mirror of
https://github.com/transmission/transmission.git
synced 2025-12-24 20:35:36 +00:00
Appropriate and improve VDKQueue (#4202)
This commit is contained in:
A Cœur
GitHub
191
macosx/VDKQueue/VDKQueue.h
Executable file → Normal file
191
macosx/VDKQueue/VDKQueue.h
Executable file → Normal file
@@ -1,8 +1,8 @@
|
||||
// VDKQueue.h
|
||||
// Created by Bryan D K Jones on 28 March 2012
|
||||
// Copyright 2013 Bryan D K Jones
|
||||
// Copyright © 2017-2022 Transmission authors and contributors.
|
||||
//
|
||||
// Based heavily on UKKQueue, which was created and copyrighted by Uli Kusterer on 21 Dec 2003.
|
||||
// Based on VDKQueue (https://github.com/bdkjones/VDKQueue) which was created and copyrighted by Bryan D K Jones on 28 March 2012.
|
||||
// Based on UKKQueue (https://github.com/uliwitness/UKFileWatcher) 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
|
||||
@@ -19,133 +19,134 @@
|
||||
// 3. This notice may not be removed or altered from any source
|
||||
// distribution.
|
||||
|
||||
// DESCRIPTION
|
||||
//
|
||||
// BASED ON UKKQUEUE:
|
||||
//
|
||||
// This is an updated, modernized and streamlined version of the excellent UKKQueue class, which was authored by Uli Kusterer.
|
||||
// UKKQueue was written back in 2003 and there have been many, many improvements to Objective-C since then. VDKQueue uses the
|
||||
// core of Uli's original class, but makes it faster and more efficient. Method calls are reduced. Grand Central Dispatch is used in place
|
||||
// of Uli's "threadProxy" objects. The memory footprint is roughly halved, as I don't create the overhead that UKKQueue does.
|
||||
//
|
||||
// VDKQueue is also simplified. The option to use it as a singleton is removed. You simply alloc/init an instance and add paths you want to
|
||||
// watch. Your objects can be alerted to changes either by notifications or by a delegate method (or both). See below.
|
||||
//
|
||||
// It also fixes several bugs. For one, it won't crash if it can't create a file descriptor to a file you ask it to watch. (By default, an OS X process can only
|
||||
// have about 3,000 file descriptors open at once. If you hit that limit, UKKQueue will crash. VDKQueue will not.)
|
||||
//
|
||||
// VDKQueue is an Objective-C wrapper around kernel queues (kQueues). It allows you to watch a file or folder for changes and be notified when they occur.
|
||||
|
||||
// USAGE
|
||||
//
|
||||
// DEPENDENCIES:
|
||||
//
|
||||
// VDKQueue requires OS 10.6+ because it relies on Grand Central Dispatch.
|
||||
//
|
||||
// You simply alloc/init an instance and add paths you want to watch. Your objects can be alerted to changes either by notifications or by a delegate method (or both).
|
||||
|
||||
//
|
||||
// IMPORTANT NOTE ABOUT ATOMIC OPERATIONS
|
||||
//
|
||||
// There are two ways of saving a file on OS X: Atomic and Non-Atomic. In a non-atomic operation, a file is saved by directly overwriting it with new data.
|
||||
// In an Atomic save, a temporary file is first written to a different location on disk. When that completes successfully, the original file is deleted and the
|
||||
// temporary one is renamed and moved into place where the original file existed.
|
||||
// There are two ways of saving a file on macOS: Atomic and Non-Atomic. In a non-atomic operation, a file is saved by directly overwriting it with new data.
|
||||
// In an Atomic save, a temporary file is first written to a different location on disk. When that completes successfully, the original file is deleted and the temporary one is renamed and moved into place where the original file existed.
|
||||
//
|
||||
// This matters a great deal. If you tell VDKQueue to watch file X, then you save file X ATOMICALLY, you'll receive a notification about that event. HOWEVER, you will
|
||||
// NOT receive any additional notifications for file X from then on. This is because the atomic operation has essentially created a new file that replaced the one you
|
||||
// told VDKQueue to watch. (This is not an issue for non-atomic operations.)
|
||||
// This matters a great deal. If you tell VDKQueue to watch file X, then you save file X ATOMICALLY, you'll receive a notification about that event. HOWEVER, you will NOT receive any additional notifications for file X from then on. This is because the atomic operation has essentially created a new file that replaced the one you told VDKQueue to watch. (This is not an issue for non-atomic operations.)
