From 083785777fe0fc770919136b60d1873cb6c0ae50 Mon Sep 17 00:00:00 2001
From: shuaichen <shuaichen@google.com>
Date: Mon, 22 Jul 2024 08:28:01 -0700
Subject: [PATCH] out_stackdriver: Add latency metric for write log entries
 HTTP request.

Signed-off-by: shuaichen <shuaichen@google.com>
---
 plugins/out_stackdriver/stackdriver.c      | 11 +++++++++++
 plugins/out_stackdriver/stackdriver.h      |  3 +++
 plugins/out_stackdriver/stackdriver_conf.c | 15 +++++++++++++--
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/plugins/out_stackdriver/stackdriver.c b/plugins/out_stackdriver/stackdriver.c
index 60b66c48ce4..0984e96da8b 100644
--- a/plugins/out_stackdriver/stackdriver.c
+++ b/plugins/out_stackdriver/stackdriver.c
@@ -2829,6 +2829,9 @@ static void cb_stackdriver_flush(struct flb_event_chunk *event_chunk,
     struct flb_connection *u_conn;
     struct flb_http_client *c;
     int compressed = FLB_FALSE;
+    uint64_t write_entries_start = 0;
+    uint64_t write_entries_end = 0;
+    float write_entries_latency = 0.0;
 #ifdef FLB_HAVE_METRICS
     char *name = (char *) flb_output_name(ctx->ins);
     uint64_t ts = cfl_time_now();
@@ -2923,9 +2926,14 @@ static void cb_stackdriver_flush(struct flb_event_chunk *event_chunk,
         flb_http_set_content_encoding_gzip(c);
     }
 
+    write_entries_start = cfl_time_now();
+
     /* Send HTTP request */
     ret = flb_http_do(c, &b_sent);
 
+    write_entries_end = cfl_time_now();
+    write_entries_latency = (float)(write_entries_end - write_entries_start) / 1000000000.0;
+
     /* validate response */
     if (ret != 0) {
         flb_plg_warn(ctx->ins, "http_do=%i", ret);
@@ -2994,6 +3002,9 @@ static void cb_stackdriver_flush(struct flb_event_chunk *event_chunk,
 #ifdef FLB_HAVE_METRICS
     if (ret_code == FLB_OK) {
         cmt_counter_inc(ctx->cmt_successful_requests, ts, 1, (char *[]) {name});
+        if (write_entries_latency > 0.0) {
+          cmt_histogram_observe(ctx->cmt_write_entries_latency, ts, write_entries_latency, 1, (char *[]) {name});
+        }
         add_record_metrics(ctx, ts, (int) event_chunk->total_events, 200, 0);
 
         /* OLD api */
diff --git a/plugins/out_stackdriver/stackdriver.h b/plugins/out_stackdriver/stackdriver.h
index 76f5a7598ea..fa5cb2e2b10 100644
--- a/plugins/out_stackdriver/stackdriver.h
+++ b/plugins/out_stackdriver/stackdriver.h
@@ -27,6 +27,8 @@
 #include <fluent-bit/flb_regex.h>
 #include <fluent-bit/flb_metrics.h>
 
+#include <cmetrics/cmt_histogram.h>
+
 /* refresh token every 50 minutes */
 #define FLB_STD_TOKEN_REFRESH 3000
 
@@ -218,6 +220,7 @@ struct flb_stackdriver {
     struct cmt_counter *cmt_requests_total;
     struct cmt_counter *cmt_proc_records_total;
     struct cmt_counter *cmt_retried_records_total;
+    struct cmt_histogram *cmt_write_entries_latency;
 #endif
 
     /* plugin instance */
diff --git a/plugins/out_stackdriver/stackdriver_conf.c b/plugins/out_stackdriver/stackdriver_conf.c
index b7de32a0a95..89582623d40 100644
--- a/plugins/out_stackdriver/stackdriver_conf.c
+++ b/plugins/out_stackdriver/stackdriver_conf.c
@@ -262,6 +262,7 @@ struct flb_stackdriver *flb_stackdriver_conf_create(struct flb_output_instance *
     const char *backwards_compatible_env_var;
     struct flb_stackdriver *ctx;
     size_t http_request_key_size;
+    struct cmt_histogram_buckets *buckets;
 
     /* Allocate config context */
     ctx = flb_calloc(1, sizeof(struct flb_stackdriver));
@@ -559,6 +560,16 @@ struct flb_stackdriver *flb_stackdriver_conf_create(struct flb_output_instance *
                                                         "Total number of retried records.",
                                                         2, (char *[]) {"status", "name"});
 
+    buckets = cmt_histogram_buckets_create(7, 1.0, 2.0, 4.0, 8.0, 16.0, 32.0, 64.0);
+    ctx->cmt_write_entries_latency = cmt_histogram_create(ins->cmt,
+                                                          "fluentbit",
+                                                          "stackdriver",
+                                                          "write_entries_latency",
+                                                          "Latency of Cloud Logging WriteLogEntries HTTP request.",
+                                                          buckets,
+                                                          1, (char *[]) {"name"});
+
+
     /* OLD api */
     flb_metrics_add(FLB_STACKDRIVER_SUCCESSFUL_REQUESTS,
                     "stackdriver_successful_requests", ctx->ins->metrics);
@@ -599,7 +610,7 @@ int flb_stackdriver_conf_destroy(struct flb_stackdriver *ctx)
         }
         flb_free(ctx->creds);
     }
-    
+
     if (ctx->env) {
         if (ctx->env->creds_file) {
             flb_sds_destroy(ctx->env->creds_file);
@@ -620,7 +631,7 @@ int flb_stackdriver_conf_destroy(struct flb_stackdriver *ctx)
     if (ctx->metadata_server) {
         flb_sds_destroy(ctx->metadata_server);
     }
-    
+
     if (ctx->resource_type == RESOURCE_TYPE_K8S){
         flb_sds_destroy(ctx->namespace_name);
         flb_sds_destroy(ctx->pod_name);