[Author: aharper]

Improve worker thread implementation:
- Handle more of the NSThread interface.
- Allow cancel or stop before we've started.
- Cache looked up pthread_setname_np symbol in thread local storage.

R=dmaclach,thomasvl
APPROVED=dmaclach
DELTA=441  (339 added, 38 deleted, 64 changed)

3 files changed, 391 insertions, 90 deletions

diff --git a/Foundation/GTMNSThread+Blocks.h b/Foundation/GTMNSThread+Blocks.h
index b5df094..23e4e60 100644
--- a/Foundation/GTMNSThread+Blocks.h
+++ b/Foundation/GTMNSThread+Blocks.h
@@ -50,8 +50,9 @@
   NSConditionLock *runLock_;
 }
 
-// Will stop the thread.
+// Will stop the thread, blocking till the thread exits.
 - (void)stop;
+
 @end
 
 #endif  // GTM_IPHONE_SDK || (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5)
diff --git a/Foundation/GTMNSThread+Blocks.m b/Foundation/GTMNSThread+Blocks.m
index f835a0b..7b38f61 100644
--- a/Foundation/GTMNSThread+Blocks.m
+++ b/Foundation/GTMNSThread+Blocks.m
@@ -22,7 +22,8 @@
 #import <dlfcn.h>
 
 // Only available 10.6 and later.
-typedef int (*pthread_setname_np_Ptr)(const char*);
+typedef int (*PThreadSetNameNPPTr)(const char*);
+static PThreadSetNameNPPTr gPThreadSetNameNP = NULL;
 
 #if NS_BLOCKS_AVAILABLE
 
@@ -59,63 +60,163 @@ typedef int (*pthread_setname_np_Ptr)(const char*);
 #if GTM_IPHONE_SDK || (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5)
 
 enum {
-  GTMSimpleThreadIsStarting = 1,
-  GTMSimpleThreadIsFinished
+  kGTMSimpleThreadInitialized = 0,
+  kGTMSimpleThreadStarting,
+  kGTMSimpleThreadRunning,
+  kGTMSimpleThreadCancel,
+  kGTMSimpleThreadFinished,
 };
 
 @implementation GTMSimpleWorkerThread
 
++ (void)initialize {
+  if ([self class] == [GTMSimpleWorkerThread class]) {
+    // Resolve pthread_setname_np() on 10.6 and later.
+    gPThreadSetNameNP = dlsym(RTLD_DEFAULT, "pthread_setname_np");
+  }
+}
+
 - (id)init {
   if ((self = [super init])) {
     runLock_ =
-        [[NSConditionLock alloc] initWithCondition:GTMSimpleThreadIsStarting];
+        [[NSConditionLock alloc] initWithCondition:kGTMSimpleThreadInitialized];
   }
   return self;
 }
 
 - (void)dealloc {
+  if ([self isExecuting]) {
+    [self stop];
+  }
   [runLock_ release];
   [super dealloc];
 }
 
 - (void)setThreadDebuggerName:(NSString *)name {
-  // [NSThread setName:] doesn't actually set the name in such a way that the
-  // debugger can see it. So we handle it here instead.
-  // pthread_setname_np only available 10.6 and later, look up dynamically.
-  pthread_setname_np_Ptr setName = dlsym(RTLD_DEFAULT, "pthread_setname_np");
-  if (!setName) return;
-  setName([name UTF8String]);
+  if (gPThreadSetNameNP) gPThreadSetNameNP([name UTF8String]);
 }
 
 - (void)main {
-  _GTMDevAssert([runLock_ condition] == GTMSimpleThreadIsStarting,
-                @"Bad start condition %d", [runLock_ condition]);
-  [runLock_ lockWhenCondition:GTMSimpleThreadIsStarting];
-  
-  [self setThreadDebuggerName:[self name]];
+  [runLock_ lock];
+  if ([runLock_ condition] != kGTMSimpleThreadStarting) {
+    // Don't start, we're already cancelled or we've been started twice.
+    [runLock_ unlock];
+    return;
+  }
+
+  // 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.
-  NSPort *tempPort = [NSPort port];
-  NSRunLoop *loop = [NSRunLoop currentRunLoop];
-  [loop addPort:tempPort forMode:NSDefaultRunLoopMode];
+  [loop addPort:[NSPort port] forMode:NSDefaultRunLoopMode];
 