|
||||
//
|
||||
// To handle this, any time you receive a change notification from VDKQueue, you should call -removePath: followed by -addPath: on the file's path, even if the path
|
||||
// has not changed. This will ensure that if the event that triggered the notification was an atomic operation, VDKQueue will start watching the "new" file that took
|
||||
// the place of the old one.
|
||||
//
|
||||
// Other frameworks out there try to work around this issue by immediately attempting to re-open the file descriptor to the path. This is not bulletproof and may fail;
|
||||
// it all depends on the timing of disk I/O. Bottom line: you could not rely on it and might miss future changes to the file path you're supposedly watching. That's why
|
||||
// VDKQueue does not take this approach, but favors the "manual" method of "stop-watching-then-rewatch".
|
||||
// To handle this, any time you receive a change notification from VDKQueue, you should call -removePath: followed by -addPath: on the file's path, even if the path has not changed.
|
||||
// This will ensure that if the event that triggered the notification was an atomic operation, VDKQueue will start watching the "new" file that took the place of the old one.
|
||||
//
|
||||
// Some try to work around this issue by immediately attempting to re-open the file descriptor to the path. This is not bulletproof and may fail; it all depends on the timing of disk I/O.
|
||||
// Bottom line: you could not rely on it and might miss future changes to the file path you're supposedly watching. That's why VDKQueue does not take this approach, but favors the "manual" method of "stop-watching-then-rewatch".
|
||||
|
||||
// LIMITATIONS of VDKQueue
|
||||
//
|
||||
// - You have to manually call -removePath: followed by -addPath: each time you receive a change notification.
|
||||
// - Callbacks are only on the main thread.
|
||||
// - Unmaintained as a standalone project.
|
||||
|
||||
#warning adopt an alternative to VDKQueue (UKFSEventsWatcher, EonilFSEvents, FileWatcher, DTFolderMonitor or SFSMonitor)
|
||||
// ALTERNATIVES (from archaic to modern)
|
||||
//
|
||||
// - FreeBSD 4.1: Kernel Queue API (kevent and kqueue)
|
||||
// (https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/kqueue.2.html)
|
||||
//
|
||||
// Example: SKQueue (https://github.com/daniel-pedersen/SKQueue) but claimed to crash and be superseded by SFSMonitor (https://stackoverflow.com/a/62167224)
|
||||
//
|
||||
// - macOS 10.1–10.8: FNSubscribe and FNNotify API
|
||||
// (https://developer.apple.com/documentation/coreservices/1566843-fnsubscribebypath)
|
||||
// "the FNNotify API has been supplanted by the FSEvents API"
|
||||
// (https://github.com/phracker/MacOSX-SDKs/blob/master/MacOSX10.7.sdk/System/Library/Frameworks/AppKit.framework/Versions/C/Headers/NSWorkspace.h)
|
||||
//
|
||||
// - macOS 10.5+: File System Events API (FSEventStreamCreate)
|
||||
// (https://developer.apple.com/documentation/coreservices/file_system_events)
|
||||
// "File system events are intended to provide notification of changes with directory-level granularity. For most purposes, this is sufficient. In some cases, however, you may need to receive notifications with finer granularity. For example, you might need to monitor only changes made to a single file. For that purpose, the kernel queue (kqueue) notification system is more appropriate.
|
||||
// If you are monitoring a large hierarchy of content, you should use file system events instead, however, because kernel queues are somewhat more complex than kernel events, and can be more resource intensive because of the additional user-kernel communication involved."
|
||||
// (https://developer.apple.com/library/archive/documentation/Darwin/Conceptual/FSEvents_ProgGuide/KernelQueues/KernelQueues.html)
|
||||
//
|
||||
// Example: UKFSEventsWatcher (https://github.com/uliwitness/UKFileWatcher)
|
||||
// Example: EonilFSEvents (https://github.com/eonil/FSEvents)
|
||||
// Example: FileWatcher (https://github.com/eonist/FileWatcher)
|
||||
//
|
||||
// - macOS 10.6+: Grand Central Dispatch API to monitor virtual filesystem nodes (DISPATCH_SOURCE_TYPE_VNODE)
|
||||
// (https://developer.apple.com/documentation/dispatch/dispatch_source_type_vnode)
|
||||
// "GCD uses kqueue under the hood and the same capabilities are made available."
