From 9cc0cdecd8ac7f504400596d0227ca9033d87af9 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Mon, 2 Jun 2014 00:05:18 -0400
Subject: Use C11 atomics.

---
 libdimension/malloc.c | 11 ++++++-----
 libdimension/pool.c   | 22 ++++++++++------------
 2 files changed, 16 insertions(+), 17 deletions(-)

(limited to 'libdimension')

diff --git a/libdimension/malloc.c b/libdimension/malloc.c
index d7816c3..6868802 100644
--- a/libdimension/malloc.c
+++ b/libdimension/malloc.c
@@ -26,9 +26,10 @@
 #include "dimension-internal.h"
 #include <stdlib.h>
 #include <string.h>
+#include <stdatomic.h>
 
 #ifndef NDEBUG
-static size_t dmnsn_allocs = 0;
+static atomic_size_t dmnsn_allocs = 0;
 #endif
 
 void *
@@ -40,7 +41,7 @@ dmnsn_malloc(size_t size)
   }
 
 #ifndef NDEBUG
-  __sync_fetch_and_add(&dmnsn_allocs, 1);
+  atomic_fetch_add(&dmnsn_allocs, 1);
 #endif
 
   return ptr;
@@ -51,7 +52,7 @@ dmnsn_realloc(void *ptr, size_t size)
 {
 #ifndef NDEBUG
   if (!ptr) {
-    __sync_fetch_and_add(&dmnsn_allocs, 1);
+    atomic_fetch_add(&dmnsn_allocs, 1);
   }
 #endif
 
@@ -75,7 +76,7 @@ dmnsn_free(void *ptr)
 {
 #ifndef NDEBUG
   if (ptr) {
-    __sync_fetch_and_sub(&dmnsn_allocs, 1);
+    atomic_fetch_sub(&dmnsn_allocs, 1);
   }
 #endif
 
@@ -86,7 +87,7 @@ dmnsn_free(void *ptr)
 DMNSN_LATE_DESTRUCTOR static void
 dmnsn_leak_check(void)
 {
-  if (dmnsn_allocs > 0) {
+  if (atomic_load_explicit(&dmnsn_allocs, memory_order_relaxed) > 0) {
     dmnsn_warning("Leaking memory.");
   }
 }
diff --git a/libdimension/pool.c b/libdimension/pool.c
index db6be14..c969bca 100644
--- a/libdimension/pool.c
+++ b/libdimension/pool.c
@@ -24,6 +24,7 @@
  */
 
 #include "dimension-internal.h"
+#include <stdatomic.h>
 
 /** A single allocation and associated destructor. */
 typedef struct dmnsn_allocation {
@@ -48,11 +49,8 @@ typedef struct dmnsn_pool_block {
 struct dmnsn_pool {
   /** Thread-local block. */
   pthread_key_t thread_block;
-
   /** Global chain of pools. */
-  dmnsn_pool_block *chain;
-  /** Mutex guarding the global chain. */
-  pthread_mutex_t mutex;
+  _Atomic(dmnsn_pool_block *) chain;
 };
 
 dmnsn_pool *
@@ -60,8 +58,7 @@ dmnsn_new_pool(void)
 {
   dmnsn_pool *pool = DMNSN_MALLOC(dmnsn_pool);
   dmnsn_key_create(&pool->thread_block, NULL);
-  pool->chain = NULL;
-  dmnsn_initialize_mutex(&pool->mutex);
+  atomic_init(&pool->chain, NULL);
   return pool;
 }
 
@@ -90,10 +87,12 @@ dmnsn_palloc_tidy(dmnsn_pool *pool, size_t size, dmnsn_callback_fn *cleanup_fn)
   if (dmnsn_unlikely(new_block != old_block)) {
     dmnsn_setspecific(pool->thread_block, new_block);
 
-    dmnsn_lock_mutex(&pool->mutex);
-      new_block->prev = pool->chain;
-      pool->chain = new_block;
-    dmnsn_unlock_mutex(&pool->mutex);
+    /* Atomically update pool->chain */
+    dmnsn_pool_block *chain;
+    do {
+      chain = atomic_load(&pool->chain);
+    } while (!atomic_compare_exchange_weak(&pool->chain, &chain, new_block));
+    new_block->prev = chain;
   }
 
   return result;
@@ -106,7 +105,7 @@ dmnsn_delete_pool(dmnsn_pool *pool)
     return;
   }
 
-  dmnsn_pool_block *block = pool->chain;
+  dmnsn_pool_block *block = atomic_load_explicit(&pool->chain, memory_order_relaxed);
   while (block) {
     /* Free all the allocations in reverse order */
     for (size_t i = block->i; i-- > 0;) {
@@ -123,7 +122,6 @@ dmnsn_delete_pool(dmnsn_pool *pool)
     dmnsn_free(saved);
   }
 
-  dmnsn_destroy_mutex(&pool->mutex);
   dmnsn_key_delete(pool->thread_block);
   dmnsn_free(pool);
 }
-- 
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