Hi
I wrote a directory scanner application that spawns 4 different threads with
independent rescan intervals and need to repeat the process if and only if a
thread has completed a scan. Basically, for each file type I'm watching, the
process is
1. Spawn a thread to sample files of the specified type
2. Wait until the thread completes
3. Schedule another pass after a given time interval has passed.
Timer's don't work for my purposes because the execution time of the thread can
easily exceed any arbitrary repeat interval I might choose which would require
the use of busy flags and testing for a busy state etc... I want to avoid that.
I tried calling NSObject's
performSelector:(SEL) aSelector withObject:(id) anArgument afterDelay:(
NSTimeInterval ) delay
But the receiver's " aSelector" method is never getting called. The only
logical place to perform this scheduling is from inside the thread because only
the thread knows when it is finished, but I'm having no luck getting the method
to run.
Here are the methods that spawn the threads
- ( void ) initDirectories
{
[ NSThread detachNewThreadSelector : @selector ( initDirectoriesInThread
:)
toTarget : self
withObject : nil ];
}
- ( void ) updateDirectories
{
// Logging function that writes messages to my app's custom console view
KCLog ([ NSString stringWithFormat : @"Checking for changes: %@" ,
userType]);
[ NSThread detachNewThreadSelector : @selector ( updateDirectoriesInThread
:)
toTarget : self
withObject : nil ];
}
And here are the corresponding thread methods
- ( void ) initDirectoriesInThread:( id ) inData
{
@synchronized ( self )
{
// allocate a new autorelease pool
NSAutoreleasePool *pool = [[ NSAutoreleasePool alloc ] init ];
KDirectory *rootDirectory = [ KDirectory directoryWithPath : path ];
rootObserver = [[ CNCDirectoryWatcher alloc ] initWithDirectory :
rootDirectory root : self ];
// add root directory to observed list
[ self addDirectory : rootObserver ];
// schedule a new pass
[ self performSelector : @selector ( updateDirectories ) withObject :
nil afterDelay : catalogInterval ];
// release the pool
[pool release ];
}
}
- ( void ) updateDirectoriesInThread:( id ) inData
{
@synchronized ( self )
{
// allocate a new autorelease pool
NSAutoreleasePool *pool = [[ NSAutoreleasePool alloc ] init ];
NSArray *dirs = [ directories copy ];
NSEnumerator *enumerator = [dirs objectEnumerator ];
CNCDirectoryWatcher *directory;
while (directory = [enumerator nextObject ])
{
[directory update ];
}
// schedule a new pass
[ self performSelector : @selector ( updateDirectories ) withObject :
nil afterDelay : catalogInterval ];
// release the pool
[pool release ];
}
}
The "initDirectoriesInThread" method is getting called and runs correctly, but
the "updateDirectoriesInThread" method never gets called.
I looked at
-(void)performSelectorOnMainThread:(SEL) aSelector withObject:(id) arg
waitUntilDone:(BOOL) wait
But it doesn't appear to have a way to schedule the execution for a specified
delay.
Is there a way to use performSelector: withObject: afterDelay: to satisfy both
step 2 and 3 above?
Thanks for any help
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