Create a new dealloc queue that is more efficient (#931)

* Fork dealloc queue in an experiment

* Fix and put back

* Use the right selector

* Go simpler

* Clarify name

* Type inference

* Use CFTypeRefs like a boss

* Improve comments

* License header

CHANGELOG.md

@@ -54,6 +54,7 @@
 - [ASCollectionNode/ASTableNode] Fix a crash occurs while remeasuring cell nodes. [Huy Nguyen](https://github.com/nguyenhuy) [#917](https://github.com/TextureGroup/Texture/pull/917)
 - Fix an issue where ASConfigurationDelegate would not call out for "control" users. If set, it now receives events whenever an experimental feature decision point occurs, whether it's enabled or not. [Adlai Holler](https://github.com/Adlai-Holler)
 - [ASDisplayNode] Fix an issue that causes a node to sometimes return an outdated calculated size or size range. [Huy Nguyen](https://github.com/nguyenhuy) [#808](https://github.com/TextureGroup/Texture/pull/808)
+- Add an experimental deallocation queue implementation that's more efficient. [Adlai Holler](https://github.com/Adlai-Holler)
 
 ## 2.6
 - [Xcode 9] Updated to require Xcode 9 (to fix warnings) [Garrett Moon](https://github.com/garrettmoon)

Schemas/configuration.json

@@ -18,7 +18,8 @@
                     "exp_interface_state_coalesce",
                     "exp_unfair_lock",
                     "exp_infer_layer_defaults",
-                    "exp_network_image_queue"
+                    "exp_network_image_queue",
+                    "exp_dealloc_queue_v2"
                 ]
     		}
 		}

Source/ASExperimentalFeatures.h

@@ -26,6 +26,7 @@ typedef NS_OPTIONS(NSUInteger, ASExperimentalFeatures) {
   ASExperimentalUnfairLock = 1 << 3,                        // exp_unfair_lock
   ASExperimentalLayerDefaults = 1 << 4,                     // exp_infer_layer_defaults
   ASExperimentalNetworkImageQueue = 1 << 5,                 // exp_network_image_queue
+  ASExperimentalDeallocQueue = 1 << 6,                      // exp_dealloc_queue_v2
   ASExperimentalFeatureAll = 0xFFFFFFFF
 };
 

Source/ASExperimentalFeatures.m

@@ -19,7 +19,8 @@ NSArray<NSString *> *ASExperimentalFeaturesGetNames(ASExperimentalFeatures flags
                                       @"exp_interface_state_coalesce",
                                       @"exp_unfair_lock",
                                       @"exp_infer_layer_defaults",
-                                      @"exp_network_image_queue"]));
+                                      @"exp_network_image_queue",
+                                      @"exp_dealloc_queue_v2"]));
   
   if (flags == ASExperimentalFeatureAll) {
     return allNames;

Source/ASRunLoopQueue.h

@@ -76,14 +76,12 @@ AS_SUBCLASSING_RESTRICTED
 
 @end
 
-
-AS_SUBCLASSING_RESTRICTED
 @interface ASDeallocQueue : NSObject
 
 @property (class, atomic, readonly) ASDeallocQueue *sharedDeallocationQueue;
 + (ASDeallocQueue *)sharedDeallocationQueue NS_RETURNS_RETAINED;
 
-- (void)test_drain;
+- (void)drain;
 
 - (void)releaseObjectInBackground:(id __strong _Nullable * _Nonnull)objectPtr;
 

Source/ASRunLoopQueue.mm

@@ -39,23 +39,41 @@ static void runLoopSourceCallback(void *info) {
 
 #pragma mark - ASDeallocQueue
 
-@implementation ASDeallocQueue {
-  NSThread *_thread;
-  NSCondition *_condition;
-  std::deque<id> _queue;
-  ASDN::RecursiveMutex _queueLock;
-}
+@interface ASDeallocQueueV1 : ASDeallocQueue
+@end
+@interface ASDeallocQueueV2 : ASDeallocQueue
+@end
+
+@implementation ASDeallocQueue
 
 + (ASDeallocQueue *)sharedDeallocationQueue NS_RETURNS_RETAINED
 {
   static ASDeallocQueue *deallocQueue = nil;
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
-    deallocQueue = [[ASDeallocQueue alloc] init];
+    if (ASActivateExperimentalFeature(ASExperimentalDeallocQueue)) {
+      deallocQueue = [[ASDeallocQueueV2 alloc] init];
+    } else {
+      deallocQueue = [[ASDeallocQueueV1 alloc] init];
+    }
   });
   return deallocQueue;
 }
 
