Merge pull request #5951 from ligfx/gametrackerworkqueuethread

GameTracker: use new Common::WorkQueueThread instead of signals/slots

Source/Core/Common/Common.vcxproj

@@ -151,6 +151,7 @@
     <ClInclude Include="TraversalClient.h" />
     <ClInclude Include="TraversalProto.h" />
     <ClInclude Include="UPnP.h" />
+    <ClInclude Include="WorkQueueThread.h" />
     <ClInclude Include="x64ABI.h" />
     <ClInclude Include="x64Emitter.h" />
     <ClInclude Include="x64Reg.h" />

Source/Core/Common/Common.vcxproj.filters

@@ -68,6 +68,7 @@
     <ClInclude Include="SysConf.h" />
     <ClInclude Include="Thread.h" />
     <ClInclude Include="Timer.h" />
+    <ClInclude Include="WorkQueueThread.h" />
     <ClInclude Include="x64ABI.h" />
     <ClInclude Include="x64Emitter.h" />
     <ClInclude Include="x64Reg.h" />

Source/Core/Common/WorkQueueThread.h

@@ -0,0 +1,86 @@
+// Copyright 2017 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <functional>
+#include <queue>
+#include <thread>
+
+#include "Common/Event.h"
+#include "Common/Flag.h"
+
+// A thread that executes the given function for every item placed into its queue.
+
+namespace Common
+{
+template <typename T>
+class WorkQueueThread
+{
+public:
+  WorkQueueThread() = default;
+  WorkQueueThread(std::function<void(T)> function) { Reset(std::move(function)); }
+  ~WorkQueueThread() { Shutdown(); }
+  void Reset(std::function<void(T)> function)
+  {
+    Shutdown();
+    m_shutdown.Clear();
+    m_function = std::move(function);
+    m_thread = std::thread([this] { ThreadLoop(); });
+  }
+
+  template <typename... Args>
+  void EmplaceItem(Args&&... args)
+  {
+    {
+      std::unique_lock<std::mutex> lg(m_lock);
+      m_items.emplace(std::forward<Args>(args)...);
+    }
+    m_wakeup.Set();
+  }
+
+private:
+  void Shutdown()
+  {
+    if (m_thread.joinable())
+    {
+      m_shutdown.Set();
+      m_wakeup.Set();
+      m_thread.join();
+    }
+  }
+
+  void ThreadLoop()
+  {
+    while (true)
+    {
+      m_wakeup.Wait();
+
+      while (true)
+      {
+        T item;
+        {
+          std::unique_lock<std::mutex> lg(m_lock);
+          if (m_items.empty())
+            break;
+          item = m_items.front();
+          m_items.pop();
+        }
+        m_function(std::move(item));
+      }
+
+      if (m_shutdown.IsSet())
+        break;
+    }
+  }
+
+  std::function<void(T)> m_function;
+  std::thread m_thread;
+  Common::Event m_wakeup;
+  Common::Flag m_shutdown;
+  std::mutex m_lock;
+  std::queue<T> m_items;
+};
+
+}  // namespace Common

Source/Core/DolphinQt2/GameList/GameTracker.cpp

@@ -17,23 +17,11 @@ static const QStringList game_filters{
 
 GameTracker::GameTracker(QObject* parent) : QFileSystemWatcher(parent)
 {
-  m_loader = new GameLoader;
-  m_loader->moveToThread(&m_loader_thread);
-
   qRegisterMetaType<QSharedPointer<GameFile>>();
-  connect(&m_loader_thread, &QThread::finished, m_loader, &QObject::deleteLater);
   connect(this, &QFileSystemWatcher::directoryChanged, this, &GameTracker::UpdateDirectory);
   connect(this, &QFileSystemWatcher::fileChanged, this, &GameTracker::UpdateFile);
-  connect(this, &GameTracker::PathChanged, m_loader, &GameLoader::LoadGame);
-  connect(m_loader, &GameLoader::GameLoaded, this, &GameTracker::GameLoaded);
 
-  m_loader_thread.start();
-}
-
-GameTracker::~GameTracker()
-{
-  m_loader_thread.quit();
-  m_loader_thread.wait();
+  m_load_thread.Reset([this](const QString& path) { LoadGame(path); });
 }
 
 void GameTracker::AddDirectory(const QString& dir)
@@ -81,7 +69,7 @@ void GameTracker::UpdateDirectory(const QString& dir)
     {
       addPath(path);
       m_tracked_files[path] = QSet<QString>{dir};
-      emit PathChanged(path);
+      m_load_thread.EmplaceItem(path);
     }
   }
 
@@ -127,7 +115,7 @@ void GameTracker::UpdateFile(const QString& file)
     GameRemoved(file);
     addPath(file);
 
-    emit PathChanged(file);
+    m_load_thread.EmplaceItem(file);
   }
   else if (removePath(file))
   {
@@ -136,7 +124,7 @@ void GameTracker::UpdateFile(const QString& file)
   }
 }
 
-void GameLoader::LoadGame(const QString& path)
+void GameTracker::LoadGame(const QString& path)
 {
   if (!DiscIO::ShouldHideFromGameList(path.toStdString()))
   {

Source/Core/DolphinQt2/GameList/GameTracker.h

@@ -9,25 +9,19 @@
 #include <QSet>
 #include <QSharedPointer>
 #include <QString>
-#include <QStringList>
-#include <QThread>
 
+#include "Common/WorkQueueThread.h"
 #include "DolphinQt2/GameList/GameFile.h"
 
-class GameLoader;
-
 // Watches directories and loads GameFiles in a separate thread.
 // To use this, just add directories using AddDirectory, and listen for the
-// GameLoaded and GameRemoved signals. Ignore the PathChanged signal, it's
-// only there because the Qt people made fileChanged and directoryChanged
-// private.
+// GameLoaded and GameRemoved signals.
 class GameTracker final : public QFileSystemWatcher
 {
   Q_OBJECT
 
 public:
   explicit GameTracker(QObject* parent = nullptr);
-  ~GameTracker();
 
   void AddDirectory(const QString& dir);
   void RemoveDirectory(const QString& dir);
@@ -36,28 +30,15 @@ signals:
   void GameLoaded(QSharedPointer<GameFile> game);
   void GameRemoved(const QString& path);
 
-  void PathChanged(const QString& path);
-
 private:
+  void LoadGame(const QString& path);
   void UpdateDirectory(const QString& dir);
   void UpdateFile(const QString& path);
   QSet<QString> FindMissingFiles(const QString& dir);
 
   // game path -> directories that track it
   QMap<QString, QSet<QString>> m_tracked_files;
-  QThread m_loader_thread;
-  GameLoader* m_loader;
-};
-
-class GameLoader final : public QObject
-{
-  Q_OBJECT
-
-public:
-  void LoadGame(const QString& path);
-
-signals:
-  void GameLoaded(QSharedPointer<GameFile> game);
+  Common::WorkQueueThread<QString> m_load_thread;
 };
 
 Q_DECLARE_METATYPE(QSharedPointer<GameFile>)