]->ptr) + && server.masterport == port) { + serverLog(LL_NOTICE,"SLAVE OF would result into synchronization with the master we are already connected with. No operation performed."); + addReplySds(c,sdsnew("+OK Already connected to specified master\r\n")); + return; + } + /* There was no previous master or the user specified a different one, + * we can continue. */ + replicationSetMaster(c->argv[1]->ptr, port); + sds client = catClientInfoString(sdsempty(),c); + serverLog(LL_NOTICE,"SLAVE OF %s:%d enabled (user request from '%s')", + server.masterhost, server.masterport, client); + sdsfree(client); + } + addReply(c,shared.ok); +} + +/* ROLE command: provide information about the role of the instance + * (master or slave) and additional information related to replication + * in an easy to process format. */ +void roleCommand(client *c) { + if (server.masterhost == NULL) { + listIter li; + listNode *ln; + void *mbcount; + int slaves = 0; + + addReplyMultiBulkLen(c,3); + addReplyBulkCBuffer(c,"master",6); + addReplyLongLong(c,server.master_repl_offset); + mbcount = addDeferredMultiBulkLength(c); + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + char ip[NET_IP_STR_LEN], *slaveip = slave->slave_ip; + + if (slaveip[0] == '\0') { + if (anetPeerToString(slave->fd,ip,sizeof(ip),NULL) == -1) + continue; + slaveip = ip; + } + if (slave->replstate != SLAVE_STATE_ONLINE) continue; + addReplyMultiBulkLen(c,3); + addReplyBulkCString(c,slaveip); + addReplyBulkLongLong(c,slave->slave_listening_port); + addReplyBulkLongLong(c,slave->repl_ack_off); + slaves++; + } + setDeferredMultiBulkLength(c,mbcount,slaves); + } else { + char *slavestate = NULL; + + addReplyMultiBulkLen(c,5); + addReplyBulkCBuffer(c,"slave",5); + addReplyBulkCString(c,server.masterhost); + addReplyLongLong(c,server.masterport); + if (slaveIsInHandshakeState()) { + slavestate = "handshake"; + } else { + switch(server.repl_state) { + case REPL_STATE_NONE: slavestate = "none"; break; + case REPL_STATE_CONNECT: slavestate = "connect"; break; + case REPL_STATE_CONNECTING: slavestate = "connecting"; break; + case REPL_STATE_TRANSFER: slavestate = "sync"; break; + case REPL_STATE_CONNECTED: slavestate = "connected"; break; + default: slavestate = "unknown"; break; + } + } + addReplyBulkCString(c,slavestate); + addReplyLongLong(c,server.master ? server.master->reploff : -1); + } +} + +/* Send a REPLCONF ACK command to the master to inform it about the current + * processed offset. If we are not connected with a master, the command has + * no effects. */ +void replicationSendAck(void) { + client *c = server.master; + + if (c != NULL) { + c->flags |= CLIENT_MASTER_FORCE_REPLY; + addReplyMultiBulkLen(c,3); + addReplyBulkCString(c,"REPLCONF"); + addReplyBulkCString(c,"ACK"); + addReplyBulkLongLong(c,c->reploff); + c->flags &= ~CLIENT_MASTER_FORCE_REPLY; + } +} + +/* ---------------------- MASTER CACHING FOR PSYNC -------------------------- */ + +/* In order to implement partial synchronization we need to be able to cache + * our master's client structure after a transient disconnection. + * It is cached into server.cached_master and flushed away using the following + * functions. */ + +/* This function is called by freeClient() in order to cache the master + * client structure instead of destryoing it. freeClient() will return + * ASAP after this function returns, so every action needed to avoid problems + * with a client that is really "suspended" has to be done by this function. + * + * The other functions that will deal with the cached master are: + * + * replicationDiscardCachedMaster() that will make sure to kill the client + * as for some reason we don't want to use it in the future. + * + * replicationResurrectCachedMaster() that is used after a successful PSYNC + * handshake in order to reactivate the cached master. + */ +void replicationCacheMaster(client *c) { + serverAssert(server.master != NULL && server.cached_master == NULL); + serverLog(LL_NOTICE,"Caching the disconnected master state."); + + /* Unlink