1 files changed, 21 insertions, 1 deletions
diff --git a/src/timestamp/timestamp.cpp b/src/timestamp/timestamp.cpp
index 4cac82a..72bd37c 100644
--- a/src/timestamp/timestamp.cpp
+++ b/src/timestamp/timestamp.cpp
@@ -6,6 +6,16 @@
 // 1 ms = 1000 us
 // 1 us = 1000 ns
 
+/*
+ * The maximum number of seconds that can be stored in the time_t value is 2147483647 –- a little over 68 years.
+ *
+ * struct timespec
+ * {
+ *     time_t tv_sec; // seconds
+ *     long tv_nsec;  // nanoseconds
+ * };
+ */
+
 struct timestamp
 {
     struct timespec ts;
@@ -18,6 +28,17 @@ struct timestamp
 
 void timestamp_update()
 {
+    /*
+     * CLOCK_MONOTONIC
+     *
+     * On Linux, that point corresponds to the number of sec‐
+     * onds that the system has been running since it was booted.
+     *
+     * The CLOCK_MONOTONIC clock is not affected by discontinuous
+     * jumps in the system time (e.g., if the system administrator
+     * manually changes the clock), but is affected by the incremen‐
+     * tal adjustments performed by adjtime(3) and NTP.
+     */
     clock_gettime(CLOCK_MONOTONIC, &g_timestamp.ts);
 
     uint64_t current_timestamp_ms = g_timestamp.ts.tv_sec * 1000 + g_timestamp.ts.tv_nsec / 1000000;
@@ -32,7 +53,6 @@ uint64_t timestamp_get_sec()
     return ATOMIC_READ(&g_timestamp.ts_in_sec);
 }
 
-// TODO uint64_t 溢出
 uint64_t timestamp_get_msec()
 {
     return ATOMIC_READ(&g_timestamp.ts_in_msec);