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