fix(IoT): Using a custom atomic dictionary for topic listeners

AWSCore/Utility/AWSSynchronizedMutableDictionary.m

@@ -74,13 +74,13 @@ - (id)objectForKey:(id)aKey {
 }
 
 - (void)setObject:(id)anObject forKey:(id)aKey {
-    dispatch_barrier_async(self.dispatchQueue, ^{
+    dispatch_barrier_sync(self.dispatchQueue, ^{
         [self.dictionary setObject:anObject forKey:aKey];
     });
 }
 
 - (void)removeObject:(id)object {
-    dispatch_barrier_async(self.dispatchQueue, ^{
+    dispatch_barrier_sync(self.dispatchQueue, ^{
         for (NSString *key in self.dictionary) {
             if (object == self.dictionary[key]) {
                 [self.dictionary removeObjectForKey:key];
@@ -91,19 +91,19 @@ - (void)removeObject:(id)object {
 }
 
 - (void)removeObjectForKey:(id)aKey {
-    dispatch_barrier_async(self.dispatchQueue, ^{
+    dispatch_barrier_sync(self.dispatchQueue, ^{
         [self.dictionary removeObjectForKey:aKey];
     });
 }
 
 - (void)removeAllObjects {
-    dispatch_barrier_async(self.dispatchQueue, ^{
+    dispatch_barrier_sync(self.dispatchQueue, ^{
         [self.dictionary removeAllObjects];
     });
 }
 
 - (void)mutateWithBlock:(void (^)(NSMutableDictionary *))block {
-    dispatch_barrier_async(self.dispatchQueue, ^{
+    dispatch_barrier_sync(self.dispatchQueue, ^{
         block(self.dictionary);
     });
 }
@@ -112,7 +112,7 @@ + (void)mutateSyncedDictionaries:(NSArray<AWSSynchronizedMutableDictionary *> *)
     AWSSynchronizedMutableDictionary *first = [dictionaries firstObject];
     if (!first) { return; }
 
-    dispatch_barrier_async(first.dispatchQueue, ^{
+    dispatch_barrier_sync(first.dispatchQueue, ^{
         [dictionaries enumerateObjectsUsingBlock:^(AWSSynchronizedMutableDictionary * _Nonnull atomicDictionary, NSUInteger index, BOOL * _Nonnull stop) {
             NSCAssert([first.syncKey isEqual:atomicDictionary.syncKey], @"Sync keys much match");
             block(atomicDictionary.instanceKey, atomicDictionary.dictionary);

AWSIoT/Internal/AWSIoTAtomicDictionary.h

@@ -0,0 +1,36 @@
+//
+// Copyright 2010-2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// A copy of the License is located at
+//
+// http://aws.amazon.com/apache2.0
+//
+// or in the "license" file accompanying this file. This file is distributed
+// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the License for the specific language governing
+// permissions and limitations under the License.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface AWSIoTAtomicDictionary<KeyType, ObjectType> : NSObject
+
+@property (readonly, copy) NSArray<KeyType> *allKeys;
+@property (readonly, copy) NSArray<ObjectType> *allValues;
+
+/// Create new instance.
+- (instancetype)init;
+
+- (id)objectForKey:(id)aKey;
+- (void)setObject:(id)anObject forKey:(id <NSCopying>)aKey;
+
+- (void)removeObjectForKey:(id)aKey;
+- (void)removeAllObjects;
+
+@end
+
+NS_ASSUME_NONNULL_END

