[Author: aharper]

Fix interaction of GTMFileSystemKqueue when the runloop isn't spinning. Also,
don't count on kCFSocketReadCallBack to keep calling us, empty the queue
whenever we can.

DELTA=93 (84 added, 0 deleted, 9 changed)
R=dmaclach,thomasvl

2 files changed, 162 insertions, 78 deletions

diff --git a/Foundation/GTMFileSystemKQueue.m b/Foundation/GTMFileSystemKQueue.m
index e423de2..7114304 100644
--- a/Foundation/GTMFileSystemKQueue.m
+++ b/Foundation/GTMFileSystemKQueue.m
@@ -6,9 +6,9 @@
 //  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
@@ -68,14 +68,14 @@ static CFSocketRef gRunLoopSocket = NULL;
       [self release];
       return nil;
     }
-    
+
     // Make sure it imples what we expect
     GTMAssertSelectorNilOrImplementedWithArguments(target_,
                                                    action_,
                                                    @encode(GTMFileSystemKQueue*),
                                                    @encode(GTMFileSystemKQueueEvents),
                                                    NULL);
-    
+
     fd_ = [self registerWithKQueue];
     if (fd_ < 0) {
       [self release];
@@ -88,7 +88,7 @@ static CFSocketRef gRunLoopSocket = NULL;
 #if GTM_SUPPORT_GC
 - (void)finalize {
   [self unregisterWithKQueue];
-  
+
   [super finalize];
 }
 #endif
@@ -96,7 +96,7 @@ static CFSocketRef gRunLoopSocket = NULL;
 - (void)dealloc {
   [self unregisterWithKQueue];
   [path_ release];
-  
+
   [super dealloc];
 }
 
@@ -113,15 +113,33 @@ static void SocketCallBack(CFSocketRef socketref, CFSocketCallBackType type,
   // autoreleased objects would never go away, so we provide our own pool here.
   NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 
-  struct kevent event;
-  
-  if (kevent(gFileSystemKQueueFileDescriptor, NULL, 0, &event, 1, NULL) == -1) {
-    _GTMDevLog(@"could not pick up kqueue event.  Errno %d", errno);  // COV_NF_LINE
-  } else {
-    GTMFileSystemKQueue *fskq = GTM_STATIC_CAST(GTMFileSystemKQueue, 
-                                                event.udata);
-    [fskq notify:event.fflags];
-  }
+  // We want to read as many events as possible so loop on the kevent call
+  // till the kqueue is empty.
+  int events = -1;
+  do {
+    // We wouldn't be here if CFSocket didn't think there was data on
+    // |gFileSystemKQueueFileDescriptor|. However, since this callback is tied
+    // to the runloop, if [... unregisterWithKQueue] was called before a runloop
+    // spin we may now be looking at an empty queue (remember,
+    // |gFileSystemKQueueFileDescriptor| isn't a normal descriptor).
+
+    // Try to consume one event with an immediate timeout.
+    struct kevent event;
+    const struct timespec noWait = { 0, 0 };
+    events = kevent(gFileSystemKQueueFileDescriptor, NULL, 0, &event, 1, &noWait);
+
+    if (events == 1) {
+      GTMFileSystemKQueue *fskq = GTM_STATIC_CAST(GTMFileSystemKQueue,
+                                                  event.udata);
+      [fskq notify:event.fflags];
+    } else if (events == -1) {
+      _GTMDevLog(@"could not pick up kqueue event.  Errno %d", errno);  // COV_NF_LINE
+    } else {
+      // |events| is zero, either we've drained the kqueue or CFSocket was
+      // notified and then the events went away before we had a chance to see
+      // them.
+    }
+  } while (events > 0);
 
   [pool drain];
 }
@@ -129,7 +147,7 @@ static void SocketCallBack(CFSocketRef socketref, CFSocketCallBackType type,
 // Cribbed from Advanced Mac OS X Programming
 - (void)addFileDescriptorMonitor:(int)fd {
   _GTMDevAssert(gRunLoopSocket == NULL, @"socket should be NULL at this point");
-  
+
   CFSocketContext context = { 0, NULL, NULL, NULL, NULL };
   gRunLoopSocket = CFSocketCreateWithNative(kCFAllocatorDefault,
                                             fd,
@@ -140,26 +158,26 @@ static void SocketCallBack(CFSocketRef socketref, CFSocketCallBackType type,
     _GTMDevLog(@"could not CFSocketCreateWithNative");  // COV_NF_LINE
     goto bailout;   // COV_NF_LINE
   }
-  
+
   CFRunLoopSourceRef rls;
   rls = CFSocketCreateRunLoopSource(NULL, gRunLoopSocket, 0);
   if (rls == NULL) {
     _GTMDevLog(@"could not create a run loop source");  // COV_NF_LINE
     goto bailout;  // COV_NF_LINE
   }
-  
+
   CFRunLoopAddSource(CFRunLoopGetCurrent(), rls,
                      kCFRunLoopDefaultMode);
   CFRelease(rls);
-  
+
  bailout:
   return;
-  
+
 }
 
