InterThreadMessaging.m

/*-*- Mode: ObjC; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4  -*-*/
/*
 * InterThreadMessaging -- InterThreadMessaging.m
 * Created by toby on Tue Jun 19 2001.
 *
 */

#import <pthread.h>
#import "InterThreadMessaging.h"
#import "KTLog.h"
#import "CKAbstractConnection.h" //for threading domain
@interface NSInvocation ( Connection )

+ (NSInvocation *)invocationWithSelector:(SEL)aSelector target:(id)aTarget arguments:(NSArray *)anArgumentArray;

@end


/* There are four types of messages that can be posted between threads: a
   notification to be posted to the default notification centre and selectors
   to be performed with a varying number of arguments.  (I was tempted to
   implement all three in terms of performSelector:withObject:withObject:
   and passing in nil for the empty arguments, but then it occurred to me
   that perhaps the receiver has overridden performSelector: and
   performSelector:withObject:.  So I think I must disambiguate between
   them all.) */

typedef enum ConnectionInterThreadMessageType ConnectionInterThreadMessageType;
enum ConnectionInterThreadMessageType
{
    kITMPostNotification = 1,
    kITMPerformSelector0Args,
    kITMPerformSelector1Args,
    kITMPerformSelector2Args
};


/* The message contents are carried between threads in this struct.  The
   struct is allocated in the sending thread and freed in the receiving thread.
   It is carried between the threads in an NSPortMessage - the NSPortMessage
   contains a single NSData argument, which is a wrapper around the pointer to
   this struct. */

typedef struct ConnectionInterThreadMessage
{
    ConnectionInterThreadMessageType type;
    union {
        NSNotification *notification;
        struct {
            SEL selector;
            id receiver;
            id arg1;
            id arg2;
        } sel;
    } data;
} ConnectionInterThreadMessage;

@interface NSObject (PrivateConnectionStuff)
- (void)postDelayedMessage:(NSNumber *)type 
					thread:(NSThread *)thread
			  notification:(NSNotification *)notification
				  selector:(SEL)selector
				  receiver:(id)receiver
					  arg1:(id)arg1
					  arg2:(id)arg2;
@end

@interface NSThread (ConnectionSecretStuff)
- (NSRunLoop *) runLoop;
- (void)delayPostingMessage:(ConnectionInterThreadMessage *)msg thread:(NSThread *)thread;
@end

/* Each thread is associated with an NSPort.  This port is used to deliver
   messages to the target thread. */

static NSMapTable *pThreadMessagePorts = NULL;
static NSMapTable *pThreadMessageLocks = NULL;
static pthread_mutex_t pGate = { 0 };

@interface ConnectionInterThreadManager : NSObject
+ (void) threadDied:(NSNotification *)notification;
+ (void) handlePortMessage:(NSPortMessage *)msg;

@end

static void
ConnectionCreateMessagePortForThread (NSThread *thread, NSRunLoop *runLoop)
{
    NSPort *port;

    assert(nil != thread);
    assert(nil != runLoop);
	if (!pThreadMessagePorts)
	{
		[ConnectionInterThreadManager class];
	}
    assert(NULL != pThreadMessagePorts);

    pthread_mutex_lock(&pGate);

    port = NSMapGet(pThreadMessagePorts, thread);
    if (nil == port) {
        port = [[NSPort allocWithZone:NULL] init];
        [port setDelegate:[ConnectionInterThreadManager class]];
        [port scheduleInRunLoop:runLoop forMode:NSDefaultRunLoopMode];
		[port scheduleInRunLoop:runLoop forMode:NSModalPanelRunLoopMode];
		NSLock *lock = [[NSRecursiveLock alloc] init];
        NSMapInsertKnownAbsent(pThreadMessagePorts, thread, port);
		NSMapInsertKnownAbsent(pThreadMessageLocks, thread, lock);
        /* Transfer ownership of this port to the map table. */
        [port release];
		[lock release];
    }

