Fix saving of xml files

Do not save XML config files (profiles.xml, toolchains.xml, etc.)
if the file has not changed.

Change-Id: I5f0dea374b33a05e7c428f4031d53c83d92de595
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

17 files changed, 214 insertions, 144 deletions

diff --git a/src/libs/utils/persistentsettings.cpp b/src/libs/utils/persistentsettings.cpp
index a9fdded9a6..7134158869 100644
--- a/src/libs/utils/persistentsettings.cpp
+++ b/src/libs/utils/persistentsettings.cpp
@@ -332,10 +332,6 @@ bool PersistentSettingsReader::load(const Utils::FileName &fileName)
     \sa Utils::PersistentSettingsReader
 */
 
-PersistentSettingsWriter::PersistentSettingsWriter()
-{
-}
-
 static void writeVariantValue(QXmlStreamWriter &w, const Context &ctx,
                               const QVariant &variant, const QString &key = QString())
 {
@@ -376,24 +372,33 @@ static void writeVariantValue(QXmlStreamWriter &w, const Context &ctx,
     }
 }
 
+PersistentSettingsWriter::PersistentSettingsWriter(const FileName &fileName, const QString &docType) :
+    m_fileName(fileName), m_docType(docType), m_mustSave(false)
+{ }
+
 void PersistentSettingsWriter::saveValue(const QString &variable, const QVariant &value)
 {
+    if (m_valueMap.contains(variable) && m_valueMap.value(variable) == value)
+        return;
+    m_mustSave = true;
     m_valueMap.insert(variable, value);
 }
 
-bool PersistentSettingsWriter::save(const Utils::FileName &fileName, const QString &docType,
-                                    QWidget *parent) const
+bool PersistentSettingsWriter::save(QWidget *parent) const
 {
+    if (!m_mustSave)
+        return true;
+
     QDir tmp;
-    tmp.mkpath(fileName.toFileInfo().path());
-    Utils::FileSaver saver(fileName.toString(), QIODevice::Text);
+    tmp.mkpath(m_fileName.toFileInfo().path());
+    Utils::FileSaver saver(m_fileName.toString(), QIODevice::Text);
     if (!saver.hasError()) {
         const Context ctx;
         QXmlStreamWriter w(saver.file());
         w.setAutoFormatting(true);
         w.setAutoFormattingIndent(1); // Historical, used to be QDom.
         w.writeStartDocument();
-        w.writeDTD(QLatin1String("<!DOCTYPE ") + docType + QLatin1Char('>'));
+        w.writeDTD(QLatin1String("<!DOCTYPE ") + m_docType + QLatin1Char('>'));
         w.writeComment(QString::fromAscii(" Written by Qt Creator %1, %2. ").
                        arg(QLatin1String(Core::Constants::IDE_VERSION_LONG),
                            QDateTime::currentDateTime().toString(Qt::ISODate)));
@@ -409,6 +414,13 @@ bool PersistentSettingsWriter::save(const Utils::FileName &fileName, const QStri
 
         saver.setResult(&w);
     }
-    return saver.finalize(parent);
+    bool ok = saver.finalize(parent);
+    if (ok)
+        m_mustSave = false;
+    return ok;
 }
+
+FileName PersistentSettingsWriter::fileName() const
+{ return m_fileName; }
+
 } // namespace Utils
diff --git a/src/libs/utils/persistentsettings.h b/src/libs/utils/persistentsettings.h
index 66528aa480..ec0d3cb0e9 100644
--- a/src/libs/utils/persistentsettings.h
+++ b/src/libs/utils/persistentsettings.h
@@ -59,12 +59,17 @@ private:
 class QTCREATOR_UTILS_EXPORT PersistentSettingsWriter
 {
 public:
-    PersistentSettingsWriter();
+    PersistentSettingsWriter(const FileName &fileName, const QString &docType);
     void saveValue(const QString &variable, const QVariant &value);
-    bool save(const FileName &fileName, const QString &docType, QWidget *parent) const;
+    bool save(QWidget *parent) const;
+
+    Utils::FileName fileName() const;
 
 private:
     QMap<QString, QVariant> m_valueMap;
+    const Utils::FileName m_fileName;
+    const QString m_docType;
+    mutable bool m_mustSave;
 };
 
 } // namespace Utils
diff --git a/src/plugins/android/androidconfigurations.cpp b/src/plugins/android/androidconfigurations.cpp
index 76dcdcd723..256c1f68ba 100644
--- a/src/plugins/android/androidconfigurations.cpp
+++ b/src/plugins/android/androidconfigurations.cpp
@@ -182,7 +182,7 @@ AndroidConfig::AndroidConfig()
 
 void AndroidConfig::save(QSettings &settings) const
 {
-    QFileInfo fileInfo(settingsFileName().toFileInfo());
+    QFileInfo fileInfo = settingsFileName().toFileInfo();
     if (fileInfo.exists())
         settings.setValue(changeTimeStamp, fileInfo.lastModified().toMSecsSinceEpoch() / 1000);
 
diff --git a/src/plugins/projectexplorer/devicesupport/devicemanager.cpp b/src/plugins/projectexplorer/devicesupport/devicemanager.cpp
index 7c4c1b5413..3616d7c538 100644
--- a/src/plugins/projectexplorer/devicesupport/devicemanager.cpp
+++ b/src/plugins/projectexplorer/devicesupport/devicemanager.cpp
@@ -80,6 +80,8 @@ public:
     QList<IDevice::Ptr> devices;
     QList<IDevice::Ptr> inactiveAutoDetectedDevices;
     QHash<Core::Id, Core::Id> defaultDevices;
+
+    Utils::PersistentSettingsWriter *writer;
 };
 DeviceManager *DeviceManagerPrivate::clonedInstance = 0;
 
