From bab8c29dc98dfa4515fffa077e0f234b541560f3 Mon Sep 17 00:00:00 2001
From: chenzizhan <chenzizhan@geedgenetworks.com>
Date: Tue, 16 Apr 2024 15:40:09 +0800
Subject: can enable delta in fse active output

---
 include/fieldstat/fieldstat_easy.h | 11 +++++++++++
 src/fieldstat_easy.c               |  5 +++++
 test/test_easy_fs.cpp              | 27 +++++++++++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/include/fieldstat/fieldstat_easy.h b/include/fieldstat/fieldstat_easy.h
index 3cb9429..7403c3f 100644
--- a/include/fieldstat/fieldstat_easy.h
+++ b/include/fieldstat/fieldstat_easy.h
@@ -27,6 +27,17 @@ void fieldstat_easy_free(struct fieldstat_easy *fse);
     * @return: 0 if success, -1 if failed to open file. -2 if the output is already enabled.
 */
 int fieldstat_easy_enable_auto_output(struct fieldstat_easy *pthis, const char *output_path, int interval_second);
+
+/*
+    affect the output of fieldstat_easy_output and fieldstat_easy_output_array.
+    let json exporter output delta value by the side of the original value(accumulated). If a cell / metric is new, the delta value is the same as the original value.
+    Outputting delta value is disabled by default.
+    When the fieldstat instance is reset, the delta value will be reset. (next output will be the original value)
+    Only affects the metrics of counter type.
+    Outputting delta value is time-consuming. Be cautious when enabling it.
+*/
+void fieldstat_easy_enable_delta_in_active_output(struct fieldstat_easy *fse);
+
 /*
     * @brief add a metric to the cube of cube_id. One metric may be associated with different cells.
     * @param metric_name: name of the metric. Cannot be NULL. Must be unique.
diff --git a/src/fieldstat_easy.c b/src/fieldstat_easy.c
index 1b56688..b8909a0 100644
--- a/src/fieldstat_easy.c
+++ b/src/fieldstat_easy.c
@@ -361,3 +361,8 @@ int fieldstat_easy_histogram_record(struct fieldstat_easy *fse, int thread_id, i
 
     return ret;
 }
+
+void fieldstat_easy_enable_delta_in_active_output(struct fieldstat_easy *fse)
+{
+    fieldstat_json_exporter_enable_delta(fse->exporter);
+}
\ No newline at end of file
diff --git a/test/test_easy_fs.cpp b/test/test_easy_fs.cpp
index 44dbed9..0595593 100644
--- a/test/test_easy_fs.cpp
+++ b/test/test_easy_fs.cpp
@@ -40,6 +40,33 @@ TEST(test_easy_fieldstat, output_to_buff)
     fieldstat_easy_free(fse);
 }
 
+TEST(test_easy_fieldstat, output_to_buff_with_delta)
+{
+    struct fieldstat_easy *fse = fieldstat_easy_new(10, NULL, &TEST_TAG_STRING, 1);
+    fieldstat_easy_enable_delta_in_active_output(fse);
+    fieldstat_easy_register_counter(fse, "metric counter");
+    fieldstat_easy_counter_incrby(fse, 0, 0, &TEST_TAG_INT, 1, 1);
+    char *buff = NULL;
+    size_t buff_len = 0;
+    fieldstat_easy_output(fse, &buff, &buff_len);
+    free(buff);
+    fieldstat_easy_counter_incrby(fse, 0, 0, &TEST_TAG_INT, 1, 1);
+    fieldstat_easy_output(fse, &buff, &buff_len);
+
+    cJSON *root = cJSON_Parse(buff);
+    cJSON *cell = cJSON_GetArrayItem(root, 0);
+    cJSON *metric = cJSON_GetObjectItem(cell, "fields");
+    long long value = cJSON_GetObjectItem(metric, "metric counter")->valueint;
+    EXPECT_EQ(value, 2);
+    cJSON *metric_delta = cJSON_GetObjectItem(cell, "fields_delta");
+    long long value_delta = cJSON_GetObjectItem(metric_delta, "metric counter")->valueint;
+    EXPECT_EQ(value_delta, 1);
+
+    cJSON_Delete(root);
+    free(buff);
+    fieldstat_easy_free(fse);
+}
+
 cJSON *read_file()
 {
     std::ifstream ifs(FILENAME);
-- 
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