the client from the server structures. */ + unlinkClient(c); + + /* Save the master. Server.master will be set to null later by + * replicationHandleMasterDisconnection(). */ + server.cached_master = server.master; + + /* Invalidate the Peer ID cache. */ + if (c->peerid) { + sdsfree(c->peerid); + c->peerid = NULL; + } + + /* Caching the master happens instead of the actual freeClient() call, + * so make sure to adjust the replication state. This function will + * also set server.master to NULL. */ + replicationHandleMasterDisconnection(); +} + +/* This function is called when a master is turend into a slave, in order to + * create from scratch a cached master for the new client, that will allow + * to PSYNC with the slave that was promoted as the new master after a + * failover. + * + * Assuming this instance was previously the master instance of the new master, + * the new master will accept its replication ID, and potentiall also the + * current offset if no data was lost during the failover. So we use our + * current replication ID and offset in order to synthesize a cached master. */ +void replicationCacheMasterUsingMyself(void) { + /* The master client we create can be set to any DBID, because + * the new master will start its replication stream with SELECT. */ + server.master_initial_offset = server.master_repl_offset; + replicationCreateMasterClient(-1,-1); + + /* Use our own ID / offset. */ + memcpy(server.master->replid, server.replid, sizeof(server.replid)); + + /* Set as cached master. */ + unlinkClient(server.master); + server.cached_master = server.master; + server.master = NULL; + serverLog(LL_NOTICE,"Before turning into a slave, using my master parameters to synthesize a cached master: I may be able to synchronize with the new master with just a partial transfer."); +} + +/* Free a cached master, called when there are no longer the conditions for + * a partial resync on reconnection. */ +void replicationDiscardCachedMaster(void) { + if (server.cached_master == NULL) return; + + serverLog(LL_NOTICE,"Discarding previously cached master state."); + server.cached_master->flags &= ~CLIENT_MASTER; + freeClient(server.cached_master); + server.cached_master = NULL; +} + +/* Turn the cached master into the current master, using the file descriptor + * passed as argument as the socket for the new master. + * + * This function is called when successfully setup a partial resynchronization + * so the stream of data that we'll receive will start from were this + * master left. */ +void replicationResurrectCachedMaster(int newfd) { + server.master = server.cached_master; + server.cached_master = NULL; + server.master->fd = newfd; + server.master->flags &= ~(CLIENT_CLOSE_AFTER_REPLY|CLIENT_CLOSE_ASAP); + server.master->authenticated = 1; + server.master->lastinteraction = server.unixtime; + server.repl_state = REPL_STATE_CONNECTED; + + /* Re-add to the list of clients. */ + listAddNodeTail(server.clients,server.master); + if (aeCreateFileEvent(server.el, newfd, AE_READABLE, + readQueryFromClient, server.master)) { + serverLog(LL_WARNING,"Error resurrecting the cached master, impossible to add the readable handler: %s", strerror(errno)); + freeClientAsync(server.master); /* Close ASAP. */ + } + + /* We may also need to install the write handler as well if there is + * pending data in the write buffers. */ + if (clientHasPendingReplies(server.master)) { + if (aeCreateFileEvent(server.el, newfd, AE_WRITABLE, + sendReplyToClient, server.master)) { + serverLog(LL_WARNING,"Error resurrecting the cached master, impossible to add the writable handler: %s", strerror(errno)); + freeClientAsync(server.master); /* Close ASAP. */ + } + } +} + +/* ------------------------- MIN-SLAVES-TO-WRITE --------------------------- */ + +/* This function counts the number of slaves with lag <= min-slaves-max-lag. + * If the option is active, the server will prevent writes if there are not + * enough connected slaves with the specified lag (or less). */ +void refreshGoodSlavesCount(void) { + listIter