From ca64896d49b70fc0ffec711a079167c972fe635e Mon Sep 17 00:00:00 2001
From: Daniel Wilhelm <daniel@wili.li>
Date: Fri, 18 Apr 2014 16:47:21 +0200
Subject: 1.4

---
 library/multithreading.cpp | 148 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 library/multithreading.cpp

(limited to 'library/multithreading.cpp')

diff --git a/library/multithreading.cpp b/library/multithreading.cpp
new file mode 100644
index 00000000..dd96eaf4
--- /dev/null
+++ b/library/multithreading.cpp
@@ -0,0 +1,148 @@
+#include "multithreading.h"
+#include <wx/utils.h>
+//#include "windows.h"
+//MessageBox(0, "hi", "", 0);
+
+/*choreography:
+
+        -------------                           ---------------
+        |main thread|                           |worker thread|
+        -------------                           ---------------
+
+1.  Instantiation (Constructor)
+-------------------------------
+        create thread
+                                                enter waiting state
+2. waitUntilReady
+-------------------------------
+        wait until thread is ready
+
+3. Call execAndUpdate
+-------------------------------
+        send signal to start
+                                                start processing
+        update UI while thread works
+                                                finish processing
+                                                wait until main thread is ready to receive signal
+        receive signal
+                                                enter waiting state
+4. Termination (Destructor)
+-------------------------------
+        wait until thread is in wait state
+        set exit flag
+        signal thread to continue (and exit)
+*/
+class WorkerThread : public wxThread
+{
+public:
+    WorkerThread(UpdateWhileExecuting* handler) :
+            readyToBeginProcessing(),
+            beginProcessing(readyToBeginProcessing),
+            threadIsInitialized(false),
+            threadExitIsRequested(false),
+            threadHandler(handler)
+    { }
+
+    ~WorkerThread() {}
+
+    ExitCode Entry()
+    {
+        readyToBeginProcessing.Lock(); //this lock needs to be called IN the thread => calling it from constructor(Main thread) would be useless
+        sharedData.Enter();
+        threadIsInitialized = true;
+        sharedData.Leave();
+
+        while (true)
+        {
+            beginProcessing.Wait();
+
+            //no mutex needed in this context
+            if (threadExitIsRequested)
+                return 0;
+
+            //actual (long running) work is done in this method
+            threadHandler->longRunner();
+
+            threadHandler->readyToReceiveResult.Lock();
+            threadHandler->receivingResult.Signal();
+            threadHandler->readyToReceiveResult.Unlock();
+        }
+
+        return 0;
+    }
+
+
+    wxMutex     readyToBeginProcessing;
+    wxCondition beginProcessing;
+
+    //shared data
+    wxCriticalSection sharedData;
+    bool threadIsInitialized;
+    bool threadExitIsRequested;
+
+
+private:
+    UpdateWhileExecuting* threadHandler;
+};
+
+
+UpdateWhileExecuting::UpdateWhileExecuting() :
+        readyToReceiveResult(),
+        receivingResult(readyToReceiveResult)
+{
+    //mutex needs to be initially locked for condition receivingResult to work properly
+    readyToReceiveResult.Lock();
+
+
+    theWorkerThread = new WorkerThread(this);
+
+    theWorkerThread->Create();
+    theWorkerThread->Run();
+
+    //wait until the thread has locked readyToBeginProcessing
+    bool threadInitialized = false;
+    while (!threadInitialized)
+    {
+        theWorkerThread->sharedData.Enter();
+        threadInitialized = theWorkerThread->threadIsInitialized;
+        theWorkerThread->sharedData.Leave();
+        wxMilliSleep(5);
+    }   //-> it's not nice, but works and is no issue
+}
+
+
+UpdateWhileExecuting::~UpdateWhileExecuting()
+{
+    //wait until thread is ready, then start and exit immediately
+    readyToReceiveResult.Unlock(); //avoid possible deadlock, when thread might be waiting to send the signal
+
+    theWorkerThread->readyToBeginProcessing.Lock();
+    //set flag to exit thread
+    theWorkerThread->threadExitIsRequested = true;
+    theWorkerThread->beginProcessing.Signal();
+
+    theWorkerThread->readyToBeginProcessing.Unlock();
+
+    //theWorkerThread deletes itself!
+}
+
+
+void UpdateWhileExecuting::waitUntilReady()
+{
+    readyToReceiveResult.Unlock(); //avoid possible deadlock, when thread might be waiting to send the signal (if abort was pressed)
+
+    theWorkerThread->readyToBeginProcessing.Lock();
+}
+//          /|\  \|/   must be called directly after each other
+
+void UpdateWhileExecuting::execAndUpdate(StatusUpdater* statusUpdater)
+{
+    readyToReceiveResult.Lock();
+
+    theWorkerThread->beginProcessing.Signal();
+    theWorkerThread->readyToBeginProcessing.Unlock();
+
+    while (receivingResult.WaitTimeout(uiUpdateInterval) == wxCOND_TIMEOUT)
+        statusUpdater->triggerUI_Refresh(); //ATTENTION: Exception "AbortThisProcess" may be thrown here!!!
+}
+
-- 
cgit