Mojo: AsyncWaiter and mojo/public/environment

mojo/public/system/async_waiter.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_SYSTEM_ASYNC_WAITER_H_
+#define MOJO_PUBLIC_SYSTEM_ASYNC_WAITER_H_
+
+#include "mojo/public/system/core.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef uintptr_t MojoAsyncWaitID;
+
+typedef void (*MojoAsyncWaitCallback)(void* closure, MojoResult result);
+
+struct MojoAsyncWaiter {
+  // Asynchronously call MojoWait on a background thread, and pass the result
+  // of MojoWait to the given MojoAsyncWaitCallback on the current thread.
+  // Returns a non-zero MojoAsyncWaitID that can be used with CancelWait to
+  // stop waiting. This identifier becomes invalid once the callback runs.
+  MojoAsyncWaitID (*AsyncWait)(MojoAsyncWaiter* waiter,
+                               MojoHandle handle,
+                               MojoWaitFlags flags,
+                               MojoDeadline deadline,
+                               MojoAsyncWaitCallback callback,
+                               void* closure);
+
+  // Cancel an existing call to AsyncWait with the given MojoAsyncWaitID. The
+  // corresponding MojoAsyncWaitCallback will not be called in this case.
+  void (*CancelWait)(MojoAsyncWaiter* waiter,
+                     MojoAsyncWaitID wait_id);
+};
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // MOJO_PUBLIC_SYSTEM_ASYNC_WAITER_H_