    pthread_mutex_unlock(&pGate);
}

static NSLock * ConnectionMessageLockForThread (NSThread *thread)
{
	assert (thread != nil);
	assert (pThreadMessageLocks != nil);
	NSLock *lock = nil;
	pthread_mutex_lock(&pGate);
    lock = NSMapGet(pThreadMessageLocks, thread);
    pthread_mutex_unlock(&pGate);
	return lock;
}

static NSPort *
ConnectionMessagePortForThread (NSThread *thread)
{
    NSPort *port = nil;

	if (!pThreadMessagePorts)
	{
		[ConnectionInterThreadManager class];
	}
    assert(NULL != pThreadMessagePorts);
	assert(nil != thread);
	
    pthread_mutex_lock(&pGate);
    port = NSMapGet(pThreadMessagePorts, thread);
    pthread_mutex_unlock(&pGate);

	if (nil == port)
	{
		ConnectionCreateMessagePortForThread(thread, [thread runLoop]);
		pthread_mutex_lock(&pGate);
		port = NSMapGet(pThreadMessagePorts, thread);
		pthread_mutex_unlock(&pGate);
	}
	
    if (nil == port) {
        [NSException raise:NSInvalidArgumentException
                     format:@"Thread %@ is not prepared to receive "
                            @"inter-thread messages.  You must invoke "
                            @"+prepareForConnectionInterThreadMessages first.", thread];
    }

    return port;
}

static void
ConnectionRemoveMessagePortForThread (NSThread *thread, NSRunLoop *runLoop)
{
    NSPort *port;

    assert(nil != thread);
	if (!pThreadMessagePorts)
	{
		[ConnectionInterThreadManager class];
	}
    assert(NULL != pThreadMessagePorts);

    pthread_mutex_lock(&pGate);
    
    port = (NSPort *) NSMapGet(pThreadMessagePorts, thread);
    if (nil != port) {
        [port removeFromRunLoop:runLoop forMode:NSDefaultRunLoopMode];
        NSMapRemove(pThreadMessagePorts, thread);
    }
	NSMapRemove(pThreadMessageLocks, thread);

    pthread_mutex_unlock(&pGate);
}

@implementation NSThread (ConnectionInterThreadMessaging)

+ (void) prepareForConnectionInterThreadMessages
{
    /* Force the class initialization. */
    [ConnectionInterThreadManager class];

    ConnectionCreateMessagePortForThread([NSThread currentThread],
                               [NSRunLoop currentRunLoop]);
}

@end

@implementation ConnectionInterThreadManager

+ (void) initialize
{
    /* Create the mutex - this should be invoked by the Objective-C runtime
       (in a thread-safe manner) before any one can use this module, so I
       don't think I need to worry about race conditions here. */
    if (nil == pThreadMessagePorts) {
        pthread_mutex_init(&pGate, NULL);

        pThreadMessagePorts =
            NSCreateMapTable(NSNonRetainedObjectMapKeyCallBacks,
                             NSObjectMapValueCallBacks, 0);
		pThreadMessageLocks = NSCreateMapTable(NSNonRetainedObjectMapKeyCallBacks,
											   NSObjectMapValueCallBacks, 0);

        [[NSNotificationCenter defaultCenter]
            addObserver:[self class]
            selector:@selector(threadDied:)
            name:NSThreadWillExitNotification
            object:nil];
    }
}

+ (void) threadDied:(NSNotification *)notification
{
    NSThread *thread;
    NSRunLoop *runLoop;

    thread = [notification object];
    runLoop = [thread runLoop];
    if (nil != runLoop) {
        ConnectionRemoveMessagePortForThread(thread, [thread runLoop]);
    }
}