-  // Run the loop using CFRunLoopRun because [NSRunLoop run] will sometimes nest
-  // runloops making it impossible to stop.
-  runLoop_ = [loop getCFRunLoop];
-  CFRunLoopRun();
-  [runLock_ unlockWithCondition:GTMSimpleThreadIsFinished];
+  // 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];
+  }
+
+  // Exit
+  [runLock_ lock];
+  [localPool drain];
+  if (runLoop_) CFRelease(runLoop_);
+  runLoop_ = NULL;
+  [runLock_ unlockWithCondition:kGTMSimpleThreadFinished];
+}
+
+- (void)start {
+  // 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];
+  [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 {
-  CFRunLoopStop(runLoop_);
-  if (![[NSThread currentThread] isEqual:self]) {
-    // If we are calling stop from a separate thread, we block until the
-    // simple thread actually leaves the runloop so there is no race condition
-    // between the current thread and the simple thread. In effect it's a
-    // join operation.
-    [runLock_ lockWhenCondition:GTMSimpleThreadIsFinished];
-    [runLock_ unlockWithCondition:GTMSimpleThreadIsFinished];
+  // 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);
   }
 }
 
@@ -129,6 +230,54 @@ enum {
   [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
 
 #endif  // GTM_IPHONE_SDK || (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5)
diff --git a/Foundation/GTMNSThread+BlocksTest.m b/Foundation/GTMNSThread+BlocksTest.m
index e900b5b..606de6d 100644
--- a/Foundation/GTMNSThread+BlocksTest.m
+++ b/Foundation/GTMNSThread+BlocksTest.m
@@ -16,6 +16,7 @@
 //  under the License.
 //
 
+#import <pthread.h>
 #import "GTMSenTestCase.h"
 #import "GTMNSThread+Blocks.h"
 
@@ -25,90 +26,240 @@
 
 @interface GTMNSThread_BlocksTest : GTMTestCase {
  @private
-  NSThread *workerThread_;
-  BOOL workerRunning_;
+  GTMSimpleWorkerThread *workerThread_;
 }
-
-@property (nonatomic, readwrite, getter=isWorkerRunning) BOOL workerRunning;
 @end
 
 @implementation GTMNSThread_BlocksTest
 
-@synthesize workerRunning = workerRunning_;
-
-- (void)stopTestRunning:(GTMUnitTestingBooleanRunLoopContext *)context{
-  [context setShouldStop:YES];
+- (void)setUp {
+  workerThread_ = [[GTMSimpleWorkerThread alloc] init];
+  [workerThread_ start];
 }
 
-- (void)workerMain:(id)object {
-  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
-  while ([self isWorkerRunning]) {
-    [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
-                             beforeDate:[NSDate distantFuture]];
-  }
-  [pool drain];
+- (void)tearDown {
+  [workerThread_ stop];
+  [workerThread_ release];
 }
 
-- (void)killWorkerThread:(GTMUnitTestingBooleanRunLoopContext *)context {
-  [self setWorkerRunning:NO];
-  [context setShouldStop:YES];
+- (void)testPerformBlockOnCurrentThread {
+  NSThread *currentThread = [NSThread currentThread];
+
+  GTMUnitTestingBooleanRunLoopContext *context =
+      [GTMUnitTestingBooleanRunLoopContext context];
+  __block NSThread *runThread = nil;
+
+  // Straight block runs right away (no runloop spin)
+  runThread = nil;
+  [context setShouldStop:NO];
+  [currentThread gtm_performBlock:^{
+    runThread = [NSThread currentThread];
+    [context setShouldStop:YES];
+  }];
+  STAssertEqualObjects(runThread, currentThread, nil);
+  STAssertTrue([context shouldStop], nil);
+
+  // Block with waiting runs immediately as well.
+  runThread = nil;
+  [context setShouldStop:NO];
+  [currentThread gtm_performWaitingUntilDone:YES block:^{
+    runThread = [NSThread currentThread];
+    [context setShouldStop:YES];
+  }];
+  STAssertEqualObjects(runThread, currentThread, nil);
+  STAssertTrue([context shouldStop], nil);
+
+  // Block without waiting requires a runloop spin.
+  runThread = nil;
+  [context setShouldStop:NO];
+  [currentThread gtm_performWaitingUntilDone:NO block:^{
+    runThread = [NSThread currentThread];
+    [context setShouldStop:YES];
+  }];
+  STAssertTrue([[NSRunLoop currentRunLoop]
+                    gtm_runUpToSixtySecondsWithContext:context], nil);
+  STAssertEqualObjects(runThread, currentThread, nil);
+  STAssertTrue([context shouldStop], nil);
 }
 
