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ioquatixioquatix
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Fix GC compaction.
1 parent 71dba42 commit f73b842

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5 files changed

+405
-162
lines changed

5 files changed

+405
-162
lines changed

‎ext/extconf.rb‎

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Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@
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append_cflags(["-DRUBY_DEBUG", "-O0"])
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end
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$srcs = ["memory/profiler/profiler.c", "memory/profiler/capture.c"]
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$srcs = ["memory/profiler/profiler.c", "memory/profiler/capture.c", "memory/profiler/allocations.c"]
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$VPATH << "$(srcdir)/memory/profiler"
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# Check for required headers

‎ext/memory/profiler/allocations.c‎

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// Released under the MIT License.
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// Copyright, 2025, by Samuel Williams.
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#include "allocations.h"
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#include "ruby.h"
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#include "ruby/debug.h"
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#include "ruby/st.h"
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#include <stdio.h>
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static VALUE Memory_Profiler_Allocations = Qnil;
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// Helper to mark object_states table values
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static int Memory_Profiler_Allocations_object_states_mark(st_data_t key, st_data_t value, st_data_t arg) {
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VALUE object = (VALUE)key;
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rb_gc_mark_movable(object);
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VALUE state = (VALUE)value;
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if (!NIL_P(state)) {
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rb_gc_mark_movable(state);
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}
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return ST_CONTINUE;
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}
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// Foreach callback for st_foreach_with_replace (iteration logic)
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static int Memory_Profiler_Allocations_object_states_foreach(st_data_t key, st_data_t value, st_data_t argp, int error) {
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// Return ST_REPLACE to trigger the replace callback for each entry
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return ST_REPLACE;
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}
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// Replace callback for st_foreach_with_replace to update object_states keys and values during compaction
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static int Memory_Profiler_Allocations_object_states_compact(st_data_t *key, st_data_t *value, st_data_t data, int existing) {
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VALUE old_object = (VALUE)*key;
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VALUE old_state = (VALUE)*value;
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VALUE new_object = rb_gc_location(old_object);
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VALUE new_state = rb_gc_location(old_state);
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// Update key if it moved
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if (old_object != new_object) {
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*key = (st_data_t)new_object;
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}
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// Update value if it moved
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if (old_state != new_state) {
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*value = (st_data_t)new_state;
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}
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return ST_CONTINUE;
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}
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// GC mark function for Allocations
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static void Memory_Profiler_Allocations_mark(void *ptr) {
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struct Memory_Profiler_Capture_Allocations *record = ptr;
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if (!record) {
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return;
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}
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if (!NIL_P(record->callback)) {
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rb_gc_mark_movable(record->callback);
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}
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// Mark object_states table if it exists
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if (record->object_states) {
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st_foreach(record->object_states, Memory_Profiler_Allocations_object_states_mark, 0);
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}
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}
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// GC free function for Allocations
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static void Memory_Profiler_Allocations_free(void *ptr) {
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struct Memory_Profiler_Capture_Allocations *record = ptr;
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if (record->object_states) {
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st_free_table(record->object_states);
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}
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xfree(record);
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}
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// GC compact function for Allocations
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static void Memory_Profiler_Allocations_compact(void *ptr) {
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struct Memory_Profiler_Capture_Allocations *record = ptr;
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// Update callback if it moved
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if (!NIL_P(record->callback)) {
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record->callback = rb_gc_location(record->callback);
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}
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// Update object_states table if it exists
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if (record->object_states && record->object_states->num_entries > 0) {
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if (st_foreach_with_replace(record->object_states, Memory_Profiler_Allocations_object_states_foreach, Memory_Profiler_Allocations_object_states_compact, 0)) {
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rb_raise(rb_eRuntimeError, "object_states modified during GC compaction");
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}
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}
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}
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static const rb_data_type_t Memory_Profiler_Allocations_type = {
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"Memory::Profiler::Allocations",
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{
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.dmark = Memory_Profiler_Allocations_mark,
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.dcompact = Memory_Profiler_Allocations_compact,
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.dfree = Memory_Profiler_Allocations_free,
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},
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0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED
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};
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// Wrap an allocations record
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VALUE Memory_Profiler_Allocations_wrap(struct Memory_Profiler_Capture_Allocations *record) {
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return TypedData_Wrap_Struct(Memory_Profiler_Allocations, &Memory_Profiler_Allocations_type, record);
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}
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// Get allocations record from wrapper
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struct Memory_Profiler_Capture_Allocations* Memory_Profiler_Allocations_get(VALUE self) {
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struct Memory_Profiler_Capture_Allocations *record;
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TypedData_Get_Struct(self, struct Memory_Profiler_Capture_Allocations, &Memory_Profiler_Allocations_type, record);
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return record;
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}
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// Allocations#new_count
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static VALUE Memory_Profiler_Allocations_new_count(VALUE self) {
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struct Memory_Profiler_Capture_Allocations *record = Memory_Profiler_Allocations_get(self);
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return SIZET2NUM(record->new_count);
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}
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// Allocations#free_count
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static VALUE Memory_Profiler_Allocations_free_count(VALUE self) {
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struct Memory_Profiler_Capture_Allocations *record = Memory_Profiler_Allocations_get(self);
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return SIZET2NUM(record->free_count);
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}
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// Allocations#retained_count
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static VALUE Memory_Profiler_Allocations_retained_count(VALUE self) {
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struct Memory_Profiler_Capture_Allocations *record = Memory_Profiler_Allocations_get(self);
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// Handle underflow when free_count > new_count
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size_t retained = record->free_count > record->new_count ? 0 : record->new_count - record->free_count;
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return SIZET2NUM(retained);
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}
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// Allocations#track { |klass| ... }
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static VALUE Memory_Profiler_Allocations_track(int argc, VALUE *argv, VALUE self) {
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struct Memory_Profiler_Capture_Allocations *record = Memory_Profiler_Allocations_get(self);
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VALUE callback;
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rb_scan_args(argc, argv, "&", &callback);
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// Use write barrier - self (Allocations wrapper) keeps Capture alive, which keeps callback alive
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RB_OBJ_WRITE(self, &record->callback, callback);
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return self;
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}
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// Clear/reset allocation counts and state for a record
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void Memory_Profiler_Allocations_clear(VALUE allocations) {
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struct Memory_Profiler_Capture_Allocations *record = Memory_Profiler_Allocations_get(allocations);
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record->new_count = 0; // Reset allocation count
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record->free_count = 0; // Reset free count
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RB_OBJ_WRITE(allocations, &record->callback, Qnil); // Clear callback with write barrier
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// Clear object states
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if (record->object_states) {
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st_free_table(record->object_states);
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record->object_states = NULL;
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}
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}
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void Init_Memory_Profiler_Allocations(VALUE Memory_Profiler)
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{
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// Allocations class - wraps allocation data for a specific class
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Memory_Profiler_Allocations = rb_define_class_under(Memory_Profiler, "Allocations", rb_cObject);
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// Allocations objects are only created internally via wrap, never from Ruby:
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rb_undef_alloc_func(Memory_Profiler_Allocations);
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rb_define_method(Memory_Profiler_Allocations, "new_count", Memory_Profiler_Allocations_new_count, 0);
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rb_define_method(Memory_Profiler_Allocations, "free_count", Memory_Profiler_Allocations_free_count, 0);
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rb_define_method(Memory_Profiler_Allocations, "retained_count", Memory_Profiler_Allocations_retained_count, 0);
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rb_define_method(Memory_Profiler_Allocations, "track", Memory_Profiler_Allocations_track, -1); // -1 to accept block
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}