|
||||
// (https://www.reddit.com/r/programming/comments/l6j3g/using_kqueue_in_cocoa/c2q74yy)
|
||||
//
|
||||
// Example: RSTDirectoryMonitor (https://github.com/varuzhnikov/HelloWorld) but unmaintained as a standalone project (abandoned 2013)
|
||||
// Example: DirectoryMonitor (https://github.com/robovm/apple-ios-samples/blob/master/ListerforwatchOSiOSandOSX/Swift/ListerKit/DirectoryMonitor.swift) but unmaintained (abandoned 2016)
|
||||
// Example: TABFileMonitor (https://github.com/tblank555/iMonitorMyFiles/tree/master/iMonitorMyFiles/Classes) but unmaintained (abandoned 2016)
|
||||
// Example: DTFolderMonitor (https://github.com/Cocoanetics/DTFoundation/tree/develop/Core/Source)
|
||||
//
|
||||
// - macOS 10.7+: NSFilePresenter API
|
||||
// (https://developer.apple.com/documentation/foundation/nsfilepresenter?language=objc)
|
||||
// "They're buggy, broken, and Apple is haven't willing to fix them for last 4 years."
|
||||
// (https://stackoverflow.com/a/26878163)
|
||||
//
|
||||
// - macOS 10.10+: DispatchSource API (makeFileSystemObjectSource)
|
||||
// (https://developer.apple.com/documentation/dispatch/dispatchsource/2300040-makefilesystemobjectsource)
|
||||
//
|
||||
// Example: SFSMonitor (https://github.com/ClassicalDude/SFSMonitor)
|
||||
|
||||
#import <Foundation/Foundation.h>
|
||||
|
||||
#include <sys/types.h>
|
||||
#include <sys/event.h>
|
||||
|
||||
@class VDKQueue;
|
||||
|
||||
//
|
||||
// Logical OR these values into the u_int that you pass in the -addPath:notifyingAbout: method
|
||||
// to specify the types of notifications you're interested in. Pass the default value to receive all of them.
|
||||
//
|
||||
#define VDKQueueNotifyAboutRename NOTE_RENAME // Item was renamed.
|
||||
#define VDKQueueNotifyAboutWrite NOTE_WRITE // Item contents changed (also folder contents changed).
|
||||
#define VDKQueueNotifyAboutDelete NOTE_DELETE // item was removed.
|
||||
#define VDKQueueNotifyAboutAttributeChange NOTE_ATTRIB // Item attributes changed.
|
||||
#define VDKQueueNotifyAboutSizeIncrease NOTE_EXTEND // Item size increased.
|
||||
#define VDKQueueNotifyAboutLinkCountChanged NOTE_LINK // Item's link count changed.
|
||||
#define VDKQueueNotifyAboutAccessRevocation NOTE_REVOKE // Access to item was revoked.
|
||||
typedef NS_OPTIONS(u_int, VDKQueueNotify)
|
||||
{
|
||||
VDKQueueNotifyAboutRename = NOTE_RENAME, ///< Item was renamed.
|
||||
VDKQueueNotifyAboutWrite = NOTE_WRITE, ///< Item contents changed (also folder contents changed).
|
||||
VDKQueueNotifyAboutDelete = NOTE_DELETE, ///< Item was removed.
|
||||
VDKQueueNotifyAboutAttributeChange = NOTE_ATTRIB, ///< Item attributes changed.
|
||||
VDKQueueNotifyAboutSizeIncrease = NOTE_EXTEND, ///< Item size increased.
|
||||
VDKQueueNotifyAboutLinkCountChanged = NOTE_LINK, ///< Item's link count changed.
|
||||
VDKQueueNotifyAboutAccessRevocation = NOTE_REVOKE, ///< Access to item was revoked.
|
||||
VDKQueueNotifyDefault = VDKQueueNotifyAboutRename | VDKQueueNotifyAboutWrite | VDKQueueNotifyAboutDelete |
|
||||
VDKQueueNotifyAboutAttributeChange | VDKQueueNotifyAboutSizeIncrease | VDKQueueNotifyAboutLinkCountChanged | VDKQueueNotifyAboutAccessRevocation
|
||||
};
|
||||
|
||||
#define VDKQueueNotifyDefault (VDKQueueNotifyAboutRename | VDKQueueNotifyAboutWrite \
|
||||
| VDKQueueNotifyAboutDelete | VDKQueueNotifyAboutAttributeChange \
|
||||
| VDKQueueNotifyAboutSizeIncrease | VDKQueueNotifyAboutLinkCountChanged \
|
||||
| VDKQueueNotifyAboutAccessRevocation)
|
||||
|
||||
//
|
||||
// Notifications that this class sends to the NSWORKSPACE notification center.
|
||||
// Notifications that this class sends to the default notification center.
