1 files changed, 101 insertions, 0 deletions
diff --git a/ipc/glue/SendStream.h b/ipc/glue/SendStream.h
new file mode 100644
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+++ b/ipc/glue/SendStream.h
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=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/. */
+
+#ifndef mozilla_ipc_SendStream_h
+#define mozilla_ipc_SendStream_h
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/ipc/PSendStreamChild.h"
+#include "mozilla/ipc/PSendStreamParent.h"
+
+class nsIInputStream;
+class nsIAsyncInputStream;
+
+namespace mozilla {
+
+namespace dom {
+class nsIContentChild;
+} // dom namespace
+
+namespace ipc {
+
+class PBackgroundChild;
+
+// The SendStream IPC actor is designed to push an nsIInputStream from child to
+// parent incrementally.  This is mainly needed for streams such as nsPipe that
+// may not yet have all their data available when the stream must be sent across
+// an IPC boundary.  While many streams are handled by SerializeInputStream(),
+// these streams cannot be serialized and must be sent using this actor.
+//
+// The SendStream actor only supports sending data from child to parent.
+//
+// The SendStream actor only support async, non-blocking streams because they
+// must be read inline on the main thread and Worker threads.
+//
+// In general, the creation and handling of the SendStream actor cannot be
+// abstracted away behind SerializeInputStream() because the actor must be
+// carefully managed.  Specifically:
+//
+//  1) The data flow must be explicitly initiated by calling
+//     SendStreamChild::Start() after the actor has been sent to the parent.
+//  2) If the actor is never sent to the parent, then the child code must
+//     call SendStreamChild::StartDestroy() to avoid memory leaks.
+//  3) The SendStreamChild actor can only be used on threads that can be
+//     guaranteed to stay alive as long as the actor is alive.  Right now
+//     this limits SendStream to the main thread and Worker threads.
+//
+// In general you should probably use the AutoIPCStreamChild RAII class
+// defined in InputStreamUtils.h instead of using SendStreamChild directly.
+class SendStreamChild : public PSendStreamChild
+{
+public:
+  // Create a SendStreamChild using a PContent IPC manager on the
+  // main thread.  This can return nullptr if the provided stream is
+  // blocking.
+  static SendStreamChild*
+  Create(nsIAsyncInputStream* aInputStream, dom::nsIContentChild* aManager);
+
+  // Create a SendStreamChild using a PBackground IPC manager on the
+  // main thread or a Worker thread.  This can return nullptr if the provided
+  // stream is blocking or if the Worker thread is already shutting down.
+  static SendStreamChild*
+  Create(nsIAsyncInputStream* aInputStream, PBackgroundChild* aManager);
+
+  // Start reading data from the nsIAsyncInputStream used to create the actor.
+  // This must be called after the actor is passed to the parent.  If you
+  // use AutoIPCStream this is handled automatically.
+  virtual void
+  Start() = 0;
+
+  // Start cleaning up the actor.  This must be called if the actor is never
+  // sent to the parent.  If you use AutoIPCStream this is handled
+  // automatically.
+  virtual void
+  StartDestroy() = 0;
+
+protected:
+  virtual
+  ~SendStreamChild() = 0;
+};
+
+// On the parent side, you must simply call TakeReader() upon receiving a
+// reference to the SendStreamParent actor.  You do not need to maintain a
+// reference to the actor itself.
+class SendStreamParent : public PSendStreamParent
+{
+public:
+  virtual already_AddRefed<nsIInputStream>
+  TakeReader() = 0;
+
+protected:
+  virtual
+  ~SendStreamParent() = 0;
+};
+
+} // namespace ipc
+} // namespace mozilla
+
+#endif // mozilla_ipc_SendStream_h