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mojo/public/platform/dart/dart_handle_watcher.h

-// Copyright 2015 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_PLATFORM_DART_DART_HANDLE_WATCHER_H_
-#define MOJO_PUBLIC_PLATFORM_DART_DART_HANDLE_WATCHER_H_
-
-#include <mojo/result.h>
-#include <mojo/system/handle.h>
-
-#include <mutex>
-#include <thread>
-#include <unordered_map>
-
-#include "dart/runtime/include/dart_api.h"
-
-#include "mojo/public/cpp/environment/logging.h"
-#include "mojo/public/cpp/system/macros.h"
-
-namespace mojo {
-namespace dart {
-
-#define MOJO_HANDLE_SIGNAL_ALL (MOJO_HANDLE_SIGNAL_READABLE |                  \
-                                MOJO_HANDLE_SIGNAL_WRITABLE |                  \
-                                MOJO_HANDLE_SIGNAL_PEER_CLOSED)
-
-// HandleWatcherCommands are sent to HandleWatchers.
-class HandleWatcherCommand {
- public:
-  enum Command {
-    kCommandAddHandle = 0,
-    kCommandRemoveHandle = 1,
-    kCommandCloseHandle = 2,
-    kCommandAddTimer = 3,
-    kCommandShutdownHandleWatcher = 4,
-  };
-
-  // Construct a command to listen for |handle| to have |signals| and ping
-  // |port| when this happens.
-  static HandleWatcherCommand Add(MojoHandle handle,
-                                  MojoHandleSignals signals,
-                                  Dart_Port port) {
-    HandleWatcherCommand result;
-    result.handle_or_deadline_ = static_cast<int64_t>(handle);
-    result.port_ = port;
-    result.set_data(kCommandAddHandle, signals);
-    return result;
-  }
-
-  // Construct a command to stop listening for |handle|.
-  static HandleWatcherCommand Remove(MojoHandle handle) {
-    HandleWatcherCommand result;
-    result.handle_or_deadline_ = static_cast<int64_t>(handle);
-    result.port_ = ILLEGAL_PORT;
-    result.set_data(kCommandRemoveHandle, MOJO_HANDLE_SIGNAL_NONE);
-    return result;
-  }
-
-  // Construct a command to close |handle| and ping |port| when done.
-  static HandleWatcherCommand Close(MojoHandle handle,
-                                    Dart_Port port) {
-    HandleWatcherCommand result;
-    result.handle_or_deadline_ = static_cast<int64_t>(handle);
-    result.port_ = port;
-    result.set_data(kCommandCloseHandle, MOJO_HANDLE_SIGNAL_NONE);
-    return result;
-  }
-
-  // Construct a command to ping |port| when it is |deadline|.
-  static HandleWatcherCommand Timer(int64_t deadline,
-                                    Dart_Port port) {
-    HandleWatcherCommand result;
-    result.handle_or_deadline_ = deadline;
-    result.port_ = port;
-    result.set_data(kCommandAddTimer, MOJO_HANDLE_SIGNAL_NONE);
-    return result;
-  }
-
-  // Construct a command to shutdown the handle watcher thread.
-  static HandleWatcherCommand Shutdown() {
-    HandleWatcherCommand result;
-    result.handle_or_deadline_ = MOJO_HANDLE_INVALID;
-    result.port_ = ILLEGAL_PORT;
-    result.set_data(kCommandShutdownHandleWatcher, MOJO_HANDLE_SIGNAL_NONE);
-    return result;
-  }
-
-  // Construct an empty command.
-  static HandleWatcherCommand Empty() {
-    HandleWatcherCommand result;
-    return result;
-  }
-
-  // Construct a command sent from Dart code.
