kdesktop: fix deadlock condition between kdesktop and kdesktop lock.

The logic to handle communication with kdesktop_lock is now running
completely in a separate thread and event loop, meaning the main GUI
thread remains responsive all the time and can handle interaction with
X11, DCOP and DBUS calls. This resolves issue #589.
The commit also solves the first problem reported in issue #640 and
loosely related to PR #526.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

1 files changed, 92 insertions, 70 deletions

diff --git a/kdesktop/lockeng.h b/kdesktop/lockeng.h
index d9285abc1..94d8f9e44 100644
--- a/kdesktop/lockeng.h
+++ b/kdesktop/lockeng.h
@@ -1,6 +1,5 @@
-//===========================================================================
 //
-// This file is part of the KDE project
+// This file is part of the TDE project
 //
 // Copyright (c) 1999 Martin R. Jones <mjones@kde.org>
 //
@@ -8,7 +7,6 @@
 #ifndef __LOCKENG_H__
 #define __LOCKENG_H__
 
-#include <tqwidget.h>
 #include <tqthread.h>
 #include <tdeprocess.h>
 #include <tqvaluevector.h>
@@ -23,31 +21,48 @@ class TDECryptographicCardDevice;
 #else
 #define TDECryptographicCardDevice void
 #endif
+
+/**
+ * Screen saver engine. Handles communication with the lock process.
+ * The engine is split into two parts, the 'SaverEngine' running in the GUI thread and
+ * the 'SaverEngineEventHandler' running in a separate thread and eventloop.
+ * The 'SaverEngine' handles communication with X11, DCOP and DBUS while the
+ * 'SaverEngineEventHandler' handles communication with the actual lock process.
+ * Several actions require cooperation of the two parts, so in various methods
+ * there will be inter-thread calls (using timers or by emitting signals) to
+ * trigger the other side remaining logic.
+ * This complex design is necessary to avoid blocking the main GUI application event loop,
+ * which has several tasks to manage and therefore can't affort to wait in a suspended state.
+ * This was previously leading to deadlock when DCOP calls where executed on the secondary
+ * thread/eventloop, for example when changing desktop while the lock process was restarting.
+ */
+
 class DCOPClientTransaction;
 class TQT_DBusMessage;
 class TQT_DBusProxy;
+class SaverEngineEventHandler;
 
-class SaverEngineThreadHelperObject : public TQObject
+// Type of lock screen
+enum LockType : int
 {
-	TQ_OBJECT
-	
-public slots:
-	void terminateThread();
-	void slotLockProcessWaiting();
-	void slotLockProcessFullyActivated();
+	DontLock = 0,
+	DefaultLock,
+	ForceLock,
+	SecureDialog
+};
 
-signals:
-	void lockProcessWaiting();
-	void lockProcessFullyActivated();
+enum SaverState
+{
+	Waiting,
+	Preparing,
+	Engaging,
+	Saving
 };
 
-//===========================================================================
-/**
- * Screen saver engine.  Handles screensaver window, starting screensaver
- * hacks, and password entry.
- */
-class SaverEngine : public TQWidget, public KScreensaverIface
+class SaverEngine : public TQObject, public KScreensaverIface
 {
+	friend class SaverEngineEventHandler;
+
 	TQ_OBJECT
 public:
 	SaverEngine();
@@ -100,80 +115,53 @@ public:
 	 */
 	virtual void saverLockReady();
 
-	/**
-	 * @internal
-	 */
 	void lockScreen(bool DCOP = false);
 
-	/**
-	 * Called by KDesktop to wait for saver engage
-	 * @internal
-	 */
-	bool waitForLockEngage();
-
-	/**
-	 * @internal
-	 */
 	void lockScreenAndDoNewSession();
-
-	/**
-	 * @internal
-	 */
 	void lockScreenAndSwitchSession(int vt);
 