|
||||
// Object = the instance of VDKQueue that was watching for changes
|
||||
// userInfo.path = the file path where the change was observed
|
||||
//
|
||||
extern NSString * VDKQueueRenameNotification;
|
||||
extern NSString * VDKQueueWriteNotification;
|
||||
extern NSString * VDKQueueDeleteNotification;
|
||||
extern NSString * VDKQueueAttributeChangeNotification;
|
||||
extern NSString * VDKQueueSizeIncreaseNotification;
|
||||
extern NSString * VDKQueueLinkCountChangeNotification;
|
||||
extern NSString * VDKQueueAccessRevocationNotification;
|
||||
|
||||
extern NSString const* VDKQueueRenameNotification;
|
||||
extern NSString const* VDKQueueWriteNotification;
|
||||
extern NSString const* VDKQueueDeleteNotification;
|
||||
extern NSString const* VDKQueueAttributeChangeNotification;
|
||||
extern NSString const* VDKQueueSizeIncreaseNotification;
|
||||
extern NSString const* VDKQueueLinkCountChangeNotification;
|
||||
extern NSString const* VDKQueueAccessRevocationNotification;
|
||||
|
||||
// You can specify a delegate and implement this protocol's method to respond to kQueue events, instead of subscribing to notifications.
|
||||
@protocol VDKQueueDelegate<NSObject>
|
||||
|
||||
//
|
||||
// Or, instead of subscribing to notifications, you can specify a delegate and implement this method to respond to kQueue events.
|
||||
// Note the required statement! For speed, this class does not check to make sure the delegate implements this method. (When I say "required" I mean it!)
|
||||
//
|
||||
@class VDKQueue;
|
||||
@protocol VDKQueueDelegate <NSObject>
|
||||
@required
|
||||
|
||||
-(void) VDKQueue:(VDKQueue *)queue receivedNotification:(NSString*)noteName forPath:(NSString*)fpath;
|
||||
- (void)VDKQueue:(VDKQueue*)queue receivedNotification:(NSString*)noteName forPath:(NSString*)fpath;
|
||||
|
||||
@end
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
@interface VDKQueue : NSObject
|
||||
{
|
||||
id<VDKQueueDelegate> __weak _delegate;
|
||||
BOOL _alwaysPostNotifications; // By default, notifications are posted only if there is no delegate set. Set this value to YES to have notes posted even when there is a delegate.
|
||||
|
||||
@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
|
||||
}
|
||||
|
||||
|
||||
// Note: there is no need to ask whether a path is already being watched.
|
||||
// Just add it or remove it and this class will take action only if appropriate.
|
||||
// (Add only if we're not already watching it, remove only if we are.)
|
||||
//
|
||||
// Note: there is no need to ask whether a path is already being watched. Just add it or remove it and this class
|
||||
// will take action only if appropriate. (Add only if we're not already watching it, remove only if we are.)
|
||||
//
|
||||
// Warning: You must pass full, root-relative paths. Do not pass tilde-abbreviated paths or file URLs.
|
||||
//
|
||||
- (void) addPath:(NSString *)aPath;
|
||||
- (void) addPath:(NSString *)aPath notifyingAbout:(u_int)flags; // See note above for values to pass in "flags"
|
||||
// Warning: You must pass full, root-relative paths. Do not pass tilde-abbreviated paths or file URLs.
|
||||
- (void)addPath:(NSString*)aPath;
|
||||
- (void)addPath:(NSString*)aPath notifyingAbout:(u_int)flags; // See note above for values to pass in "flags"
|
||||
|
||||
- (void) removePath:(NSString *)aPath;
|
||||
- (void) removeAllPaths;
|
||||
- (void)removePath:(NSString*)aPath;
|
||||
- (void)removeAllPaths;
|
||||
|
||||
@property(nonatomic, weak) id<VDKQueueDelegate> delegate;
|
||||
|
||||
@property (nonatomic, readonly) NSUInteger numberOfWatchedPaths; // Returns the number of paths that this VDKQueue instance is actively watching.
|
||||
|
||||
|
||||
|
||||
@property (weak) id<VDKQueueDelegate> delegate;
|
||||
@property (assign) BOOL alwaysPostNotifications;
|
||||
/// By default, notifications are posted only if there is no delegate set. Set this value to YES to have notes posted even when there is a delegate.
|
||||
@property(nonatomic, assign) BOOL alwaysPostNotifications;
|
||||
|
||||
@end
|
||||
|
||||
Reference in New Issue
Block a user