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// VDKQueue.m
// Created by Bryan D K Jones on 28 March 2012
// Copyright 2013 Bryan D K Jones
//
// Based heavily on UKKQueue, which was created and copyrighted by Uli Kusterer on 21 Dec 2003.
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 3. This notice may not be removed or altered from any source
// distribution.
#import "VDKQueue.h"
#import <unistd.h>
#import <fcntl.h>
#include <sys/stat.h>
NSString * VDKQueueRenameNotification = @"VDKQueueFileRenamedNotification";
NSString * VDKQueueWriteNotification = @"VDKQueueFileWrittenToNotification";
NSString * VDKQueueDeleteNotification = @"VDKQueueFileDeletedNotification";
NSString * VDKQueueAttributeChangeNotification = @"VDKQueueFileAttributesChangedNotification";
NSString * VDKQueueSizeIncreaseNotification = @"VDKQueueFileSizeIncreasedNotification";
NSString * VDKQueueLinkCountChangeNotification = @"VDKQueueLinkCountChangedNotification";
NSString * VDKQueueAccessRevocationNotification = @"VDKQueueAccessWasRevokedNotification";
#pragma mark -
#pragma mark VDKQueuePathEntry
#pragma mark -
#pragma ------------------------------------------------------------------------------------------------------------------------------------------------------------
// This is a simple model class used to hold info about each path we watch.
@interface VDKQueuePathEntry : NSObject
{
NSString* _path;
int _watchedFD;
u_int _subscriptionFlags;
}
- (id) initWithPath:(NSString*)inPath andSubscriptionFlags:(u_int)flags;
@property (atomic, copy) NSString *path;
@property (atomic, assign) int watchedFD;
@property (atomic, assign) u_int subscriptionFlags;
@end
@implementation VDKQueuePathEntry
@synthesize path = _path, watchedFD = _watchedFD, subscriptionFlags = _subscriptionFlags;
- (id) initWithPath:(NSString*)inPath andSubscriptionFlags:(u_int)flags;
{
self = [super init];
if (self)
{
_path = [inPath copy];
_watchedFD = open([_path fileSystemRepresentation], O_EVTONLY, 0);
if (_watchedFD < 0)
{
[self autorelease];
return nil;
}
_subscriptionFlags = flags;
}
return self;
}
-(void) dealloc
{
[_path release];
_path = nil;
if (_watchedFD >= 0) close(_watchedFD);
_watchedFD = -1;
[super dealloc];
}
@end
#pragma mark -
#pragma mark VDKQueue
#pragma mark -
#pragma ------------------------------------------------------------------------------------------------------------------------------------------------------------
@interface VDKQueue ()
- (void) watcherThread:(id)sender;
@end
@implementation VDKQueue
@synthesize delegate = _delegate, alwaysPostNotifications = _alwaysPostNotifications;
#pragma mark -
#pragma mark INIT/DEALLOC
- (id) init
{
self = [super init];
if (self)
{
_coreQueueFD = kqueue();
if (_coreQueueFD == -1)
{
[self autorelease];
return nil;
}
_alwaysPostNotifications = NO;
_watchedPathEntries = [[NSMutableDictionary alloc] init];
}
return self;
}
- (void) dealloc
{
// Shut down the thread that's scanning for kQueue events
_keepWatcherThreadRunning = NO;
// Do this to close all the open file descriptors for files we're watching
[self removeAllPaths];
[_watchedPathEntries release];
_watchedPathEntries = nil;
[super dealloc];
}
#pragma mark -
#pragma mark PRIVATE METHODS
- (VDKQueuePathEntry *) addPathToQueue:(NSString *)path notifyingAbout:(u_int)flags
{
@synchronized(self)
{
// Are we already watching this path?
VDKQueuePathEntry *pathEntry = [_watchedPathEntries objectForKey:path];
if (pathEntry)
{
// All flags already set?
if(([pathEntry subscriptionFlags] & flags) == flags)
{
return [[pathEntry retain] autorelease];
}
flags |= [pathEntry subscriptionFlags];
}
struct timespec nullts = { 0, 0 };
struct kevent ev;
if (!pathEntry)
{
pathEntry = [[[VDKQueuePathEntry alloc] initWithPath:path andSubscriptionFlags:flags] autorelease];
}
if (pathEntry)
{
EV_SET(&ev, [pathEntry watchedFD], EVFILT_VNODE, EV_ADD | EV_ENABLE | EV_CLEAR, flags, 0, pathEntry);
[pathEntry setSubscriptionFlags:flags];
[_watchedPathEntries setObject:pathEntry forKey:path];
kevent(_coreQueueFD, &ev, 1, NULL, 0, &nullts);
// Start the thread that fetches and processes our events if it's not already running.
if(!_keepWatcherThreadRunning)
{
_keepWatcherThreadRunning = YES;
[NSThread detachNewThreadSelector:@selector(watcherThread:) toTarget:self withObject:nil];
}
}
return [[pathEntry retain] autorelease];
}
return nil;
}
//
// WARNING: This thread has no active autorelease pool, so if you make changes, you must manually manage
// memory without relying on autorelease. Otherwise, you will leak!
//
- (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.
int theFD = _coreQueueFD; // So we don't have to risk accessing iVars when the thread is terminated.
NSMutableArray *notesToPost = [[NSMutableArray alloc] initWithCapacity:5];
#if DEBUG_LOG_THREAD_LIFETIME
NSLog(@"watcherThread started.");
#endif
while(_keepWatcherThreadRunning)
{
@try
{
n = kevent(theFD, NULL, 0, &ev, 1, &timeout);
if (n > 0)
{
//NSLog( @"KEVENT returned %d", n );
if (ev.filter == EVFILT_VNODE)
{
//NSLog( @"KEVENT filter is EVFILT_VNODE" );
if (ev.fflags)
{
//NSLog( @"KEVENT flags are set" );
//
// Note: VDKQueue gets tested by thousands of CodeKit users who each watch several thousand files at once.