AWSIoT/Internal/AWSIoTAtomicDictionary.m

@@ -0,0 +1,75 @@
+//
+// Copyright 2010-2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License").
+// You may not use this file except in compliance with the License.
+// A copy of the License is located at
+//
+// http://aws.amazon.com/apache2.0
+//
+// or in the "license" file accompanying this file. This file is distributed
+// on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+// express or implied. See the License for the specific language governing
+// permissions and limitations under the License.
+//
+
+#import "AWSIoTAtomicDictionary.h"
+
+@interface AWSIoTAtomicDictionary()
+
+@property (nonatomic, strong) NSMutableDictionary *dictionary;
+@property (nonatomic, strong) NSLock *lock;
+
+@end
+
+@implementation AWSIoTAtomicDictionary
+
+- (instancetype)init {
+    self = [super init];
+    if (self) {
+        _lock = [[NSLock alloc] init];
+        _dictionary = [NSMutableDictionary new];
+    }
+    return self;
+}
+
+- (NSArray *)allKeys {
+    [self.lock lock];
+    NSArray * result = self.dictionary.allKeys;
+    [self.lock unlock];
+    return result;
+}
+
+- (NSArray *)allValues {
+    [self.lock lock];
+    NSArray * result = self.dictionary.allValues;
+    [self.lock unlock];
+    return result;
+}
+
+- (id)objectForKey:(id)aKey {
+    [self.lock lock];
+    id result = [self.dictionary objectForKey:aKey];
+    [self.lock unlock];
+    return result;
+}
+
+- (void)setObject:(id)anObject forKey:(id)aKey {
+    [self.lock lock];
+    [self.dictionary setObject:anObject forKey:aKey];
+    [self.lock unlock];
+}
+
+- (void)removeObjectForKey:(id)aKey {
+    [self.lock lock];
+    [self.dictionary removeObjectForKey:aKey];
+    [self.lock unlock];
+}
+
+- (void)removeAllObjects {
+    [self.lock lock];
+    [self.dictionary removeAllObjects];
+    [self.lock unlock];
+}
+
+@end

AWSIoT/Internal/AWSIoTMQTTClient.m

@@ -25,6 +25,7 @@
 #import "AWSMQTTMessage.h"
 #import "AWSIoTManager.h"
 #import "AWSIoTStreamThread.h"
+#import "AWSIoTAtomicDictionary.h"
 
 @implementation AWSIoTMQTTTopicModel
 @end
@@ -38,7 +39,7 @@ @interface AWSIoTMQTTClient() <AWSSRWebSocketDelegate, NSStreamDelegate, AWSMQTT
 
 @property(atomic, assign, readwrite) AWSIoTMQTTStatus mqttStatus;
 @property(nonatomic, strong) AWSMQTTSession* session;
-@property(nonatomic, strong) AWSSynchronizedMutableDictionary * topicListeners;
+@property(nonatomic, strong) AWSIoTAtomicDictionary *topicListeners;
 
 @property(atomic, assign) BOOL userDidIssueDisconnect; //Flag to indicate if requestor has issued a disconnect
 @property(atomic, assign) BOOL userDidIssueConnect; //Flag to indicate if requestor has issued a connect
@@ -91,7 +92,7 @@ @implementation AWSIoTMQTTClient
 
 - (instancetype)init {
     if (self = [super init]) {
-        _topicListeners = [AWSSynchronizedMutableDictionary new];
+        _topicListeners = [AWSIoTAtomicDictionary new];
         _clientCerts = nil;
         _session.delegate = nil;
         _session = nil;

