Changeset 57631 in vbox for trunk/src/VBox/Frontends

Timestamp:

Sep 4, 2015 1:55:49 PM (9 years ago)

Author:

vboxsync

Message:

FE/Qt: Thread-pool: Cleanup/rework.

File:

• trunk/src/VBox/Frontends/VirtualBox/src/globals/UIThreadPool.cpp (modified) (20 diffs)

trunk/src/VBox/Frontends/VirtualBox/src/globals/UIThreadPool.cpp

@@ -33 +33 @@
 #endif /* !VBOX_WITH_PRECOMPILED_HEADERS */
 
-
 /** QThread extension used as worker-thread.
   * Capable of executing COM-related tasks. */
@@ -52 +51 @@
 
     /** Returns worker-thread index within the worker-thread pool registry. */
-    int getIndex() const { return m_iIndex; }
+    int index() const { return m_iIndex; }
 
     /** Disables sigFinished signal, for optimizing worker-thread pool termination. */
-    void setNoFinishedSignal()
-    {
-        m_fNoFinishedSignal = true;
-    }
+    void setNoFinishedSignal() { m_fNoFinishedSignal = true; }
 
 private:
@@ -74 +70 @@
     bool m_fNoFinishedSignal;
 };
-
 
 UIThreadPool::UIThreadPool(ulong cMaxWorkers /* = 3 */, ulong cMsWorkerIdleTimeout /* = 5000 */)
@@ -81 +76 @@
     , m_cWorkers(0)
     , m_cIdleWorkers(0)
-    , m_fTerminating(false) /* termination status */
+    , m_fTerminating(false)
 {
 }
@@ -87 +82 @@
 UIThreadPool::~UIThreadPool()
 {
-    /* Set termination status and alert all idle worker threads: */
+    /* Set termination status: */
     setTerminating();
 
-    m_everythingLocker.lock(); /* paranoia */
+    /* Lock initially: */
+    m_everythingLocker.lock();
 
     /* Cleanup all the workers: */
     for (int idxWorker = 0; idxWorker < m_workers.size(); ++idxWorker)
     {
-        UIThreadWorker *pWorker = m_workers[idxWorker];
-        m_workers[idxWorker] = NULL;
-
-        /* Clean up the worker, if there was one. */
+        /* Acquire the worker: */
+        UIThreadWorker *pWorker = m_workers.at(idxWorker);
+        /* Remove it from the registry: */
+        m_workers[idxWorker] = 0;
+
+        /* Clean up the worker, if there was one: */
         if (pWorker)
         {
-            m_cWorkers--;
+            /* Decrease the number of workers: */
+            --m_cWorkers;
+            /* Unlock temporary to let the worker finish: */
             m_everythingLocker.unlock();
-
+            /* Wait for the worker to finish: */
             pWorker->wait();
-
+            /* Lock again: */
             m_everythingLocker.lock();
+            /* Delete the worker finally: */
             delete pWorker;
         }
     }
 
+    /* Unlock finally: */
     m_everythingLocker.unlock();
 }
@@ -116 +118 @@
 bool UIThreadPool::isTerminating() const
 {
+    /* Lock initially: */
+    m_everythingLocker.lock();
+
     /* Acquire termination-flag: */
-    m_everythingLocker.lock();
     bool fTerminating = m_fTerminating;
-    m_everythingLocker.unlock();
-
+
+    /* Unlock finally: */
+    m_everythingLocker.unlock();
+
+    /* Return termination-flag: */
     return fTerminating;
 }
@@ -126 +133 @@
 void UIThreadPool::setTerminating()
 {
-    m_everythingLocker.lock();
-
-    /* Indicate that we're terminating: */
+    /* Lock initially: */
+    m_everythingLocker.lock();
+
+    /* Assign termination-flag: */
     m_fTerminating = true;
 
@@ -134 +142 @@
     for (int idxWorker = 0; idxWorker < m_workers.size(); ++idxWorker)
     {
-        UIThreadWorker *pWorker = m_workers[idxWorker];
+        UIThreadWorker *pWorker = m_workers.at(idxWorker);
         if (pWorker)
             pWorker->setNoFinishedSignal();
@@ -142 +150 @@
     m_taskCondition.wakeAll();
 
+    /* Unlock finally: */
     m_everythingLocker.unlock();
 }
@@ -147 +156 @@
 void UIThreadPool::enqueueTask(UITask *pTask)
 {
-    Assert(!isTerminating());
+    /* Do nothing if terminating: */
+    AssertReturnVoid(!isTerminating());
 
     /* Prepare task: */
-    connect(pTask, SIGNAL(sigComplete(UITask*)), this, SLOT(sltHandleTaskComplete(UITask*)), Qt::QueuedConnection);
-
-    m_everythingLocker.lock();
-
-    /* Put the task onto the queue: */
+    connect(pTask, SIGNAL(sigComplete(UITask*)),
+            this, SLOT(sltHandleTaskComplete(UITask*)), Qt::QueuedConnection);
+
+    /* Lock initially: */
+    m_everythingLocker.lock();
+
+    /* Put the task into the queue: */
     m_tasks.enqueue(pTask);
 