@@ -134,10 +136,8 @@ void DeviceManager::copy(const DeviceManager *source, DeviceManager *target, boo
 
 void DeviceManager::save()
 {
-    Utils::PersistentSettingsWriter writer;
-    writer.saveValue(QLatin1String(DeviceManagerKey), toMap());
-    writer.save(settingsFilePath(QLatin1String("/qtcreator/devices.xml")),
-                QLatin1String("QtCreatorDevices"), Core::ICore::mainWindow());
+    d->writer->saveValue(QLatin1String(DeviceManagerKey), toMap());
+    d->writer->save(Core::ICore::mainWindow());
 }
 
 void DeviceManager::load()
@@ -332,6 +332,8 @@ const IDeviceFactory *DeviceManager::restoreFactory(const QVariantMap &map)
 
 DeviceManager::DeviceManager(bool isInstance) : d(new DeviceManagerPrivate)
 {
+    d->writer = new Utils::PersistentSettingsWriter(settingsFilePath(QLatin1String("/qtcreator/devices.xml")),
+                                                    QLatin1String("QtCreatorDevices"));
     if (isInstance) {
         load();
         connect(Core::ICore::instance(), SIGNAL(saveSettingsRequested()), SLOT(save()));
@@ -340,6 +342,7 @@ DeviceManager::DeviceManager(bool isInstance) : d(new DeviceManagerPrivate)
 
 DeviceManager::~DeviceManager()
 {
+    delete d->writer;
     delete d;
 }
 
diff --git a/src/plugins/projectexplorer/devicesupport/devicemanager.h b/src/plugins/projectexplorer/devicesupport/devicemanager.h
index 534b7385a8..e9caad505a 100644
--- a/src/plugins/projectexplorer/devicesupport/devicemanager.h
+++ b/src/plugins/projectexplorer/devicesupport/devicemanager.h
@@ -35,6 +35,8 @@
 #include <projectexplorer/projectexplorer_export.h>
 #include <utils/fileutils.h>
 
+#include <utils/fileutils.h>
+
 #include <QObject>
 
 namespace ProjectExplorer {
diff --git a/src/plugins/projectexplorer/profilemanager.cpp b/src/plugins/projectexplorer/profilemanager.cpp
index 23ea06480a..e91878a42c 100644
--- a/src/plugins/projectexplorer/profilemanager.cpp
+++ b/src/plugins/projectexplorer/profilemanager.cpp
@@ -86,14 +86,19 @@ public:
     bool m_initialized;
     QList<ProfileInformation *> m_informationList;
     QList<Profile *> m_profileList;
+    Utils::PersistentSettingsWriter *m_writer;
 };
 
 ProfileManagerPrivate::ProfileManagerPrivate()
-    : m_defaultProfile(0), m_initialized(false)
+    : m_defaultProfile(0), m_initialized(false),
+      m_writer(new Utils::PersistentSettingsWriter(settingsFileName(), QLatin1String("QtCreatorProfiles")))
 { }
 
 ProfileManagerPrivate::~ProfileManagerPrivate()
 {
+    qDeleteAll(m_informationList);
+    qDeleteAll(m_profileList);
+    delete m_writer;
 }
 
 QList<Task> ProfileManagerPrivate::validateProfile(Profile *p) const
@@ -213,8 +218,6 @@ void ProfileManager::restoreProfiles()
 ProfileManager::~ProfileManager()
 {
     // Clean out profile information to avoid calling them during deregistration:
-    qDeleteAll(d->m_informationList);
-    qDeleteAll(d->m_profileList);
     delete d;
     m_instance = 0;
 }
@@ -224,21 +227,20 @@ void ProfileManager::saveProfiles()
     if (!d->m_initialized) // ignore save requests while we are not initialized.
         return;
 
-    PersistentSettingsWriter writer;
-    writer.saveValue(QLatin1String(PROFILE_FILE_VERSION_KEY), 1);
+    d->m_writer->saveValue(QLatin1String(PROFILE_FILE_VERSION_KEY), 1);
 
     int count = 0;
     foreach (Profile *p, profiles()) {
         QVariantMap tmp = p->toMap();
         if (tmp.isEmpty())
             continue;
-        writer.saveValue(QString::fromLatin1(PROFILE_DATA_KEY) + QString::number(count), tmp);
+        d->m_writer->saveValue(QString::fromLatin1(PROFILE_DATA_KEY) + QString::number(count), tmp);
         ++count;
     }
-    writer.saveValue(QLatin1String(PROFILE_COUNT_KEY), count);
-    writer.saveValue(QLatin1String(PROFILE_DEFAULT_KEY),
+    d->m_writer->saveValue(QLatin1String(PROFILE_COUNT_KEY), count);
+    d->m_writer->saveValue(QLatin1String(PROFILE_DEFAULT_KEY),
                      d->m_defaultProfile ? QString::fromLatin1(d->m_defaultProfile->id().name()) : QString());
-    writer.save(settingsFileName(), QLatin1String("QtCreatorProfiles"), Core::ICore::mainWindow());
+    d->m_writer->save(Core::ICore::mainWindow());
 }
 
 bool greaterPriority(ProfileInformation *a, ProfileInformation *b)
diff --git a/src/plugins/projectexplorer/project.cpp b/src/plugins/projectexplorer/project.cpp
index e1a2c75118..c8b29d4789 100644
--- a/src/plugins/projectexplorer/project.cpp
+++ b/src/plugins/projectexplorer/project.cpp
@@ -87,23 +87,28 @@ class ProjectPrivate
 {
 public:
     ProjectPrivate();
+    ~ProjectPrivate();
+
     QList<Target *> m_targets;
     Target *m_activeTarget;
     EditorConfiguration *m_editorConfiguration;
     Core::Context m_projectContext;
     Core::Context m_projectLanguage;
     QVariantMap m_pluginSettings;
+    SettingsAccessor *m_accessor;
 };
 
 ProjectPrivate::ProjectPrivate() :
     m_activeTarget(0),
-    m_editorConfiguration(new EditorConfiguration())
-{
-}
+    m_editorConfiguration(new EditorConfiguration()),
+    m_accessor(0)
+{ }
+
+ProjectPrivate::~ProjectPrivate()
+{ delete m_accessor; }
 
