From ff9ec241b670a7be6ee6af2016c25eaa9143e830 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Tue, 22 Oct 2024 12:24:12 +0200
Subject: [PATCH 1/3] Enable GC.auto_compact in test suite

Reproduces: https://github.com/jhawthorn/vernier/issues/100
---
 test/test_helper.rb | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/test/test_helper.rb b/test/test_helper.rb
index feff941..713982d 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -23,3 +23,5 @@ def assert_valid_result(result)
     end
   end
 end
+
+GC.auto_compact = true

From 5b0579fa3a568629b2ddd2ec44ffa4dcc3190303 Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Wed, 23 Oct 2024 15:26:24 +0200
Subject: [PATCH 2/3] Handle collector->object_list being moved

---
 ext/vernier/vernier.cc | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/ext/vernier/vernier.cc b/ext/vernier/vernier.cc
index ba4e880..28ba72c 100644
--- a/ext/vernier/vernier.cc
+++ b/ext/vernier/vernier.cc
@@ -1360,6 +1360,9 @@ class BaseCollector {
         rb_gc_mark(stack_table_value);
     };
 
+    virtual void compact() {
+    };
+
     virtual VALUE get_markers() {
         return rb_ary_new();
     };
@@ -1547,6 +1550,13 @@ class RetainedCollector : public BaseCollector {
         rb_gc_mark(tp_newobj);
         rb_gc_mark(tp_freeobj);
     }
+
+    void compact() {
+        RetainedCollector *collector = this;
+        for (auto& obj: collector->object_list) {
+            obj = rb_gc_location(obj);
+        }
+    }
 };
 
 class GlobalSignalHandler {
@@ -1969,12 +1979,19 @@ collector_free(void *data) {
     delete collector;
 }
 
+static void
+collector_compact(void *data) {
+    BaseCollector *collector = static_cast<BaseCollector *>(data);
+    collector->compact();
+}
+
 static const rb_data_type_t rb_collector_type = {
     .wrap_struct_name = "vernier/collector",
     .function = {
         //.dmemsize = rb_collector_memsize,
         .dmark = collector_mark,
         .dfree = collector_free,
+        .dcompact = collector_compact,
     },
 };
 

From a4babd8c54ecd3a54184356a605e3c360e918060 Mon Sep 17 00:00:00 2001
From: Joshua Young <djry1999@gmail.com>
Date: Thu, 24 Oct 2024 19:30:41 +1000
Subject: [PATCH 3/3] Update collector->object_frames to reflect object_list
 move

---
 ext/vernier/vernier.cc | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/ext/vernier/vernier.cc b/ext/vernier/vernier.cc
index 28ba72c..39d8bbc 100644
--- a/ext/vernier/vernier.cc
+++ b/ext/vernier/vernier.cc
@@ -1554,7 +1554,17 @@ class RetainedCollector : public BaseCollector {
     void compact() {
         RetainedCollector *collector = this;
         for (auto& obj: collector->object_list) {
-            obj = rb_gc_location(obj);
+            VALUE reloc_obj = rb_gc_location(obj);
+            
+            const auto search = collector->object_frames.find(obj);
+            if (search != collector->object_frames.end()) {
+                int stack_index = search->second;
+                
+                collector->object_frames.erase(search);
+                collector->object_frames.emplace(reloc_obj, stack_index);
+            }
+            
+            obj = reloc_obj;
         }
     }
 };