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// 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_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_
#define MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_
#include <map>
#include "base/callback.h"
#include "base/containers/stack_container.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequence_checker.h"
#include "base/synchronization/waitable_event.h"
#include "mojo/public/cpp/bindings/bindings_export.h"
#include "mojo/public/cpp/system/core.h"
#include "mojo/public/cpp/system/wait_set.h"
namespace mojo {
// SyncHandleRegistry is a sequence-local storage to register handles that want
// to be watched together.
//
// This class is thread unsafe.
class MOJO_CPP_BINDINGS_EXPORT SyncHandleRegistry
: public base::RefCounted<SyncHandleRegistry> {
public:
// Returns a sequence-local object.
static scoped_refptr<SyncHandleRegistry> current();
using HandleCallback = base::Callback<void(MojoResult)>;
// Registers a |Handle| to be watched for |handle_signals|. If any such
// signals are satisfied during a Wait(), the Wait() is woken up and
// |callback| is run.
bool RegisterHandle(const Handle& handle,
MojoHandleSignals handle_signals,
const HandleCallback& callback);
void UnregisterHandle(const Handle& handle);
// Registers a |base::WaitableEvent| which can be used to wake up
// Wait() before any handle signals. |event| is not owned, and if it signals
// during Wait(), |callback| is invoked. Note that |event| may be registered
// multiple times with different callbacks.
void RegisterEvent(base::WaitableEvent* event, const base::Closure& callback);
// Unregisters a specific |event|+|callback| pair.
void UnregisterEvent(base::WaitableEvent* event,
const base::Closure& callback);
// Waits on all the registered handles and events and runs callbacks
// synchronously for any that become ready.
// The method:
// - returns true when any element of |should_stop| is set to true;
// - returns false when any error occurs.
bool Wait(const bool* should_stop[], size_t count);
private:
friend class base::RefCounted<SyncHandleRegistry>;
using EventCallbackList = base::StackVector<base::Closure, 1>;
using EventMap = std::map<base::WaitableEvent*, EventCallbackList>;
SyncHandleRegistry();
~SyncHandleRegistry();
void RemoveInvalidEventCallbacks();
WaitSet wait_set_;
std::map<Handle, HandleCallback> handles_;
EventMap events_;
// |true| iff this registry is currently dispatching event callbacks in
// Wait(). Used to allow for safe event registration/unregistration from event
// callbacks.
bool is_dispatching_event_callbacks_ = false;
// Indicates if one or more event callbacks was unregistered during the most
// recent event callback dispatch.
bool remove_invalid_event_callbacks_after_dispatch_ = false;
SEQUENCE_CHECKER(sequence_checker_);
DISALLOW_COPY_AND_ASSIGN(SyncHandleRegistry);
};
} // namespace mojo
#endif // MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_
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