 Project::Project() : d(new ProjectPrivate)
-{
-}
+{ }
 
 Project::~Project()
 {
@@ -281,12 +286,16 @@ Target *Project::restoreTarget(const QVariantMap &data)
 void Project::saveSettings()
 {
     emit aboutToSaveSettings();
-    SettingsAccessor::instance()->saveSettings(this, toMap());
+    if (!d->m_accessor)
+        d->m_accessor = new SettingsAccessor(this);
+    d->m_accessor->saveSettings(toMap());
 }
 
 bool Project::restoreSettings()
 {
-    QVariantMap map(SettingsAccessor::instance()->restoreSettings(this));
+    if (!d->m_accessor)
+        d->m_accessor = new SettingsAccessor(this);
+    QVariantMap map(d->m_accessor->restoreSettings());
     bool ok = fromMap(map);
     if (ok)
         emit settingsLoaded();
diff --git a/src/plugins/projectexplorer/session.cpp b/src/plugins/projectexplorer/session.cpp
index 70f82606ed..79e3ae6fc2 100644
--- a/src/plugins/projectexplorer/session.cpp
+++ b/src/plugins/projectexplorer/session.cpp
@@ -91,7 +91,8 @@ SessionManager::SessionManager(QObject *parent)
     m_sessionName(QLatin1String("default")),
     m_virginSession(true),
     m_loadingSession(false),
-    m_startupProject(0)
+    m_startupProject(0),
+    m_writer(0)
 {
     connect(ModeManager::instance(), SIGNAL(currentModeChanged(Core::IMode*)),
             this, SLOT(saveActiveMode(Core::IMode*)));
@@ -111,6 +112,7 @@ SessionManager::SessionManager(QObject *parent)
 SessionManager::~SessionManager()
 {
     emit aboutToUnloadSession(m_sessionName);
+    delete m_writer;
 }
 
 
@@ -304,12 +306,15 @@ bool SessionManager::save()
 
     emit aboutToSaveSession();
 
-    PersistentSettingsWriter writer;
+    if (!m_writer || m_writer->fileName() != sessionNameToFileName(m_sessionName)) {
+        delete m_writer;
+        m_writer = new Utils::PersistentSettingsWriter(sessionNameToFileName(m_sessionName),
+                                                       QLatin1String("QtCreatorSession"));
+    }
 
     // save the startup project
-    if (m_startupProject) {
-        writer.saveValue(QLatin1String("StartupProject"), m_startupProject->document()->fileName());
-    }
+    if (m_startupProject)
+        m_writer->saveValue(QLatin1String("StartupProject"), m_startupProject->document()->fileName());
 
     QStringList projectFiles;
     foreach (Project *pro, m_projects)
@@ -321,7 +326,7 @@ bool SessionManager::save()
         if (!projectFiles.contains(failed))
             projectFiles << failed;
 
-    writer.saveValue(QLatin1String("ProjectList"), projectFiles);
+    m_writer->saveValue(QLatin1String("ProjectList"), projectFiles);
 
     QMap<QString, QVariant> depMap;
     QMap<QString, QStringList>::const_iterator i = m_depMap.constBegin();
@@ -334,7 +339,7 @@ bool SessionManager::save()
         depMap.insert(key, values);
         ++i;
     }
-    writer.saveValue(QLatin1String("ProjectDependencies"), QVariant(depMap));
+    m_writer->saveValue(QLatin1String("ProjectDependencies"), QVariant(depMap));
 
     int editorCount = 0;
     QList<Core::IEditor *> editors = ICore::editorManager()->openedEditors();
@@ -343,25 +348,24 @@ bool SessionManager::save()
         if (!editor->isTemporary())
             ++editorCount;
     }
-    writer.saveValue(QLatin1String("OpenEditors"), editorCount);
-    writer.saveValue(QLatin1String("EditorSettings"),
-                     ICore::editorManager()->saveState().toBase64());
+    m_writer->saveValue(QLatin1String("OpenEditors"), editorCount);
+    m_writer->saveValue(QLatin1String("EditorSettings"),
+                        ICore::editorManager()->saveState().toBase64());
 
     QMap<QString, QVariant>::const_iterator it, end;
     end = m_values.constEnd();
     QStringList keys;
     for (it = m_values.constBegin(); it != end; ++it) {
-        writer.saveValue(QLatin1String("value-") + it.key(), it.value());
+        m_writer->saveValue(QLatin1String("value-") + it.key(), it.value());
         keys << it.key();
     }
 
-    writer.saveValue(QLatin1String("valueKeys"), keys);
+    m_writer->saveValue(QLatin1String("valueKeys"), keys);
 
-    Utils::FileName fileName = sessionNameToFileName(m_sessionName);
-    bool result = writer.save(fileName, QLatin1String("QtCreatorSession"), Core::ICore::mainWindow());
+    bool result = m_writer->save(Core::ICore::mainWindow());
     if (!result) {
         QMessageBox::warning(0, tr("Error while saving session"),
-                                tr("Could not save session to file %1").arg(fileName.toUserOutput()));
+                                tr("Could not save session to file %1").arg(m_writer->fileName().toUserOutput()));
     }
 
     if (debug)
diff --git a/src/plugins/projectexplorer/session.h b/src/plugins/projectexplorer/session.h
index 75000e4ff9..881b100cab 100644
--- a/src/plugins/projectexplorer/session.h
+++ b/src/plugins/projectexplorer/session.h
@@ -176,6 +176,7 @@ private:
     QMap<QString, QStringList> m_depMap;
     QMap<QString, QVariant> m_values;
     QFutureInterface<void> m_future;
+    Utils::PersistentSettingsWriter *m_writer;
 };
 