-- (void)setUp {
-  [self setWorkerRunning:YES];
-  workerThread_ = [[NSThread alloc] initWithTarget:self
-                                          selector:@selector(workerMain:)
-                                            object:nil];
-  [workerThread_ start];
+- (void)testPerformBlockInBackground {
+  GTMUnitTestingBooleanRunLoopContext *context =
+      [GTMUnitTestingBooleanRunLoopContext context];
+  __block NSThread *runThread = nil;
+  [NSThread gtm_performBlockInBackground:^{
+    runThread = [NSThread currentThread];
+    [context setShouldStop:YES];
+  }];
+  STAssertTrue([[NSRunLoop currentRunLoop]
+                    gtm_runUpToSixtySecondsWithContext:context], nil);
+  STAssertNotNil(runThread, nil);
+  STAssertNotEqualObjects(runThread, [NSThread currentThread], nil);
 }
 
-- (void)tearDown {
-  GTMUnitTestingBooleanRunLoopContext *context
-      = [GTMUnitTestingBooleanRunLoopContext context];
-  [self performSelector:@selector(killWorkerThread:)
-               onThread:workerThread_
-             withObject:context
-          waitUntilDone:NO];
-  NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
-  STAssertTrue([runLoop gtm_runUpToSixtySecondsWithContext:context], nil);
-  [workerThread_ release];
+- (void)testWorkerThreadBasics {
+  // Unstarted worker isn't running.
+  GTMSimpleWorkerThread *worker = [[GTMSimpleWorkerThread alloc] init];
+  STAssertFalse([worker isExecuting], nil);
+  STAssertFalse([worker isFinished], nil);
+
+  // Unstarted worker can be stopped without error.
+  [worker stop];
+  STAssertFalse([worker isExecuting], nil);
+  STAssertTrue([worker isFinished], nil);
+
+  // And can be stopped again
+  [worker stop];
+  STAssertFalse([worker isExecuting], nil);
+  STAssertTrue([worker isFinished], nil);
+
+  // A thread we start can be stopped with correct state.
+  worker = [[GTMSimpleWorkerThread alloc] init];
+  STAssertFalse([worker isExecuting], nil);
+  STAssertFalse([worker isFinished], nil);
+  [worker start];
+  STAssertTrue([worker isExecuting], nil);
+  STAssertFalse([worker isFinished], nil);
+  [worker stop];
+  STAssertFalse([worker isExecuting], nil);
+  STAssertTrue([worker isFinished], nil);
+
+  // A cancel is also honored
+  worker = [[GTMSimpleWorkerThread alloc] init];
+  STAssertFalse([worker isExecuting], nil);
+  STAssertFalse([worker isFinished], nil);
+  [worker start];
+  STAssertTrue([worker isExecuting], nil);
+  STAssertFalse([worker isFinished], nil);
+  [worker cancel];
+  // And after some time we're done. We're generous here, this needs to
+  // exceed the worker thread's runloop timeout.
+  sleep(5);
+  STAssertFalse([worker isExecuting], nil);
+  STAssertTrue([worker isFinished], nil);
 }
 
-- (void)testPerformBlock {
-  NSThread *currentThread = [NSThread currentThread];
-  GTMUnitTestingBooleanRunLoopContext *context
-      = [GTMUnitTestingBooleanRunLoopContext context];
+- (void)testWorkerThreadStopTiming {
+  // Throw a sleep and make sure that we stop as soon as we can.
+  NSDate *start = [NSDate date];
+  NSConditionLock *threadLock = [[[NSConditionLock alloc] initWithCondition:0]
+                                    autorelease];
   [workerThread_ gtm_performBlock:^{
-    [self performSelector:@selector(stopTestRunning:)
-                 onThread:currentThread
-               withObject:context
-            waitUntilDone:YES];
+    [threadLock lock];
+    [threadLock unlockWithCondition:1];
+    sleep(10);
   }];
-  NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
-  STAssertTrue([runLoop gtm_runUpToSixtySecondsWithContext:context], nil);
+  [threadLock lockWhenCondition:1];
+  [threadLock unlock];
+  [workerThread_ stop];
+  STAssertFalse([workerThread_ isExecuting], nil);
+  STAssertTrue([workerThread_ isFinished], nil);
+  STAssertEqualsWithAccuracy(-[start timeIntervalSinceNow], 10.0, 2.0, nil);
 }
 
