don't poll every second for kevents

Author: gobbledegook

VDKQueue.h

@@ -124,7 +124,7 @@ extern NSString * VDKQueueAccessRevocationNotification;
 @private
     int						_coreQueueFD;                           // The actual kqueue ID (Unix file descriptor).
 	NSMutableDictionary    *_watchedPathEntries;                    // List of VDKQueuePathEntries. Keys are NSStrings of the path that each VDKQueuePathEntry is for.
-    BOOL                    _keepWatcherThreadRunning;              // Set to NO to cancel the thread that watches _coreQueueFD for kQueue events
+    BOOL                    _keepWatcherThreadRunning;              // Keeps track of whether the thread is running or not.
 }
 
 

VDKQueue.m

@@ -194,6 +194,8 @@ - (VDKQueuePathEntry *)	addPathToQueue:(NSString *)path notifyingAbout:(u_int)fl
 			{
 				_keepWatcherThreadRunning = YES;
 				[NSThread detachNewThreadSelector:@selector(watcherThread:) toTarget:self withObject:nil];
+				// register a custom event that we will trigger to stop the thread
+				kevent(_coreQueueFD, &(struct kevent){0, EVFILT_USER, EV_ADD, NOTE_FFNOP, 0, NULL}, 1, NULL, 0, &nullts);
 			}
         }
 
@@ -212,7 +214,8 @@ - (void) watcherThread:(id)sender
 {
     int					n;
     struct kevent		ev;
-    struct timespec     timeout = { 1, 0 };     // 1 second timeout. Should be longer, but we need this thread to exit when a kqueue is dealloced, so 1 second timeout is quite a while to wait.
+    // no timeout needed. Instead of polling every second, we can pass NULL to wait indefinitely
+    // for vnode events or for an EVFILT_USER event to stop the thread.
 	int					theFD = _coreQueueFD;	// So we don't have to risk accessing iVars when the thread is terminated.
 
     NSMutableArray      *notesToPost = [[NSMutableArray alloc] initWithCapacity:5];
@@ -221,11 +224,14 @@ - (void) watcherThread:(id)sender
 	NSLog(@"watcherThread started.");
 #endif
 
-    while(_keepWatcherThreadRunning)
+    while(1)
     {
         @try 
         {
-            n = kevent(theFD, NULL, 0, &ev, 1, &timeout);
+            n = kevent(theFD, NULL, 0, &ev, 1, NULL);
+            if (ev.filter == EVFILT_USER) {
+            	break;
+            }
             if (n > 0)
             {
                 //NSLog( @"KEVENT returned %d", n );
@@ -424,7 +430,7 @@ - (void) stopWatching
     @synchronized(self)
     {
         // Shut down the thread that's scanning for kQueue events
-        _keepWatcherThreadRunning = NO;
+        kevent(_coreQueueFD, &(struct kevent){0, EVFILT_USER, EV_ENABLE, NOTE_TRIGGER, 0, NULL}, 1, NULL, 0, &(struct timespec){0,0});
 
         // Do this to close all the open file descriptors for files we're watching
         [_watchedPathEntries removeAllObjects];