+ (void) handlePortMessage:(NSPortMessage *)portMessage
{
    ConnectionInterThreadMessage *msg;
    NSArray *components;
    NSData *data;

    components = [portMessage components];
    assert(1 == [components count]);

    data = [components objectAtIndex:0];
    msg = *((ConnectionInterThreadMessage **) [data bytes]);
    
    switch (msg->type)
    {
        case kITMPostNotification:
            [[NSNotificationCenter defaultCenter]
                postNotification:msg->data.notification];
            [msg->data.notification release];
            break;

        case kITMPerformSelector0Args:
            [msg->data.sel.receiver performSelector:msg->data.sel.selector withObject:nil afterDelay:0.0];
            [msg->data.sel.receiver release];
            break;

        case kITMPerformSelector1Args:
            [msg->data.sel.receiver performSelector:msg->data.sel.selector
                                    withObject:msg->data.sel.arg1
										 afterDelay:0.0];
            [msg->data.sel.receiver release];
            [msg->data.sel.arg1 release];
            break;

        case kITMPerformSelector2Args:
            [msg->data.sel.receiver performSelector:msg->data.sel.selector
                                    withObject:msg->data.sel.arg1
                                    withObject:msg->data.sel.arg2];
            [msg->data.sel.receiver release];
            [msg->data.sel.arg1 release];
            [msg->data.sel.arg2 release];
            break;

        default:
            assert(0);
    }

    free(msg);
}

@end





static void
ConnectionPostMessage (ConnectionInterThreadMessage *message, NSThread *thread, NSDate *limitDate)
{
    NSPortMessage *portMessage;
    NSMutableArray *components;
    NSPort *port, *replyPort;
    NSData *data;
    BOOL retval;

    if (nil == thread) { thread = [NSThread currentThread]; }
    port = ConnectionMessagePortForThread(thread);
	replyPort = ConnectionMessagePortForThread([NSThread currentThread]);
    assert(nil != port);

    data = [[NSData alloc] initWithBytes:&message length:sizeof(void *)];
    components = [[NSMutableArray alloc] initWithObjects:&data count:1];
    portMessage = [[NSPortMessage alloc] initWithSendPort:port
                                         receivePort:replyPort
                                         components:components];

    if (nil == limitDate || [limitDate timeIntervalSinceNow] > 0 ) { limitDate = [NSDate dateWithTimeIntervalSinceNow:1.5]; }
	NSLock *ourLock = ConnectionMessageLockForThread([NSThread currentThread]);
	NSLock *receiverLock = ConnectionMessageLockForThread(thread);
	if (![ourLock tryLock])
	{
		[[NSThread currentThread] delayPostingMessage:message thread:thread];
		[portMessage release];
		[components release];
		[data release];
		return;
	}
	if (![receiverLock tryLock])
	{
		[ourLock unlock];
		[[NSThread currentThread] delayPostingMessage:message thread:thread];
		[portMessage release];
		[components release];
		[data release];
		return;
	}
	@try {
		retval = [portMessage sendBeforeDate:limitDate];
	}
    @catch (NSException *ex) {
		
	}
	@finally {
		if (!retval)
		{
			[[NSThread currentThread] delayPostingMessage:message thread:thread];
		}
		[ourLock unlock];
		[receiverLock unlock];
		[portMessage release];
		[components release];
		[data release];
	}
}

static void
ConnectionPerformSelector (ConnectionInterThreadMessageType type, SEL selector, id receiver,
                 id object1, id object2, NSThread *thread, NSDate *limitDate)
{
    ConnectionInterThreadMessage *msg;

    assert(NULL != selector);
    
    if (nil != receiver) {
        msg = (ConnectionInterThreadMessage *) malloc(sizeof(struct ConnectionInterThreadMessage));
        bzero(msg, sizeof(struct ConnectionInterThreadMessage));
        msg->type = type;
        msg->data.sel.selector = selector;
        msg->data.sel.receiver = [receiver retain];
        msg->data.sel.arg1 = [object1 retain];
        msg->data.sel.arg2 = [object2 retain];

        ConnectionPostMessage(msg, thread, limitDate);
    }
}

static void
ConnectionPostNotification (NSNotification *notification, NSThread *thread,
                  NSDate *limitDate)
{
    ConnectionInterThreadMessage *msg;

    assert(nil != notification);
    
    msg = (ConnectionInterThreadMessage *) malloc(sizeof(struct ConnectionInterThreadMessage));
    bzero(msg, sizeof(struct ConnectionInterThreadMessage));
    msg->type = kITMPostNotification;
    msg->data.notification = [notification retain];

