From 920c17dc94239baae05b513046b27967f11a3569 Mon Sep 17 00:00:00 2001
From: KJ Tsanaktsidis <ktsanaktsidis@zendesk.com>
Date: Thu, 1 Feb 2024 15:33:30 +1100
Subject: [PATCH] Backport #20157 to Ruby 3.3 (#9428)

* Fix GC.measure_total_time regression

Commit 93ac7405b80cc61930d73da04441fa09af1851e1 introduced a regression
where measurements would still be taken after setting
GC.measure_total_time = false.

Fixes [Bug #20157]

* Add test case for GC.measure_total_time

---------

Co-authored-by: Rian McGuire <rian@rian.id.au>
---
 gc.c                 | 24 ++++++++++++++++--------
 test/ruby/test_gc.rb | 17 +++++++++++++++++
 2 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/gc.c b/gc.c
index 6d62ca293d..6419f8ff25 100644
--- a/gc.c
+++ b/gc.c
@@ -9749,10 +9749,6 @@ gc_enter_count(enum gc_enter_event event)
     }
 }
 
-#ifndef MEASURE_GC
-#define MEASURE_GC (objspace->flags.measure_gc)
-#endif
-
 static bool current_process_time(struct timespec *ts);
 
 static void
@@ -9822,12 +9818,18 @@ gc_exit(rb_objspace_t *objspace, enum gc_enter_event event, unsigned int *lock_l
     RB_VM_LOCK_LEAVE_LEV(lock_lev);
 }
 
+#ifndef MEASURE_GC
+#define MEASURE_GC (objspace->flags.measure_gc)
+#endif
+
 static void
 gc_marking_enter(rb_objspace_t *objspace)
 {
     GC_ASSERT(during_gc != 0);
 
-    gc_clock_start(&objspace->profile.marking_start_time);
+    if (MEASURE_GC) {
+        gc_clock_start(&objspace->profile.marking_start_time);
+    }
 }
 
 static void
@@ -9835,7 +9837,9 @@ gc_marking_exit(rb_objspace_t *objspace)
 {
     GC_ASSERT(during_gc != 0);
 
-    objspace->profile.marking_time_ns += gc_clock_end(&objspace->profile.marking_start_time);
+    if (MEASURE_GC) {
+        objspace->profile.marking_time_ns += gc_clock_end(&objspace->profile.marking_start_time);
+    }
 }
 
 static void
@@ -9843,7 +9847,9 @@ gc_sweeping_enter(rb_objspace_t *objspace)
 {
     GC_ASSERT(during_gc != 0);
 
-    gc_clock_start(&objspace->profile.sweeping_start_time);
+    if (MEASURE_GC) {
+        gc_clock_start(&objspace->profile.sweeping_start_time);
+    }
 }
 
 static void
@@ -9851,7 +9857,9 @@ gc_sweeping_exit(rb_objspace_t *objspace)
 {
     GC_ASSERT(during_gc != 0);
 
-    objspace->profile.sweeping_time_ns += gc_clock_end(&objspace->profile.sweeping_start_time);
+    if (MEASURE_GC) {
+        objspace->profile.sweeping_time_ns += gc_clock_end(&objspace->profile.sweeping_start_time);
+    }
 }
 
 static void *
diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index 4c4a7f6a27..39b001c3d0 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -231,6 +231,23 @@ class TestGc < Test::Unit::TestCase
     assert_equal stat[:total_freed_objects], stat_heap_sum[:total_freed_objects]
   end
 
+  def test_measure_total_time
+    assert_separately([], __FILE__, __LINE__, <<~RUBY)
+      GC.measure_total_time = false
+
+      time_before = GC.stat(:time)
+
+      # Generate some garbage
+      Random.new.bytes(100 * 1024 * 1024)
+      GC.start
+
+      time_after = GC.stat(:time)
+
+      # If time measurement is disabled, the time stat should not change
+      assert_equal time_before, time_after
+    RUBY
+  end
+
   def test_latest_gc_info
     omit 'stress' if GC.stress