1 files changed, 195 insertions, 51 deletions

diff --git a/Foundation/GTMNSThread+Blocks.m b/Foundation/GTMNSThread+Blocks.m
index e754f6f..8318193 100644
--- a/Foundation/GTMNSThread+Blocks.m
+++ b/Foundation/GTMNSThread+Blocks.m
@@ -53,76 +53,220 @@
 
 #endif  // NS_BLOCKS_AVAILABLE
 
-@implementation GTMSimpleWorkerThread {
-  NSLock *sourceLock_;
-  CFRunLoopSourceRef source_;  // Protected by sourceLock_
-  CFRunLoopRef cfRunLoop_;
-}
+enum {
+  kGTMSimpleThreadInitialized = 0,
+  kGTMSimpleThreadStarting,
+  kGTMSimpleThreadRunning,
+  kGTMSimpleThreadCancel,
+  kGTMSimpleThreadFinished,
+};
+
+@implementation GTMSimpleWorkerThread
 
-static void RunLoopContextEmptyFunc(void *info) {
-  // Empty because the source is used solely for signalling.
-  // The documentation for CFRunLoopSourceContext does not
-  // make it clear if you can have a null perform method.
+- (id)init {
+  if ((self = [super init])) {
+    runLock_ =
+        [[NSConditionLock alloc] initWithCondition:kGTMSimpleThreadInitialized];
+  }
+  return self;
 }
 
-- (void)main {
-  NSRunLoop *nsRunLoop = [NSRunLoop currentRunLoop];
-  {  // Braces are just to denote what is protected by sourceLock_
-    [sourceLock_ lock];
-    cfRunLoop_ = [nsRunLoop getCFRunLoop];
-    CFRetain(cfRunLoop_);
-    CFRunLoopSourceContext context = {0};
-    context.perform = RunLoopContextEmptyFunc;
-    source_ = CFRunLoopSourceCreate(NULL, 0, &context);
-    CFRunLoopAddSource(cfRunLoop_, source_, kCFRunLoopCommonModes);
-    [sourceLock_ unlock];
+- (void)dealloc {
+  if ([self isExecuting]) {
+    [self stop];
   }
-  while (true) {
-    BOOL cancelled = [self isCancelled];
-    if (cancelled) {
-      break;
-    }
-    BOOL ranLoop = [nsRunLoop runMode:NSDefaultRunLoopMode
-                           beforeDate:[NSDate distantFuture]];
-    if (!ranLoop) {
-      break;
-    }
+  [runLock_ release];
+  [super dealloc];
+}
+
+- (void)setThreadDebuggerName:(NSString *)name {
+  if ([name length]) {
+    pthread_setname_np([name UTF8String]);
+  } else {
+    pthread_setname_np("");
   }
 }
 
-- (void)dealloc {
-  if (cfRunLoop_) {
-    CFRelease(cfRunLoop_);
+- (void)main {
+  [runLock_ lock];
+  if ([runLock_ condition] != kGTMSimpleThreadStarting) {
+    // Don't start, we're already cancelled or we've been started twice.
+    [runLock_ unlock];
+    return;
   }
-  if (source_) {
-    CFRelease(source_);
+
+  // Give ourself an autopool
+  NSAutoreleasePool *localPool = [[NSAutoreleasePool alloc] init];
+
+  // Expose the current runloop so other threads can stop (but see caveat
+  // below).
+  NSRunLoop *loop = [NSRunLoop currentRunLoop];
+  runLoop_ = [loop getCFRunLoop];
+  if (runLoop_) CFRetain(runLoop_);  // NULL check is pure paranoia.
+
+  // Add a port to the runloop so that it stays alive. Without a port attached
+  // to it, a runloop will immediately return when you call run on it.
+  [loop addPort:[NSPort port] forMode:NSDefaultRunLoopMode];
+
+  // Name ourself
+  [self setThreadDebuggerName:[self name]];
+
+  // We're officially running.
+  [runLock_ unlockWithCondition:kGTMSimpleThreadRunning];
+
+  while (![self isCancelled] &&
+         [runLock_ tryLockWhenCondition:kGTMSimpleThreadRunning]) {
+    [runLock_ unlock];
+    // We can't control nesting of runloops, so we spin with a short timeout. If
+    // another thread cancels us the CFRunloopStop() we might get it right away,
+    // if there is no nesting, otherwise our timeout will still get us to exit
+    // in reasonable time.
+    [loop runMode:NSDefaultRunLoopMode
+         beforeDate:[NSDate dateWithTimeIntervalSinceNow:1.0]];
+    [localPool drain];
+    localPool = [[NSAutoreleasePool alloc] init];
   }
-  [super dealloc];
+
+  // Exit
+  [runLock_ lock];
+  [localPool drain];
+  if (runLoop_) CFRelease(runLoop_);
+  runLoop_ = NULL;
+  [runLock_ unlockWithCondition:kGTMSimpleThreadFinished];
 }
 
