talk/base/maccocoathreadhelper.mm

/*
 * libjingle
 * Copyright 2007, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
// Helper function for using Cocoa with Posix threading.

#import <assert.h>
#import <Foundation/Foundation.h>

#import "talk/base/maccocoathreadhelper.h"

// A dummy thread object which essentially does nothing.
// This is used in InitCocoaMultiThreading method.
@interface DummyThreadObject : NSObject {
}

+ (void)dummyFunc:(NSObject*)obj;

@end

@implementation DummyThreadObject

+ (void)dummyFunc:(NSObject*)obj {
  // nothing to do
}

@end

namespace talk_base {

// Cocoa must be "put into multithreading mode" before Cocoa functionality can
// be used on POSIX threads. The way to do that is to spawn one thread that may
// immediately exit.
void InitCocoaMultiThreading() {
  if ([NSThread isMultiThreaded] == NO) {
    // The sole purpose of this autorelease pool is to avoid a console
    // message on Leopard that tells us we're autoreleasing the thread
    // with no autorelease pool in place; we can't set up an autorelease
    // pool before this, because this is executed from an initializer,
    // which is run before main.  This means we leak an autorelease pool,
    // and one thread, and if other objects are set up in initializers after
    // this they'll be silently added to this pool and never released.

    // Doing NSAutoreleasePool* hack = [[NSAutoreleasePool alloc] init];
    // causes unused variable error.
    NSAutoreleasePool* hack;
    hack = [[NSAutoreleasePool alloc] init];
    [NSThread detachNewThreadSelector:@selector(dummyFunc:)
                             toTarget:[DummyThreadObject class]
                           withObject:nil];
  }

  assert([NSThread isMultiThreaded]);
}

}  // namespace talk_base