 } // namespace ProjectExplorer
diff --git a/src/plugins/projectexplorer/settingsaccessor.cpp b/src/plugins/projectexplorer/settingsaccessor.cpp
index e9401c3a48..1816a9bb3c 100644
--- a/src/plugins/projectexplorer/settingsaccessor.cpp
+++ b/src/plugins/projectexplorer/settingsaccessor.cpp
@@ -450,20 +450,25 @@ static QVariantMap processHandlerNodes(const HandlerNode &node, const QVariantMa
 // -------------------------------------------------------------------------
 // UserFileAccessor
 // -------------------------------------------------------------------------
-SettingsAccessor::SettingsAccessor() :
+SettingsAccessor::SettingsAccessor(Project *project) :
     m_firstVersion(-1),
     m_lastVersion(-1),
     m_userFileAcessor(QByteArray("qtcUserFileName"),
                       QLatin1String(".user"),
                       QString::fromLocal8Bit(qgetenv("QTC_EXTENSION")),
                       true,
-                      true),
+                      true,
+                      this),
     m_sharedFileAcessor(QByteArray("qtcSharedFileName"),
                         QLatin1String(".shared"),
                         QString::fromLocal8Bit(qgetenv("QTC_SHARED_EXTENSION")),
                         false,
-                        false)
+                        false,
+                        this),
+    m_project(project)
 {
+    QTC_CHECK(m_project);
+
     addVersionHandler(new Version0Handler);
     addVersionHandler(new Version1Handler);
     addVersionHandler(new Version2Handler);
@@ -483,11 +488,8 @@ SettingsAccessor::~SettingsAccessor()
     qDeleteAll(m_handlers);
 }
 
-SettingsAccessor *SettingsAccessor::instance()
-{
-    static SettingsAccessor acessor;
-    return &acessor;
-}
+Project *SettingsAccessor::project() const
+{ return m_project; }
 
 namespace {
 
@@ -589,17 +591,21 @@ void trackUserStickySettings(QVariantMap *userMap, const QVariantMap &sharedMap)
 } // Anonymous
 
 
-QVariantMap SettingsAccessor::restoreSettings(Project *project) const
+QVariantMap SettingsAccessor::restoreSettings() const
 {
-    if (m_lastVersion < 0 || !project)
+    if (m_lastVersion < 0)
         return QVariantMap();
 
     SettingsData settings;
-    if (!m_userFileAcessor.readFile(project, &settings))
+    QString fn = project()->property(m_userFileAcessor.id()).toString();
+    if (fn.isEmpty())
+        fn = project()->document()->fileName() + m_userFileAcessor.suffix();
+    settings.m_fileName = Utils::FileName::fromString(fn);
+    if (!m_userFileAcessor.readFile(&settings))
         settings.clear(); // No user settings, but there can still be shared ones.
 
     if (settings.isValid()) {
-        if (settings.m_version > SettingsAccessor::instance()->m_lastVersion + 1) {
+        if (settings.m_version > m_lastVersion + 1) {
             QMessageBox::information(
                 Core::ICore::mainWindow(),
                 QApplication::translate("ProjectExplorer::SettingsAccessor",
@@ -652,7 +658,7 @@ QVariantMap SettingsAccessor::restoreSettings(Project *project) const
 
     // Time to consider shared settings...
     SettingsData sharedSettings;
-    if (m_sharedFileAcessor.readFile(project, &sharedSettings)) {
+    if (m_sharedFileAcessor.readFile(&sharedSettings)) {
         bool useSharedSettings = true;
         if (sharedSettings.m_version != settings.m_version) {
             int baseFileVersion;
@@ -692,20 +698,20 @@ QVariantMap SettingsAccessor::restoreSettings(Project *project) const
             if (useSharedSettings) {
                 // We now update the user and shared settings so they are compatible.
                 for (int i = sharedSettings.m_version; i < baseFileVersion; ++i)
-                    sharedSettings.m_map = m_handlers.value(i)->update(project, sharedSettings.m_map);
+                    sharedSettings.m_map = m_handlers.value(i)->update(m_project, sharedSettings.m_map);
 
                 if (!settings.isValid()) {
-                    project->setProperty(SHARED_SETTINGS, sharedSettings.m_map);
+                    m_project->setProperty(SHARED_SETTINGS, sharedSettings.m_map);
                     return sharedSettings.m_map;
                 }
                 for (int i = settings.m_version; i < baseFileVersion; ++i)
-                    settings.m_map = m_handlers.value(i)->update(project, settings.m_map);
+                    settings.m_map = m_handlers.value(i)->update(m_project, settings.m_map);
                 settings.m_version = baseFileVersion;
             }
         }
 
         if (useSharedSettings) {
-            project->setProperty(SHARED_SETTINGS, sharedSettings.m_map);
+            m_project->setProperty(SHARED_SETTINGS, sharedSettings.m_map);
             if (!settings.isValid())
                 return sharedSettings.m_map;
 
@@ -718,22 +724,26 @@ QVariantMap SettingsAccessor::restoreSettings(Project *project) const
 
     // Update from the base version to Creator's version.
     for (int i = settings.m_version; i <= m_lastVersion; ++i)
-        settings.m_map = m_handlers.value(i)->update(project, settings.m_map);
+        settings.m_map = m_handlers.value(i)->update(m_project, settings.m_map);
 
     return settings.m_map;
 }
 
-bool SettingsAccessor::saveSettings(const Project *project, const QVariantMap &map) const
+bool SettingsAccessor::saveSettings(const QVariantMap &map) const
 {
-    if (!project || map.isEmpty())
+    if (map.isEmpty())
         return false;
 
     SettingsData settings(map);
-    const QVariant &shared = project->property(SHARED_SETTINGS);
+    QString fn = project()->property(m_userFileAcessor.id()).toString();
+    if (fn.isEmpty())
+        fn = project()->document()->fileName() + m_userFileAcessor.suffix();
+    settings.m_fileName = Utils::FileName::fromString(fn);
+    const QVariant &shared = m_project->property(SHARED_SETTINGS);
     if (shared.isValid())
         trackUserStickySettings(&settings.m_map, shared.toMap());
 
