mojo/embedder/embedder.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MOJO_EMBEDDER_EMBEDDER_H_
   6 #define MOJO_EMBEDDER_EMBEDDER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/task_runner.h"
  11 #include "mojo/embedder/scoped_platform_handle.h"
  12 #include "mojo/public/cpp/system/core.h"
  13 #include "mojo/system/system_impl_export.h"
  14
  15 namespace mojo {
  16 namespace embedder {
  17
  18 // Must be called first to initialize the (global, singleton) system.
  19 MOJO_SYSTEM_IMPL_EXPORT void Init();
  20
  21 // Creates a new "channel", returning a handle to the bootstrap message pipe on
  22 // that channel. |platform_handle| should be an OS-dependent handle to one side
  23 // of a suitable bidirectional OS "pipe" (e.g., a file descriptor to a socket on
  24 // POSIX, a handle to a named pipe on Windows); this "pipe" should be connected
  25 // and ready for operation (e.g., to be written to or read from).
  26 // |io_thread_task_runner| should be a |TaskRunner| for the thread on which the
  27 // "channel" will run (read data and demultiplex).
  28 //
  29 // On completion, it will run |callback| with a pointer to a |ChannelInfo|
  30 // (which is meant to be opaque to the embedder). If
  31 // |callback_thread_task_runner| is non-null, it the callback will be posted to
  32 // that task runner. Otherwise, it will be run on the I/O thread directly.
  33 //
  34 // Returns an invalid |MOJO_HANDLE_INVALID| on error. Note that this will happen
  35 // only if, e.g., the handle table is full (operation of the channel begins
  36 // asynchronously and if, e.g., the other end of the "pipe" is closed, this will
  37 // report an error to the returned handle in the usual way).
  38 //
  39 // Notes: The handle returned is ready for use immediately, with messages
  40 // written to it queued. E.g., it would be perfectly valid for a message to be
  41 // immediately written to the returned handle and the handle closed, all before
  42 // the channel has begun operation on the IO thread. In this case, the channel
  43 // is expected to connect as usual, send the queued message, and report that the
  44 // handle was closed to the other side. (This message may well contain another
  45 // handle, so there may well still be message pipes "on" this channel.)
  46 //
  47 // TODO(vtl): Figure out channel teardown.
  48 struct ChannelInfo;
  49 typedef base::Callback<void(ChannelInfo*)> DidCreateChannelCallback;
  50 MOJO_SYSTEM_IMPL_EXPORT ScopedMessagePipeHandle CreateChannel(
  51     ScopedPlatformHandle platform_handle,
  52     scoped_refptr<base::TaskRunner> io_thread_task_runner,
  53     DidCreateChannelCallback callback,
  54     scoped_refptr<base::TaskRunner> callback_thread_task_runner);
  55
  56 MOJO_SYSTEM_IMPL_EXPORT void DestroyChannelOnIOThread(
  57     ChannelInfo* channel_info);
  58
  59 }  // namespace embedder
  60 }  // namespace mojo
  61
  62 #endif  // MOJO_EMBEDDER_EMBEDDER_H_