From 23a1dd51fdfc77c672c8057057d9e2598af40ba9 Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@collectd.org>
Date: Fri, 5 Jan 2024 09:53:03 +0100
Subject: [PATCH] cpu plugin: Implement `usage_ratio`.

---
 src/cpu.c      | 10 +++++++--
 src/cpu_test.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/src/cpu.c b/src/cpu.c
index 19c20d418..b13e0c78f 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -445,8 +445,7 @@ static gauge_t usage_global_rate(usage_t u, state_t state) {
   return us.has_value ? us.rate : NAN;
 }
 
-__attribute__((unused)) static gauge_t usage_rate(usage_t u, size_t cpu,
-                                                  state_t state) {
+static gauge_t usage_rate(usage_t u, size_t cpu, state_t state) {
   if (state == STATE_ACTIVE) {
     return usage_active_rate(u, cpu);
   }
@@ -469,6 +468,13 @@ __attribute__((unused)) static void usage_reset(usage_t *u) {
   u->states_num = 0;
 }
 
+__attribute__((unused)) static gauge_t usage_ratio(usage_t u, size_t cpu,
+                                                   state_t state) {
+  gauge_t global_rate =
+      usage_global_rate(u, STATE_ACTIVE) + usage_global_rate(u, STATE_IDLE);
+  return usage_rate(u, cpu, state) / global_rate;
+}
+
 /* Takes the zero-index number of a CPU and makes sure that the module-global
  * cpu_states buffer is large enough. Returne ENOMEM on erorr. */
 static int cpu_states_alloc(size_t cpu_num) /* {{{ */
diff --git a/src/cpu_test.c b/src/cpu_test.c
index 2140c4392..8b8722f12 100644
--- a/src/cpu_test.c
+++ b/src/cpu_test.c
@@ -22,7 +22,7 @@
 #include "cpu.c" /* sic */
 #include "testing.h"
 
-DEF_TEST(usage_simple_rate) {
+DEF_TEST(usage_rate) {
   usage_t usage = {0};
 
   cdtime_t t0 = TIME_T_TO_CDTIME_T(100);
@@ -57,7 +57,57 @@ DEF_TEST(usage_simple_rate) {
   return 0;
 }
 
-DEF_TEST(usage_active) {
+DEF_TEST(usage_ratio) {
+  usage_t usage = {0};
+
+  cdtime_t t0 = TIME_T_TO_CDTIME_T(100);
+  usage_init(&usage, t0);
+  for (size_t cpu = 0; cpu < 4; cpu++) {
+    for (state_t s = 0; s < STATE_ACTIVE; s++) {
+      usage_record(&usage, cpu, s, 1000);
+    }
+  }
+
+  cdtime_t t1 = t0 + TIME_T_TO_CDTIME_T(10);
+  usage_init(&usage, t1);
+  derive_t global_increment = 0;
+  for (size_t cpu = 0; cpu < 4; cpu++) {
+    for (state_t s = 0; s < STATE_ACTIVE; s++) {
+      derive_t increment = ((derive_t)cpu * STATE_ACTIVE) + ((derive_t)s);
+      global_increment += increment;
+      usage_record(&usage, cpu, s, 1000 + increment);
+    }
+  }
+
+  for (size_t cpu = 0; cpu < 4; cpu++) {
+    derive_t active_increment = 0;
+    for (state_t s = 0; s < STATE_ACTIVE; s++) {
+      derive_t increment = ((derive_t)cpu * STATE_ACTIVE) + ((derive_t)s);
+      if (s != STATE_IDLE) {
+        active_increment += increment;
+      }
+      gauge_t want_ratio = ((gauge_t)increment) / ((gauge_t)global_increment);
+      EXPECT_EQ_DOUBLE(want_ratio, usage_ratio(usage, cpu, s));
+    }
+    gauge_t want_active_ratio =
+        ((gauge_t)active_increment) / ((gauge_t)global_increment);
+    EXPECT_EQ_DOUBLE(want_active_ratio, usage_ratio(usage, cpu, STATE_ACTIVE));
+  }
+
+  gauge_t sum = 0;
+  for (size_t cpu = 0; cpu < 4; cpu++) {
+    for (state_t s = 0; s < STATE_ACTIVE; s++) {
+      gauge_t rate = usage_ratio(usage, cpu, s);
+      sum += rate;
+    }
+  }
+  EXPECT_EQ_DOUBLE(1.0, sum);
+
+  usage_reset(&usage);
+  return 0;
+}
+
+DEF_TEST(usage_active_rate) {
   usage_t usage = {0};
 
   cdtime_t t0 = TIME_T_TO_CDTIME_T(100);
@@ -139,8 +189,9 @@ DEF_TEST(usage_global_rate) {
 }
 
 int main(void) {
-  RUN_TEST(usage_simple_rate);
-  RUN_TEST(usage_active);
+  RUN_TEST(usage_rate);
+  RUN_TEST(usage_ratio);
+  RUN_TEST(usage_active_rate);
   RUN_TEST(usage_global_rate);
 
   END_TEST;
-- 
2.47.2