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arc_session_impl.h
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arc_session_impl.h
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// Copyright 2017 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 COMPONENTS_ARC_ARC_SESSION_IMPL_H_
#define COMPONENTS_ARC_ARC_SESSION_IMPL_H_
#include <memory>
#include <ostream>
#include <string>
#include "base/callback.h"
#include "base/files/scoped_file.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/thread_checker.h"
#include "chromeos/dbus/session_manager_client.h"
#include "components/arc/arc_session.h"
namespace arc {
namespace mojom {
class ArcBridgeHost;
} // namespace mojom
class ArcSessionImpl : public ArcSession,
public chromeos::SessionManagerClient::Observer {
public:
// The possible states of the session. Expected state changes are as follows.
//
// NOT_STARTED
// -> StartMiniInstance() ->
// STARTING_MINI_INSTANCE
// -> OnMiniInstanceStarted() ->
// RUNNING_MINI_INSTANCE.
// -> RequestUpgrade() ->
// STARTING_FULL_INSTANCE
// -> OnUpgraded() ->
// CONNECTING_MOJO
// -> OnMojoConnected() ->
// RUNNING_FULL_INSTANCE
//
// Note that, if RequestUpgrade() is called during STARTING_MINI_INSTANCE
// state, the state change to STARTING_FULL_INSTANCE is suspended until
// the state becomes RUNNING_MINI_INSTANCE.
//
// At any state, Stop() can be called. It may not immediately stop the
// instance, but will eventually stop it. The actual stop will be notified
// via ArcSession::Observer::OnSessionStopped().
//
// When Stop() is called, it makes various behavior based on the current
// phase.
//
// NOT_STARTED:
// Do nothing. Immediately transition to the STOPPED state.
// STARTING_{MINI,FULL}_INSTANCE:
// The ARC instance is starting via SessionManager. Stop() just sets the
// flag and return. On the main task completion, a callback will run on the
// thread, and the flag is checked at the beginning of them. This should
// work under the assumption that the main tasks do not block indefinitely.
// In its callback, it checks if ARC instance is successfully started or
// not. In case of success, a request to stop the ARC instance is sent to
// SessionManager. Its completion will be notified via ArcInstanceStopped.
// Otherwise, it just turns into STOPPED state.
// CONNECTING_MOJO:
// The main task runs on TaskScheduler's thread, but it is a blocking call.
// So, Stop() sends a request to cancel the blocking by closing the pipe
// whose read side is also polled. Then, in its callback, similar to
// STARTING_{MINI,FULL}_INSTANCE, a request to stop the ARC instance is
// sent to SessionManager, and ArcInstanceStopped handles remaining
// procedure.
// RUNNING_{MINI,FULL}_INSTANCE:
// There is no more callback which runs on normal flow, so Stop() requests
// to stop the ARC instance via SessionManager.
//
// Another trigger to change the state coming from outside of this class
// is an event ArcInstanceStopped() sent from SessionManager, when ARC
// instace unexpectedly terminates. ArcInstanceStopped() turns the state into
// STOPPED immediately.
//
// In NOT_STARTED or STOPPED state, the instance can be safely destructed.
// Specifically, in STOPPED state, there may be inflight operations or
// pending callbacks. Though, what they do is just do-nothing conceptually
// and they can be safely ignored.
//
// Note: Order of constants below matters. Please make sure to sort them
// in chronological order.
enum class State {
// ARC is not yet started.
NOT_STARTED,
// The request to start a mini instance has been sent.
STARTING_MINI_INSTANCE,
// The instance is set up, but only a handful of processes NOT including
// arcbridgeservice (i.e. mojo endpoint) are running.
RUNNING_MINI_INSTANCE,
// The request to upgrade to a full instance has been sent.
STARTING_FULL_INSTANCE,
// The instance has started. Waiting for it to connect to the IPC bridge.
CONNECTING_MOJO,
// The instance is fully set up.
