Mojo: Armed Watchers

mojo/edk/system/watcher_set.h

 // Copyright 2016 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_EDK_SYSTEM_WATCHER_SET_H_
 #define MOJO_EDK_SYSTEM_WATCHER_SET_H_
 
-#include <unordered_map>
+#include <map>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "mojo/edk/system/handle_signals_state.h"
 #include "mojo/edk/system/watcher.h"
 #include "mojo/public/c/system/types.h"
 
 namespace mojo {
 namespace edk {
 
 // A WatcherSet maintains a set of Watchers attached to a single handle and
 // keyed on an arbitrary user context.
 class WatcherSet {
  public:
   WatcherSet();
   ~WatcherSet();
 
-  // Notifies all Watchers of a state change.
-  void NotifyForStateChange(const HandleSignalsState& state);
+  // Notifies all Watchers of the handle's current signals state.
+  void NotifyState(const HandleSignalsState& state);
 
   // Notifies all Watchers that their watched handle has been closed.
   void NotifyClosed();
 
   // Adds a new watcher to watch for signals in |signals| to be satisfied or
-  // unsatisfiable. |current_state| is the current signals state of the
-  // handle being watched.
+  // unsatisfiable.
   MojoResult Add(MojoHandleSignals signals,
                  const Watcher::WatchCallback& callback,
                  uintptr_t context,
                  const HandleSignalsState& current_state);
 
+  // Attempts to arm a watcher. May fail depending on |current_state|. See
+  // public |MojoArmWatcher()| documentation for error code details.
+  MojoResult Arm(uintptr_t context, const HandleSignalsState& current_state);
+
   // Removes a watcher from the set.
   MojoResult Remove(uintptr_t context);
 
  private:
   // A map of watchers keyed on context value.
-  std::unordered_map<uintptr_t, scoped_refptr<Watcher>> watchers_;
+  std::map<uintptr_t, scoped_refptr<Watcher>> watchers_;
 
   DISALLOW_COPY_AND_ASSIGN(WatcherSet);
 };
 
 }  // namespace edk
 }  // namespace mojo
 
 #endif  // MOJO_EDK_SYSTEM_WATCHER_SET_H_