‎ext/memory/profiler/allocations.h‎

Lines changed: 31 additions & 0 deletions
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@@ -0,0 +1,31 @@
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// Released under the MIT License.
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// Copyright, 2025, by Samuel Williams.
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#pragma once
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#include "ruby.h"
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#include "ruby/st.h"
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// Per-class allocation tracking record
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struct Memory_Profiler_Capture_Allocations {
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VALUE callback; // Optional Ruby proc/lambda to call on allocation
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size_t new_count; // Total allocations seen since tracking started
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size_t free_count; // Total frees seen since tracking started
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// Live count = new_count - free_count
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// For detailed tracking: map object (VALUE) => state (VALUE)
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// State is returned from callback on :newobj and passed back on :freeobj
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st_table *object_states;
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};
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// Wrap an allocations record in a VALUE
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VALUE Memory_Profiler_Allocations_wrap(struct Memory_Profiler_Capture_Allocations *record);
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// Get allocations record from wrapper VALUE
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struct Memory_Profiler_Capture_Allocations* Memory_Profiler_Allocations_get(VALUE self);
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// Clear/reset allocation counts and state for a record
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void Memory_Profiler_Allocations_clear(VALUE allocations);
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// Initialize the Allocations class
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void Init_Memory_Profiler_Allocations(VALUE Memory_Profiler);

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