forked from qt-creator/qt-creator
Utils: Introduce FileSystemWatcher.
Remove duplicated classes ProjectExplorer::FileWatcher and QmlProjectManager::FileSystemWatcher, create Utils::FileSystemWatcher from them, merging the functionality. Also use in HelpManager/Maemo, reducing the number of QFileSystemWatcher instances (and thus, shutdown time).
This commit is contained in:
Friedemann Kleint
404
src/libs/utils/filesystemwatcher.cpp
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404
src/libs/utils/filesystemwatcher.cpp
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/**************************************************************************
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**
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** This file is part of Qt Creator
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**
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** Copyright (c) 2011 Nokia Corporation and/or its subsidiary(-ies).
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**
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** Contact: Nokia Corporation (info@qt.nokia.com)
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**
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**
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** GNU Lesser General Public License Usage
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**
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** This file may be used under the terms of the GNU Lesser General Public
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** License version 2.1 as published by the Free Software Foundation and
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** appearing in the file LICENSE.LGPL included in the packaging of this file.
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** Please review the following information to ensure the GNU Lesser General
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** Public License version 2.1 requirements will be met:
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** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** Other Usage
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**
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** Alternatively, this file may be used in accordance with the terms and
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** conditions contained in a signed written agreement between you and Nokia.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**************************************************************************/
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#include "filesystemwatcher.h"
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#include <QtCore/QDebug>
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#include <QtCore/QDir>
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#include <QtCore/QFileInfo>
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#include <QtCore/QFileSystemWatcher>
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#include <QtCore/QDateTime>
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enum { debug = 0 };
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// Returns upper limit of file handles that can be opened by this process at
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// once. (which is limited on MacOS, exceeding it will probably result in
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// crashes).
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static inline quint64 getFileLimit()
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{
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#ifdef Q_OS_MAC
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struct rlimit rl;
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getrlimit(RLIMIT_NOFILE, &rl);
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return rl.rlim_cur; // quint64
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#else
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return 0xFFFFFFFF;
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#endif
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}
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/*!
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\class Utils::FileSystemWatcher
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\brief File watcher that internally uses a centralized QFileSystemWatcher
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and enforces limits on Mac OS.
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\section1 Design Considerations
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Constructing/Destructing a QFileSystemWatcher is expensive. This can be
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worked around by using a centralized watcher.
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\note It is (still) possible to create several instances of a
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QFileSystemWatcher by passing an (arbitrary) integer id != 0 to the
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constructor. This allows separating watchers that
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easily exceed operating system limits from others (see below).
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\section1 Mac OS Specifics
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There is a hard limit on the number of file handles that can be open at
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one point per process on Mac OS X (e.g. it is 2560 on Mac OS X Snow Leopard
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Server, as shown by \c{ulimit -a}). Opening one or several \c .qmlproject's
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with a large number of directories to watch easily exceeds this. The
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results are crashes later on, e.g. when threads cannot be created any more.
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This class implements a heuristic that the file system watcher used for
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\c .qmlproject files never uses more than half the number of available
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file handles. It also increases the number from \c rlim_cur to \c rlim_max
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- the old code in main.cpp failed, see last section in
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\l{http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man2/setrlimit.2.html}
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for details.
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*/
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namespace Utils {
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// Centralized file watcher static data per integer id.
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class FileSystemWatcherStaticData
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{
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public:
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FileSystemWatcherStaticData() :
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maxFileOpen(getFileLimit()) , m_objectCount(0), m_watcher(0) {}
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quint64 maxFileOpen;
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int m_objectCount;
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QHash<QString, int> m_fileCount;
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QHash<QString, int> m_directoryCount;
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QFileSystemWatcher *m_watcher;
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};
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typedef QMap<int, FileSystemWatcherStaticData> FileSystemWatcherStaticDataMap;
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Q_GLOBAL_STATIC(FileSystemWatcherStaticDataMap, fileSystemWatcherStaticDataMap)
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class WatchEntry
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{
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public:
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typedef FileSystemWatcher::WatchMode WatchMode;
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explicit WatchEntry(const QString &file, WatchMode wm) :
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watchMode(wm), modifiedTime(QFileInfo(file).lastModified()) {}
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WatchEntry() : watchMode(FileSystemWatcher::WatchAllChanges) {}
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bool trigger(const QString &fileName);
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WatchMode watchMode;
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QDateTime modifiedTime;
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};
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// Check if watch should trigger on signal considering watchmode.