-    return m_userFileAcessor.writeFile(project, &settings);
+    return m_userFileAcessor.writeFile(&settings);
 }
 
 void SettingsAccessor::addVersionHandler(UserFileVersionHandler *handler)
@@ -800,14 +810,21 @@ SettingsAccessor::FileAccessor::FileAccessor(const QByteArray &id,
                                              const QString &defaultSuffix,
                                              const QString &environmentSuffix,
                                              bool envSpecific,
-                                             bool versionStrict)
+                                             bool versionStrict, SettingsAccessor *accessor)
     : m_id(id)
     , m_environmentSpecific(envSpecific)
     , m_versionStrict(versionStrict)
+    , m_accessor(accessor)
+    , m_writer(0)
 {
     assignSuffix(defaultSuffix, environmentSuffix);
 }
 
+SettingsAccessor::FileAccessor::~FileAccessor()
+{
+    delete m_writer;
+}
+
 void SettingsAccessor::FileAccessor::assignSuffix(const QString &defaultSuffix,
                                                   const QString &environmentSuffix)
 {
@@ -820,11 +837,6 @@ void SettingsAccessor::FileAccessor::assignSuffix(const QString &defaultSuffix,
     }
 }
 
-QString SettingsAccessor::FileAccessor::assembleFileName(const Project *project) const
-{
-    return project->document()->fileName() + m_suffix;
-}
-
 bool SettingsAccessor::FileAccessor::findNewestCompatibleSetting(SettingsData *settings) const
 {
     const QString baseFileName = settings->m_fileName.toString();
@@ -833,7 +845,6 @@ bool SettingsAccessor::FileAccessor::findNewestCompatibleSetting(SettingsData *s
     settings->m_version = -1;
 
     PersistentSettingsReader reader;
-    SettingsAccessor *acessor = SettingsAccessor::instance();
 
     QFileInfo fileInfo(baseFileName);
     QStringList fileNameFilter(fileInfo.fileName() + QLatin1String(".*"));
@@ -845,10 +856,10 @@ bool SettingsAccessor::FileAccessor::findNewestCompatibleSetting(SettingsData *s
         const QString &suffix = file.mid(fileInfo.fileName().length() + 1);
         const QString &candidateFileName = baseFileName + QLatin1String(".") + suffix;
         candidates.append(candidateFileName);
-        for (int candidateVersion = acessor->m_lastVersion;
-             candidateVersion >= acessor->m_firstVersion;
+        for (int candidateVersion = m_accessor->m_lastVersion;
+             candidateVersion >= m_accessor->m_firstVersion;
              --candidateVersion) {
-            if (suffix == acessor->m_handlers.value(candidateVersion)->displayUserFileVersion()) {
+            if (suffix == m_accessor->m_handlers.value(candidateVersion)->displayUserFileVersion()) {
                 if (candidateVersion > settings->m_version) {
                     settings->m_version = candidateVersion;
                     settings->m_fileName = Utils::FileName::fromString(candidateFileName);
@@ -876,7 +887,7 @@ bool SettingsAccessor::FileAccessor::findNewestCompatibleSetting(SettingsData *s
         if (reader.load(fn)) {
             settings->m_map = reader.restoreValues();
             int candidateVersion = settings->m_map.value(QLatin1String(VERSION_KEY), 0).toInt();
-            if (candidateVersion == acessor->m_lastVersion + 1) {
+            if (candidateVersion == m_accessor->m_lastVersion + 1) {
                 settings->m_version = candidateVersion;
                 settings->m_fileName = fn;
                 return true;
@@ -890,11 +901,9 @@ bool SettingsAccessor::FileAccessor::findNewestCompatibleSetting(SettingsData *s
     return false;
 }
 
-bool SettingsAccessor::FileAccessor::readFile(Project *project,
-                                             SettingsData *settings) const
+bool SettingsAccessor::FileAccessor::readFile(SettingsData *settings) const
 {
     PersistentSettingsReader reader;
-    settings->m_fileName = Utils::FileName::fromString(assembleFileName(project));
     if (!reader.load(settings->m_fileName))
         return false;
 
@@ -905,43 +914,41 @@ bool SettingsAccessor::FileAccessor::readFile(Project *project,
     if (!m_versionStrict)
         return true;
 
-    if (settings->m_version < SettingsAccessor::instance()->m_firstVersion) {
+    if (settings->m_version < m_accessor->m_firstVersion) {
         qWarning() << "Version" << settings->m_version << "in" << m_suffix << "too old.";
         return false;
     }
 
-    if (settings->m_version > SettingsAccessor::instance()->m_lastVersion + 1) {
+    if (settings->m_version > m_accessor->m_lastVersion + 1) {
         if (!findNewestCompatibleSetting(settings))
             return false;
 
         settings->m_usingBackup = true;
-        project->setProperty(m_id.constData(), settings->m_fileName.toString());
+        m_accessor->project()->setProperty(m_id.constData(), settings->m_fileName.toString());
     }
 
     return true;
 }
 
-bool SettingsAccessor::FileAccessor::writeFile(const Project *project,
-                                              const SettingsData *settings) const
+bool SettingsAccessor::FileAccessor::writeFile(const SettingsData *settings) const
 {
-    PersistentSettingsWriter writer;
+    if (!m_writer || m_writer->fileName() != settings->m_fileName) {
+        delete m_writer;
+        m_writer = new Utils::PersistentSettingsWriter(settings->m_fileName, QLatin1String("QtCreatorProject"));
+    }
+
     for (QVariantMap::const_iterator i = settings->m_map.constBegin();
          i != settings->m_map.constEnd();
          ++i) {
-        writer.saveValue(i.key(), i.value());
+        m_writer->saveValue(i.key(), i.value());
     }
 
-    writer.saveValue(QLatin1String(VERSION_KEY), SettingsAccessor::instance()->m_lastVersion + 1);
-
-    if (m_environmentSpecific) {
-        writer.saveValue(QLatin1String(ENVIRONMENT_ID_KEY),
-                         ProjectExplorerPlugin::instance()->projectExplorerSettings().environmentId.toString());
-    }
+    m_writer->saveValue(QLatin1String(VERSION_KEY), m_accessor->m_lastVersion + 1);
 