    ConnectionPostMessage(msg, thread, limitDate);
}

@implementation NSObject (ConnectionInterThreadMessaging)

- (void)postDelayedMessage:(NSNumber *)type 
					thread:(NSThread *)thread
			  notification:(NSNotification *)notification
				  selector:(SEL)selector
				  receiver:(id)receiver
					  arg1:(id)arg1
					  arg2:(id)arg2
{
	KTLog(CKThreadingDomain, KTLogDebug, @"resending delayed message: %@ to %@", NSStringFromSelector(selector), receiver);
	ConnectionInterThreadMessage *msg = (ConnectionInterThreadMessage *) malloc(sizeof(struct ConnectionInterThreadMessage));
	bzero(msg, sizeof(struct ConnectionInterThreadMessage));
	// we have already retained our args from the initial creation of the msg
	switch([type unsignedIntValue])
	{
		case kITMPostNotification:
			msg->type = kITMPostNotification;
			msg->data.notification = notification;
			break;
		case kITMPerformSelector0Args:
			msg->type = kITMPerformSelector0Args;
			msg->data.sel.receiver = receiver;
			msg->data.sel.selector = selector;
			msg->data.sel.arg1 = nil;
			msg->data.sel.arg2 = nil;
			break;
		case kITMPerformSelector1Args:
			msg->type = kITMPerformSelector1Args;
			msg->data.sel.receiver = receiver;
			msg->data.sel.selector = selector;
			msg->data.sel.arg1 = arg1;
			msg->data.sel.arg2 = nil;
			break;
		case kITMPerformSelector2Args:
			msg->type = kITMPerformSelector2Args;
			msg->data.sel.receiver = receiver;
			msg->data.sel.selector = selector;
			msg->data.sel.arg1 = arg1;
			msg->data.sel.arg2 = arg2;
			break;
		default:
			assert(0);
	}
	ConnectionPostMessage(msg, thread, nil);
}

- (void)delayPostingMessage:(ConnectionInterThreadMessage *)msg thread:(NSThread *)thread
{
	KTLog(CKThreadingDomain, KTLogDebug, @"delaying message: %@ to %@", NSStringFromSelector(msg->data.sel.selector), msg->data.sel.receiver);
	NSInvocation *inv = [NSInvocation invocationWithSelector:@selector(postDelayedMessage:thread:notification:selector:receiver:arg1:arg2:)
													  target:self
												   arguments:[NSArray array]];
	NSNumber *type = [NSNumber numberWithUnsignedInt:msg->type];
	[inv setArgument:&type atIndex:2];
	[inv setArgument:&thread atIndex:3];
	if (msg->type == kITMPostNotification)
	{
		[inv setArgument:&msg->data.notification atIndex:4];
	}
	else
	{
		[inv setArgument:&msg->data.sel.selector atIndex:5];
		[inv setArgument:&msg->data.sel.receiver atIndex:6];
		if (msg->data.sel.arg1)
			[inv setArgument:&msg->data.sel.arg1 atIndex:7];
		if (msg->data.sel.arg2)
			[inv setArgument:&msg->data.sel.arg2 atIndex:8];
	}
	[inv retainArguments];
	[inv performSelector:@selector(invoke) withObject:nil afterDelay:0.0];
	
	free(msg);
}

- (void) performSelector:(SEL)selector
         inThread:(NSThread *)thread
{
    ConnectionPerformSelector(kITMPerformSelector0Args, selector, self, nil, nil,
                    thread, nil);
}

- (void) performSelector:(SEL)selector
         inThread:(NSThread *)thread
         beforeDate:(NSDate *)limitDate
{
    ConnectionPerformSelector(kITMPerformSelector0Args, selector, self, nil, nil,
                    thread, limitDate);
}

