comparison src/fswatcher.h @ 538:bdc9de794839 fswatcher

Start separate FsWatcher class to manage filesystem watch policy

+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    EasyMercurial
+
+    Based on HgExplorer by Jari Korhonen
+    Copyright (c) 2010 Jari Korhonen
+    Copyright (c) 2011 Chris Cannam
+    Copyright (c) 2011 Queen Mary, University of London
+    
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef FSWATCHER_H
+#define FSWATCHER_H
+
+#include <QObject>
+#include <QMutex>
+#include <QString>
+#include <QSet>
+#include <QHash>
+#include <QMap>
+#include <QStringList>
+#include <QFileSystemWatcher>
+
+class FsWatcher : public QObject
+{
+    Q_OBJECT
+
+public:
+    FsWatcher();
+    virtual ~FsWatcher();
+
+    /**
+     * Set the root path of the work directory to be monitored.
+     */
+    void setWorkDirPath(QString path);
+
+    /**
+     * Provide a set of prefixes to ignore. Files whose names start
+     * with a prefix in this set will be ignored when they change.
+     */
+    void setIgnoredFilePrefixes(QStringList prefixes);
+
+    /**
+     * Provide a set of suffixes to ignore. Files whose names end
+     * with a suffix in this set will be ignored when they change.
+     */
+    void setIgnoredFileSuffixes(QStringList suffixes);
+
+    /**
+     * Return a token to identify the current caller in subsequent
+     * calls to getChangedPaths().  Only changes that occur after this
+     * has been called can be detected by the caller.
+     */
+    int getNewToken();
+    
+    /**
+     * Return a list of all non-ignored file paths that have been
+     * observed to have changed since the last call to getChangedPaths
+     * with the same token.
+     */
+    QSet<QString> getChangedPaths(int token);
+    
+signals:
+    /**
+     * Emitted when something has changed. Use the asynchronous
+     * interface to find out what.
+     */
+    void changed();
+
+private slots:
+    void fsDirectoryChanged(QString);
+    void fsFileChanged(QString);
+
+private:
+    // call with lock already held
+    void addWorkDirectory(QString path);
+
+    // call with lock already held
+    bool shouldIgnore(QString path);
+
+private:
+    /**
+     * A change associates a filename with a counter (the
+     * size_t). Each time a file is changed, its counter is assigned
+     * from m_lastCounter and m_lastCounter is incremented.
+     *
+     * This is not especially efficient -- we often want to find "all
+     * files whose counter is greater than X" which involves a
+     * traversal. Maybe something better later.
+     */
+    QHash<QString, size_t> m_changes;
+
+    /**
+     * Associates a token (the client identifier) with a counter. The
+     * counter represents the value of m_lastCounter at the moment
+     * getChangedPaths last completed for that token. Any files in
+     * m_changes whose counters are larger must have been modified.
+     */
+    QMap<int, size_t> m_tokenMap;
+
+    QStringList m_ignoredPrefixes;
+    QStringList m_ignoredSuffixes;
+
+    /// Everything in this class is synchronised.
+    QMutex m_mutex;
+
+    QString m_workDirPath;
+    int m_lastToken;
+    size_t m_lastCounter;
+    QFileSystemWatcher m_watcher;
+};
+
+#endif