AWSiOSSDKv2.xcodeproj/project.pbxproj

@@ -635,6 +635,8 @@
 		68A45BBC2B8D6ADE00A0851E /* AWSDDMultiFormatter.h in Headers */ = {isa = PBXBuildFile; fileRef = 68A45BAB2B8D6ADE00A0851E /* AWSDDMultiFormatter.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		68A45BBF2B8E74F900A0851E /* AWSCLIColor.h in Headers */ = {isa = PBXBuildFile; fileRef = 68A45BBD2B8E74F800A0851E /* AWSCLIColor.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		68A45BC02B8E74F900A0851E /* AWSCLIColor.m in Sources */ = {isa = PBXBuildFile; fileRef = 68A45BBE2B8E74F900A0851E /* AWSCLIColor.m */; };
+		68DD11862C5AF52B004E1C37 /* AWSIoTAtomicDictionary.h in Headers */ = {isa = PBXBuildFile; fileRef = 68DD11842C5AF52B004E1C37 /* AWSIoTAtomicDictionary.h */; };
+		68DD11872C5AF52B004E1C37 /* AWSIoTAtomicDictionary.m in Sources */ = {isa = PBXBuildFile; fileRef = 68DD11852C5AF52B004E1C37 /* AWSIoTAtomicDictionary.m */; };
 		68EE1A6C2B713D8100B7CF41 /* AWSIoTStreamThread.h in Headers */ = {isa = PBXBuildFile; fileRef = 68EE1A6B2B713D8100B7CF41 /* AWSIoTStreamThread.h */; };
 		68EE1A6E2B713D8900B7CF41 /* AWSIoTStreamThread.m in Sources */ = {isa = PBXBuildFile; fileRef = 68EE1A6D2B713D8900B7CF41 /* AWSIoTStreamThread.m */; };
 		6BE9D6AA25A54EBA00AB5C9A /* AWSIotDataManagerRetainTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6BE9D6A925A54EBA00AB5C9A /* AWSIotDataManagerRetainTests.swift */; };
@@ -3250,6 +3252,8 @@
 		68A45BAB2B8D6ADE00A0851E /* AWSDDMultiFormatter.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AWSDDMultiFormatter.h; sourceTree = "<group>"; };
 		68A45BBD2B8E74F800A0851E /* AWSCLIColor.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AWSCLIColor.h; sourceTree = "<group>"; };
 		68A45BBE2B8E74F900A0851E /* AWSCLIColor.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AWSCLIColor.m; sourceTree = "<group>"; };
+		68DD11842C5AF52B004E1C37 /* AWSIoTAtomicDictionary.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = AWSIoTAtomicDictionary.h; sourceTree = "<group>"; };
+		68DD11852C5AF52B004E1C37 /* AWSIoTAtomicDictionary.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = AWSIoTAtomicDictionary.m; sourceTree = "<group>"; };
 		68EE1A6B2B713D8100B7CF41 /* AWSIoTStreamThread.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = AWSIoTStreamThread.h; sourceTree = "<group>"; };
 		68EE1A6D2B713D8900B7CF41 /* AWSIoTStreamThread.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = AWSIoTStreamThread.m; sourceTree = "<group>"; };
 		6BE9D6A925A54EBA00AB5C9A /* AWSIotDataManagerRetainTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AWSIotDataManagerRetainTests.swift; sourceTree = "<group>"; };
@@ -7209,6 +7213,8 @@
 		CE9DE6351C6A78D70060793F /* Internal */ = {
 			isa = PBXGroup;
 			children = (
+				68DD11842C5AF52B004E1C37 /* AWSIoTAtomicDictionary.h */,
+				68DD11852C5AF52B004E1C37 /* AWSIoTAtomicDictionary.m */,
 				CE9DE6361C6A78D70060793F /* AWSIoTCSR.h */,
 				CE9DE6371C6A78D70060793F /* AWSIoTCSR.m */,
 				CE9DE6381C6A78D70060793F /* AWSIoTKeychain.h */,
@@ -8457,6 +8463,7 @@
 				CE9DE6501C6A78D70060793F /* AWSIoTDataModel.h in Headers */,
 				CE9DE6541C6A78D70060793F /* AWSIoTDataService.h in Headers */,
 				CE9DE64D1C6A78D70060793F /* AWSIoTData.h in Headers */,
+				68DD11862C5AF52B004E1C37 /* AWSIoTAtomicDictionary.h in Headers */,
 				CE9DE64E1C6A78D70060793F /* AWSIoTDataManager.h in Headers */,
 				CE9DE66E1C6A78D70060793F /* AWSMQttTxFlow.h in Headers */,
 				03427765269D15A400379263 /* AWSIoTMessage.h in Headers */,
@@ -13393,6 +13400,7 @@
 				0342776A269D185200379263 /* AWSIoTMessage+AWSMQTTMessage.m in Sources */,
 				CE9DE66B1C6A78D70060793F /* AWSMQTTMessage.m in Sources */,
 				CE9DE65D1C6A78D70060793F /* AWSIoTService.m in Sources */,
+				68DD11872C5AF52B004E1C37 /* AWSIoTAtomicDictionary.m in Sources */,
 				CE9DE6571C6A78D70060793F /* AWSIoTManager.m in Sources */,
 				CE9DE6591C6A78D70060793F /* AWSIoTModel.m in Sources */,
 				CE9DE6691C6A78D70060793F /* AWSMQTTEncoder.m in Sources */,

CHANGELOG.md

@@ -2,10 +2,8 @@
 
 ## Unreleased
 
-- **AWSCore** 
-  - Fixing concurrency issues in `AWSSynchronizedMutableDictionary` (#5413)
-
 - **AWSIoT** 
+  - Using custom atomic dictionary for topic listeners (#5415)
   - Fixing random crash when a connection is attempted just after disconnecting
 
 ## 2.36.6