From 04c561d6a965b35df35d860c262ce0e8e4819b27 Mon Sep 17 00:00:00 2001
From: Charles Otto <ottochar@gmail.com>
Date: Wed, 31 Jul 2013 13:34:27 -0400
Subject: [PATCH] Revert previous changes to thread pooling in br.cpp/meta.cpp

---
 app/br/br.cpp           |  4 +---
 openbr/plugins/meta.cpp | 39 +++++++++++++--------------------------
 2 files changed, 14 insertions(+), 29 deletions(-)

diff --git a/app/br/br.cpp b/app/br/br.cpp
index 8b6eee6..efd0483 100644
--- a/app/br/br.cpp
+++ b/app/br/br.cpp
@@ -235,10 +235,8 @@ int main(int argc, char *argv[])
 {
     br_initialize(argc, argv);
 
-    QThreadPool separate;
-    separate.setMaxThreadCount(1);
     FakeMain *fakeMain = new FakeMain(argc, argv);
-    separate.start(fakeMain);
+    QThreadPool::globalInstance()->start(fakeMain);
     QCoreApplication::exec();
 
     br_finalize();
diff --git a/openbr/plugins/meta.cpp b/openbr/plugins/meta.cpp
index a77d315..7f827dc 100644
--- a/openbr/plugins/meta.cpp
+++ b/openbr/plugins/meta.cpp
@@ -597,26 +597,6 @@ static void _projectList(const Transform *transform, const TemplateList *src, Te
     transform->project(*src, *dst);
 }
 
-class ProjectListJob : public QRunnable
-{
-public:
-    ProjectListJob(Transform * _transform, const TemplateList * _src, TemplateList * _dst)
-    {
-        transform = _transform;
-        src = _src;
-        dst = _dst;
-        this->setAutoDelete(true);
-    }
-
-    Transform * transform;
-    const TemplateList * src;
-    TemplateList * dst;
-    void run()
-    {
-        _projectList(transform, src, dst);
-    }
-};
-
 class DistributeTemplateTransform : public MetaTransform
 {
     Q_OBJECT
@@ -665,22 +645,29 @@ public:
         QList<TemplateList> input_buffer;
         input_buffer.reserve(src.size());
 
+        QFutureSynchronizer<void> futures;
+
         for (int i =0; i < src.size();i++) {
             input_buffer.append(TemplateList());
             output_buffer.append(TemplateList());
         }
-
+        QList<QFuture<void> > temp;
+        temp.reserve(src.size());
         for (int i=0; i<src.size(); i++) {
             input_buffer[i].append(src[i]);
 
-            if (Globals->parallelism)
-                QThreadPool::globalInstance()->start(new ProjectListJob(transform, &input_buffer[i], &output_buffer[i]), 0);
+            if (Globals->parallelism > 1) temp.append(QtConcurrent::run(_projectList, transform, &input_buffer[i], &output_buffer[i]));
             else _projectList(transform, &input_buffer[i], &output_buffer[i]);
         }
+        // We add the futures in reverse order, since in Qt 5.1 at least the
+        // waiting thread will wait on them in the order added (which for uniform priority
+        // threads is the order of execution), and we want the waiting thread to go in the opposite order
+        // so that it can steal runnables and do something besides wait.
+        for (int i = temp.size() - 1; i > 0; i--) {
+            futures.addFuture(temp[i]);
+        }
 
-        bool wait_res = QThreadPool::globalInstance()->waitForDone();
-        if (!wait_res)
-            qDebug("global thread pool wait failed!");
+        futures.waitForFinished();
 
         for (int i=0; i<src.size(); i++) dst.append(output_buffer[i]);
     }
--
libgit2 0.21.4