-  static HandleWatcherCommand FromDart(int64_t command,
-                                       int64_t handle_or_deadline,
-                                       Dart_Port port,
-                                       int64_t signals) {
-    switch (command) {
-      case kCommandAddHandle:
-        return Add(handle_or_deadline, signals, port);
-      break;
-      case kCommandRemoveHandle:
-        return Remove(handle_or_deadline);
-      break;
-      case kCommandCloseHandle:
-        return Close(handle_or_deadline, port);
-      break;
-      case kCommandAddTimer:
-        return Timer(handle_or_deadline, port);
-      break;
-      case kCommandShutdownHandleWatcher:
-        return Shutdown();
-      break;
-      default:
-        // Unreachable.
-        MOJO_CHECK(false);
-        return Empty();
-    }
-  }
-
-  // Get the command.
-  Command command() const {
-    return static_cast<Command>((data_ >> 3));
-  }
-
-  // Get the signals associated with the command.
-  MojoHandleSignals signals() const {
-    return data_ & MOJO_HANDLE_SIGNAL_ALL;
-  }
-
-  // Get the handle associated with the command.
-  MojoHandle handle() const {
-    return static_cast<MojoHandle>(handle_or_deadline_);
-  }
-
-  // Get the deadline associated with the command.
-  int64_t deadline() const {
-    return handle_or_deadline_;
-  }
-
-  // Get the port associated with the command.
-  Dart_Port port() const {
-    return port_;
-  }
-
- private:
-  HandleWatcherCommand() {
-    handle_or_deadline_ = 0;
-    port_ = ILLEGAL_PORT;
-    data_ = 0;
-  }
-
-  void set_data(Command command, MojoHandleSignals signals) {
-    MOJO_CHECK(MOJO_HANDLE_SIGNAL_ALL < (1 << 3));
-    data_ = (command << 3) | (signals & MOJO_HANDLE_SIGNAL_ALL);
-  }
-
-  int64_t handle_or_deadline_;
-  Dart_Port port_;
-  int64_t data_;
-};
-
-
-// A Dart HandleWatcher can be started by calling |HandleWatcher::Start|.
-// Each |Start| call creates a message pipe for communicating with the
-// handle watcher and spawns a thread where the handle watcher waits for
-// events on handles.
-//
-// NOTE: If multiple handle watchers are needed, |Start| can be safely called
-// multiple times because all state is held inside the spawned thread.
-class HandleWatcher {
- public:
-  // Starts a new HandleWatcher thread and returns the message pipe handle
-  // that is used to communicate with the handle watcher. Returns
-  // the handle that should be passed to |SendCommand|.
-  static MojoHandle Start();
-
-  // Encode a |command| for the handle watcher and write it to
-  // |control_pipe_producer_handle|.
-  static MojoResult SendCommand(MojoHandle control_pipe_producer_handle,
-                                const HandleWatcherCommand& command);
-
-  // Stops and joins the handle watcher thread at the other end of the
-  // given pipe handle.
-  static void Stop(MojoHandle control_pipe_consumer_handle);
-
-  // Stops and joins all handle watcher threads.
-  static void StopAll();
-
- private:
-  static void ThreadMain(MojoHandle control_pipe_consumer_handle);
-
-  // Remove the mapping for |handle| from |handle_watcher_threads_| and return
-  // the associated thread object. Assumes |handle_watcher_threads_mutex_| is
-  // held.
-  static std::thread* RemoveLocked(MojoHandle handle);
-
-  // Remove the mapping for |handle| from |handle_watcher_threads_| and join
-  // the associated thread. Assumes |handle_watcher_threads_mutex_| is held.
-  static void StopLocked(MojoHandle handle);
-
-  // A mapping from control handle to handle watcher thread.
-  static std::unordered_map<MojoHandle, std::thread*> handle_watcher_threads_;
-
-  // Protects |handle_watcher_threads_|
-  static std::mutex handle_watcher_threads_mutex_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(HandleWatcher);
-};
-
-
-}  // namespace dart
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_PLATFORM_DART_DART_HANDLE_WATCHER_H_