+	void enableExports(); // Enable wallpaper exports
+
 signals:
-	void terminateHelperThread();
-	void asyncLock();
+	void activateSaverOrLockSignal(LockType lock_type);
+	void lockScreenSignal(bool);
+	void terminateEventHandlerThread();
 
 public slots:
-	void slotLockProcessReady();
-	void lockProcessWaiting();
-	void lockProcessFullyActivated();
 	void handleDBusSignal(const TQT_DBusMessage&);
+	void terminateTDESession();
 
 protected slots:
 	void idleTimeout();
-	void lockProcessExited();
 
 private slots:
-	void handleSecureDialog();
-	void slotSAKProcessExited();
-
 	void cryptographicCardInserted(TDECryptographicCardDevice*);
 	void cryptographicCardRemoved(TDECryptographicCardDevice*);
-
-	/**
-	 * Enable wallpaper exports
-	 */
-	void enableExports();
-	void recoverFromHackingAttempt();
 	void cardStartupTimeout();
-
 	bool dBusReconnect();
 
+	// The following slots are invoked by corresponding methods named without the 'GUI' suffix
+	// in 'SaverEngineEventHandler' to complete the remaining X11 part of the actions
+	void activateSaverOrLockGUI();
+	void lockProcessFullyActivatedGUI();
+	void lockProcessWaitingGUI();
+	void lockScreenGUI();
+	void stopLockProcessGUI();
+
 private:
-	bool restartDesktopLockProcess();
 	void dBusClose();
 	bool dBusConnect();
 	void onDBusServiceRegistered(const TQString&);
 	void onDBusServiceUnregistered(const TQString&);
 
 protected:
-	enum SaverState { Waiting, Preparing, Engaging, Saving };
-	enum LockType { DontLock, DefaultLock, ForceLock, SecureDialog };
-	bool startLockProcess( LockType lock_type );
-	bool waitForLockProcessStart();
-	void stopLockProcess();
-	bool handleKeyPress(XKeyEvent *xke);
 	void processLockTransactions();
 	xautolock_corner_t applyManualSettings(int);
 
 protected:
 	bool mEnabled;
 
-	SaverState mState;
 	XAutoLock *mXAutoLock;
-	TDEProcess mLockProcess;
 	int mTimeout;
 
 	// the original X screensaver parameters
@@ -182,26 +170,60 @@ protected:
 	int mXBlanking;
 	int mXExposures;
 
-	bool mBlankOnly;  // only use the blanker, not the defined saver
 	TQValueVector< DCOPClientTransaction* > mLockTransactions;
 
 public:
-	SaverEngineThreadHelperObject* m_threadHelperObject;
+	bool mBlankOnly;  // only use the blanker, not the defined saver // protected
+	SaverEngineEventHandler *m_saverEngineEventHandler;
 
 private:
-	TQEventLoopThread* m_helperThread;
-	sigset_t mThreadBlockSet;
-	TDEProcess* mSAKProcess;
-	bool mTerminationRequested;
-	bool mSaverProcessReady;
+	TQEventLoopThread* m_eventHandlerThread;
 	bool mNewVTAfterLockEngage;
 	bool mValidCryptoCardInserted;
 	int mSwitchVTAfterLockEngage;
 	struct sigaction mSignalAction;
 	TQT_DBusConnection dBusConn;
-	TQT_DBusProxy* dBusLocal;
-	TQT_DBusProxy* dBusWatch;
-	TQT_DBusProxy* systemdSession;
+	TQT_DBusProxy *dBusLocal;
+	TQT_DBusProxy *dBusWatch;
+	TQT_DBusProxy *systemdSession;
+};
+
+class SaverEngineEventHandler : public TQObject
+{
+	TQ_OBJECT
+	
+public:
+	SaverEngineEventHandler(SaverEngine *engine);
+
+	SaverState getState() const { return m_state; }
+
+	void lockProcessExited();
+	void lockProcessFullyActivated();
+	void lockProcessReady();
+	void terminateLockProcess();
+
+public slots:
+	bool activateSaverOrLock(LockType lock_type);
+	void lockScreen(bool DCOP = false);
+	bool restartLockProcess();
+	void saveScreen();
+	void stopLockProcess();
+	void terminateThread();
+
+protected slots:
+	void slotLockProcessExited();
+	void slotSAKProcessExited();
+
+protected:
+	void startSAKProcess();
+
+	bool m_saverProcessReady;
+	bool m_lockProcessRestarting;
+	bool m_terminationRequest;
+	SaverState m_state;
+	SaverEngine *m_saverEngine;
+	TDEProcess *m_SAKProcess;
+	TDEProcess m_lockProcess;
 };
 
 #endif