Fix locking deadlock on app resume

monal-im · Dec 16, 2024 · d0ebcae · d0ebcae
1 parent 61cd5ef
commit d0ebcae
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Showing 2 changed files with 55 additions and 18 deletions.
diff --git a/Monal/Classes/HelperTools.m b/Monal/Classes/HelperTools.m
@@ -75,14 +75,23 @@ @interface MLDelayableTimer()
 -(void) invalidate;
 @end
 
+//make method visible
+@interface DDLog()
+-(void) queueLogMessage:(DDLogMessage*) logMessage asynchronously:(BOOL) asyncFlag;
+@end
+
+@interface DDLog (AllowQueueFreeze)
+-(void) swizzled_queueLogMessage:(DDLogMessage*) logMessage asynchronously:(BOOL) asyncFlag;
+@end
+
 static char* _crashBundleName = "UnifiedReport";
 static NSString* _processID;
 static DDFileLogger* _fileLogger = nil;
 static char _origLogfilePath[1024] = "";
 static char _logfilePath[1024] = "";
 static NSObject* _isAppExtensionLock = nil;
-static NSObject* _suspensionHandlingLock = nil;
-static BOOL _suspensionHandlingIsSuspended = NO;
+static NSObject* _suspensionHandling_lock = nil;
+static BOOL _suspensionHandling_isSuspended = NO;
 static NSMutableDictionary* _versionInfoCache;
 static MLStreamRedirect* _stdoutRedirector = nil;
 static MLStreamRedirect* _stderrRedirector = nil;
@@ -293,12 +302,36 @@ -(id) initWithObj:(id) obj
 }
 @end
 
+@implementation DDLog (AllowQueueFreeze)
+
+-(void) swizzled_queueLogMessage:(DDLogMessage*) logMessage asynchronously:(BOOL) asyncFlag
+{
+    //don't do sync logging for any message (usually ERROR), while the global logging queue is suspended
+    @synchronized(_suspensionHandling_lock) {
+        return [self swizzled_queueLogMessage:logMessage asynchronously:_suspensionHandling_isSuspended ? YES : asyncFlag];
+    }
+}
+
+//see https://stackoverflow.com/a/13326633 and https://fek.io/blog/method-swizzling-in-obj-c-and-swift/
++(void) load
+{
+    if(self == DDLog.self)
+    {
+        static dispatch_once_t onceToken;
+        dispatch_once(&onceToken, ^{
+            swizzle([self class], @selector(queueLogMessage:asynchronously:), @selector(swizzled_queueLogMessage:asynchronously:));
+        });
+    }
+}
+
+@end
+
 @implementation HelperTools
 
 +(void) initialize
 {
-    _suspensionHandlingLock = [NSObject new];
-    _suspensionHandlingIsSuspended = NO;
+    _suspensionHandling_lock = [NSObject new];
+    _suspensionHandling_isSuspended = NO;
     _isAppExtensionLock = [NSObject new];
     _versionInfoCache = [NSMutableDictionary new];
 
@@ -1880,27 +1913,31 @@ +(void) flushLogsWithTimeout:(double) timeout
 
 +(void) signalSuspension
 {
-    @synchronized(_suspensionHandlingLock) {
-        if(!_suspensionHandlingIsSuspended)
+    @synchronized(_suspensionHandling_lock) {
+        if(!_suspensionHandling_isSuspended)
         {
             DDLogVerbose(@"Suspending logger queue...");
             [HelperTools flushLogsWithTimeout:0.100];
             dispatch_suspend([DDLog loggingQueue]);
-            _suspensionHandlingIsSuspended = YES;
+            _suspensionHandling_isSuspended = YES;
+
+            DDLogVerbose(@"Posting kMonalFrozen notification now...");
+            [[NSNotificationCenter defaultCenter] postNotificationName:kMonalFrozen object:nil];
         }
     }
-    DDLogVerbose(@"Posting kMonalIsFreezed notification now...");
-    [[NSNotificationCenter defaultCenter] postNotificationName:kMonalIsFreezed object:nil];
 }
 
 +(void) signalResumption
 {
-    @synchronized(_suspensionHandlingLock) {
-        if(_suspensionHandlingIsSuspended)
+    @synchronized(_suspensionHandling_lock) {
+        if(_suspensionHandling_isSuspended)
         {
             DDLogVerbose(@"Resuming logger queue...");
             dispatch_resume([DDLog loggingQueue]);
-            _suspensionHandlingIsSuspended = NO;
+            _suspensionHandling_isSuspended = NO;
+
+            DDLogVerbose(@"Posting kMonalUnfrozen notification now...");
+            [[NSNotificationCenter defaultCenter] postNotificationName:kMonalUnfrozen object:nil];
         }
     }
 }

diff --git a/Monal/Classes/MonalAppDelegate.m b/Monal/Classes/MonalAppDelegate.m
@@ -1595,9 +1595,6 @@ -(void) handleBackgroundProcessingTask:(BGTask*) task
         }];
     };
 
-    //resume logging and other core tasks
-    [HelperTools signalResumption];
-
     //only proceed with our BGTASK if the NotificationServiceExtension is not running
     [MLProcessLock lock];
     [[IPC sharedInstance] sendMessage:@"Monal.disconnectAll" withData:nil to:@"NotificationServiceExtension"];
@@ -1702,9 +1699,6 @@ -(void) handleBackgroundRefreshingTask:(BGTask*) task
         }];
     };
 
-    //resume logging and other core tasks
-    [HelperTools signalResumption];
-
     //only proceed with our BGTASK if the NotificationServiceExtension is not running
     [MLProcessLock lock];
     [[IPC sharedInstance] sendMessage:@"Monal.disconnectAll" withData:nil to:@"NotificationServiceExtension"];
@@ -1748,6 +1742,9 @@ -(void) handleBackgroundRefreshingTask:(BGTask*) task
 -(void) configureBackgroundTasks
 {
     [[BGTaskScheduler sharedScheduler] registerForTaskWithIdentifier:kBackgroundProcessingTask usingQueue:dispatch_get_main_queue() launchHandler:^(BGTask *task) {
+        //resume logging and other core tasks
+        [HelperTools signalResumption];
+
         DDLogDebug(@"RUNNING BGPROCESSING LAUNCH HANDLER");
         DDLogInfo(@"BG time available: %f", [UIApplication sharedApplication].backgroundTimeRemaining);
         if(![HelperTools isInBackground])
@@ -1768,6 +1765,9 @@ -(void) configureBackgroundTasks
     }];
 
     [[BGTaskScheduler sharedScheduler] registerForTaskWithIdentifier:kBackgroundRefreshingTask usingQueue:dispatch_get_main_queue() launchHandler:^(BGTask *task) {
+        //resume logging and other core tasks
+        [HelperTools signalResumption];
+
         DDLogDebug(@"RUNNING BGREFRESHING LAUNCH HANDLER");
         DDLogInfo(@"BG time available: %f", [UIApplication sharedApplication].backgroundTimeRemaining);
         if(![HelperTools isInBackground])