1 files changed, 95 insertions, 0 deletions
diff --git a/xbmc/threads/Event.cpp b/xbmc/threads/Event.cpp
new file mode 100644
index 0000000..1c67f4e
--- /dev/null
+++ b/xbmc/threads/Event.cpp
@@ -0,0 +1,95 @@
+/*
+ *  Copyright (c) 2002 Frodo
+ *      Portions Copyright (c) by the authors of ffmpeg and xvid
+ *  Copyright (C) 2002-2018 Team Kodi
+ *  This file is part of Kodi - https://kodi.tv
+ *
+ *  SPDX-License-Identifier: GPL-2.0-or-later
+ *  See LICENSES/README.md for more information.
+ */
+
+#include "Event.h"
+
+#include <algorithm>
+#include <limits>
+#include <mutex>
+
+using namespace std::chrono_literals;
+
+void CEvent::addGroup(XbmcThreads::CEventGroup* group)
+{
+  std::unique_lock<CCriticalSection> lock(groupListMutex);
+  if (!groups)
+    groups.reset(new std::vector<XbmcThreads::CEventGroup*>);
+
+  groups->push_back(group);
+}
+
+void CEvent::removeGroup(XbmcThreads::CEventGroup* group)
+{
+  std::unique_lock<CCriticalSection> lock(groupListMutex);
+  if (groups)
+  {
+    groups->erase(std::remove(groups->begin(), groups->end(), group), groups->end());
+    if (groups->empty())
+    {
+      groups.reset();
+    }
+  }
+}
+
+// locking is ALWAYS done in this order:
+//  CEvent::groupListMutex -> CEventGroup::mutex -> CEvent::mutex
+void CEvent::Set()
+{
+  // Originally I had this without locking. Thanks to FernetMenta who
+  // pointed out that this creates a race condition between setting
+  // checking the signal and calling wait() on the Wait call in the
+  // CEvent class. This now perfectly matches the boost example here:
+  // http://www.boost.org/doc/libs/1_41_0/doc/html/thread/synchronization.html#thread.synchronization.condvar_ref
+  {
+    std::unique_lock<CCriticalSection> slock(mutex);
+    signaled = true;
+  }
+
+  actualCv.notifyAll();
+
+  std::unique_lock<CCriticalSection> l(groupListMutex);
+  if (groups)
+  {
+    for (auto* group : *groups)
+      group->Set(this);
+  }
+}
+
+namespace XbmcThreads
+{
+  /**
+   * This will block until any one of the CEvents in the group are
+   * signaled at which point a pointer to that CEvents will be
+   * returned.
+   */
+  CEvent* CEventGroup::wait()
+  {
+    return wait(std::chrono::milliseconds::max());
+  }
+
+  CEventGroup::CEventGroup(std::initializer_list<CEvent*> eventsList)
+  : events{eventsList}
+  {
+    // we preping for a wait, so we need to set the group value on
+    // all of the CEvents.
+    for (auto* event : events)
+    {
+      event->addGroup(this);
+    }
+  }
+
+  CEventGroup::~CEventGroup()
+  {
+    for (auto* event : events)
+    {
+      event->removeGroup(this);
+    }
+  }
+}