Check for failures while acquiring read lock

krakjoe · Feb 7, 2021 · 61f3c16 · 61f3c16
1 parent 78b6c78
commit 61f3c16
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Showing 4 changed files with 56 additions and 20 deletions.
diff --git a/apc_cache.c b/apc_cache.c
@@ -797,7 +797,10 @@ PHP_APCU_API apc_cache_entry_t *apc_cache_find(apc_cache_t* cache, zend_string *
 		return NULL;
 	}
 
-	APC_RLOCK(cache->header);
+	if (!APC_RLOCK(cache->header)) {
+		return NULL;
+	}
+
 	entry = apc_cache_rlocked_find_incref(cache, key, t);
 	APC_RUNLOCK(cache->header);
 
@@ -815,7 +818,10 @@ PHP_APCU_API zend_bool apc_cache_fetch(apc_cache_t* cache, zend_string *key, tim
 		return 0;
 	}
 
-	APC_RLOCK(cache->header);
+	if (!APC_RLOCK(cache->header)) {
+		return 0;
+	}
+
 	entry = apc_cache_rlocked_find_incref(cache, key, t);
 	APC_RUNLOCK(cache->header);
 
@@ -841,7 +847,10 @@ PHP_APCU_API zend_bool apc_cache_exists(apc_cache_t* cache, zend_string *key, ti
 		return 0;
 	}
 
-	APC_RLOCK(cache->header);
+	if (!APC_RLOCK(cache->header)) {
+		return 0;
+	}
+
 	entry = apc_cache_rlocked_find_nostat(cache, key, t);
 	APC_RUNLOCK(cache->header);
 
@@ -913,7 +922,10 @@ PHP_APCU_API zend_bool apc_cache_atomic_update_long(
 	}
 
 retry_update:
-	APC_RLOCK(cache->header);
+	if (!APC_RLOCK(cache->header)) {
+		return 0;
+	}
+
 	entry = apc_cache_rlocked_find_nostat(cache, key, t);
 	if (entry) {
 		/* Only supports integers */
@@ -1057,12 +1069,15 @@ PHP_APCU_API zend_bool apc_cache_info(zval *info, apc_cache_t *cache, zend_bool
 	apc_cache_entry_t *p;
 	zend_ulong i, j;
 
+	ZVAL_NULL(info);
 	if (!cache) {
-		ZVAL_NULL(info);
 		return 0;
 	}
 
-	APC_RLOCK(cache->header);
+	if (!APC_RLOCK(cache->header)) {
+		return 0;
+	}
+
 	php_apc_try {
 		array_init(info);
 		add_assoc_long(info, "num_slots", cache->nslots);
@@ -1133,7 +1148,10 @@ PHP_APCU_API void apc_cache_stat(apc_cache_t *cache, zend_string *key, zval *sta
 	/* calculate hash and slot */
 	apc_cache_hash_slot(cache, key, &h, &s);
 
-	APC_RLOCK(cache->header);
+	if (!APC_RLOCK(cache->header)) {
+		return;
+	}
+
 	php_apc_try {
 		/* find head */
 		apc_cache_entry_t *entry = cache->slots[s];

diff --git a/apc_iterator.c b/apc_iterator.c
@@ -218,7 +218,10 @@ static int apc_iterator_fetch_active(apc_iterator_t *iterator) {
 		apc_iterator_item_dtor(apc_stack_pop(iterator->stack));
 	}
 
-	APC_RLOCK(apc_user_cache->header);
+	if (!APC_RLOCK(apc_user_cache->header)) {
+		return count;
+	}
+
 	php_apc_try {
 		while (count <= iterator->chunk_size && iterator->slot_idx < apc_user_cache->nslots) {
 			apc_cache_entry_t *entry = apc_user_cache->slots[iterator->slot_idx];
@@ -250,7 +253,10 @@ static int apc_iterator_fetch_deleted(apc_iterator_t *iterator) {
 	int count = 0;
 	apc_iterator_item_t *item;
 
-	APC_RLOCK(apc_user_cache->header);
+	if (!APC_RLOCK(apc_user_cache->header)) {
+		return count;
+	}
+
 	php_apc_try {
 		apc_cache_entry_t *entry = apc_user_cache->header->gc;
 		while (entry && count <= iterator->slot_idx) {
@@ -283,7 +289,10 @@ static void apc_iterator_totals(apc_iterator_t *iterator) {
 	time_t t = apc_time();
 	int i;
 