 // Returns the FD we got in registering
 - (int)registerWithKQueue {
-  
+
   // Make sure we have our kqueue.
   if (gFileSystemKQueueFileDescriptor == 0) {
     gFileSystemKQueueFileDescriptor = kqueue();
@@ -174,15 +192,15 @@ static void SocketCallBack(CFSocketRef socketref, CFSocketCallBackType type,
     // Add the kqueue file descriptor to the runloop.
     [self addFileDescriptorMonitor:gFileSystemKQueueFileDescriptor];
   }
-  
+
   int newFD = open([path_ fileSystemRepresentation], O_EVTONLY, 0);
   if (newFD >= 0) {
 
     // Add a new event for the file.
     struct kevent filter;
-    EV_SET(&filter, newFD, EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR, 
+    EV_SET(&filter, newFD, EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR,
            events_, 0, self);
-    
+
     const struct timespec noWait = { 0, 0 };
     if (kevent(gFileSystemKQueueFileDescriptor, &filter, 1, NULL, 0, &noWait) == -1) {
       // COV_NF_START
@@ -192,7 +210,7 @@ static void SocketCallBack(CFSocketRef socketref, CFSocketCallBackType type,
       // COV_NF_END
     }
   }
-  
+
   return newFD;
 }
 
@@ -217,14 +235,14 @@ static void SocketCallBack(CFSocketRef socketref, CFSocketCallBackType type,
 - (void)notify:(GTMFileSystemKQueueEvents)eventFFlags {
 
   // Some notifications get a little bit of overhead first
-  
+
   if (eventFFlags & NOTE_REVOKE) {
     // COV_NF_START - no good way to do this in a unittest
     // Assume revoke means unmount and give up
     [self unregisterWithKQueue];
     // COV_NF_END
   }
-  
+
   if (eventFFlags & NOTE_DELETE) {
     [self unregisterWithKQueue];
     if (acrossReplace_) {
diff --git a/Foundation/GTMFileSystemKQueueTest.m b/Foundation/GTMFileSystemKQueueTest.m
index a64fd2b..d80f161 100644
--- a/Foundation/GTMFileSystemKQueueTest.m
+++ b/Foundation/GTMFileSystemKQueueTest.m
@@ -6,9 +6,9 @@
 //  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
@@ -18,8 +18,16 @@
 
 #import "GTMSenTestCase.h"
 #import "GTMFileSystemKQueue.h"
+#import "GTMGarbageCollection.h"
 #import "GTMUnitTestDevLog.h"
 
+
+// Private methods of GTMFileSystemKQueue we use for some tests
+@interface GTMFileSystemKQueue (PrivateMethods)
+- (void)unregisterWithKQueue;
+@end
+
+
 @interface GTMFileSystemKQueueTest : GTMTestCase {
  @private
   NSString *testPath_;
@@ -38,13 +46,13 @@
 