// I was receiving about 3 EXC_BAD_ACCESS (SIGSEGV) crash reports a month that listed the 'path' objc_msgSend
// as the culprit. That suggests the KEVENT is being sent back to us with a udata value that is NOT what we assigned
// to the queue, though I don't know why and I don't know why it's intermittent. Regardless, I've added an extra
// check here to try to eliminate this (infrequent) problem. In theory, a KEVENT that does not have a VDKQueuePathEntry
// object attached as the udata parameter is not an event we registered for, so we should not be "missing" any events. In theory.
//
id pe = ev.udata;
if (pe && [pe respondsToSelector:@selector(path)])
{
NSString *fpath = [((VDKQueuePathEntry *)pe).path retain]; // Need to retain so it does not disappear while the block at the bottom is waiting to run on the main thread. Released in that block.
if (!fpath) continue;
[[NSWorkspace sharedWorkspace] noteFileSystemChanged:fpath];
// Clear any old notifications
[notesToPost removeAllObjects];
// Figure out which notifications we need to issue
if ((ev.fflags & NOTE_RENAME) == NOTE_RENAME)
{
[notesToPost addObject:VDKQueueRenameNotification];
}
if ((ev.fflags & NOTE_WRITE) == NOTE_WRITE)
{
[notesToPost addObject:VDKQueueWriteNotification];
}
if ((ev.fflags & NOTE_DELETE) == NOTE_DELETE)
{
[notesToPost addObject:VDKQueueDeleteNotification];
}
if ((ev.fflags & NOTE_ATTRIB) == NOTE_ATTRIB)
{
[notesToPost addObject:VDKQueueAttributeChangeNotification];
}
if ((ev.fflags & NOTE_EXTEND) == NOTE_EXTEND)
{
[notesToPost addObject:VDKQueueSizeIncreaseNotification];
}
if ((ev.fflags & NOTE_LINK) == NOTE_LINK)
{
[notesToPost addObject:VDKQueueLinkCountChangeNotification];
}
if ((ev.fflags & NOTE_REVOKE) == NOTE_REVOKE)
{
[notesToPost addObject:VDKQueueAccessRevocationNotification];
}
NSArray *notes = [[NSArray alloc] initWithArray:notesToPost]; // notesToPost will be changed in the next loop iteration, which will likely occur before the block below runs.
// Post the notifications (or call the delegate method) on the main thread.
dispatch_async(dispatch_get_main_queue(),
^{
for (NSString *note in notes)
{
[_delegate VDKQueue:self receivedNotification:note forPath:fpath];
if (!_delegate || _alwaysPostNotifications)
{
NSDictionary *userInfoDict = [[NSDictionary alloc] initWithObjectsAndKeys:fpath, @"path", nil];
[[[NSWorkspace sharedWorkspace] notificationCenter] postNotificationName:note object:self userInfo:userInfoDict];
[userInfoDict release];
}
}
[fpath release];
[notes release];
});
}
}
}
}
}
@catch (NSException *localException)
{
NSLog(@"Error in VDKQueue watcherThread: %@", localException);
}
}
// Close our kqueue's file descriptor
if(close(theFD) == -1) {
NSLog(@"VDKQueue watcherThread: Couldn't close main kqueue (%d)", errno);
}
[notesToPost release];
#if DEBUG_LOG_THREAD_LIFETIME
NSLog(@"watcherThread finished.");
#endif
}
#pragma mark -
#pragma mark PUBLIC METHODS
#pragma -----------------------------------------------------------------------------------------------------------------------------------------------------
- (void) addPath:(NSString *)aPath
{
if (!aPath) return;
[aPath retain];
@synchronized(self)
{
VDKQueuePathEntry *entry = [_watchedPathEntries objectForKey:aPath];
// Only add this path if we don't already have it.
if (!entry)
{
entry = [self addPathToQueue:aPath notifyingAbout:VDKQueueNotifyDefault];
if (!entry) {
NSLog(@"VDKQueue tried to add the path %@ to watchedPathEntries, but the VDKQueuePathEntry was nil. \nIt's possible that the host process has hit its max open file descriptors limit.", aPath);
}
}
}
[aPath release];
}
- (void) addPath:(NSString *)aPath notifyingAbout:(u_int)flags
{
if (!aPath) return;
[aPath retain];
@synchronized(self)
{
VDKQueuePathEntry *entry = [_watchedPathEntries objectForKey:aPath];
// Only add this path if we don't already have it.
if (!entry)
{
entry = [self addPathToQueue:aPath notifyingAbout:flags];
if (!entry) {
NSLog(@"VDKQueue tried to add the path %@ to watchedPathEntries, but the VDKQueuePathEntry was nil. \nIt's possible that the host process has hit its max open file descriptors limit.", aPath);
}
}
}
[aPath release];
}
- (void) removePath:(NSString *)aPath
{
if (!aPath) return;
[aPath retain];
@synchronized(self)
{
VDKQueuePathEntry *entry = [_watchedPathEntries objectForKey:aPath];
// Remove it only if we're watching it.
if (entry) {
[_watchedPathEntries removeObjectForKey:aPath];
}
}
[aPath release];
}
- (void) removeAllPaths
{
@synchronized(self)
{
[_watchedPathEntries removeAllObjects];
}
}
- (NSUInteger) numberOfWatchedPaths
{
NSUInteger count;
@synchronized(self)
{
count = [_watchedPathEntries count];
}
return count;
}
@end
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