blob: ef2f55a7f7233baab82bac1a3b64a6427f74f23e [file] [log] [blame]
// Copyright 2013 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.
#include <stdint.h>
#include <functional>
#include <memory>
#include <set>
#include <unordered_map>
#include "base/macros.h"
#include "base/message_loop/message_pump.h"
#include "base/observer_list.h"
#include "base/synchronization/lock.h"
#include "base/synchronization/waitable_event.h"
#include "base/time/time.h"
#include "mojo/message_pump/mojo_message_pump_export.h"
#include "mojo/public/cpp/system/core.h"
namespace mojo {
namespace common {
class MessagePumpMojoHandler;
// Mojo implementation of MessagePump.
class MOJO_MESSAGE_PUMP_EXPORT MessagePumpMojo : public base::MessagePump {
Observer() {}
virtual void WillSignalHandler() = 0;
virtual void DidSignalHandler() = 0;
virtual ~Observer() {}
~MessagePumpMojo() override;
// Static factory function (for using with |base::Thread::Options|, wrapped
// using |base::Bind()|).
static std::unique_ptr<base::MessagePump> Create();
// Returns the MessagePumpMojo instance of the current thread, if it exists.
static MessagePumpMojo* current();
static bool IsCurrent() { return !!current(); }
// Registers a MessagePumpMojoHandler for the specified handle. Only one
// handler can be registered for a specified handle.
// NOTE: a value of 0 for |deadline| indicates an indefinite timeout.
void AddHandler(MessagePumpMojoHandler* handler,
const Handle& handle,
MojoHandleSignals wait_signals,
base::TimeTicks deadline);
void RemoveHandler(const Handle& handle);
void AddObserver(Observer*);
void RemoveObserver(Observer*);
// MessagePump:
void Run(Delegate* delegate) override;
void Quit() override;
void ScheduleWork() override;
void ScheduleDelayedWork(const base::TimeTicks& delayed_work_time) override;
struct RunState;
// Contains the data needed to track a request to AddHandler().
struct Handler {
Handler() : handler(NULL), wait_signals(MOJO_HANDLE_SIGNAL_NONE), id(0) {}
MessagePumpMojoHandler* handler;
MojoHandleSignals wait_signals;
base::TimeTicks deadline;
// See description of |MessagePumpMojo::next_handler_id_| for details.
int id;
struct HandleHasher {
size_t operator()(const Handle& handle) const {
return std::hash<uint32_t>()(static_cast<uint32_t>(handle.value()));
using HandleToHandler = std::unordered_map<Handle, Handler, HandleHasher>;
// Implementation of Run().
void DoRunLoop(RunState* run_state, Delegate* delegate);
// Services the set of handles ready. If |block| is true this waits for a
// handle to become ready, otherwise this does not block. Returns |true| if a
// handle has become ready, |false| otherwise.
bool DoInternalWork(const RunState& run_state, bool block);
bool DoNonMojoWork(const RunState& run_state, bool block);
// Waits for handles in the wait set to become ready. Returns |true| if ready
// handles may be available, or |false| if the wait's deadline was exceeded.
// Note, ready handles may be unavailable, even though |true| was returned.
bool WaitForReadyHandles(const RunState& run_state) const;
// Retrieves any 'ready' handles from the wait set, and runs the handler's
// OnHandleReady() or OnHandleError() functions as necessary. Returns |true|
// if any handles were ready and processed.
bool ProcessReadyHandles();
// Removes any handles that have expired their deadline. Runs the handler's
// OnHandleError() function with |MOJO_RESULT_DEADLINE_EXCEEDED| as the
// result. Returns |true| if any handles were removed.
bool RemoveExpiredHandles();
void SignalControlPipe();
// Returns the deadline for the call to MojoWait().
MojoDeadline GetDeadlineForWait(const RunState& run_state) const;
// Run |OnHandleReady()| for the handler registered with |handle|. |handle|
// must be registered.
void SignalHandleReady(Handle handle);
// Run |OnHandleError()| for the handler registered with |handle| and the
// error code |result|. |handle| must be registered, and will be removed
// before calling |OnHandleError()|.
void SignalHandleError(Handle handle, MojoResult result);
void WillSignalHandler();
void DidSignalHandler();
// If non-NULL we're running (inside Run()). Member is reference to value on
// stack.
RunState* run_state_;
// Lock for accessing |run_state_|. In general the only method that we have to
// worry about is ScheduleWork(). All other methods are invoked on the same
// thread.
base::Lock run_state_lock_;
HandleToHandler handlers_;
// Set of handles that have a deadline set. Avoids iterating over all elements
// in |handles_| in the common case (no deadline set).
// TODO(amistry): Make this better and avoid special-casing deadlines.
std::set<Handle> deadline_handles_;
// An ever increasing value assigned to each Handler::id. Used to detect
// uniqueness while notifying. That is, while notifying expired timers we copy
// |handlers_| and only notify handlers whose id match. If the id does not
// match it means the handler was removed then added so that we shouldn't
// notify it.
int next_handler_id_;
base::ObserverList<Observer> observers_;
// Mojo handle for the wait set.
ScopedHandle wait_set_handle_;
// Used to wake up run loop from |SignalControlPipe()|.
ScopedMessagePipeHandle read_handle_;
ScopedMessagePipeHandle write_handle_;
// Used to sleep until there is more work to do, when the Mojo EDK is shutting
// down.
base::WaitableEvent event_;
} // namespace common
} // namespace mojo