-    const QString &fileName = project->property(m_id).toString();
-    return writer.save(Utils::FileName::fromString(fileName.isEmpty() ? assembleFileName(project) : fileName),
-                       QLatin1String("QtCreatorProject"),
-                       Core::ICore::mainWindow());
+    if (m_environmentSpecific)
+        m_writer->saveValue(QLatin1String(ENVIRONMENT_ID_KEY),
+                            ProjectExplorerPlugin::instance()->projectExplorerSettings().environmentId.toString());
+    return m_writer->save(Core::ICore::mainWindow());
 }
 
 // -------------------------------------------------------------------------
diff --git a/src/plugins/projectexplorer/settingsaccessor.h b/src/plugins/projectexplorer/settingsaccessor.h
index 30f17650fd..00d6dc4136 100644
--- a/src/plugins/projectexplorer/settingsaccessor.h
+++ b/src/plugins/projectexplorer/settingsaccessor.h
@@ -32,8 +32,7 @@
 #define PROJECTMANAGER_USERFILEACCESSOR_H
 
 #include <utils/fileutils.h>
-
-#include <QVariantMap>
+#include <utils/persistentsettings.h>
 
 namespace ProjectExplorer {
 
@@ -46,15 +45,15 @@ class UserFileVersionHandler;
 class SettingsAccessor
 {
 public:
+    SettingsAccessor(Project *project);
     ~SettingsAccessor();
 
-    static SettingsAccessor *instance();
+    Project *project() const;
 
-    QVariantMap restoreSettings(Project *project) const;
-    bool saveSettings(const Project *project, const QVariantMap &map) const;
+    QVariantMap restoreSettings() const;
+    bool saveSettings(const QVariantMap &map) const;
 
 private:
-    SettingsAccessor();
 
     // Takes ownership of the handler!
     void addVersionHandler(Internal::UserFileVersionHandler *handler);
@@ -83,10 +82,15 @@ private:
                      const QString &defaultSuffix,
                      const QString &environmentSuffix,
                      bool envSpecific,
-                     bool versionStrict);
+                     bool versionStrict,
+                     SettingsAccessor *accessor);
+        ~FileAccessor();
+
+        bool readFile(SettingsData *settings) const;
+        bool writeFile(const SettingsData *settings) const;
 
-        bool readFile(Project *project, SettingsData *settings) const;
-        bool writeFile(const Project *project, const SettingsData *settings) const;
+        QString suffix() const { return m_suffix; }
+        QByteArray id() const { return m_id; }
 
     private:
         void assignSuffix(const QString &defaultSuffix, const QString &environmentSuffix);
@@ -97,6 +101,8 @@ private:
         QString m_suffix;
         bool m_environmentSpecific;
         bool m_versionStrict;
+        SettingsAccessor *m_accessor;
+        mutable Utils::PersistentSettingsWriter *m_writer;
     };
 
     static bool verifyEnvironmentId(const QString &id);
@@ -106,6 +112,8 @@ private:
     int m_lastVersion;
     const FileAccessor m_userFileAcessor;
     const FileAccessor m_sharedFileAcessor;
+
+    Project *m_project;
 };
 
 } // namespace ProjectExplorer
diff --git a/src/plugins/projectexplorer/toolchainmanager.cpp b/src/plugins/projectexplorer/toolchainmanager.cpp
index 207281101b..b286c9db53 100644
--- a/src/plugins/projectexplorer/toolchainmanager.cpp
+++ b/src/plugins/projectexplorer/toolchainmanager.cpp
@@ -76,21 +76,27 @@ class ToolChainManagerPrivate
 {
 public:
     ToolChainManagerPrivate(ToolChainManager *parent);
+    ~ToolChainManagerPrivate();
 
     QList<ToolChain *> &toolChains();
 
     ToolChainManager *q;
     bool m_initialized;
     QMap<QString, Utils::FileName> m_abiToDebugger;
+    Utils::PersistentSettingsWriter *m_writer;
 
 private:
     QList<ToolChain *> m_toolChains;
 };
 
 ToolChainManagerPrivate::ToolChainManagerPrivate(ToolChainManager *parent)
-    : q(parent), m_initialized(false)
+    : q(parent), m_initialized(false),
+      m_writer(new Utils::PersistentSettingsWriter(settingsFileName(QLatin1String(TOOLCHAIN_FILENAME)), QLatin1String("QtCreatorToolChains")))
 { }
 
+ToolChainManagerPrivate::~ToolChainManagerPrivate()
+{ delete m_writer; }
+
 QList<ToolChain *> &ToolChainManagerPrivate::toolChains()
 {
     if (!m_initialized) {
@@ -203,8 +209,7 @@ ToolChainManager::~ToolChainManager()
 
 void ToolChainManager::saveToolChains()
 {
-    PersistentSettingsWriter writer;
-    writer.saveValue(QLatin1String(TOOLCHAIN_FILE_VERSION_KEY), 1);
+    d->m_writer->saveValue(QLatin1String(TOOLCHAIN_FILE_VERSION_KEY), 1);
 
     int count = 0;
     foreach (ToolChain *tc, d->toolChains()) {
@@ -212,12 +217,12 @@ void ToolChainManager::saveToolChains()
             QVariantMap tmp = tc->toMap();
             if (tmp.isEmpty())
                 continue;
-            writer.saveValue(QString::fromLatin1(TOOLCHAIN_DATA_KEY) + QString::number(count), tmp);
+            d->m_writer->saveValue(QString::fromLatin1(TOOLCHAIN_DATA_KEY) + QString::number(count), tmp);
             ++count;
         }
     }
-    writer.saveValue(QLatin1String(TOOLCHAIN_COUNT_KEY), count);
-    writer.save(settingsFileName(QLatin1String(TOOLCHAIN_FILENAME)), QLatin1String("QtCreatorToolChains"), Core::ICore::mainWindow());
+    d->m_writer->saveValue(QLatin1String(TOOLCHAIN_COUNT_KEY), count);
+    d->m_writer->save(Core::ICore::mainWindow());
 
