diff src/fswatcher.cpp @ 548:dca5bd5b2a06

Merge from branch "fswatcher"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/fswatcher.cpp	Tue Feb 14 17:55:39 2012 +0000
@@ -0,0 +1,271 @@
+/* -*- 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.
+*/
+
+#include "fswatcher.h"
+#include "debug.h"
+
+#include <QMutexLocker>
+#include <QDir>
+
+#include <deque>
+
+#define DEBUG_FSWATCHER 1
+
+/*
+ * Watching the filesystem is trickier than it seems at first glance.
+ *
+ * We ideally should watch every directory, and every file that is
+ * tracked by Hg. If a new file is created in a directory, then we
+ * need to respond in order to show it as a potential candidate to be
+ * added.
+ *
+ * Complicating matters though is that Hg itself might modify the
+ * filesystem. This can happen even in "read-only" operations: for
+ * example, hg stat creates files called hg-checklink and hg-checkexec
+ * to test properties of the filesystem. So we need to know to ignore
+ * those files; unfortunately, when watching a directory (which is how
+ * we find out about the creation of new files) we are notified only
+ * that the directory has changed -- we aren't told what changed.
+ *
+ * This means that, when a directory changes, we need to rescan the
+ * directory to learn whether the set of files in it _excluding_ files
+ * matching our ignore patterns differs from the previous scan, and
+ * ignore the change if it doesn't.
+ */
+
+FsWatcher::FsWatcher() :
+    m_lastToken(0),
+    m_lastCounter(0)
+{
+    connect(&m_watcher, SIGNAL(directoryChanged(QString)),
+	    this, SLOT(fsDirectoryChanged(QString)));
+    connect(&m_watcher, SIGNAL(fileChanged(QString)),
+	    this, SLOT(fsFileChanged(QString)));
+}
+
+FsWatcher::~FsWatcher()
+{
+}
+
+void
+FsWatcher::setWorkDirPath(QString path)
+{
+    QMutexLocker locker(&m_mutex);
+    if (m_workDirPath == path) return;
+    m_watcher.removePaths(m_watcher.directories());
+    m_watcher.removePaths(m_watcher.files());
+    m_workDirPath = path;
+    addWorkDirectory(path);
+    debugPrint();
+}
+
+void
+FsWatcher::setTrackedFilePaths(QStringList paths)
+{
+    QMutexLocker locker(&m_mutex);
+
+    QSet<QString> alreadyWatched = 
+	QSet<QString>::fromList(m_watcher.files());
+
+    foreach (QString path, paths) {
+        path = m_workDirPath + QDir::separator() + path;
+        if (!alreadyWatched.contains(path)) {
+            m_watcher.addPath(path);
+        } else {
+            alreadyWatched.remove(path);
+        }
+    }
+
+    // Remove the remaining paths, those that were being watched
+    // before but that are not in the list we were given
+    foreach (QString path, alreadyWatched) {
+        m_watcher.removePath(path);
+    }
+
+    debugPrint();
+}
+
+void
+FsWatcher::addWorkDirectory(QString path)
+{
+    // QFileSystemWatcher will refuse to add a file or directory to
+    // its watch list that it is already watching -- fine -- but it
+    // prints a warning when this happens, which we wouldn't want.  So
+    // we'll check for duplicates ourselves.