- (void) performSelector:(SEL)selector
         withObject:(id)object
         inThread:(NSThread *)thread
{
    ConnectionPerformSelector(kITMPerformSelector1Args, selector, self, object, nil,
                    thread, nil);
}

- (void) performSelector:(SEL)selector
         withObject:(id)object
         inThread:(NSThread *)thread
         beforeDate:(NSDate *)limitDate
{
    ConnectionPerformSelector(kITMPerformSelector1Args, selector, self, object, nil,
                    thread, limitDate);
}

- (void) performSelector:(SEL)selector
         withObject:(id)object1
         withObject:(id)object2
         inThread:(NSThread *)thread
{
    ConnectionPerformSelector(kITMPerformSelector2Args, selector, self, object1, object2,
                    thread, nil);
}

- (void) performSelector:(SEL)selector
         withObject:(id)object1
         withObject:(id)object2
         inThread:(NSThread *)thread
         beforeDate:(NSDate *)limitDate
{
    ConnectionPerformSelector(kITMPerformSelector2Args, selector, self, object1, object2,
                    thread, limitDate);
}

@end



@implementation NSNotificationCenter (ConnectionInterThreadMessaging)

- (void) postNotification:(NSNotification *)notification
         inThread:(NSThread *)thread
{
    ConnectionPostNotification(notification, thread, nil);
}

- (void) postNotification:(NSNotification *)notification
         inThread:(NSThread *)thread
         beforeDate:(NSDate *)limitDate
{
    ConnectionPostNotification(notification, thread, limitDate);
}

- (void) postNotificationName:(NSString *)name
         object:(id)object
         inThread:(NSThread *)thread
{
    NSNotification *notification;
    
    notification = [NSNotification notificationWithName:name
                                   object:object
                                   userInfo:nil];
    ConnectionPostNotification(notification, thread, nil);
}

- (void) postNotificationName:(NSString *)name
         object:(id)object
         inThread:(NSThread *)thread
         beforeDate:(NSDate *)limitDate
{
    NSNotification *notification;
    
    notification = [NSNotification notificationWithName:name
                                   object:object
                                   userInfo:nil];
    ConnectionPostNotification(notification, thread, limitDate);
}

- (void) postNotificationName:(NSString *)name
         object:(id)object
         userInfo:(NSDictionary *)userInfo
         inThread:(NSThread *)thread
{
    NSNotification *notification;
    
    notification = [NSNotification notificationWithName:name
                                   object:object
                                   userInfo:userInfo];
    ConnectionPostNotification(notification, thread, nil);
}

- (void) postNotificationName:(NSString *)name
         object:(id)object
         userInfo:(NSDictionary *)userInfo
         inThread:(NSThread *)thread
         beforeDate:(NSDate *)limitDate
{
    NSNotification *notification;
    
    notification = [NSNotification notificationWithName:name
                                   object:object
                                   userInfo:userInfo];
    ConnectionPostNotification(notification, thread, limitDate);
}

@end

@implementation NSInvocation ( Connection )

+ (NSInvocation *)invocationWithSelector:(SEL)aSelector target:(id)aTarget arguments:(NSArray *)anArgumentArray
{
    NSMethodSignature *methodSignature = [aTarget methodSignatureForSelector:aSelector];
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:methodSignature];
    if ( nil != invocation )
    {
        [invocation setSelector:aSelector];
		if (nil != aTarget)
		{
			[invocation setTarget:aTarget];
		}
        if ( (nil != anArgumentArray) && ([anArgumentArray count] > 0) )
        {
            NSEnumerator *e = [anArgumentArray objectEnumerator];
            id argument;
            int argumentIndex = 2; // arguments start at index 2 per NSInvocation.h
            while ( argument = [e nextObject] )
            {
                if ( [argument isMemberOfClass:[NSNull class]] )
                {
                    [invocation setArgument:nil atIndex:argumentIndex];
                }
                else
                {
                    [invocation setArgument:&argument atIndex:argumentIndex];
                }
                argumentIndex++;
            }
            [invocation retainArguments];
        }
    }
	
    return invocation;
}

@end