     // Do not save default debuggers! Those are set by the SDK!
 }
diff --git a/src/plugins/qtsupport/qtversionmanager.cpp b/src/plugins/qtsupport/qtversionmanager.cpp
index 9335cbfb5b..14ec9a7659 100644
--- a/src/plugins/qtsupport/qtversionmanager.cpp
+++ b/src/plugins/qtsupport/qtversionmanager.cpp
@@ -120,7 +120,8 @@ QtVersionManager *QtVersionManager::m_self = 0;
 
 QtVersionManager::QtVersionManager() :
     m_configFileWatcher(0),
-    m_fileWatcherTimer(new QTimer(this))
+    m_fileWatcherTimer(new QTimer(this)),
+    m_writer(0)
 {
     m_self = this;
     m_idcount = 1;
@@ -163,6 +164,7 @@ bool QtVersionManager::delayedInitialize()
 
 QtVersionManager::~QtVersionManager()
 {
+    delete m_writer;
     qDeleteAll(m_versions);
     m_versions.clear();
 }
@@ -233,8 +235,8 @@ void QtVersionManager::updateFromInstaller()
 {
     m_fileWatcherTimer->stop();
 
-    // Handle overwritting of data:
     const Utils::FileName path = globalSettingsFileName();
+    // Handle overwritting of data:
     if (m_configFileWatcher) {
         m_configFileWatcher->removeFile(path.toString());
         m_configFileWatcher->addFile(path.toString(), Utils::FileSystemWatcher::WatchModifiedDate);
@@ -357,8 +359,10 @@ void QtVersionManager::updateFromInstaller()
 
 void QtVersionManager::saveQtVersions()
 {
-    Utils::PersistentSettingsWriter writer;
-    writer.saveValue(QLatin1String(QTVERSION_FILE_VERSION_KEY), 1);
+    if (!m_writer)
+        m_writer = new Utils::PersistentSettingsWriter(settingsFileName(QLatin1String(QTVERSION_FILENAME)),
+                                                       QLatin1String("QtCreatorQtVersions"));
+    m_writer->saveValue(QLatin1String(QTVERSION_FILE_VERSION_KEY), 1);
 
     int count = 0;
     foreach (BaseQtVersion *qtv, m_versions) {
@@ -366,11 +370,11 @@ void QtVersionManager::saveQtVersions()
         if (tmp.isEmpty())
             continue;
         tmp.insert(QLatin1String(QTVERSION_TYPE_KEY), qtv->type());
-        writer.saveValue(QString::fromLatin1(QTVERSION_DATA_KEY) + QString::number(count), tmp);
+        m_writer->saveValue(QString::fromLatin1(QTVERSION_DATA_KEY) + QString::number(count), tmp);
         ++count;
 
     }
-    writer.save(settingsFileName(QLatin1String(QTVERSION_FILENAME)), QLatin1String("QtCreatorQtVersions"), Core::ICore::mainWindow());
+    m_writer->save(Core::ICore::mainWindow());
 }
 
 void QtVersionManager::findSystemQt()
diff --git a/src/plugins/qtsupport/qtversionmanager.h b/src/plugins/qtsupport/qtversionmanager.h
index 2b378895ed..f2f4697c44 100644
--- a/src/plugins/qtsupport/qtversionmanager.h
+++ b/src/plugins/qtsupport/qtversionmanager.h
@@ -37,7 +37,11 @@
 #include <QSet>
 #include <QStringList>
 
-namespace Utils { class FileSystemWatcher; }
+namespace Utils {
+class FileSystemWatcher;
+class PersistentSettingsWriter;
+} // namespace Utils
+
 namespace ProjectExplorer { class ProfileInformation; }
 
 namespace QtSupport {
@@ -143,6 +147,7 @@ private:
 
     Utils::FileSystemWatcher *m_configFileWatcher;
     QTimer *m_fileWatcherTimer;
+    Utils::PersistentSettingsWriter *m_writer;
 };
 
 namespace Internal {
diff --git a/src/plugins/texteditor/codestylepool.cpp b/src/plugins/texteditor/codestylepool.cpp
index d3462fcc63..e2707f4c11 100644
--- a/src/plugins/texteditor/codestylepool.cpp
+++ b/src/plugins/texteditor/codestylepool.cpp
@@ -120,9 +120,11 @@ QString CodeStylePool::settingsDir() const
     return customCodeStylesPath().append(suffix);
 }
 
-QString CodeStylePool::settingsPath(const QString &id) const
+Utils::FileName CodeStylePool::settingsPath(const QString &id) const
 {
-    return settingsDir() + QLatin1Char('/') + id + QLatin1String(".xml");
+    Utils::FileName path = Utils::FileName::fromString(settingsDir());
+    path.appendPath(id + QLatin1String(".xml"));
+    return path;
 }
 
 QList<ICodeStylePreferences *> CodeStylePool::codeStyles() const
@@ -200,7 +202,7 @@ void CodeStylePool::removeCodeStyle(ICodeStylePreferences *codeStyle)
     d->m_idToCodeStyle.remove(codeStyle->id());
 
     QDir dir(settingsDir());
-    dir.remove(QFileInfo(settingsPath(codeStyle->id())).fileName());
+    dir.remove(settingsPath(codeStyle->id()).toFileInfo().fileName());
 
     delete codeStyle;
 }
@@ -218,11 +220,11 @@ void CodeStylePool::loadCustomCodeStyles()
         const QString codeStyleFile = codeStyleFiles.at(i);
         // filter out styles which id is the same as one of built-in styles
         if (!d->m_idToCodeStyle.contains(QFileInfo(codeStyleFile).completeBaseName()))
-            loadCodeStyle(dir.absoluteFilePath(codeStyleFile));
+            loadCodeStyle(Utils::FileName::fromString(dir.absoluteFilePath(codeStyleFile)));
     }
 }
 