+    QSet<QString> alreadyWatched = 
+	QSet<QString>::fromList(m_watcher.directories());
+    
+    std::deque<QString> pending;
+    pending.push_back(path);
+
+    while (!pending.empty()) {
+
+        QString path = pending.front();
+        pending.pop_front();
+        if (!alreadyWatched.contains(path)) {
+            m_watcher.addPath(path);
+            m_dirContents[path] = scanDirectory(path);
+        }
+
+        QDir d(path);
+        if (d.exists()) {
+            d.setFilter(QDir::Dirs | QDir::NoDotAndDotDot |
+                        QDir::Readable | QDir::NoSymLinks);
+            foreach (QString entry, d.entryList()) {
+                if (entry.startsWith('.')) continue;
+                QString entryPath = d.absoluteFilePath(entry);
+                pending.push_back(entryPath);
+            }
+        }
+    }
+}
+
+void
+FsWatcher::setIgnoredFilePrefixes(QStringList prefixes)
+{
+    QMutexLocker locker(&m_mutex);
+    m_ignoredPrefixes = prefixes;
+}
+
+void
+FsWatcher::setIgnoredFileSuffixes(QStringList suffixes)
+{
+    QMutexLocker locker(&m_mutex);
+    m_ignoredSuffixes = suffixes;
+}
+
+int
+FsWatcher::getNewToken()
+{
+    QMutexLocker locker(&m_mutex);
+    int token = ++m_lastToken;
+    m_tokenMap[token] = m_lastCounter;
+    return token;
+}
+
+QSet<QString>
+FsWatcher::getChangedPaths(int token)
+{
+    QMutexLocker locker(&m_mutex);
+    size_t lastUpdatedAt = m_tokenMap[token];
+    QSet<QString> changed;
+    for (QHash<QString, size_t>::const_iterator i = m_changes.begin();
+	 i != m_changes.end(); ++i) {
+	if (i.value() > lastUpdatedAt) {
+	    changed.insert(i.key());
+	}
+    }
+    m_tokenMap[token] = m_lastCounter;
+    return changed;
+}
+
+void
+FsWatcher::fsDirectoryChanged(QString path)
+{
+    {
+	QMutexLocker locker(&m_mutex);
+
+	if (shouldIgnore(path)) return;
+
+        QSet<QString> files = scanDirectory(path);
+        if (files == m_dirContents[path]) {
+#ifdef DEBUG_FSWATCHER
+            std::cerr << "FsWatcher: Directory " << path << " has changed, but not in a way that we are monitoring" << std::endl;
+#endif
+            return;
+        } else {
+#ifdef DEBUG_FSWATCHER
+            std::cerr << "FsWatcher: Directory " << path << " has changed" << std::endl;
+#endif
+            m_dirContents[path] = files;
+        }
+
+        size_t counter = ++m_lastCounter;
+        m_changes[path] = counter;
+    }
+
+    emit changed();
+}
+
+void
+FsWatcher::fsFileChanged(QString path)
+{
+    {
+        QMutexLocker locker(&m_mutex);
+
+        // We don't check whether the file matches an ignore pattern,
+        // because we are only notified for file changes if we are
+        // watching the file explicitly, i.e. the file is in the
+        // tracked file paths list. So we never want to ignore them
+
+        std::cerr << "FsWatcher: Tracked file " << path << " has changed" << std::endl;
+
+        size_t counter = ++m_lastCounter;
+        m_changes[path] = counter;
+    }
+
+    emit changed();
+}
+
+bool
+FsWatcher::shouldIgnore(QString path)
+{
+    QFileInfo fi(path);
+    QString fn(fi.fileName());
+    foreach (QString pfx, m_ignoredPrefixes) {
+        if (fn.startsWith(pfx)) {
+            std::cerr << "(ignoring: " << path << ")" << std::endl;
+            return true;
+        }
+    }
+    foreach (QString sfx, m_ignoredSuffixes) {
+        if (fn.endsWith(sfx)) {
+            std::cerr << "(ignoring: " << path << ")" << std::endl;
+            return true;
+        }
+    }
+    return false;
+}
+
+QSet<QString>
+FsWatcher::scanDirectory(QString path)
+{
+    QSet<QString> files;
+    QDir d(path);
+    if (d.exists()) {
+        d.setFilter(QDir::Files | QDir::NoDotAndDotDot |
+                    QDir::Readable | QDir::NoSymLinks);
+        foreach (QString entry, d.entryList()) {
+            if (entry.startsWith('.')) continue;
+            if (shouldIgnore(entry)) continue;
+            files.insert(entry);
+        }
+    }
+//    std::cerr << "scanDirectory:" << std::endl;
+//    foreach (QString f, files) std::cerr << f << std::endl;
+    return files;
+}
+
+void
+FsWatcher::debugPrint()
+{
+#ifdef DEBUG_FSWATCHER
+    std::cerr << "FsWatcher: Now watching " << m_watcher.directories().size()
+              << " directories and " << m_watcher.files().size()
+              << " files" << std::endl;
+#endif
+}