Make sure QQmlDebugServer does not deadlock in blocking mode

Previously, the server could wake the helloCondition before the main
thread was waiting on it. This would lead to the main thread then
waiting forever once it hit the wait() statement.

Change-Id: I694d65f72cf6be6e4c5a0c65ea4aea8a5878bf5b
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

1 files changed, 9 insertions, 8 deletions

diff --git a/src/qml/debugger/qqmldebugserver.cpp b/src/qml/debugger/qqmldebugserver.cpp
index 4d5e3f5605..4974bce8d8 100644
--- a/src/qml/debugger/qqmldebugserver.cpp
+++ b/src/qml/debugger/qqmldebugserver.cpp
@@ -222,7 +222,6 @@ struct StartTcpServerAction {
         if (!d->init(QLatin1String("qmldbg_tcp"), block))
             return false;
         d->m_thread->setPortRange(portFrom, portTo == -1 ? portFrom : portTo, block, hostAddress);
-        d->m_thread->start();
         return true;
     }
 };
@@ -239,7 +238,6 @@ struct ConnectToLocalAction {
         if (!d->init(QLatin1String("qmldbg_local"), block))
             return false;
         d->m_thread->setFileName(fileName, block);
-        d->m_thread->start();
         return true;
     }
 };
@@ -372,7 +370,12 @@ void QQmlDebugServerThread::run()
             }
         }
 
-        server->m_connection = connection;
+        {
+            QMutexLocker connectionLocker(&server->m_helloMutex);
+            server->m_connection = connection;
+            server->m_helloCondition.wakeAll();
+        }
+
         if (m_block)
             connection->waitForConnection();
     } else {
@@ -790,13 +793,11 @@ bool QQmlDebugServerImpl::enable(Action action)
         return false;
     if (!action(this))
         return false;
-    while (!m_connection) {
-        if (!m_thread)
-            return false;
-    }
     QMutexLocker locker(&m_helloMutex);
+    m_thread->start();
+    m_helloCondition.wait(&m_helloMutex); // wait for connection
     if (m_blockingMode && !m_gotHello)
-        m_helloCondition.wait(&m_helloMutex);
+        m_helloCondition.wait(&m_helloMutex); // wait for hello
     return true;
 #else
     Q_UNUSED(action);