 @implementation GTMFSKQTestHelper
 
-- (void)callbackForQueue:(GTMFileSystemKQueue *)queue 
+- (void)callbackForQueue:(GTMFileSystemKQueue *)queue
                   events:(GTMFileSystemKQueueEvents)event {
   // Can't use standard ST macros here because our helper
   // is not a subclass of GTMTestCase. This is intentional.
   if (queue != queue_) {
     NSString *file = [NSString stringWithUTF8String:__FILE__];
-    NSException *exception 
+    NSException *exception
       = [NSException failureInEqualityBetweenObject:queue
                                           andObject:queue_
                                              inFile:file
@@ -52,7 +60,7 @@
                                     withDescription:nil];
     [exception raise];
   }
-  
+
   if (event & kGTMFileSystemKQueueWriteEvent) {
     ++writes_;
   }
@@ -115,7 +123,7 @@
   [fm removeFileAtPath:testPath_ handler:nil];
   [fm removeFileAtPath:testPath2_ handler:nil];
 #endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
-  
+
   [testPath_ release];
   testPath_ = nil;
   [testPath2_ release];
@@ -126,13 +134,13 @@
   GTMFileSystemKQueue *testKQ;
   GTMFSKQTestHelper *helper = [[[GTMFSKQTestHelper alloc] init] autorelease];
   STAssertNotNil(helper, nil);
-  
+
   // init should fail
   [GTMUnitTestDevLog expectString:@"Don't call init, use "
                      @"initWithPath:forEvents:acrossReplace:target:action:"];
   testKQ = [[[GTMFileSystemKQueue alloc] init] autorelease];
   STAssertNil(testKQ, nil);
-  
+
   // no path
   testKQ
     = [[[GTMFileSystemKQueue alloc] initWithPath:nil
@@ -141,7 +149,7 @@
                                           target:helper
                                           action:@selector(callbackForQueue:events:)] autorelease];
   STAssertNil(testKQ, nil);
-  
+
   // not events
   testKQ
     = [[[GTMFileSystemKQueue alloc] initWithPath:@"/var/log/system.log"
@@ -150,7 +158,7 @@
                                           target:helper
                                           action:@selector(callbackForQueue:events:)] autorelease];
   STAssertNil(testKQ, nil);
-  
+
   // no target
   testKQ
     = [[[GTMFileSystemKQueue alloc] initWithPath:@"/var/log/system.log"
@@ -159,7 +167,7 @@
                                           target:nil
                                           action:@selector(callbackForQueue:events:)] autorelease];
   STAssertNil(testKQ, nil);
-  
+
   // no handler
   testKQ
     = [[[GTMFileSystemKQueue alloc] initWithPath:@"/var/log/system.log"
@@ -169,7 +177,7 @@
                                           action:nil] autorelease];
   STAssertNil(testKQ, nil);
 
-  
+
   // path that doesn't exist
   testKQ
     = [[[GTMFileSystemKQueue alloc] initWithPath:@"/path/that/does/not/exist"
@@ -191,15 +199,15 @@
 }
 
 - (void)testWriteAndDelete {
-  
+
   NSFileManager *fm = [NSFileManager defaultManager];
   GTMFSKQTestHelper *helper = [[[GTMFSKQTestHelper alloc] init] autorelease];
   STAssertNotNil(helper, nil);
-  
+
   STAssertTrue([fm createFileAtPath:testPath_ contents:nil attributes:nil], nil);
   NSFileHandle *testFH = [NSFileHandle fileHandleForWritingAtPath:testPath_];
   STAssertNotNil(testFH, nil);
-  
+
   // Start monitoring the file
   GTMFileSystemKQueue *testKQ
     = [[GTMFileSystemKQueue alloc] initWithPath:testPath_
@@ -210,14 +218,14 @@
   STAssertNotNil(testKQ, nil);
   STAssertEqualObjects([testKQ path], testPath_, nil);
   [helper setKQueue:testKQ];
-  
+
   // Write to the file
   [testFH writeData:[@"doh!" dataUsingEncoding:NSUnicodeStringEncoding]];
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 1, nil);
-  
+
   // Close and delete
   [testFH closeFile];
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
@@ -226,34 +234,34 @@
 #else
   STAssertTrue([fm removeFileAtPath:testPath_ handler:nil], nil);
 #endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
-  
+
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 2, nil);
 
   // Clean up the kqueue
   [testKQ release];
   testKQ = nil;
-  
+
   STAssertEquals([helper writes], 1, nil);
   STAssertEquals([helper deletes], 1, nil);
   STAssertEquals([helper renames], 0, nil);
 }
 
 - (void)testWriteAndDeleteAndWrite {
-  
+
   // One will pass YES to |acrossReplace|, the other will pass NO.
-  
+
   NSFileManager *fm = [NSFileManager defaultManager];
   GTMFSKQTestHelper *helper = [[[GTMFSKQTestHelper alloc] init] autorelease];
   STAssertNotNil(helper, nil);
   GTMFSKQTestHelper *helper2 = [[[GTMFSKQTestHelper alloc] init] autorelease];
   STAssertNotNil(helper, nil);
-  
+
   // Create a temp file path
   STAssertTrue([fm createFileAtPath:testPath_ contents:nil attributes:nil], nil);
   NSFileHandle *testFH = [NSFileHandle fileHandleForWritingAtPath:testPath_];
   STAssertNotNil(testFH, nil);
-  
+
   // Start monitoring the file
   GTMFileSystemKQueue *testKQ
     = [[GTMFileSystemKQueue alloc] initWithPath:testPath_
@@ -264,7 +272,7 @@
   STAssertNotNil(testKQ, nil);
   STAssertEqualObjects([testKQ path], testPath_, nil);
   [helper setKQueue:testKQ];
-  
+
   GTMFileSystemKQueue *testKQ2
     = [[GTMFileSystemKQueue alloc] initWithPath:testPath_
                                       forEvents:kGTMFileSystemKQueueAllEvents
@@ -274,7 +282,7 @@
   STAssertNotNil(testKQ2, nil);
   STAssertEqualObjects([testKQ2 path], testPath_, nil);
   [helper2 setKQueue:testKQ2];
-  
+
   // Write to the file
   [testFH writeData:[@"doh!" dataUsingEncoding:NSUnicodeStringEncoding]];
 