li; + listNode *ln; + int good = 0; + + if (!server.repl_min_slaves_to_write || + !server.repl_min_slaves_max_lag) return; + + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + time_t lag = server.unixtime - slave->repl_ack_time; + + if (slave->replstate == SLAVE_STATE_ONLINE && + lag <= server.repl_min_slaves_max_lag) good++; + } + server.repl_good_slaves_count = good; +} + +/* ----------------------- REPLICATION SCRIPT CACHE -------------------------- + * The goal of this code is to keep track of scripts already sent to every + * connected slave, in order to be able to replicate EVALSHA as it is without + * translating it to EVAL every time it is possible. + * + * We use a capped collection implemented by a hash table for fast lookup + * of scripts we can send as EVALSHA, plus a linked list that is used for + * eviction of the oldest entry when the max number of items is reached. + * + * We don't care about taking a different cache for every different slave + * since to fill the cache again is not very costly, the goal of this code + * is to avoid that the same big script is trasmitted a big number of times + * per second wasting bandwidth and processor speed, but it is not a problem + * if we need to rebuild the cache from scratch from time to time, every used + * script will need to be transmitted a single time to reappear in the cache. + * + * This is how the system works: + * + * 1) Every time a new slave connects, we flush the whole script cache. + * 2) We only send as EVALSHA what was sent to the master as EVALSHA, without + * trying to convert EVAL into EVALSHA specifically for slaves. + * 3) Every time we trasmit a script as EVAL to the slaves, we also add the + * corresponding SHA1 of the script into the cache as we are sure every + * slave knows about the script starting from now. + * 4) On SCRIPT FLUSH command, we replicate the command to all the slaves + * and at the same time flush the script cache. + * 5) When the last slave disconnects, flush the cache. + * 6) We handle SCRIPT LOAD as well since that's how scripts are loaded + * in the master sometimes. + */ + +/* Initialize the script cache, only called at startup. */ +void replicationScriptCacheInit(void) { + server.repl_scriptcache_size = 10000; + server.repl_scriptcache_dict = dictCreate(&replScriptCacheDictType,NULL); + server.repl_scriptcache_fifo = listCreate(); +} + +/* Empty the script cache. Should be called every time we are no longer sure + * that every slave knows about all the scripts in our set, or when the + * current AOF "context" is no longer aware of the script. In general we + * should flush the cache: + * + * 1) Every time a new slave reconnects to this master and performs a + * full SYNC (PSYNC does not require flushing). + * 2) Every time an AOF rewrite is performed. + * 3) Every time we are left without slaves at all, and AOF is off, in order + * to reclaim otherwise unused memory. + */ +void replicationScriptCacheFlush(void) { + dictEmpty(server.repl_scriptcache_dict,NULL); + listRelease(server.repl_scriptcache_fifo); + server.repl_scriptcache_fifo = listCreate(); +} + +/* Add an entry into the script cache, if we reach max number of entries the + * oldest is removed from the list. */ +void replicationScriptCacheAdd(sds sha1) { + int retval; + sds key = sdsdup(sha1); + + /* Evict oldest. */ + if (listLength(server.repl_scriptcache_fifo) == server.repl_scriptcache_size) + { + listNode *ln = listLast(server.repl_scriptcache_fifo); + sds oldest = listNodeValue(ln); + + retval = dictDelete(server.repl_scriptcache_dict,oldest); + serverAssert(retval == DICT_OK); + listDelNode(server.repl_scriptcache_fifo,ln); + } + + /* Add current. */ + retval = dictAdd(server.repl_scriptcache_dict,key,NULL); + listAddNodeHead(server.repl_scriptcache_fifo,key); + serverAssert(retval == DICT_OK); +} + +/* Returns non-zero if the specified entry exists inside the cache, that is, + * if all the slaves are aware of this script SHA1. */ +int replicationScriptCacheExists(sds