1 files changed, 105 insertions, 0 deletions
diff --git a/dom/media/webrtc/transport/transportflow.h b/dom/media/webrtc/transport/transportflow.h
new file mode 100644
index 0000000000..43253a260b
--- /dev/null
+++ b/dom/media/webrtc/transport/transportflow.h
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Original author: ekr@rtfm.com
+
+#ifndef transportflow_h__
+#define transportflow_h__
+
+#include <deque>
+#include <string>
+
+#include "nscore.h"
+#include "nsISupportsImpl.h"
+#include "mozilla/UniquePtr.h"
+#include "transportlayer.h"
+#include "m_cpp_utils.h"
+
+// A stack of transport layers acts as a flow.
+// Generally, one reads and writes to the top layer.
+
+// This code has a confusing hybrid threading model which
+// probably needs some eventual refactoring.
+// TODO(ekr@rtfm.com): Bug 844891
+//
+// TransportFlows are not inherently bound to a thread *but*
+// TransportLayers can be. If any layer in a flow is bound
+// to a given thread, then all layers in the flow MUST be
+// bound to that thread and you can only manipulate the
+// flow (push layers, write, etc.) on that thread.
+//
+// The sole official exception to this is that you are
+// allowed to *destroy* a flow off the bound thread provided
+// that there are no listeners on its signals. This exception
+// is designed to allow idioms where you create the flow
+// and then something goes wrong and you destroy it and
+// you don't want to bother with a thread dispatch.
+//
+// Eventually we hope to relax the "no listeners"
+// restriction by thread-locking the signals, but previous
+// attempts have caused deadlocks.
+//
+// Most of these invariants are enforced by hard asserts
+// (i.e., those which fire even in production builds).
+
+namespace mozilla {
+
+class TransportFlow final : public nsISupports {
+ public:
+  TransportFlow()
+      : id_("(anonymous)"), layers_(new std::deque<TransportLayer*>) {}
+  explicit TransportFlow(const std::string id)
+      : id_(id), layers_(new std::deque<TransportLayer*>) {}
+
+  const std::string& id() const { return id_; }
+
+  // Layer management. Note PushLayer() is not thread protected, so
+  // either:
+  // (a) Do it in the thread handling the I/O
+  // (b) Do it before you activate the I/O system
+  //
+  // The flow takes ownership of the layers after a successful
+  // push.
+  void PushLayer(TransportLayer* layer);
+
+  TransportLayer* GetLayer(const std::string& id) const;
+
+  NS_DECL_THREADSAFE_ISUPPORTS
+
+ private:
+  ~TransportFlow();
+
+  DISALLOW_COPY_ASSIGN(TransportFlow);
+
+  // Check if we are on the right thread
+  void CheckThread() const {
+    if (!CheckThreadInt()) MOZ_CRASH();
+  }
+
+  bool CheckThreadInt() const {
+    bool on;
+
+    if (!target_)  // OK if no thread set.
+      return true;
+    if (NS_FAILED(target_->IsOnCurrentThread(&on))) return false;
+
+    return on;
+  }
+
+  void EnsureSameThread(TransportLayer* layer);
+
+  static void DestroyFinal(UniquePtr<std::deque<TransportLayer*>> layers);
+
+  // Overload needed because we use deque internally and queue externally.
+  static void ClearLayers(std::deque<TransportLayer*>* layers);
+
+  std::string id_;
+  UniquePtr<std::deque<TransportLayer*>> layers_;
+  nsCOMPtr<nsIEventTarget> target_;
+};
+
+}  // namespace mozilla
+#endif