ObjFW  Artifact [7d4ea0e843]

Artifact 7d4ea0e843f57c45825a0789fa1dabd8a952d96d37b5538eb9ec28a60228949a:

• File src/OFNotificationCenter.m — part of check-in [93851ccd0f] at 2021-10-31 18:02:13 on branch notifications — OFNotificationCenter: Move posting out of the lock

  This prevents a deadlock when modifying observers from a handler. (user: js, size: 5217) [annotate] [blame] [check-ins using]

/*
 * Copyright (c) 2008-2021 Jonathan Schleifer <js@nil.im>
 *
 * All rights reserved.
 *
 * This file is part of ObjFW. It may be distributed under the terms of the
 * Q Public License 1.0, which can be found in the file LICENSE.QPL included in
 * the packaging of this file.
 *
 * Alternatively, it may be distributed under the terms of the GNU General
 * Public License, either version 2 or 3, which can be found in the file
 * LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
 * file.
 */

#include "config.h"

#import "OFNotificationCenter.h"
#import "OFArray.h"
#import "OFDictionary.h"
#ifdef OF_HAVE_THREADS
# import "OFMutex.h"
#endif
#import "OFSet.h"
#import "OFString.h"

@interface OFDefaultNotificationCenter: OFNotificationCenter
@end

@interface OFNotificationHandler: OFObject
{
@public
	id _observer;
	SEL _selector;
	unsigned long _selectorHash;
	id _object;
}

- (instancetype)initWithObserver: (id)observer
			selector: (SEL)selector
			  object: (id)object;
@end

static OFNotificationCenter *defaultCenter;

@implementation OFNotificationHandler
- (instancetype)initWithObserver: (id)observer
			selector: (SEL)selector
			  object: (id)object
{
	self = [super init];

	@try {
		void *pool = objc_autoreleasePoolPush();

		_observer = [observer retain];
		_selector = selector;
		_object = [object retain];

		_selectorHash = [[OFString stringWithUTF8String:
		    sel_getName(_selector)] hash];

		objc_autoreleasePoolPop(pool);
	} @catch (id e) {
		[self release];
		@throw e;
	}

	return self;
}

- (void)dealloc
{
	[_observer release];
	[_object release];

	[super dealloc];
}

- (bool)isEqual: (OFNotificationHandler *)handler
{
	if (![handler isKindOfClass: [OFNotificationHandler class]])
		return false;

	if (![handler->_observer isEqual: _observer])
		return false;

	if (!sel_isEqual(handler->_selector, _selector))
		return false;

	if (handler->_object != _object && ![handler->_object isEqual: _object])
		return false;

	return true;
}

- (unsigned long)hash
{
	unsigned long hash;

	OFHashInit(&hash);

	OFHashAddHash(&hash, [_observer hash]);
	OFHashAddHash(&hash, _selectorHash);
	OFHashAddHash(&hash, [_object hash]);

	OFHashFinalize(&hash);

	return hash;
}
@end

@implementation OFNotificationCenter
+ (void)initialize
{
	if (self != [OFNotificationCenter class])
		return;

	defaultCenter = [[OFDefaultNotificationCenter alloc] init];
}

+ (OFNotificationCenter *)defaultCenter
{
	return defaultCenter;
}

- (instancetype)init
{
	self = [super init];

	@try {
#ifdef OF_HAVE_THREADS
		_mutex = [[OFMutex alloc] init];
#endif
		_notifications = [[OFMutableDictionary alloc] init];
	} @catch (id e) {
		[self release];
		@throw e;
	}

	return self;
}

- (void)dealloc
{
#ifdef OF_HAVE_THREADS
	[_mutex release];
#endif
	[_notifications release];

	[super dealloc];
}

- (void)addObserver: (id)observer
	   selector: (SEL)selector
	       name: (OFNotificationName)name
	     object: (id)object
{
	void *pool = objc_autoreleasePoolPush();
	OFNotificationHandler *handler = [[[OFNotificationHandler alloc]
	    initWithObserver: observer
		    selector: selector
		      object: object] autorelease];

#ifdef OF_HAVE_THREADS
	[_mutex lock];
	@try {
#endif
		OFMutableSet *notificationsForName =
		    [_notifications objectForKey: name];

		if (notificationsForName == nil) {
			notificationsForName = [OFMutableSet set];
			[_notifications setObject: notificationsForName
					   forKey: name];
		}

		[notificationsForName addObject: handler];
#ifdef OF_HAVE_THREADS
	} @finally {
		[_mutex unlock];
	}
#endif

	objc_autoreleasePoolPop(pool);
}

- (void)removeObserver: (id)observer
	      selector: (SEL)selector
		  name: (OFNotificationName)name
		object: (id)object
{
	void *pool = objc_autoreleasePoolPush();
	OFNotificationHandler *handler = [[[OFNotificationHandler alloc]
	    initWithObserver: observer
		    selector: selector
		      object: object] autorelease];

#ifdef OF_HAVE_THREADS
	[_mutex lock];
	@try {
#endif
		[[_notifications objectForKey: name] removeObject: handler];
#ifdef OF_HAVE_THREADS
	} @finally {
		[_mutex unlock];
	}
#endif

	objc_autoreleasePoolPop(pool);
}

- (void)postNotification: (OFNotification *)notification
{
	void *pool = objc_autoreleasePoolPush();
	OFMutableArray *matchedHandlers = [OFMutableArray array];

#ifdef OF_HAVE_THREADS
	[_mutex lock];
	@try {
#endif
		for (OFNotificationHandler *handler in
		    [_notifications objectForKey: notification.name])
			if (handler->_object == nil ||
			    handler->_object == notification.object)
				[matchedHandlers addObject: handler];
#ifdef OF_HAVE_THREADS
	} @finally {
		[_mutex unlock];
	}
#endif

	for (OFNotificationHandler *handler in matchedHandlers) {
		void (*callback)(id, SEL, OFNotification *) =
		    (void (*)(id, SEL, OFNotification *))
		    [handler->_observer methodForSelector: handler->_selector];

		callback(handler->_observer, handler->_selector, notification);
	}

	objc_autoreleasePoolPop(pool);
}
@end

@implementation OFDefaultNotificationCenter
- (instancetype)autorelease
{
	return self;
}

- (instancetype)retain
{
	return self;
}

- (void)release
{
}

- (unsigned int)retainCount
{
	return OFMaxRetainCount;
}
@end