 - (void)start {
-  // Protect lock in case we are "started" twice in different threads.
-  // NSThread has no documentation regarding the safety of this, so
-  // making safe by default.
-  @synchronized (self) {
-    if (sourceLock_) {
-      return;
-    }
-    sourceLock_ = [[NSLock alloc] init];
+  // Before we start the thread we need to make sure its not already running
+  // and that the lock is past kGTMSimpleThreadInitialized so an immediate
+  // stop is safe.
+  [runLock_ lock];
+  if ([runLock_ condition] != kGTMSimpleThreadInitialized) {
+    [runLock_ unlock];
+    return;
   }
+  [runLock_ unlockWithCondition:kGTMSimpleThreadStarting];
   [super start];
 }
 
 - (void)cancel {
+  // NSThread appears to not propagate [... isCancelled] to our thread in
+  // this subclass, so we'll let super know and then use our condition lock.
   [super cancel];
-  {  // Braces are just to denote what is protected by sourceLock_
-    [sourceLock_ lock];
-    if (source_) {
-      CFRunLoopSourceSignal(source_);
-      CFRunLoopWakeUp(cfRunLoop_);
-    }
-    [sourceLock_ unlock];
+  [runLock_ lock];
+  switch ([runLock_ condition]) {
+    case kGTMSimpleThreadInitialized:
+    case kGTMSimpleThreadStarting:
+      // Cancelled before we started? Transition straight to finished.
+      [runLock_ unlockWithCondition:kGTMSimpleThreadFinished];
+      return;
+    case kGTMSimpleThreadRunning:
+      // If the thread has exited without changing lock state we detect that
+      // here. Note this is a direct call to [super isExecuting] to prevent
+      // deadlock on |runLock_| in [self isExecuting].
+      if (![super isExecuting]) {
+        // Thread died in some unanticipated way, clean up on its behalf.
+        if (runLoop_) {
+          CFRelease(runLoop_);
+          runLoop_ = NULL;
+        }
+        [runLock_ unlockWithCondition:kGTMSimpleThreadFinished];
+        return;
+      } else {
+        // We need to cancel the running loop. We'd like to stop the runloop
+        // right now if we can (but see the caveat above about nested runloops).
+        if (runLoop_) CFRunLoopStop(runLoop_);
+        [runLock_ unlockWithCondition:kGTMSimpleThreadCancel];
+        return;
+      }
+    case kGTMSimpleThreadCancel:
+    case kGTMSimpleThreadFinished:
+      // Already cancelled or finished. There's an outside chance the thread
+      // will have died now (imagine a [... dealloc] that calls pthread_exit())
+      // but we'll ignore those cases.
+      [runLock_ unlock];
+      return;
+  }
+}
+
+- (void)stop {
+  // Cancel does the heavy lifting...
+  [self cancel];
+
+  // If we're the current thread then the stop was called from within our
+  // own runloop and we need to return control now. [... main] will handle
+  // the shutdown on its own.
+  if ([[NSThread currentThread] isEqual:self]) return;
+
+  // From all other threads block till we're finished. Note that [... cancel]
+  // handles ensuring we will either already be in this state or transition
+  // there after thread exit.
+  [runLock_ lockWhenCondition:kGTMSimpleThreadFinished];
+  [runLock_ unlock];
+
+  // We could still be waiting for thread teardown at this point (lock is in
+  // the right state, but thread is not quite torn down), so spin till we say
+  // execution is complete (our implementation checks superclass).
+  while ([self isExecuting]) {
+    usleep(10);
+  }
+}
+
+- (void)setName:(NSString *)name {
+  if ([self isExecuting]) {
+    [self performSelector:@selector(setThreadDebuggerName:)
+                 onThread:self
+               withObject:name
+            waitUntilDone:YES];
+  }
+  [super setName:name];
+}
+
+- (BOOL)isCancelled {
+  if ([super isCancelled]) return YES;
+  BOOL cancelled = NO;
+  [runLock_ lock];
+  if ([runLock_ condition] == kGTMSimpleThreadCancel) {
+    cancelled = YES;
+  }
+  [runLock_ unlock];
+  return cancelled;
+}
+
+- (BOOL)isExecuting {
+  if ([super isExecuting]) return YES;
+  [runLock_ lock];
+  switch ([runLock_ condition]) {
+    case kGTMSimpleThreadStarting:
+      // While starting we may not be executing yet, but we'll pretend we are.
+      [runLock_ unlock];
+      return YES;
+    case kGTMSimpleThreadCancel:
+    case kGTMSimpleThreadRunning:
+      // Both of these imply we're running, but [super isExecuting] failed,
+      // so the thread died for other reasons. Clean up.
+      if (runLoop_) {
+        CFRelease(runLoop_);
+        runLoop_ = NULL;
+      }
+      [runLock_ unlockWithCondition:kGTMSimpleThreadFinished];
+      break;
+    default:
+      [runLock_ unlock];
+      break;
+  }
+  return NO;
+}
+
+- (BOOL)isFinished {
+  if ([super isFinished]) return YES;
+  if ([self isExecuting]) return NO;  // Will clean up dead thread.
+  BOOL finished = NO;
+  [runLock_ lock];
+  if ([runLock_ condition] == kGTMSimpleThreadFinished) {
+    finished = YES;
   }
+  [runLock_ unlock];
+  return finished;
 }
 
 @end