Added the thread safe TSQueue and using it in mainwindow to replace the adhoc queue implementation.

.gitignore

@@ -1,5 +1,6 @@
 debug/
 release/
+DIST/
 Makefile
 Makefile.Debug
 Makefile.Release

Ivory.pro

@@ -12,7 +12,7 @@ TARGET = Ivory
 TEMPLATE = app
 
 INCLUDEPATH += C:\prog\include
-
+DEFINES += WIN32_LEAN_AND_MEAN
 LIBS += c:\prog\lib\libpq.lib
 
 SOURCES += main.cpp\
@@ -24,7 +24,10 @@ SOURCES += main.cpp\
     sqlhighlighter.cpp \
     jsoncpp.cpp \
     queryexplainmodel.cpp \
-    explaintreemodelitem.cpp
+    explaintreemodelitem.cpp \
+    asyncdbconnection.cpp \
+    tsqueue.cpp \
+    win32event.cpp
 
 HEADERS  += mainwindow.h \
     serverproperties.h \
@@ -33,7 +36,10 @@ HEADERS  += mainwindow.h \
     queryresultmodel.h \
     sqlhighlighter.h \
     queryexplainmodel.h \
-    explaintreemodelitem.h
+    explaintreemodelitem.h \
+    asyncdbconnection.h \
+    tsqueue.h \
+    win32event.h
 
 FORMS    += mainwindow.ui \
     serverproperties.ui

asyncdbconnection.cpp

@@ -0,0 +1,61 @@
+#include "asyncdbconnection.h"
+
+ASyncDBConnection::ASyncDBConnection()
+{
+
+}
+
+void ASyncDBConnection::setupConnection(const std::string &connstring)
+{}
+
+void ASyncDBConnection::closeConnection()
+{}
+
+void ASyncDBConnection::setStateCallback(on_state_callback state_callback)
+{}
+
+
+void ASyncDBConnection::Thread::run()
+{
+	while (!terminateRequested) {
+
+		// make or recover connection
+		if (makeConnection()) {
+			// send commands and receive results
+			communicate();
+		}
+
+	}
+
+	// close connection
+}
+
+bool ASyncDBConnection::Thread::makeConnection()
+{
+	while (!terminateRequested) {
+
+		// start connecting
+
+		// poll till complete or failed (we can get an abort command)
+
+		// if connected return true
+		// else retry (unless we get a command to stop then return false)
+	}
+	return false;
+}
+
+void ASyncDBConnection::Thread::communicate()
+{
+	while (!terminateRequested) {
+		// wait for something to do:
+		// - command to send to server
+		//   - wait for results and (notifies can also come in)
+		//   - pass each result on to the completion routine
+		// - notify comming in from the server
+		//   - pass to notify callback
+		// - connection raises an error
+		//   - return
+		// - stop signal
+		//   - return
+	}
+}

asyncdbconnection.h

@@ -0,0 +1,68 @@
+#ifndef ASYNCDBCONNECTION_H
+#define ASYNCDBCONNECTION_H
+
+#include "PgsqlConn.h"
+#include <functional>
+#include <vector>
+
+class ASyncDBConnection {
+public:
+	enum class State {
+		NotConnected,
+		Connecting,
+		Connected,
+		QuerySend,
+		CancelSend
+	};
+
+	using on_result_callback = std::function<void(Pgsql::Result)>;
+	using on_state_callback = std::function<void(State)>;
+
+	ASyncDBConnection();
+
+	void setupConnection(const std::string &connstring);
+	void closeConnection();
+
+	void setStateCallback(on_state_callback state_callback);
+
+	/** Sends command to the server.
+
+	When the result is in and no result_task_queue was passed then on_result will be
+	called directly within the thread.
+
+	If the command gives multiple results on_result will be called for each result.
+	*/
+	bool send(const std::string &command, on_result_callback on_result);
+
+private:
+
+	class Command {
+	public:
+		std::string command;
+		on_result_callback on_result;
+	};
+
+	/// Contains all the members accessed by the thread
+	class Thread {
+	public:
+		on_state_callback m_state_callback;
+		std::string m_init_string;
+
+		/// Is started as a seperate thread by ASyncDBConnection
+		void run();
+
+		/// Sends a cancel request to the DB server
+		void cancel();
+	private:
+
+		Pgsql::Connection m_connection;
+		bool terminateRequested = false; ///< is set when the thread should stop
+
+		bool makeConnection();
+		void communicate();
+	};
+
+	Thread thread;
+};
+
+#endif // ASYNCDBCONNECTION_H

mainwindow.cpp

@@ -40,7 +40,6 @@ MainWindow::MainWindow(QWidget *parent) :
 	ui->queryEdit->setFont(font);
 	highlighter.reset(new SqlHighlighter(ui->queryEdit->document()));
 	ui->queryEdit->setPlainText(test_query);
-
 	ui->connectionStringEdit->setText("user=postgres dbname=foutrapport password=admin");
 
 	QAction *action;
@@ -60,10 +59,9 @@ MainWindow::MainWindow(QWidget *parent) :
 MainWindow::~MainWindow()
 {}
 
