From c73886a7c8bf31efb962a73d583662f92b7bf111 Mon Sep 17 00:00:00 2001
From: Eero Tamminen <eero.t.tamminen@intel.com>
Date: Mon, 19 Feb 2024 17:56:56 +0200
Subject: [PATCH] WIP: write_prometheus: fix AVL tree family key

Resource labels are part of metric family identification, not just the
family name.

Signed-off-by: Eero Tamminen <eero.t.tamminen@intel.com>
---
 src/write_prometheus.c | 48 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 42 insertions(+), 6 deletions(-)

diff --git a/src/write_prometheus.c b/src/write_prometheus.c
index df1aab8a79..5120741e65 100644
--- a/src/write_prometheus.c
+++ b/src/write_prometheus.c
@@ -758,31 +758,54 @@ static int prom_init() {
   return 0;
 }
 
+
+static bool family_key(metric_family_t const *fam, strbuf_t *buf) {
+  bool fail = strbuf_print(buf, fam->name);
+
+  for (size_t i = 0; i < fam->resource.num; i++) {
+    fail = fail || strbuf_print(buf, "/");
+    fail = fail || strbuf_print(buf, fam->resource.ptr[i].name);
+    fail = fail || strbuf_print(buf, "=");
+    fail = fail || strbuf_print(buf, fam->resource.ptr[i].value);
+  }
+
+  return !fail;
+}
+
 static int prom_write(metric_family_t const *fam,
                       __attribute__((unused)) user_data_t *ud) {
+  strbuf_t keybuf = STRBUF_CREATE;
+  if (!family_key(fam, &keybuf)) {
+    ERROR("write_prometheus plugin: Metric \"%s\" identity creation failed.", fam->name);
+    STRBUF_DESTROY(keybuf);
+    return -1;
+  }
   pthread_mutex_lock(&prom_metrics_lock);
 
   metric_family_t *prom_fam = NULL;
-  if (c_avl_get(prom_metrics, fam->name, (void *)&prom_fam) != 0) {
+  if (c_avl_get(prom_metrics, keybuf.ptr, (void *)&prom_fam) != 0) {
     prom_fam = metric_family_clone(fam);
     if (prom_fam == NULL) {
       ERROR("write_prometheus plugin: Clone metric \"%s\" failed.", fam->name);
       pthread_mutex_unlock(&prom_metrics_lock);
+      STRBUF_DESTROY(keybuf);
       return -1;
     }
     /* Sort the metrics so that lookup is fast. */
     qsort(prom_fam->metric.ptr, prom_fam->metric.num,
           sizeof(*prom_fam->metric.ptr), prom_metric_cmp);
 
-    int status = c_avl_insert(prom_metrics, prom_fam->name, prom_fam);
+    int status = c_avl_insert(prom_metrics, keybuf.ptr, prom_fam);
     if (status != 0) {
       ERROR("write_prometheus plugin: Adding \"%s\" failed.", prom_fam->name);
       metric_family_free(prom_fam);
       pthread_mutex_unlock(&prom_metrics_lock);
+      STRBUF_DESTROY(keybuf);
       return -1;
     }
 
     pthread_mutex_unlock(&prom_metrics_lock);
+    STRBUF_DESTROY(keybuf);
     return 0;
   }
 
@@ -827,11 +850,20 @@ static int prom_write(metric_family_t const *fam,
 static int prom_missing(metric_family_t const *fam,
                         __attribute__((unused)) user_data_t *ud) {
 
+  strbuf_t keybuf = STRBUF_CREATE;
+  if (!family_key(fam, &keybuf)) {
+    ERROR("write_prometheus plugin: Metric \"%s\" identity creation failed.", fam->name);
+    STRBUF_DESTROY(keybuf);
+    return -1;
+  }
   pthread_mutex_lock(&prom_metrics_lock);
 
   metric_family_t *prom_fam = NULL;
-  if (c_avl_get(prom_metrics, fam->name, (void *)&prom_fam) != 0)
+  if (c_avl_get(prom_metrics, keybuf.ptr, (void *)&prom_fam) != 0) {
+    pthread_mutex_unlock(&prom_metrics_lock);
+    STRBUF_DESTROY(keybuf);
     return 0;
+  }
 
   for (size_t i = 0; i < fam->metric.num; i++) {
     metric_t const *m = &fam->metric.ptr[i];
@@ -850,7 +882,7 @@ static int prom_missing(metric_family_t const *fam,
     }
 
     if (prom_fam->metric.num == 0) {
-      int status = c_avl_remove(prom_metrics, prom_fam->name, NULL, NULL);
+      int status = c_avl_remove(prom_metrics, keybuf.ptr, NULL, NULL);
       if (status != 0) {
         ERROR("write_prometheus plugin: Deleting metric family \"%s\" failed "
               "with status %d",
@@ -863,6 +895,7 @@ static int prom_missing(metric_family_t const *fam,
   }
 
   pthread_mutex_unlock(&prom_metrics_lock);
+  STRBUF_DESTROY(keybuf);
   return 0;
 }
 
@@ -877,8 +910,11 @@ static int prom_shutdown() {
     char *name;
     metric_family_t *prom_fam;
     while (c_avl_pick(prom_metrics, (void *)&name, (void *)&prom_fam) == 0) {
-      assert(name == prom_fam->name);
-      name = NULL;
+      strbuf_t keybuf = STRBUF_CREATE;
+      if (family_key(prom_fam, &keybuf)) {
+	assert(name == keybuf.ptr);
+      }
+      STRBUF_DESTROY(keybuf);
       metric_family_free(prom_fam);
     }
     c_avl_destroy(prom_metrics);