1 /*

     2  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.

     3  *

     4  * Redistribution and use in source and binary forms, with or without

     5  * modification, are permitted provided that the following conditions

     6  * are met:

     7  *

     8  * 1.  Redistributions of source code must retain the above copyright

     9  *     notice, this list of conditions and the following disclaimer.

    10  * 2.  Redistributions in binary form must reproduce the above copyright

    11  *     notice, this list of conditions and the following disclaimer in the

    12  *     documentation and/or other materials provided with the distribution.

    13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of

    14  *     its contributors may be used to endorse or promote products derived

    15  *     from this software without specific prior written permission.

    16  *

    17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY

    18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

    19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

    20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

    21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

    22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

    23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

    24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

    25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

    26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    27  */

    28 

    29 #import "WebNSObjectExtras.h"

    30 

    31 #import <wtf/Assertions.h>

    32 

    33 @interface WebMainThreadInvoker : NSProxy

    34 {

    35     id target;

    36     id exception;

    37 }

    38 @end

    39 

    40 static bool returnTypeIsObject(NSInvocation *invocation)

    41 {

    42     // Could use either _C_ID or NSObjCObjectType, but it seems that neither is

    43     // both available and non-deprecated on all versions of Mac OS X we support.

    44     return strchr([[invocation methodSignature] methodReturnType], '@');

    45 }

    46 

    47 @implementation WebMainThreadInvoker

    48 

    49 - (id)initWithTarget:(id)passedTarget

    50 {

    51     target = passedTarget;

    52     return self;

    53 }

    54 

    55 - (void)forwardInvocation:(NSInvocation *)invocation

    56 {

    57     [invocation setTarget:target];

    58     [invocation performSelectorOnMainThread:@selector(_webkit_invokeAndHandleException:) withObject:self waitUntilDone:YES];

    59     if (exception) {

    60         id exceptionToThrow = [exception autorelease];

    61         exception = nil;

    62         @throw exceptionToThrow;

    63     } else if (returnTypeIsObject(invocation)) {

    64         // _webkit_invokeAndHandleException retained the return value on the main thread.

    65         // Now autorelease it on the calling thread.

    66         id returnValue;

    67         [invocation getReturnValue:&returnValue];

    68         [returnValue autorelease];

    69     }

    70 }

    71 

    72 - (NSMethodSignature *)methodSignatureForSelector:(SEL)selector

    73 {

    74     return [target methodSignatureForSelector:selector];

    75 }

    76 

    77 - (void)handleException:(id)passedException

    78 {

    79     ASSERT(!exception);

    80     exception = [passedException retain];

    81 }

    82 

    83 @end

    84 

    85 @implementation NSInvocation (WebMainThreadInvoker)

    86 

    87 - (void)_webkit_invokeAndHandleException:(WebMainThreadInvoker *)exceptionHandler

    88 {

    89     @try {

    90         [self invoke];

    91     } @catch (id exception) {

    92         [exceptionHandler handleException:exception];

    93         return;

    94     }

    95     if (returnTypeIsObject(self)) {

    96         // Retain the return value on the main thread.

    97         // -[WebMainThreadInvoker forwardInvocation:] will autorelease it on the calling thread.

    98         id value;

    99         [self getReturnValue:&value];

   100         [value retain];

   101     }

   102 }

   103 

   104 @end

   105 

   106 @implementation NSObject (WebNSObjectExtras)

   107 

   108 + (id)_webkit_invokeOnMainThread

   109 {

   110     return [[[WebMainThreadInvoker alloc] initWithTarget:self] autorelease];

   111 }

   112 

   113 - (id)_webkit_invokeOnMainThread

   114 {

   115     return [[[WebMainThreadInvoker alloc] initWithTarget:self] autorelease];

   116 }

   117 

   118 @end