Foundation/GTMNSThread+Blocks.m

//
//  GTMNSThread+Blocks.m
//
//  Copyright 2012 Google Inc.
//
//  Licensed under the Apache License, Version 2.0 (the "License"); you may not
//  use this file except in compliance with the License.  You may obtain a copy
//  of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
//  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
//  License for the specific language governing permissions and limitations
//  under the License.
//

#import "GTMNSThread+Blocks.h"

#import <pthread.h>
#import <dlfcn.h>

#if NS_BLOCKS_AVAILABLE

@implementation NSThread (GTMBlocksAdditions)

+ (void)gtm_runBlockOnCurrentThread:(void (^)(void))block {
  block();
}

- (void)gtm_performBlock:(void (^)(void))block {
  if ([[NSThread currentThread] isEqual:self]) {
    block();
  } else {
    [self gtm_performWaitingUntilDone:NO block:block];
  }
}

- (void)gtm_performWaitingUntilDone:(BOOL)waitDone block:(void (^)(void))block {
  [NSThread performSelector:@selector(gtm_runBlockOnCurrentThread:)
                   onThread:self
                 withObject:[[block copy] autorelease]
              waitUntilDone:waitDone];
}

+ (void)gtm_performBlockInBackground:(void (^)(void))block {
  [NSThread performSelectorInBackground:@selector(gtm_runBlockOnCurrentThread:)
                             withObject:[[block copy] autorelease]];
}

@end

#endif  // NS_BLOCKS_AVAILABLE

@implementation GTMSimpleWorkerThread

- (void)main {
  NSRunLoop *nsRunLoop = [NSRunLoop currentRunLoop];
  // According to the NSRunLoop docs, a port must be added to the
  // runloop to keep the loop alive, otherwise when you call
  // runMode:beforeDate: it will immediately return with NO. We never
  // send anything over this port, it's only here to keep the run loop
  // looping.
  [nsRunLoop addPort:[NSPort port] forMode:NSDefaultRunLoopMode];
  while (true) {
    if (self.isCancelled) {
      break;
    }
    BOOL ranLoop = [nsRunLoop runMode:NSDefaultRunLoopMode
                           beforeDate:[NSDate distantFuture]];
    if (!ranLoop) {
      break;
    }
  }
}

- (void)cancel {
  [super cancel];
  if (![[NSThread currentThread] isEqual:self]) {
    // This call just forces the runloop in main to spin allowing main to see
    // that the isCancelled flag has been set. Note that this is only really
    // needed if there are no blocks/selectors in the queue for the thread. If
    // there are other items to be processed in the queue, the next one will be
    // executed and then the "cancel" will be seen in main, and it will exit
    // (and the other blocks will be dropped).
    [self performSelector:@selector(class)
                 onThread:self
               withObject:nil
            waitUntilDone:NO];
  }
}

- (void)stop {
  if ([[NSThread currentThread] isEqual:self]) {
    [super cancel];
  } else {
    // This call forces the runloop in main to spin allowing main to see that
    // the isCancelled flag has been set. Note that we explicitly want to send
    // it to the thread to process so it is added to the end of the queue of
    // blocks to be processed. 'stop' guarantees that all items in the queue
    // will be processed before it ends.
    [self performSelector:@selector(cancel)
                 onThread:self
               withObject:nil
            waitUntilDone:YES];
    while (![self isFinished] || [self isExecuting]) {
      // Spin until the thread is really done.
      usleep(10);
    }
  }
}

@end