Fix a bug where the engine would skip a song that didn't exist, but then not play the next song.

src/engines/gstengine.cpp

@@ -24,7 +24,6 @@
 #include "config.h"
 #include "gstengine.h"
 #include "gstenginepipeline.h"
-#include "core/boundfuturewatcher.h"
 #include "core/utilities.h"
 
 #ifdef HAVE_IMOBILEDEVICE
@@ -493,8 +492,8 @@ bool GstEngine::Play(quint64 offset_nanosec) {
     return false;
 
   QFuture<GstStateChangeReturn> future = current_pipeline_->SetState(GST_STATE_PLAYING);
-  BoundFutureWatcher<GstStateChangeReturn, quint64>* watcher =
-      new BoundFutureWatcher<GstStateChangeReturn, quint64>(offset_nanosec, this);
+  PlayFutureWatcher* watcher = new PlayFutureWatcher(
+        PlayFutureWatcherArg(offset_nanosec, current_pipeline_.get()), this);
   watcher->setFuture(future);
   connect(watcher, SIGNAL(finished()), SLOT(PlayDone()));
 
@@ -502,17 +501,22 @@ bool GstEngine::Play(quint64 offset_nanosec) {
 }
 
 void GstEngine::PlayDone() {
-  BoundFutureWatcher<GstStateChangeReturn, quint64>* watcher =
-      static_cast<BoundFutureWatcher<GstStateChangeReturn, quint64>*>(sender());
+  PlayFutureWatcher* watcher = static_cast<PlayFutureWatcher*>(sender());
   watcher->deleteLater();
 
   GstStateChangeReturn ret = watcher->result();
-  quint64 offset_nanosec = watcher->data();
+  quint64 offset_nanosec = watcher->data().first;
 
   if (!current_pipeline_) {
     return;
   }
 
+  // Don't dereference this - it might be invalid
+  GstEnginePipeline* dangerous_pipeline = watcher->data().second;
+  if (dangerous_pipeline != current_pipeline_.get()) {
+    return;
+  }
+
   if (ret == GST_STATE_CHANGE_FAILURE) {
     // Failure, but we got a redirection URL - try loading that instead
     QUrl redirect_url = current_pipeline_->redirect_url();
@@ -675,6 +679,10 @@ void GstEngine::timerEvent(QTimerEvent* e) {
 }
 
 void GstEngine::HandlePipelineError(const QString& message, int domain, int error_code) {
+  GstEnginePipeline* pipeline_sender = qobject_cast<GstEnginePipeline*>(sender());
+  if (!pipeline_sender || pipeline_sender != current_pipeline_.get())
+    return;
+
   qWarning() << "Gstreamer error:" << message;
 
   current_pipeline_.reset();

src/engines/gstengine.h

@@ -24,6 +24,7 @@
 
 #include "bufferconsumer.h"
 #include "enginebase.h"
+#include "core/boundfuturewatcher.h"
 #include "core/timeconstants.h"
 
 #include <QFuture>
@@ -125,6 +126,9 @@ class GstEngine : public Engine::Base, public BufferConsumer {
   void PlayDone();
 
  private:
+  typedef QPair<quint64, GstEnginePipeline*> PlayFutureWatcherArg;
+  typedef BoundFutureWatcher<GstStateChangeReturn, PlayFutureWatcherArg> PlayFutureWatcher;
+
   // Callbacks
   static void CanDecodeNewPadCallback(GstElement*, GstPad*, gboolean, gpointer);
   static void CanDecodeLastCallback(GstElement*, gpointer);

src/engines/gstenginepipeline.cpp

@@ -54,7 +54,6 @@ GstEnginePipeline::GstEnginePipeline(GstEngine* engine)
     next_end_offset_nanosec_(-1),
     ignore_next_seek_(false),
     ignore_tags_(false),
-    ignore_errors_(false),
     pipeline_is_initialised_(false),
     pipeline_is_connected_(false),
     pending_seek_nanosec_(-1),
@@ -109,7 +108,6 @@ bool GstEnginePipeline::ReplaceDecodeBin(GstElement* new_bin) {
     // deletion in the main thread
   }
 
-  ignore_errors_ = false;
   uridecodebin_ = new_bin;
   segment_start_ = 0;
   segment_start_received_ = false;
@@ -310,10 +308,7 @@ GstBusSyncReply GstEnginePipeline::BusCallbackSync(GstBus*, GstMessage* msg, gpo
       break;
 
     case GST_MESSAGE_ERROR:
-      if (!instance->ignore_errors_) {
-        instance->ignore_errors_ = true;
-        QtConcurrent::run(instance, &GstEnginePipeline::ErrorMessageReceived, msg);
-      }
+      instance->ErrorMessageReceived(msg);
       break;
 
     case GST_MESSAGE_ELEMENT:

src/engines/gstenginepipeline.h

@@ -188,9 +188,6 @@ class GstEnginePipeline : public QObject {
   // get sent while the Player still thinks it's playing the last song
   bool ignore_tags_;
 
-  // Set after the first error to ignore any others that arrive.
-  bool ignore_errors_;
-
   // When the gstreamer source requests a redirect we store the URL here and
   // callers can pick it up after the state change to PLAYING fails.
   QUrl redirect_url_;