-ICodeStylePreferences *CodeStylePool::importCodeStyle(const QString &fileName)
+ICodeStylePreferences *CodeStylePool::importCodeStyle(const Utils::FileName &fileName)
 {
     TextEditor::ICodeStylePreferences *codeStyle = loadCodeStyle(fileName);
     if (codeStyle)
@@ -230,14 +232,14 @@ ICodeStylePreferences *CodeStylePool::importCodeStyle(const QString &fileName)
     return codeStyle;
 }
 
-ICodeStylePreferences *CodeStylePool::loadCodeStyle(const QString &fileName)
+ICodeStylePreferences *CodeStylePool::loadCodeStyle(const Utils::FileName &fileName)
 {
     TextEditor::ICodeStylePreferences *codeStyle = 0;
     Utils::PersistentSettingsReader reader;
-    reader.load(Utils::FileName::fromString(fileName));
+    reader.load(fileName);
     QVariantMap m = reader.restoreValues();
     if (m.contains(QLatin1String(codeStyleDataKey))) {
-        const QString id = QFileInfo(fileName).completeBaseName();
+        const QString id = fileName.toFileInfo().completeBaseName();
         const QString displayName = reader.restoreValue(QLatin1String(displayNameKey)).toString();
         const QVariantMap map = reader.restoreValue(QLatin1String(codeStyleDataKey)).toMap();
         if (d->m_factory) {
@@ -280,14 +282,13 @@ void CodeStylePool::saveCodeStyle(ICodeStylePreferences *codeStyle) const
     exportCodeStyle(settingsPath(codeStyle->id()), codeStyle);
 }
 
-void CodeStylePool::exportCodeStyle(const QString &fileName, ICodeStylePreferences *codeStyle) const
+void CodeStylePool::exportCodeStyle(const Utils::FileName &fileName, ICodeStylePreferences *codeStyle) const
 {
     QVariantMap map;
     codeStyle->toMap(QString::null, &map);
-    Utils::PersistentSettingsWriter writer;
+    Utils::PersistentSettingsWriter writer(fileName, QLatin1String(codeStyleDocKey));
     writer.saveValue(QLatin1String(displayNameKey), codeStyle->displayName());
     writer.saveValue(QLatin1String(codeStyleDataKey), map);
-    writer.save(Utils::FileName::fromString(fileName), QLatin1String(codeStyleDocKey), 0);
+    writer.save(0);
 }
 
-
diff --git a/src/plugins/texteditor/codestylepool.h b/src/plugins/texteditor/codestylepool.h
index 9d690e517b..4dd1bd9147 100644
--- a/src/plugins/texteditor/codestylepool.h
+++ b/src/plugins/texteditor/codestylepool.h
@@ -33,6 +33,8 @@
 
 #include "texteditor_global.h"
 
+#include <utils/fileutils.h>
+
 #include <QObject>
 
 namespace TextEditor {
@@ -68,8 +70,8 @@ public:
 
     void loadCustomCodeStyles();
 
-    ICodeStylePreferences *importCodeStyle(const QString &fileName);
-    void exportCodeStyle(const QString &fileName, ICodeStylePreferences *codeStyle) const;
+    ICodeStylePreferences *importCodeStyle(const Utils::FileName &fileName);
+    void exportCodeStyle(const Utils::FileName &fileName, ICodeStylePreferences *codeStyle) const;
 
 signals:
     void codeStyleAdded(ICodeStylePreferences *);
@@ -80,12 +82,11 @@ private slots:
 
 private:
     QString settingsDir() const;
-    QString settingsPath(const QString &id) const;
-    ICodeStylePreferences *loadCodeStyle(const QString &fileName);
+    Utils::FileName settingsPath(const QString &id) const;
+    ICodeStylePreferences *loadCodeStyle(const Utils::FileName &fileName);
     void saveCodeStyle(ICodeStylePreferences *codeStyle) const;
 
     Internal::CodeStylePoolPrivate *d;
-
 };
 
 } // namespace TextEditor
diff --git a/src/plugins/texteditor/codestyleselectorwidget.cpp b/src/plugins/texteditor/codestyleselectorwidget.cpp
index beea626c77..ded0e3ac6f 100644
--- a/src/plugins/texteditor/codestyleselectorwidget.cpp
+++ b/src/plugins/texteditor/codestyleselectorwidget.cpp
@@ -343,8 +343,9 @@ void CodeStyleSelectorWidget::slotRemoveClicked()
 
 void CodeStyleSelectorWidget::slotImportClicked()
 {
-    const QString fileName = QFileDialog::getOpenFileName(this, tr("Import Code Style"), QString::null,
-                             tr("Code styles (*.xml);;All files (*)"));
+    const Utils::FileName fileName =
+            Utils::FileName::fromString(QFileDialog::getOpenFileName(this, tr("Import Code Style"), QString::null,
+                                                                     tr("Code styles (*.xml);;All files (*)")));
     if (!fileName.isEmpty()) {
         CodeStylePool *codeStylePool = m_codeStyle->delegatingPool();
         ICodeStylePreferences *importedStyle = codeStylePool->importCodeStyle(fileName);
@@ -352,7 +353,7 @@ void CodeStyleSelectorWidget::slotImportClicked()
             m_codeStyle->setCurrentDelegate(importedStyle);
         else
             QMessageBox::warning(this, tr("Import Code Style"),
-                                 tr("Cannot import code style"));
+                                 tr("Cannot import code style from %1"), fileName.toUserOutput());
     }
 }
 
@@ -364,7 +365,7 @@ void CodeStyleSelectorWidget::slotExportClicked()
                              tr("Code styles (*.xml);;All files (*)"));
     if (!fileName.isEmpty()) {
         CodeStylePool *codeStylePool = m_codeStyle->delegatingPool();
-        codeStylePool->exportCodeStyle(fileName, currentPreferences);
+        codeStylePool->exportCodeStyle(Utils::FileName::fromString(fileName), currentPreferences);
     }
 }