+- (void)releaseObjectInBackground:(id  _Nullable __strong *)objectPtr
+{
+  ASDisplayNodeFailAssert(@"Abstract method.");
+}
+
+@end
+
+@implementation ASDeallocQueueV1 {
+  NSThread *_thread;
+  NSCondition *_condition;
+  std::deque<id> _queue;
+  ASDN::RecursiveMutex _queueLock;
+}
+
 - (void)releaseObjectInBackground:(id  _Nullable __strong *)objectPtr
 {
   if (objectPtr != NULL && *objectPtr != nil) {
@@ -147,12 +165,12 @@ static void runLoopSourceCallback(void *info) {
   _thread = nil;
 }
 
-- (void)test_drain
+- (void)drain
 {
-  [self performSelector:@selector(_test_drain) onThread:_thread withObject:nil waitUntilDone:YES];
+  [self performSelector:@selector(_drain) onThread:_thread withObject:nil waitUntilDone:YES];
 }
 
-- (void)_test_drain
+- (void)_drain
 {
   while (true) {
     @autoreleasepool {
@@ -182,6 +200,57 @@ static void runLoopSourceCallback(void *info) {
 
 @end
 
+@implementation ASDeallocQueueV2 {
+  std::vector<CFTypeRef> _queue;
+  ASDN::Mutex _lock;
+}
+
+- (void)dealloc
+{
+  ASDisplayNodeFailAssert(@"Singleton should not dealloc.");
+}
+
+- (void)releaseObjectInBackground:(id  _Nullable __strong *)objectPtr
+{
+  NSParameterAssert(objectPtr != NULL);
+  
+  // Cast to CFType so we can manipulate retain count manually.
+  auto cfPtr = (CFTypeRef *)(void *)objectPtr;
+  if (!cfPtr || !*cfPtr) {
+    return;
+  }
+  
+  _lock.lock();
+  auto isFirstEntry = _queue.empty();
+  // Push the pointer into our queue and clear their pointer.
+  // This "steals" the +1 from ARC and nils their pointer so they can't
+  // access or release the object.
+  _queue.push_back(*cfPtr);
+  *cfPtr = NULL;
+  _lock.unlock();
+  
+  if (isFirstEntry) {
+    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.100 * NSEC_PER_SEC)), dispatch_get_global_queue(QOS_CLASS_DEFAULT, 0), ^{
+      [self drain];
+    });
+  }
+}
+
+- (void)drain
+{
+  @autoreleasepool {
+    _lock.lock();
+    auto q = std::move(_queue);
+    _lock.unlock();
+    for (auto ref : q) {
+      // NOTE: Could check that retain count is 1 and retry later if not.
+      CFRelease(ref);
+    }
+  }
+}
+
+@end
+
 #if AS_KDEBUG_ENABLE
 /**
  * This is real, private CA API. Valid as of iOS 10.

Tests/Common/ASTestCase.m

@@ -95,7 +95,7 @@ static __weak ASTestCase *currentTestCase;
   }
 
   // Now that the autorelease pool is drained, drain the dealloc queue also.
-  [[ASDeallocQueue sharedDeallocationQueue] test_drain];
+  [[ASDeallocQueue sharedDeallocationQueue] drain];
 }
 
 + (ASTestCase *)currentTestCase

examples/CatDealsCollectionView/Sample/AppDelegate.m

@@ -1,18 +1,18 @@
 //
 //  AppDelegate.m
-//  Sample
+//  Texture
 //
 //  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
 //  This source code is licensed under the BSD-style license found in the
-//  LICENSE file in the root directory of this source tree. An additional grant
-//  of patent rights can be found in the PATENTS file in the same directory.
+//  LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
+//  grant of patent rights can be found in the PATENTS file in the same directory.
 //
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//  Modifications to this file made after 4/13/2017 are: Copyright (c) through the present,
+//  Pinterest, Inc.  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
 //
 
 #import "AppDelegate.h"
@@ -55,3 +55,14 @@
 }
 
 @end
+
+@implementation ASConfiguration (UserProvided)
+
++ (ASConfiguration *)textureConfiguration
+{
+  ASConfiguration *cfg = [[ASConfiguration alloc] init];
+  cfg.experimentalFeatures = ASExperimentalDeallocQueue;
+  return cfg;
+}
+
+@end