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bool WatchEntry::trigger(const QString &fileName)
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{
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if (watchMode == FileSystemWatcher::WatchAllChanges)
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return true;
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// Modified changed?
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const QFileInfo fi(fileName);
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const QDateTime newModifiedTime = fi.exists() ? fi.lastModified() : QDateTime();
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if (newModifiedTime != modifiedTime) {
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modifiedTime = newModifiedTime;
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return true;
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}
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return false;
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}
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typedef QHash<QString, WatchEntry> WatchEntryMap;
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typedef WatchEntryMap::iterator WatchEntryMapIterator;
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class FileSystemWatcherPrivate
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{
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public:
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explicit FileSystemWatcherPrivate(int id) : m_id(id), m_staticData(0) {}
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WatchEntryMap m_files;
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WatchEntryMap m_directories;
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bool checkLimit() const;
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const int m_id;
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FileSystemWatcherStaticData *m_staticData;
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};
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bool FileSystemWatcherPrivate::checkLimit() const
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{
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// We are potentially watching a _lot_ of directories. This might crash
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// qtcreator when we hit the upper limit.
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// Heuristic is therefore: Do not use more than half of the file handles
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// available in THIS watcher.
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return quint64(m_directories.size() + m_files.size()) <
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(m_staticData->maxFileOpen / 2);
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}
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/*!
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\brief Add to watcher 0.
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*/
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FileSystemWatcher::FileSystemWatcher(QObject *parent) :
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QObject(parent), d(new FileSystemWatcherPrivate(0))
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{
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init();
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}
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/*!
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\brief Add to a watcher with specified id.
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*/
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FileSystemWatcher::FileSystemWatcher(int id, QObject *parent) :
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QObject(parent), d(new FileSystemWatcherPrivate(id))
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{
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init();
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}
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void FileSystemWatcher::init()
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{
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// Check for id in map/
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FileSystemWatcherStaticDataMap &map = *fileSystemWatcherStaticDataMap();
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FileSystemWatcherStaticDataMap::iterator it = map.find(d->m_id);
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if (it == map.end())
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it = map.insert(d->m_id, FileSystemWatcherStaticData());
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d->m_staticData = &it.value();
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if (!d->m_staticData->m_watcher) {
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d->m_staticData->m_watcher = new QFileSystemWatcher();
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if (debug)
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qDebug() << this << "Created watcher for id " << d->m_id;
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}
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++(d->m_staticData->m_objectCount);
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connect(d->m_staticData->m_watcher, SIGNAL(fileChanged(QString)),
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this, SLOT(slotFileChanged(QString)));
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connect(d->m_staticData->m_watcher, SIGNAL(directoryChanged(QString)),
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this, SLOT(slotDirectoryChanged(QString)));
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}
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FileSystemWatcher::~FileSystemWatcher()
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{
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if (!d->m_files.isEmpty())
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removeFiles(files());
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if (!d->m_directories.isEmpty())
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removeDirectories(directories());
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if (--(d->m_staticData->m_objectCount) == 0) {
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delete d->m_staticData->m_watcher;
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d->m_staticData->m_watcher = 0;
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d->m_staticData->m_fileCount.clear();
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d->m_staticData->m_directoryCount.clear();
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if (debug)
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qDebug() << this << "Deleted watcher" << d->m_id;
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}
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}
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bool FileSystemWatcher::watchesFile(const QString &file) const
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{
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return d->m_files.contains(file);
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}
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void FileSystemWatcher::addFile(const QString &file, WatchMode wm)
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{
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addFiles(QStringList(file), wm);
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}
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void FileSystemWatcher::addFiles(const QStringList &files, WatchMode wm)
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{
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if (debug)
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qDebug() << this << d->m_id << "addFiles mode=" << wm << files
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<< " limit currently: " << (d->m_files.size() + d->m_directories.size())
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<< " of " << d->m_staticData->maxFileOpen;
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QStringList toAdd;
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foreach (const QString &file, files) {
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if (watchesFile(file)) {
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qWarning("FileSystemWatcher: File %s is already being watched", qPrintable(file));
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continue;
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}
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if (!d->checkLimit()) {
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qWarning("File %s is not watched: Too many file handles are already open (max is %u).",
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qPrintable(file), unsigned(d->m_staticData->maxFileOpen));
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break;
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}
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d->m_files.insert(file, WatchEntry(file, wm));
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const int count = ++d->m_staticData->m_fileCount[file];
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Q_ASSERT(count > 0);
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if (count == 1)
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toAdd << file;
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}
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if (!toAdd.isEmpty())
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d->m_staticData->m_watcher->addPaths(toAdd);