RUNNING_FULL_INSTANCE,
// ARC is terminated.
STOPPED,
};
static const char kPackagesCacheModeCopy[];
static const char kPackagesCacheModeSkipCopy[];
// Delegate interface to emulate ArcBridgeHost mojo connection establishment.
class Delegate {
public:
// Used for ConnectMojo completion callback.
using ConnectMojoCallback =
base::OnceCallback<void(std::unique_ptr<mojom::ArcBridgeHost>)>;
virtual ~Delegate() = default;
// Connects ArcBridgeHost via |socket_fd|, and invokes |callback| with
// connected ArcBridgeHost instance if succeeded (or nullptr if failed).
// Returns a FD which cancels the current connection on close(2).
virtual base::ScopedFD ConnectMojo(base::ScopedFD socket_fd,
ConnectMojoCallback callback) = 0;
};
explicit ArcSessionImpl(std::unique_ptr<Delegate> delegate);
~ArcSessionImpl() override;
// Returns default delegate implementation used for the production.
static std::unique_ptr<Delegate> CreateDelegate(
ArcBridgeService* arc_bridge_service);
State GetStateForTesting() { return state_; }
// ArcSession overrides:
void StartMiniInstance() override;
void RequestUpgrade() override;
void Stop() override;
bool IsStopRequested() override;
void OnShutdown() override;
private:
// D-Bus callback for StartArcInstance() for a mini instance.
// In case of success, |container_instance_id| must not be empty, and
// |socket_fd| is /dev/null.
// TODO(hidehiko): Remove |socket_fd| from this callback.
void OnMiniInstanceStarted(
chromeos::SessionManagerClient::StartArcInstanceResult result,
const std::string& container_instance_id,
base::ScopedFD socket_fd);
// Sends a D-Bus message to upgrade to a full instance.
void DoUpgrade();
// D-Bus callback for StartArcInstance() for an upgrade. |socket_fd| should be
// a socket which should be accept(2)ed to connect ArcBridgeService Mojo
// channel.
void OnUpgraded(chromeos::SessionManagerClient::StartArcInstanceResult result,
const std::string& container_instance_id, // unused
base::ScopedFD socket_fd);
// Called when Mojo connection is established (or canceled during the
// connect.)
void OnMojoConnected(std::unique_ptr<mojom::ArcBridgeHost> arc_bridge_host);
// Request to stop ARC instance via DBus.
void StopArcInstance();
// chromeos::SessionManagerClient::Observer:
void ArcInstanceStopped(bool clean,
const std::string& container_instance_id) override;
// Completes the termination procedure. Note that calling this may end up with
// deleting |this| because the function calls observers' OnSessionStopped().
void OnStopped(ArcStopReason reason);
// Checks whether a function runs on the thread where the instance is
// created.
THREAD_CHECKER(thread_checker_);
// Delegate implementation.
std::unique_ptr<Delegate> delegate_;
// The state of the session.
State state_ = State::NOT_STARTED;
// When Stop() is called, this flag is set.
bool stop_requested_ = false;
// Whether the full container has been requested
bool upgrade_requested_ = false;
// Container instance id passed from session_manager.
// Should be available only after On{Mini,Full}InstanceStarted().
std::string container_instance_id_;
// In CONNECTING_MOJO state, this is set to the write side of the pipe
// to notify cancelling of the procedure.
base::ScopedFD accept_cancel_pipe_;
// Mojo endpoint.
std::unique_ptr<mojom::ArcBridgeHost> arc_bridge_host_;
// WeakPtrFactory to use callbacks.
base::WeakPtrFactory<ArcSessionImpl> weak_factory_;
DISALLOW_COPY_AND_ASSIGN(ArcSessionImpl);
};
// Stringified output for logging purpose.
std::ostream& operator<<(std::ostream& os, ArcSessionImpl::State state);
} // namespace arc
#endif // COMPONENTS_ARC_ARC_SESSION_IMPL_H_