-void MainWindow::QueueTask(callable c)
+void MainWindow::QueueTask(TSQueue::t_Callable c)
 {
-	std::lock_guard<std::mutex> lg(m_mutexCallableQueue);
-	m_callableQueue.emplace_back(std::move(c));
+	m_taskQueue.add(c);
 	// Theoretically this needs to be only called if the queue was empty because otherwise it already would
 	// be busy emptying the queue. For now however I think it is safer to call it just to make sure.
 	QMetaObject::invokeMethod(this, "processCallableQueue",	Qt::QueuedConnection); // queues on main thread
@@ -71,20 +69,12 @@ void MainWindow::QueueTask(callable c)
 
 void MainWindow::processCallableQueue()
 {
-	bool empty;
-	callable c;
-	{ // narrow scope for lock guard
-		std::lock_guard<std::mutex> lg(m_mutexCallableQueue);
-		c = m_callableQueue.back();
-		m_callableQueue.pop_back();
-		empty = m_callableQueue.empty();
-	}
-
-	c();
-
-	if (!empty) {
-		// This gives other events a chance to be processed to keep the UI snappy.
-		QTimer::singleShot(0, this, SLOT(processCallableQueue()));
+	if (!m_taskQueue.empty()) {
+		auto c = m_taskQueue.pop();
+		c();
+		if (!m_taskQueue.empty()) {
+			QTimer::singleShot(0, this, SLOT(processCallableQueue()));
+		}
 	}
 }
 
@@ -148,6 +138,7 @@ void MainWindow::performQuery()
 	queryCancel = std::move(connection->getCancel());
 
 	QString command = ui->queryEdit->toPlainText();
+
 	std::thread([this,command]()
 		{
 			auto res = std::make_shared<Pgsql::Result>(connection->query(command));

mainwindow.h

@@ -1,6 +1,7 @@
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
+#include "tsqueue.h"
 #include <QMainWindow>
 #include <QSocketNotifier>
 #include <memory>
@@ -36,20 +37,16 @@ class MainWindow : public QMainWindow
 	Q_OBJECT
 
 public:
-	using callable = std::function<void()>;
-
 	explicit MainWindow(QWidget *parent = 0);
 	~MainWindow();
 
 	/* Meant to be called from other threads to pass a code block
 	 * that has to be executed in the context of the thread of the window.
 	 */
-	void QueueTask(callable c);
+	void QueueTask(TSQueue::t_Callable c);
 
 private:
-	using t_CallableQueue = std::deque<callable>;
-	std::mutex m_mutexCallableQueue;
-	t_CallableQueue m_callableQueue;
+	TSQueue m_taskQueue;
 
 
 	std::unique_ptr<Ui::MainWindow> ui;

tsqueue.cpp

@@ -0,0 +1,34 @@
+#include "tsqueue.h"
+
+TSQueue::TSQueue()
+	: newData(Win32Event::Reset::Manual, Win32Event::Initial::Clear)
+{}
+
+void TSQueue::add(t_Callable callable)
+{
+	std::lock_guard<std::mutex> g(m);
+	futureQueue.push_back(std::move(callable));
+	newData.Set();
+}
+
+bool TSQueue::empty()
+{
+	std::lock_guard<std::mutex> g(m);
+	return futureQueue.empty();
+}
+
+TSQueue::t_Callable TSQueue::pop()
+{
+	std::lock_guard<std::mutex> g(m);
+	auto f = std::move(futureQueue.front());
+	futureQueue.pop_front();
+	if (futureQueue.empty()) {
+		newData.Reset();
+	}
+	return f;
+}
+
+HANDLE TSQueue::getNewDataEventHandle()
+{
+	return newData.GetHandle();
+}

tsqueue.h

@@ -0,0 +1,27 @@
+#ifndef TSQUEUE_H
+#define TSQUEUE_H
+
+#include "Win32Event.h"
+#include <deque>
+#include <functional>
+#include <mutex>
+
+class TSQueue {
+public:
+	using t_Callable = std::function<void()>;
+
+	TSQueue();
+	void add(t_Callable callable);
+	bool empty();
+	t_Callable pop();
+
+	HANDLE getNewDataEventHandle();
+private:
+	using t_CallableQueue = std::deque<t_Callable>;
+
+	Win32Event newData;
+	std::mutex m;
+	t_CallableQueue futureQueue;
+};
+
+#endif // TSQUEUE_H

win32event.cpp

@@ -0,0 +1 @@
+#include "win32event.h"

win32event.h

@@ -0,0 +1,40 @@
+#ifndef WIN32EVENT_H
+#define WIN32EVENT_H
+
+
+#include <windows.h>
+/** Simpel wrapper around a Win32 Event object.
+
+Mostly to make cleanup automatic.*/
+class Win32Event {
+public:
+	enum class Reset { Auto=0, Manual=1 };
+	enum class Initial { Clear=0, Set=1 };
+
+	Win32Event(Reset r, Initial is)
+		: hEvent(CreateEvent(
+			nullptr,  // _In_opt_ LPSECURITY_ATTRIBUTES lpEventAttributes,
+			BOOL(r),  // _In_     BOOL                  bManualReset,
+			BOOL(is), // _In_     BOOL                  bInitialState,
+			nullptr   //_In_opt_ LPCTSTR               lpName
+			))
+	{}
+
+	~Win32Event()
+	{
+		CloseHandle(hEvent);
+	}
+
+	Win32Event(const Win32Event &) = delete;
+	Win32Event &operator=(const Win32Event &) = delete;
+
+	void Set() { SetEvent(hEvent); }
+
+	void Reset() { ResetEvent(hEvent); }
+
+	HANDLE GetHandle() { return hEvent; }
+private:
+	HANDLE hEvent;
+};
+
+#endif // WIN32EVENT_H