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}
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void FileSystemWatcher::removeFile(const QString &file)
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{
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removeFiles(QStringList(file));
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}
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void FileSystemWatcher::removeFiles(const QStringList &files)
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{
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if (debug)
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qDebug() << this << d->m_id << "removeFiles " << files;
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QStringList toRemove;
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foreach (const QString &file, files) {
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WatchEntryMapIterator it = d->m_files.find(file);
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if (it == d->m_files.end()) {
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qWarning("FileSystemWatcher: File %s is not watched.", qPrintable(file));
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continue;
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}
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d->m_files.erase(it);
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const int count = --(d->m_staticData->m_fileCount[file]);
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Q_ASSERT(count >= 0);
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if (!count) {
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toRemove << file;
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}
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}
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if (!toRemove.isEmpty())
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d->m_staticData->m_watcher->removePaths(toRemove);
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}
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QStringList FileSystemWatcher::files() const
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{
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return d->m_files.keys();
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}
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bool FileSystemWatcher::watchesDirectory(const QString &directory) const
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{
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return d->m_directories.contains(directory);
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}
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void FileSystemWatcher::addDirectory(const QString &directory, WatchMode wm)
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{
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addDirectories(QStringList(directory), wm);
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}
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void FileSystemWatcher::addDirectories(const QStringList &directories, WatchMode wm)
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{
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if (debug)
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qDebug() << this << d->m_id << "addDirectories mode " << wm << directories
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<< " limit currently: " << (d->m_files.size() + d->m_directories.size())
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<< " of " << d->m_staticData->maxFileOpen;
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QStringList toAdd;
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foreach (const QString &directory, directories) {
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if (watchesDirectory(directory)) {
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qWarning("FileSystemWatcher: Directory %s is already being watched.", qPrintable(directory));
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continue;
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}
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if (!d->checkLimit()) {
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qWarning("Directory %s is not watched: Too many file handles are already open (max is %u).",
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qPrintable(directory), unsigned(d->m_staticData->maxFileOpen));
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break;
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}
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d->m_directories.insert(directory, WatchEntry(directory, wm));
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const int count = ++d->m_staticData->m_directoryCount[directory];
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Q_ASSERT(count > 0);
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if (count == 1)
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toAdd << directory;
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}
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if (!toAdd.isEmpty())
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d->m_staticData->m_watcher->addPaths(toAdd);
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}
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void FileSystemWatcher::removeDirectory(const QString &directory)
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{
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removeDirectories(QStringList(directory));
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}
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void FileSystemWatcher::removeDirectories(const QStringList &directories)
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{
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if (debug)
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qDebug() << this << d->m_id << "removeDirectories" << directories;
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QStringList toRemove;
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foreach (const QString &directory, directories) {
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WatchEntryMapIterator it = d->m_directories.find(directory);
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if (it == d->m_directories.end()) {
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qWarning("FileSystemWatcher: Directory %s is not watched.", qPrintable(directory));
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continue;
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}
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d->m_directories.erase(it);
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const int count = --d->m_staticData->m_directoryCount[directory];
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Q_ASSERT(count >= 0);
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if (!count) {
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toRemove << directory;
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}
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}
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if (!toRemove.isEmpty())
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d->m_staticData->m_watcher->removePaths(toRemove);
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}
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QStringList FileSystemWatcher::directories() const
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{
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return d->m_directories.keys();
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}
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void FileSystemWatcher::slotFileChanged(const QString &path)
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{
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const WatchEntryMapIterator it = d->m_files.find(path);
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if (it != d->m_files.end() && it.value().trigger(path)) {
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if (debug)
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qDebug() << this << "triggers on file " << path
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<< it.value().watchMode
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<< it.value().modifiedTime.toString(Qt::ISODate);
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emit fileChanged(path);
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}
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}
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void FileSystemWatcher::slotDirectoryChanged(const QString &path)
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{
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const WatchEntryMapIterator it = d->m_directories.find(path);
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if (it != d->m_directories.end() && it.value().trigger(path)) {
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if (debug)
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qDebug() << this << "triggers on dir " << path
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<< it.value().watchMode
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<< it.value().modifiedTime.toString(Qt::ISODate);
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emit directoryChanged(path);
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}
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}
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} // namespace Utils
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