sha1) { + return dictFind(server.repl_scriptcache_dict,sha1) != NULL; +} + +/* ----------------------- SYNCHRONOUS REPLICATION -------------------------- + * Redis synchronous replication design can be summarized in points: + * + * - Redis masters have a global replication offset, used by PSYNC. + * - Master increment the offset every time new commands are sent to slaves. + * - Slaves ping back masters with the offset processed so far. + * + * So synchronous replication adds a new WAIT command in the form: + * + * WAIT <num_replicas> <milliseconds_timeout> + * + * That returns the number of replicas that processed the query when + * we finally have at least num_replicas, or when the timeout was + * reached. + * + * The command is implemented in this way: + * + * - Every time a client processes a command, we remember the replication + * offset after sending that command to the slaves. + * - When WAIT is called, we ask slaves to send an acknowledgement ASAP. + * The client is blocked at the same time (see blocked.c). + * - Once we receive enough ACKs for a given offset or when the timeout + * is reached, the WAIT command is unblocked and the reply sent to the + * client. + */ + +/* This just set a flag so that we broadcast a REPLCONF GETACK command + * to all the slaves in the beforeSleep() function. Note that this way + * we "group" all the clients that want to wait for synchronouns replication + * in a given event loop iteration, and send a single GETACK for them all. */ +void replicationRequestAckFromSlaves(void) { + server.get_ack_from_slaves = 1; +} + +/* Return the number of slaves that already acknowledged the specified + * replication offset. */ +int replicationCountAcksByOffset(long long offset) { + listIter li; + listNode *ln; + int count = 0; + + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + if (slave->replstate != SLAVE_STATE_ONLINE) continue; + if (slave->repl_ack_off >= offset) count++; + } + return count; +} + +/* WAIT for N replicas to acknowledge the processing of our latest + * write command (and all the previous commands). */ +void waitCommand(client *c) { + mstime_t timeout; + long numreplicas, ackreplicas; + long long offset = c->woff; + + if (server.masterhost) { + addReplyError(c,"WAIT cannot be used with slave instances. Please also note that since Redis 4.0 if a slave is configured to be writable (which is not the default) writes to slaves are just local and are not propagated."); + return; + } + + /* Argument parsing. */ + if (getLongFromObjectOrReply(c,c->argv[1],&numreplicas,NULL) != C_OK) + return; + if (getTimeoutFromObjectOrReply(c,c->argv[2],&timeout,UNIT_MILLISECONDS) + != C_OK) return; + + /* First try without blocking at all. */ + ackreplicas = replicationCountAcksByOffset(c->woff); + if (ackreplicas >= numreplicas || c->flags & CLIENT_MULTI) { + addReplyLongLong(c,ackreplicas); + return; + } + + /* Otherwise block the client and put it into our list of clients + * waiting for ack from slaves. */ + c->bpop.timeout = timeout; + c->bpop.reploffset = offset; + c->bpop.numreplicas = numreplicas; + listAddNodeTail(server.clients_waiting_acks,c); + blockClient(c,BLOCKED_WAIT); + + /* Make sure that the server will send an ACK request to all the slaves + * before returning to the event loop. */ + replicationRequestAckFromSlaves(); +} + +/* This is called by unblockClient() to perform the blocking op type + * specific cleanup. We just remove the client from the list of clients + * waiting for replica acks. Never call it directly, call unblockClient() + * instead. */ +void unblockClientWaitingReplicas(client *c) { + listNode *ln = listSearchKey(server.clients_waiting_acks,c); + serverAssert(ln != NULL); + listDelNode(server.clients_waiting_acks,ln); +} + +/* Check if there are clients blocked in WAIT that can be unblocked since + * we received enough ACKs from slaves. */ +void processClientsWaitingReplicas(void) { + long long last_offset = 0; + int last_numreplicas = 0; + + listIter li; + listNode *ln; + + listRewind(server.clients_waiting_acks,&li); + while((ln = listNext(&li))) { + client *c = ln->value; + + /* Every time we find a client that is satisfied for a given + * offset and number of replicas, we remember it so the next client + * may be unblocked without calling replicationCountAcksByOffset() + * if the requested offset / replicas were equal or less. */ + if (last_offset && last_offset > c->bpop.reploffset && + last_numreplicas > c->bpop.numreplicas) + { + unblockClient(c); + addReplyLongLong(c,last_numreplicas); + } else { + int numreplicas = replicationCountAcksByOffset(c->bpop.reploffset); + + if (numreplicas >= c->bpop.numreplicas) { + last_offset = c->bpop.reploffset; + last_numreplicas = numreplicas; + unblockClient(c); + addReplyLongLong(c,numreplicas); + } + } + } +} + +/* Return the slave replication offset for this instance, that is + * the offset for which we already processed the master replication stream. */ +long long replicationGetSlaveOffset(void) { + long long offset = 0; + + if (server.masterhost != NULL) { + if (server.master) { + offset = server.master->reploff; + } else if (server.cached_master) { + offset = server.cached_master->reploff; + } + } + /* offset may be -1 when the master does not support it at all, however + * this function is designed to return an offset that can express the + * amount of data processed by the master, so we return a positive + * integer. */ + if (offset < 0) offset = 0; + return offset; +} + +/* --------------------------- REPLICATION CRON ---------------------------- */ + +/* Replication cron function, called 1 time per second. */ +void replicationCron(void) { + static long long replication_cron_loops = 0; + + /* Non blocking connection timeout? */ + if (server.masterhost && + (server.repl_state == REPL_STATE_CONNECTING || + slaveIsInHandshakeState()) && + (time(NULL)-server.repl_transfer_lastio) > server.repl_timeout) + { + serverLog(LL_WARNING,"Timeout connecting to the MASTER..."); + cancelReplicationHandshake(); + } + + /* Bulk transfer I/O timeout? */ + if (server.masterhost && server.repl_state == REPL_STATE_TRANSFER && + (time(NULL)-server.repl_transfer_lastio) > server.repl_timeout) + { + serverLog(LL_WARNING,"Timeout receiving bulk data from MASTER... If the problem persists try to set the 'repl-timeout' parameter in redis.conf to a larger value."); + cancelReplicationHandshake(); + } + + /* Timed out master when we are an already connected slave? */ + if (server.masterhost && server.repl_state == REPL_STATE_CONNECTED && + (time(NULL)-server.master->lastinteraction) > server.repl_timeout) + { + serverLog(LL_WARNING,"MASTER timeout: no data nor PING received..."); + freeClient(server.master); + } + + /* Check if we should connect to a MASTER */ + if (server.repl_state == REPL_STATE_CONNECT) { + serverLog(LL_NOTICE,"Connecting to MASTER %s:%d", + server.masterhost, server.masterport); + if (connectWithMaster() == C_OK) { + serverLog(LL_NOTICE,"MASTER <-> SLAVE sync started"); + } + } + + /* Send ACK to master from time to time. + * Note that we do not send periodic acks to masters that don't + * support PSYNC and replication offsets. */ + if (server.masterhost && server.master && + !(server.master->flags & CLIENT_PRE_PSYNC)) + replicationSendAck(); + + /* If we have attached slaves, PING them from time to time. + * So slaves can implement an explicit timeout to masters, and will + * be able to detect a link disconnection even if the TCP connection + * will not actually go down. */ + listIter li; + listNode *ln; + robj *ping_argv[1]; + + /* First, send PING according to ping_slave_period. */ + if ((replication_cron_loops % server.repl_ping_slave_period) == 0 && + listLength(server.slaves)) + { + ping_argv[0] = createStringObject("PING",4); + replicationFeedSlaves(server.slaves, server.slaveseldb, + ping_argv, 1); + decrRefCount(ping_argv[0]); + } + + /* Second, send a newline to all the slaves in pre-synchronization + * stage, that is, slaves waiting for the master to create the RDB file. + * + * Also send