-- (void)testPerformBlockWaitUntilDone {
-  GTMUnitTestingBooleanRunLoopContext *context
-      = [GTMUnitTestingBooleanRunLoopContext context];
+- (void)testPerformBlockOnWorkerThread {
+  GTMUnitTestingBooleanRunLoopContext *context =
+      [GTMUnitTestingBooleanRunLoopContext context];
+  __block NSThread *runThread = nil;
+
+  // Runs on the other thread
+  runThread = nil;
+  [context setShouldStop:NO];
+  [workerThread_ gtm_performBlock:^{
+    runThread = [NSThread currentThread];
+    [context setShouldStop:YES];
+  }];
+  STAssertTrue([[NSRunLoop currentRunLoop]
+                    gtm_runUpToSixtySecondsWithContext:context], nil);
+  STAssertNotNil(runThread, nil);
+  STAssertEqualObjects(runThread, workerThread_, nil);
+
+  // Other thread no wait.
+  runThread = nil;
+  [context setShouldStop:NO];
+  [workerThread_ gtm_performWaitingUntilDone:NO block:^{
+    runThread = [NSThread currentThread];
+    [context setShouldStop:YES];
+  }];
+  STAssertTrue([[NSRunLoop currentRunLoop]
+                    gtm_runUpToSixtySecondsWithContext:context], nil);
+  STAssertNotNil(runThread, nil);
+  STAssertEqualObjects(runThread, workerThread_, nil);
+
+  // Waiting requires no runloop spin
+  runThread = nil;
+  [context setShouldStop:NO];
   [workerThread_ gtm_performWaitingUntilDone:YES block:^{
+    runThread = [NSThread currentThread];
     [context setShouldStop:YES];
   }];
   STAssertTrue([context shouldStop], nil);
+  STAssertNotNil(runThread, nil);
+  STAssertEqualObjects(runThread, workerThread_, nil);
 }
 
-- (void)testPerformBlockInBackground {
-  NSThread *currentThread = [NSThread currentThread];
-  GTMUnitTestingBooleanRunLoopContext *context
-      = [GTMUnitTestingBooleanRunLoopContext context];
-  [NSThread gtm_performBlockInBackground:^{
-    [self performSelector:@selector(stopTestRunning:)
-                 onThread:currentThread
-               withObject:context
-            waitUntilDone:YES];
+- (void)testExitingBlockIsExecuting {
+  NSConditionLock *threadLock = [[[NSConditionLock alloc] initWithCondition:0]
+                                    autorelease];
+  [workerThread_ gtm_performWaitingUntilDone:NO block:^{
+    [threadLock lock];
+    [threadLock unlockWithCondition:1];
+    pthread_exit(NULL);
+  }];
+  [threadLock lockWhenCondition:1];
+  [threadLock unlock];
+  // Give the pthread_exit() a bit of time
+  sleep(5);
+  // Did we notice the thread died? Does [... isExecuting] clean up?
+  STAssertFalse([workerThread_ isExecuting], nil);
+  STAssertTrue([workerThread_ isFinished], nil);
+}
+
+- (void)testExitingBlockCancel {
+  NSConditionLock *threadLock = [[[NSConditionLock alloc] initWithCondition:0]
+                                    autorelease];
+  [workerThread_ gtm_performWaitingUntilDone:NO block:^{
+    [threadLock lock];
+    [threadLock unlockWithCondition:1];
+    pthread_exit(NULL);
+  }];
+  [threadLock lockWhenCondition:1];
+  [threadLock unlock];
+  // Give the pthread_exit() a bit of time
+  sleep(5);
+  // Cancel/stop the thread
+  [workerThread_ stop];
+  // Did we notice the thread died? Did we clean up?
+  STAssertFalse([workerThread_ isExecuting], nil);
+  STAssertTrue([workerThread_ isFinished], nil);
+}
+
+- (void)testStopFromThread {
+  NSConditionLock *threadLock = [[[NSConditionLock alloc] initWithCondition:0]
+                                    autorelease];
+  [workerThread_ gtm_performWaitingUntilDone:NO block:^{
+    [threadLock lock];
+    [workerThread_ stop];  // Shold not block.
+    [threadLock unlockWithCondition:1];
+  }];
+  // Block should complete before the stop occurs.
+  [threadLock lockWhenCondition:1];
+  [threadLock unlock];
+  // Still need to give the thread a moment to not be executing
+  sleep(5);
+  STAssertFalse([workerThread_ isExecuting], nil);
+  STAssertTrue([workerThread_ isFinished], nil);
+}
+
+- (void)testPThreadName {
+  NSString *testName = @"InigoMontoya";
+  [workerThread_ setName:testName];
+  [workerThread_ gtm_performWaitingUntilDone:NO block:^{
+    STAssertEqualObjects([workerThread_ name], testName, nil);
+    char threadName[100];
+    pthread_getname_np(pthread_self(), threadName, 100);
+    STAssertEqualObjects([NSString stringWithUTF8String:threadName],
+                         testName, nil);
   }];
-  NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
-  STAssertTrue([runLoop gtm_runUpToSixtySecondsWithContext:context], nil);
 }
 
 @end