-	APC_RLOCK(apc_user_cache->header);
+	if (!APC_RLOCK(apc_user_cache->header)) {
+		return;
+	}
+
 	php_apc_try {
 		for (i=0; i < apc_user_cache->nslots; i++) {
 			apc_cache_entry_t *entry = apc_user_cache->slots[i];

diff --git a/apc_lock.c b/apc_lock.c
@@ -37,7 +37,7 @@ PHP_APCU_API zend_bool apc_lock_create(apc_lock_t *lock) {
 	return NULL != apc_windows_cs_create(lock);
 }
 
-PHP_APCU_API zend_bool apc_lock_rlock(apc_lock_t *lock) {
+static inline zend_bool apc_lock_rlock_impl(apc_lock_t *lock) {
 	apc_windows_cs_rdlock(lock);
 	return 1;
 }
@@ -94,9 +94,8 @@ PHP_APCU_API zend_bool apc_lock_create(apc_lock_t *lock) {
 	return pthread_rwlock_init(lock, &apc_lock_attr) == SUCCESS;
 }
 
-PHP_APCU_API zend_bool apc_lock_rlock(apc_lock_t *lock) {
-	pthread_rwlock_rdlock(lock);
-	return 1;
+static inline zend_bool apc_lock_rlock_impl(apc_lock_t *lock) {
+	return pthread_rwlock_rdlock(lock) == 0;
 }
 
 static inline zend_bool apc_lock_wlock_impl(apc_lock_t *lock) {
@@ -154,9 +153,8 @@ PHP_APCU_API zend_bool apc_lock_create(apc_lock_t *lock) {
 	return 1;
 }
 
-PHP_APCU_API zend_bool apc_lock_rlock(apc_lock_t *lock) {
-	pthread_mutex_lock(lock);
-	return 1;
+static inline zend_bool apc_lock_rlock_impl(apc_lock_t *lock) {
+	return pthread_mutex_lock(lock) == 0;
 }
 
 static inline zend_bool apc_lock_wlock_impl(apc_lock_t *lock) {
@@ -227,7 +225,7 @@ PHP_APCU_API zend_bool apc_lock_create(apc_lock_t *lock) {
 	lock->state = 0;
 }
 
-PHP_APCU_API zend_bool apc_lock_rlock(apc_lock_t *lock) {
+static inline zend_bool apc_lock_rlock_impl(apc_lock_t *lock) {
 	apc_lock_get(lock);
 	return 1;
 }
@@ -291,7 +289,7 @@ PHP_APCU_API zend_bool apc_lock_create(apc_lock_t *lock) {
 	}
 }
 
-PHP_APCU_API zend_bool apc_lock_rlock(apc_lock_t *lock) {
+static inline zend_bool apc_lock_rlock_impl(apc_lock_t *lock) {
 	apc_fcntl_call((*lock), F_SETLKW, F_RDLCK, 0, SEEK_SET, 0);
 	return 1;
 }
@@ -329,3 +327,14 @@ PHP_APCU_API zend_bool apc_lock_wlock(apc_lock_t *lock) {
 	apc_warning("Failed to acquire write lock");
 	return 0;
 }
+
+PHP_APCU_API zend_bool apc_lock_rlock(apc_lock_t *lock) {
+	HANDLE_BLOCK_INTERRUPTIONS();
+	if (apc_lock_rlock_impl(lock)) {
+		return 1;
+	}
+
+	HANDLE_UNBLOCK_INTERRUPTIONS();
+	apc_warning("Failed to acquire read lock");
+	return 0;
+}
diff --git a/apc_lock.h b/apc_lock.h
@@ -89,7 +89,7 @@ PHP_APCU_API void apc_lock_destroy(apc_lock_t *lock); /* }}} */
 #define DESTROY_LOCK(lock)    apc_lock_destroy(lock)
 #define WLOCK(lock)           apc_lock_wlock(lock)
 #define WUNLOCK(lock)         { apc_lock_wunlock(lock); HANDLE_UNBLOCK_INTERRUPTIONS(); }
-#define RLOCK(lock)           { HANDLE_BLOCK_INTERRUPTIONS(); apc_lock_rlock(lock); }
+#define RLOCK(lock)           apc_lock_rlock(lock)
 #define RUNLOCK(lock)         { apc_lock_runlock(lock); HANDLE_UNBLOCK_INTERRUPTIONS(); }
 /* }}} */