From 6b1b599275d2f00f7a35f74b8b1fe745a1a57ced Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Sat, 19 Mar 2016 19:41:33 +0000
Subject: [PATCH] refs #623 Fixed CDataPageQueue performance.

---
 src/blackmisc/datacache.cpp | 27 ++++++++++++---------------
 src/blackmisc/datacache.h   |  4 ++--
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/blackmisc/datacache.cpp b/src/blackmisc/datacache.cpp
index bed38e642..60d897d07 100644
--- a/src/blackmisc/datacache.cpp
+++ b/src/blackmisc/datacache.cpp
@@ -161,31 +161,28 @@ namespace BlackMisc
         auto *queue = new CDataPageQueue(page);
         connect(page, &CValuePage::valuesWantToCache, this, &CDataCache::changeValues);
         connect(this, &CDataCache::valuesChanged, queue, &CDataPageQueue::queueValuesFromCache, Qt::DirectConnection);
-
-        auto *timer = new QTimer(page);
-        connect(timer, &QTimer::timeout, queue, &CDataPageQueue::trySetQueuedValuesFromCache);
-        timer->start(0);
     }
 
     void CDataPageQueue::queueValuesFromCache(const CValueCachePacket &values, QObject *changedBy)
     {
         QMutexLocker lock(&m_mutex);
+        if (m_queue.isEmpty())
+        {
+            QTimer::singleShot(0, this, &CDataPageQueue::setQueuedValuesFromCache);
+        }
         m_queue.push_back(std::make_pair(values, changedBy));
     }
 
-    void CDataPageQueue::trySetQueuedValuesFromCache()
+    void CDataPageQueue::setQueuedValuesFromCache()
     {
-        bool locked = m_mutex.tryLock(0);
-        if (locked)
-        {
-            decltype(m_queue) queue;
-            qSwap(m_queue, queue);
-            m_mutex.unlock();
+        QMutexLocker lock(&m_mutex);
+        decltype(m_queue) queue;
+        qSwap(m_queue, queue);
+        lock.unlock();
 
-            for (const auto &pair : queue)
-            {
-                m_page->setValuesFromCache(pair.first, pair.second);
-            }
+        for (const auto &pair : queue)
+        {
+            m_page->setValuesFromCache(pair.first, pair.second);
         }
     }
 
diff --git a/src/blackmisc/datacache.h b/src/blackmisc/datacache.h
index 214d00c68..b910717c8 100644
--- a/src/blackmisc/datacache.h
+++ b/src/blackmisc/datacache.h
@@ -40,8 +40,8 @@ namespace BlackMisc
             //! \threadsafe
             void queueValuesFromCache(const BlackMisc::CValueCachePacket &values, QObject *changedBy);
 
-            //! Synchronize with changes queued by queueValuesFromCache, if the mutex is not currently locked.
-            void trySetQueuedValuesFromCache();
+            //! Synchronize with changes queued by queueValuesFromCache.
+            void setQueuedValuesFromCache();
 
             //! Synchronize with one specific change in the queue, leave the rest for later.
             void setQueuedValueFromCache(const QString &key);