@@ -168 +180 @@
         int idxFirstUnused = m_workers.size();
         while (idxFirstUnused-- > 0)
-            if (m_workers[idxFirstUnused] == NULL)
+            if (m_workers.at(idxFirstUnused) == 0)
             {
                 /* Prepare the new worker: */
                 UIThreadWorker *pWorker = new UIThreadWorker(this, idxFirstUnused);
-                connect(pWorker, SIGNAL(sigFinished(UIThreadWorker*)), this,
-                        SLOT(sltHandleWorkerFinished(UIThreadWorker*)), Qt::QueuedConnection);
+                connect(pWorker, SIGNAL(sigFinished(UIThreadWorker*)),
+                        this, SLOT(sltHandleWorkerFinished(UIThreadWorker*)), Qt::QueuedConnection);
                 m_workers[idxFirstUnused] = pWorker;
-                m_cWorkers++;
+                ++m_cWorkers;
 
                 /* And start it: */
@@ -182 +194 @@
             }
     }
-    /* else: wait for some worker to complete whatever it's busy with and jump to it. */
-
+    /* else: wait for some worker to complete
+     * whatever it's busy with and jump to it. */
+
+    /* Unlock finally: */
     m_everythingLocker.unlock();
 }
@@ -189 +203 @@
 UITask* UIThreadPool::dequeueTask(UIThreadWorker *pWorker)
 {
+    /* Lock initially: */
+    m_everythingLocker.lock();
+
     /* Dequeue a task, watching out for terminations.
-     * For opimal efficiency in enqueueTask() we keep count of idle threads.
-     * If the wait times out, we'll return NULL and terminate the thread. */
-    m_everythingLocker.lock();
-
+     * For optimal efficiency in enqueueTask() we keep count of idle threads.
+     * If the wait times out, we'll return 0 and terminate the thread. */
     bool fIdleTimedOut = false;
     while (!m_fTerminating)
     {
-        Assert(m_workers[pWorker->getIndex()] == pWorker); /* paranoia */
+        /* Make sure that worker has proper index: */
+        Assert(m_workers.at(pWorker->index()) == pWorker);
 
         /* Dequeue task if there is one: */
@@ -205 +221 @@
             if (pTask)
             {
+                /* Unlock finally: */
                 m_everythingLocker.unlock();
+
+                /* Return dequeued task: */
                 return pTask;
             }
@@ -211 +230 @@
 
         /* If we timed out already, then quit the worker thread. To prevent a
-           race between enqueueTask and the queue removal of the thread from
-           the workers vector, we remove it here already. (This does not apply
-           to the termination scenario.) */
+         * race between enqueueTask and the queue removal of the thread from
+         * the workers vector, we remove it here already. (This does not apply
+         * to the termination scenario.) */
         if (fIdleTimedOut)
         {
-            m_workers[pWorker->getIndex()] = NULL;
-            m_cWorkers--;
+            m_workers[pWorker->index()] = 0;
+            --m_cWorkers;
             break;
         }
 
-        /* Wait for a task or timeout.*/
-        m_cIdleWorkers++;
+        /* Wait for a task or timeout: */
+        ++m_cIdleWorkers;
         fIdleTimedOut = !m_taskCondition.wait(&m_everythingLocker, m_cMsIdleTimeout);
-        m_cIdleWorkers--;
-    }
-
-    m_everythingLocker.unlock();
-
-    return NULL;
+        --m_cIdleWorkers;
+    }
+
+    /* Unlock finally: */
+    m_everythingLocker.unlock();
+
+    /* Return 0 by default: */
+    return 0;
 }
 
@@ -245 +266 @@
 {
     /* Wait for the thread to finish completely, then delete the thread
-       object. We have already removed the thread from the workers vector.
-       Note! We don't want to use 'this' here, in case it's invalid. */
+     * object. We have already removed the thread from the workers vector.
+     * Note! We don't want to use 'this' here, in case it's invalid. */
     pWorker->wait();
     delete pWorker;
 }
 
-
 UITask::UITask(const QVariant &data)
     : m_data(data)
@@ -261 +281 @@
     /* Run task: */
     run();
-    /* Notify listener: */
+    /* Notify listeners: */
     emit sigComplete(this);
 }
-
 
 UIThreadWorker::UIThreadWorker(UIThreadPool *pPool, int iIndex)
@@ -278 +297 @@
     COMBase::InitializeCOM(false);
 
-    /* Try get a task from the pool queue. */
+    /* Try get a task from the pool queue: */
     while (UITask *pTask = m_pPool->dequeueTask(this))
     {
@@ -290 +309 @@
     COMBase::CleanupCOM();
 
-    /* Queue a signal to for the pool to do thread cleanup, unless the pool is
+    /* Queue a signal for the pool to do thread cleanup, unless the pool is
        already terminating and doesn't need the signal. */
     if (!m_fNoFinishedSignal)
@@ -296 +315 @@
 }
 
-
 #include "UIThreadPool.moc"