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233 lines
6.5 KiB
C++
233 lines
6.5 KiB
C++
//
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// DirectoryWatcher.h
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//
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// Library: Foundation
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// Package: Filesystem
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// Module: DirectoryWatcher
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//
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// Definition of the DirectoryWatcher class.
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//
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// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
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// and Contributors.
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//
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// SPDX-License-Identifier: BSL-1.0
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//
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#ifndef Foundation_DirectoryWatcher_INCLUDED
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#define Foundation_DirectoryWatcher_INCLUDED
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#include "Poco/Foundation.h"
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#ifndef POCO_NO_INOTIFY
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#include "Poco/File.h"
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#include "Poco/BasicEvent.h"
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#include "Poco/Runnable.h"
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#include "Poco/Thread.h"
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#include "Poco/AtomicCounter.h"
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namespace Poco {
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class DirectoryWatcherStrategy;
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class Foundation_API DirectoryWatcher: protected Runnable
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/// This class is used to get notifications about changes
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/// to the filesystem, more specifically, to a specific
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/// directory. Changes to a directory are reported via
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/// events.
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///
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/// A thread will be created that watches the specified
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/// directory for changes. Events are reported in the context
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/// of this thread.
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///
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/// Note that changes to files in subdirectories of the watched
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/// directory are not reported. Separate DirectoryWatcher objects
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/// must be created for these directories if they should be watched.
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///
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/// Changes to file attributes are not reported.
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///
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/// On Windows, this class is implemented using FindFirstChangeNotification()/FindNextChangeNotification().
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/// On Linux, this class is implemented using inotify.
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/// On FreeBSD and Darwin (Mac OS X, iOS), this class uses kevent/kqueue.
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/// On all other platforms, the watched directory is periodically scanned
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/// for changes. This can negatively affect performance if done too often.
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/// Therefore, the interval in which scans are done can be specified in
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/// the constructor. Note that periodic scanning will also be done on FreeBSD
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/// and Darwin if events for changes to files (DW_ITEM_MODIFIED) are enabled.
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///
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/// DW_ITEM_MOVED_FROM and DW_ITEM_MOVED_TO events will only be reported
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/// on Linux. On other platforms, a file rename or move operation
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/// will be reported via a DW_ITEM_REMOVED and a DW_ITEM_ADDED event.
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/// The order of these two events is not defined.
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///
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/// An event mask can be specified to enable only certain events.
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{
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public:
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enum DirectoryEventType
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{
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DW_ITEM_ADDED = 1,
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/// A new item has been created and added to the directory.
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DW_ITEM_REMOVED = 2,
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/// An item has been removed from the directory.
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DW_ITEM_MODIFIED = 4,
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/// An item has been modified.
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DW_ITEM_MOVED_FROM = 8,
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/// An item has been renamed or moved. This event delivers the old name.
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DW_ITEM_MOVED_TO = 16
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/// An item has been renamed or moved. This event delivers the new name.
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};
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enum DirectoryEventMask
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{
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DW_FILTER_ENABLE_ALL = 31,
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/// Enables all event types.
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DW_FILTER_DISABLE_ALL = 0
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/// Disables all event types.
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};
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enum
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{
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DW_DEFAULT_SCAN_INTERVAL = 5 /// Default scan interval for platforms that don't provide a native notification mechanism.
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};
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struct DirectoryEvent
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{
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DirectoryEvent(const File& f, DirectoryEventType ev):
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item(f),
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event(ev)
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{
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}
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const File& item; /// The directory or file that has been changed.
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DirectoryEventType event; /// The kind of event.
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};
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BasicEvent<const DirectoryEvent> itemAdded;
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/// Fired when a file or directory has been created or added to the directory.
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BasicEvent<const DirectoryEvent> itemRemoved;
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/// Fired when a file or directory has been removed from the directory.
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BasicEvent<const DirectoryEvent> itemModified;
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/// Fired when a file or directory has been modified.
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BasicEvent<const DirectoryEvent> itemMovedFrom;
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/// Fired when a file or directory has been renamed. This event delivers the old name.
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BasicEvent<const DirectoryEvent> itemMovedTo;
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/// Fired when a file or directory has been moved. This event delivers the new name.
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BasicEvent<const Exception> scanError;
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/// Fired when an error occurs while scanning for changes.
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DirectoryWatcher(const std::string& path, int eventMask = DW_FILTER_ENABLE_ALL, int scanInterval = DW_DEFAULT_SCAN_INTERVAL);
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/// Creates a DirectoryWatcher for the directory given in path.
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/// To enable only specific events, an eventMask can be specified by
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/// OR-ing the desired event IDs (e.g., DW_ITEM_ADDED | DW_ITEM_MODIFIED).
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/// On platforms where no native filesystem notifications are available,
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/// scanInterval specifies the interval in seconds between scans
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/// of the directory.
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DirectoryWatcher(const File& directory, int eventMask = DW_FILTER_ENABLE_ALL, int scanInterval = DW_DEFAULT_SCAN_INTERVAL);
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/// Creates a DirectoryWatcher for the specified directory
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/// To enable only specific events, an eventMask can be specified by
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/// OR-ing the desired event IDs (e.g., DW_ITEM_ADDED | DW_ITEM_MODIFIED).
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/// On platforms where no native filesystem notifications are available,
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/// scanInterval specifies the interval in seconds between scans
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/// of the directory.
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~DirectoryWatcher();
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/// Destroys the DirectoryWatcher.
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void suspendEvents();
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/// Suspends sending of events. Can be called multiple times, but every
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/// call to suspendEvent() must be matched by a call to resumeEvents().
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void resumeEvents();
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/// Resumes events, after they have been suspended with a call to suspendEvents().
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bool eventsSuspended() const;
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/// Returns true iff events are suspended.
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int eventMask() const;
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/// Returns the value of the eventMask passed to the constructor.
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int scanInterval() const;
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/// Returns the scan interval in seconds.
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const File& directory() const;
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/// Returns the directory being watched.
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bool supportsMoveEvents() const;
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/// Returns true iff the platform supports DW_ITEM_MOVED_FROM/itemMovedFrom and
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/// DW_ITEM_MOVED_TO/itemMovedTo events.
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protected:
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void init();
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void stop();
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void run();
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private:
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DirectoryWatcher();
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DirectoryWatcher(const DirectoryWatcher&);
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DirectoryWatcher& operator = (const DirectoryWatcher&);
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Thread _thread;
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File _directory;
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int _eventMask;
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AtomicCounter _eventsSuspended;
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int _scanInterval;
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DirectoryWatcherStrategy* _pStrategy;
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};
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//
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// inlines
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//
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inline bool DirectoryWatcher::eventsSuspended() const
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{
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return _eventsSuspended.value() > 0;
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}
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inline int DirectoryWatcher::eventMask() const
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{
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return _eventMask;
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}
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inline int DirectoryWatcher::scanInterval() const
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{
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return _scanInterval;
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}
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inline const File& DirectoryWatcher::directory() const
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{
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return _directory;
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}
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} // namespace Poco
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#endif // POCO_NO_INOTIFY
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#endif // Foundation_DirectoryWatcher_INCLUDED
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