@@ -297,7 +305,7 @@
   testFH = [NSFileHandle fileHandleForWritingAtPath:testPath_];
   STAssertNotNil(testFH, nil);
   [testFH writeData:[@"ha!" dataUsingEncoding:NSUnicodeStringEncoding]];
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 2, nil);
@@ -305,12 +313,12 @@
 
   // Write to it again
   [testFH writeData:[@"continued..." dataUsingEncoding:NSUnicodeStringEncoding]];
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 3, nil);
   STAssertEquals([helper2 totals], 2, nil);
-  
+
   // Close and delete
   [testFH closeFile];
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
@@ -318,18 +326,18 @@
 #else
   STAssertTrue([fm removeFileAtPath:testPath_ handler:nil], nil);
 #endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 4, nil);
   STAssertEquals([helper2 totals], 2, nil);
-  
+
   // Clean up the kqueue
   [testKQ release];
   testKQ = nil;
   [testKQ2 release];
   testKQ2 = nil;
-  
+
   STAssertEquals([helper writes], 2, nil);
   STAssertEquals([helper deletes], 2, nil);
   STAssertEquals([helper renames], 0, nil);
@@ -339,7 +347,7 @@
 }
 
 - (void)testWriteAndRenameAndWrite {
-  
+
   // One will pass YES to |acrossReplace|, the other will pass NO.
 
   NSFileManager *fm = [NSFileManager defaultManager];
@@ -347,12 +355,12 @@
   STAssertNotNil(helper, nil);
   GTMFSKQTestHelper *helper2 = [[[GTMFSKQTestHelper alloc] init] autorelease];
   STAssertNotNil(helper2, nil);
-  
+
   // Create a temp file path
   STAssertTrue([fm createFileAtPath:testPath_ contents:nil attributes:nil], nil);
   NSFileHandle *testFH = [NSFileHandle fileHandleForWritingAtPath:testPath_];
   STAssertNotNil(testFH, nil);
-  
+
   // Start monitoring the file
   GTMFileSystemKQueue *testKQ
     = [[GTMFileSystemKQueue alloc] initWithPath:testPath_
@@ -363,7 +371,7 @@
   STAssertNotNil(testKQ, nil);
   STAssertEqualObjects([testKQ path], testPath_, nil);
   [helper setKQueue:testKQ];
-  
+
   GTMFileSystemKQueue *testKQ2
     = [[GTMFileSystemKQueue alloc] initWithPath:testPath_
                                       forEvents:kGTMFileSystemKQueueAllEvents
@@ -373,43 +381,43 @@
   STAssertNotNil(testKQ2, nil);
   STAssertEqualObjects([testKQ2 path], testPath_, nil);
   [helper2 setKQueue:testKQ2];
-  
+
   // Write to the file
   [testFH writeData:[@"doh!" dataUsingEncoding:NSUnicodeStringEncoding]];
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 1, nil);
   STAssertEquals([helper2 totals], 1, nil);
-  
+
   // Move it and create the file again
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
   NSError *error = nil;
-  STAssertTrue([fm moveItemAtPath:testPath_ toPath:testPath2_ error:&error], 
+  STAssertTrue([fm moveItemAtPath:testPath_ toPath:testPath2_ error:&error],
                @"Error: %@", error);
 #else
   STAssertTrue([fm movePath:testPath_ toPath:testPath2_ handler:nil], nil);
 #endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
-  
+
   STAssertTrue([fm createFileAtPath:testPath_ contents:nil attributes:nil], nil);
   NSFileHandle *testFHPrime
     = [NSFileHandle fileHandleForWritingAtPath:testPath_];
   STAssertNotNil(testFHPrime, nil);
   [testFHPrime writeData:[@"eh?" dataUsingEncoding:NSUnicodeStringEncoding]];
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 2, nil);
   STAssertEquals([helper2 totals], 2, nil);
-  
+
   // Write to the new file
   [testFHPrime writeData:[@"continue..." dataUsingEncoding:NSUnicodeStringEncoding]];
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 3, nil);
   STAssertEquals([helper2 totals], 2, nil);
-  
+
   // Write to the old file
   [testFH writeData:[@"continue old..." dataUsingEncoding:NSUnicodeStringEncoding]];
 
