Added background save for config (to work better on ZFS)

CONTRIBUTING.md

@@ -5,7 +5,7 @@ Welcome and thank you for your interest in contributing.
 
 ### Compiling Code
 
-Project uses Qt 5 and Qt Creator is the preferred development environment.
+Project uses Qt 5.12.8 and Qt Creator is the preferred development environment.
 
 All code is situated in `src` directory.
 
@@ -56,7 +56,7 @@ all test cases.
 Fixes can be contributed using pull requests. Do note project is under MIT
 license and any contribution will inherit the same.
 
-LF line ending is strongly preffered. To have Git check it for you, configure
+LF line ending is strongly preferred. To have Git check it for you, configure
 `core.whitespace` setting:
 
     git config core.whitespace blank-at-eol,blank-at-eof,space-before-tab,cr-at-eol
@@ -68,7 +68,7 @@ All textual files should be encoded as UTF-8 without BOM.
 
 For non code files (xml, etc), use the best judgment. Albeit, do note that `tab`
 character should be avoided and a number of `space` characters should be used
-instead (4 being preffered).
+instead (4 being preferred).
 
 Code uses K&R coding style. Please do make sure any contribution follows the
 coding style already in use.

src/medo/config.cpp

@@ -15,6 +15,7 @@ Config::PortableStatus Config::_isPortable(PortableStatus::Unknown);
 bool Config::_immediateSave(true);
 Config::ConfigFile* Config::_configFile(nullptr);
 Config::ConfigFile* Config::_stateFile(nullptr);
+Config::ConfigSaveThread Config::_configSaveThread{};
 
 void Config::reset() {
     qDebug().noquote().nospace() << "[Config] reset()";
@@ -130,7 +131,7 @@ bool Config::immediateSave() {
 void Config::setImmediateSave(bool saveImmediately) {
     QMutexLocker locker(&_publicAccessMutex);
     _immediateSave = saveImmediately;
-    if (_immediateSave) { save(); } //to ensure any pending writes are cleared
+    if (_immediateSave) { Config::_configSaveThread.requestSave(); } //to ensure any pending writes are cleared
 }
 
 
@@ -630,6 +631,58 @@ void Config::resetStateFile() {
 }
 
 
+Config::ConfigSaveThread::ConfigSaveThread(void) {
+    this->setObjectName("ConfigSaveThread");
+    this->start(LowPriority);
+}
+
+Config::ConfigSaveThread::~ConfigSaveThread() {
+    this->requestInterruption();
+    this->wait();
+}
+
+void Config::ConfigSaveThread::requestSave() {
+    QMutexLocker locker(&_syncRoot);
+    _saveRequested = true;
+}
+
+void Config::ConfigSaveThread::run() {
+    while (!this->isInterruptionRequested()) {
+        QMutexLocker locker(&_syncRoot);
+        bool saveRequested = _saveRequested;
+        locker.unlock();
+        if (saveRequested) {
+            qDebug().noquote().nospace() << "[Config] Background save()";
+            QElapsedTimer stopwatch; stopwatch.start();
+            if (Config::getConfigFile()->save()) {
+                locker.relock();
+                _saveRequested = false;
+                locker.unlock();
+                qDebug().noquote().nospace() << "[Config] Background save() done in " << stopwatch.elapsed() << "ms";
+            } else {
+                qDebug().noquote().nospace() << "[Config] Background save() failed in " << stopwatch.elapsed() << "ms";
+                this->msleep(2500);  // give it some time
+            }
+        }
+        this->msleep(250);
+    }
+
+    {  // check once more when exiting
+        QMutexLocker locker(&_syncRoot);
+        bool saveRequested = _saveRequested;
+        locker.unlock();
+        if (saveRequested) {
+            qDebug().noquote().nospace() << "[Config] Final background save()";
+            QElapsedTimer stopwatch; stopwatch.start();
+            if (Config::getConfigFile()->save()) {
+                qDebug().noquote().nospace() << "[Config] Final background save() done in " << stopwatch.elapsed() << "ms";
+            } else {
+                qDebug().noquote().nospace() << "[Config] Final background save() failed in " << stopwatch.elapsed() << "ms";
+            }
+        }
+    }
+}
+
 Config::ConfigFile::ConfigFile(QString filePath) {
     QString fileContent;
     QString lineEnding = QString();
@@ -964,7 +1017,7 @@ void Config::ConfigFile::writeOne(QString key, QString value) {
         }
     }
 
-    if (_immediateSave) { save(); }
+    if (_immediateSave) { Config::_configSaveThread.requestSave(); }
 }
 
 void Config::ConfigFile::writeMany(QString key, QStringList values) {
@@ -1018,7 +1071,7 @@ void Config::ConfigFile::writeMany(QString key, QStringList values) {
         }
     }
 
-    if (_immediateSave) { save(); }
+    if (_immediateSave) { Config::_configSaveThread.requestSave(); }
 }
 
 void Config::ConfigFile::removeMany(QString key) {
@@ -1031,15 +1084,15 @@ void Config::ConfigFile::removeMany(QString key) {
             _lines.removeAt(i);
         }
     }
-    if (_immediateSave) { save(); }
+    if (_immediateSave) { Config::_configSaveThread.requestSave(); }
 }
 
 void Config::ConfigFile::removeAll() {
     QMutexLocker locker(&_cacheMutex);
     _cache.clear(); //invalidate cache
 
     _lines.clear();
-    if (_immediateSave) { save(); }
+    if (_immediateSave) { Config::_configSaveThread.requestSave(); }
 }
 
 

src/medo/config.h

@@ -1,5 +1,6 @@
 /* Josip Medved <[email protected]> * www.medo64.com * MIT License */
 
+// 2021-12-10: Added background save
 // 2020-05-25: Using strongly typed enums
 // 2020-05-05: Added stateRead/stateWrite for integers, longs, and doubles
 //             Allowing : and = in key name
@@ -9,14 +10,15 @@
 // 2019-11-01: Fixed readMany implementation
 // 2019-11-17: Added stateReadMany and stateWriteMany
 //             Added option to set paths manually
-// 2020-03-15: If QApplication hasn't bee initializesd, assume installed on Linux
+// 2020-03-15: If QApplication hasn't been initialized, assume installed on Linux
 
 #pragma once
 
 #include <QHash>
 #include <QMutex>
 #include <QString>
 #include <QStringList>
+#include <QThread>
 #include <QVariant>
 #include <QVector>
 
@@ -291,6 +293,25 @@ class Config {
         static QString dataDirectoryPathWhenPortable();
         static QString dataDirectoryPathWhenInstalled();
 
+    private:
+        class ConfigSaveThread : private QThread {
+            public:
+                explicit ConfigSaveThread(void);
+                ~ConfigSaveThread();
+
+            public:
+                void requestSave();
+
+            public:
+                ConfigSaveThread(const ConfigSaveThread&) = delete;
+                void operator=(const ConfigSaveThread&) = delete;
+
+            private:
+                QMutex _syncRoot;
+                bool _saveRequested = false;
+                void run();
+        };
+
     private:
         class ConfigFile {
             public:
@@ -364,5 +385,6 @@ class Config {
         static ConfigFile* getStateFile();
         static void resetStateFile();
         static ConfigFile* _stateFile;
+        static Config::ConfigSaveThread _configSaveThread;
 
 };