the a newline to all the chained slaves we have, if we lost + * connection from our master, to keep the slaves aware that their + * master is online. This is needed since sub-slaves only receive proxied + * data from top-level masters, so there is no explicit pinging in order + * to avoid altering the replication offsets. This special out of band + * pings (newlines) can be sent, they will have no effect in the offset. + * + * The newline will be ignored by the slave but will refresh the + * last interaction timer preventing a timeout. In this case we ignore the + * ping period and refresh the connection once per second since certain + * timeouts are set at a few seconds (example: PSYNC response). */ + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + int is_presync = + (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START || + (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_END && + server.rdb_child_type != RDB_CHILD_TYPE_SOCKET)); + + if (is_presync) { + if (write(slave->fd, "\n", 1) == -1) { + /* Don't worry about socket errors, it's just a ping. */ + } + } + } + + /* Disconnect timedout slaves. */ + if (listLength(server.slaves)) { + listIter li; + listNode *ln; + + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + + if (slave->replstate != SLAVE_STATE_ONLINE) continue; + if (slave->flags & CLIENT_PRE_PSYNC) continue; + if ((server.unixtime - slave->repl_ack_time) > server.repl_timeout) + { + serverLog(LL_WARNING, "Disconnecting timedout slave: %s", + replicationGetSlaveName(slave)); + freeClient(slave); + } + } + } + + /* If this is a master without attached slaves and there is a replication + * backlog active, in order to reclaim memory we can free it after some + * (configured) time. Note that this cannot be done for slaves: slaves + * without sub-slaves attached should still accumulate data into the + * backlog, in order to reply to PSYNC queries if they are turned into + * masters after a failover. */ + if (listLength(server.slaves) == 0 && server.repl_backlog_time_limit && + server.repl_backlog && server.masterhost == NULL) + { + time_t idle = server.unixtime - server.repl_no_slaves_since; + + if (idle > server.repl_backlog_time_limit) { + freeReplicationBacklog(); + serverLog(LL_NOTICE, + "Replication backlog freed after %d seconds " + "without connected slaves.", + (int) server.repl_backlog_time_limit); + } + } + + /* If AOF is disabled and we no longer have attached slaves, we can + * free our Replication Script Cache as there is no need to propagate + * EVALSHA at all. */ + if (listLength(server.slaves) == 0 && + server.aof_state == AOF_OFF && + listLength(server.repl_scriptcache_fifo) != 0) + { + replicationScriptCacheFlush(); + } + + /* Start a BGSAVE good for replication if we have slaves in + * WAIT_BGSAVE_START state. + * + * In case of diskless replication, we make sure to wait the specified + * number of seconds (according to configuration) so that other slaves + * have the time to arrive before we start streaming. */ + if (server.rdb_child_pid == -1 && server.aof_child_pid == -1) { + time_t idle, max_idle = 0; + int slaves_waiting = 0; + int mincapa = -1; + listNode *ln; + listIter li; + + listRewind(server.slaves,&li); + while((ln = listNext(&li))) { + client *slave = ln->value; + if (slave->replstate == SLAVE_STATE_WAIT_BGSAVE_START) { + idle = server.unixtime - slave->lastinteraction; + if (idle > max_idle) max_idle = idle; + slaves_waiting++; + mincapa = (mincapa == -1) ? slave->slave_capa : + (mincapa & slave->slave_capa); + } + } + + if (slaves_waiting && + (!server.repl_diskless_sync || + max_idle > server.repl_diskless_sync_delay)) + { + /* Start the BGSAVE. The called function may start a + * BGSAVE with socket target or disk target depending on the + * configuration and slaves capabilities. */ + startBgsaveForReplication(mincapa); + } + } + + /* Refresh the number of slaves with lag <= min-slaves-max-lag. */ + refreshGoodSlavesCount(); + replication_cron_loops++; /* Incremented with frequency 1 HZ. */ +} |