@@ -417,7 +425,7 @@
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 3, nil);
   STAssertEquals([helper2 totals], 3, nil);
-  
+
   // and now close old
   [testFH closeFile];
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
@@ -425,12 +433,12 @@
 #else
   STAssertTrue([fm removeFileAtPath:testPath2_ handler:nil], nil);
 #endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 3, nil);
   STAssertEquals([helper2 totals], 4, nil);
-  
+
   // and now close new
   [testFHPrime closeFile];
 #if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
@@ -438,18 +446,18 @@
 #else
   STAssertTrue([fm removeFileAtPath:testPath_ handler:nil], nil);
 #endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
-  
+
   // Spin the runloop for a second so that the helper callbacks fire
   [self spinForEvents:helper];
   STAssertEquals([helper totals], 4, nil);
   STAssertEquals([helper2 totals], 4, nil);
-  
+
   // Clean up the kqueue
   [testKQ release];
   testKQ = nil;
   [testKQ2 release];
   testKQ2 = nil;
-  
+
   STAssertEquals([helper writes], 2, nil);
   STAssertEquals([helper deletes], 1, nil);
   STAssertEquals([helper renames], 1, nil);
@@ -458,4 +466,62 @@
   STAssertEquals([helper2 renames], 1, nil);
 }
 
+- (void)testNoSpinHang {
+  // This case tests a specific historically problematic interaction of
+  // GTMFileSystemKQueue and the runloop. GTMFileSystemKQueue uses the CFSocket
+  // notifications (and thus the runloop) for monitoring, however, you can
+  // dealloc the instance (and thus unregister the underlying kevent descriptor)
+  // prior to any runloop spin. The unregister removes the pending notifications
+  // from the monitored main kqueue file descriptor that CFSocket has previously
+  // noticed but not yet called back. At that point a kevent() call in the
+  // socket callback without a timeout would hang the runloop.
+
+  // Warn this may hang
+  NSLog(@"%s on failure this will hang.", __PRETTY_FUNCTION__);
+
+  NSFileManager *fm = [NSFileManager defaultManager];
+  GTMFSKQTestHelper *helper = [[[GTMFSKQTestHelper alloc] init] autorelease];
+  STAssertNotNil(helper, nil);
+  STAssertTrue([fm createFileAtPath:testPath_ contents:nil attributes:nil], nil);
+  NSFileHandle *testFH = [NSFileHandle fileHandleForWritingAtPath:testPath_];
+  STAssertNotNil(testFH, nil);
+
+  // Start monitoring the file
+  GTMFileSystemKQueue *testKQ
+    = [[GTMFileSystemKQueue alloc] initWithPath:testPath_
+                                      forEvents:kGTMFileSystemKQueueAllEvents
+                                  acrossReplace:YES
+                                         target:helper
+                                         action:@selector(callbackForQueue:events:)];
+  STAssertNotNil(testKQ, nil);
+  STAssertEqualObjects([testKQ path], testPath_, nil);
+  [helper setKQueue:testKQ];
+
+  // Write to the file
+  [testFH writeData:[@"doh!" dataUsingEncoding:NSUnicodeStringEncoding]];
+  // Close and delete
+  [testFH closeFile];
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
+  NSError *error = nil;
+  STAssertTrue([fm removeItemAtPath:testPath_ error:&error], @"Err: %@", error);
+#else
+  STAssertTrue([fm removeFileAtPath:testPath_ handler:nil], nil);
+#endif  // MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
+
+  // Now destroy the queue, with events outstanding from the CFSocket, but
+  // unconsumed. For GC this involves us using a private method since |helper|
+  // still has a reference. For non-GC we'll force the release.
+  if (GTMIsGarbageCollectionEnabled()) {
+    [testKQ unregisterWithKQueue];
+  } else {
+    STAssertEquals([testKQ retainCount], (NSUInteger)1, nil);
+    [testKQ release];
+    testKQ = nil;
+  }
+
+  // Spin the runloop, no events were delivered (and we should not hang)
+  [self spinForEvents:helper];
+  STAssertEquals([helper totals], 0, nil);
+}
+
 @end