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// 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 COMPONENTS_CRYPTAUTH_SYNC_SCHEDULER_H_
#define COMPONENTS_CRYPTAUTH_SYNC_SCHEDULER_H_
#include <memory>
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
namespace cryptauth {
// Interface for scheduling the next CryptAuth sync (e.g. enrollment or device
// sync). The scheduler has two different strategies affecting when to perform
// the next operation:
// PERIODIC_REFRESH: The last sync was made successfully, so we can wait a
// relatively long time before making another sync.
// AGGRESSIVE_RECOVERY: The last sync failed, so we try more aggressively to
// make enrollment attempts with subsequent backoff for repeated
// failures.
// A random jitter is applied to each sync period to smooth qps to the server.
class SyncScheduler {
public:
// The sync strategies mentioned in the class comments.
enum class Strategy { PERIODIC_REFRESH, AGGRESSIVE_RECOVERY };
// The states that the scheduler can be in.
enum class SyncState { NOT_STARTED, WAITING_FOR_REFRESH, SYNC_IN_PROGRESS };
// An instance is passed to the delegate when the scheduler fires for each
// sync attempt. The delegate should call |Complete()| when the sync succeeds
// or fails to resume the scheduler.
class SyncRequest {
public:
explicit SyncRequest(base::WeakPtr<SyncScheduler> sync_scheduler);
~SyncRequest();
void OnDidComplete(bool success);
protected:
// The parent scheduler that dispatched this request.
base::WeakPtr<SyncScheduler> sync_scheduler_;
// True if |OnDidComplete()| has been called.
bool completed_;
DISALLOW_COPY_AND_ASSIGN(SyncRequest);
};
// Handles the actual sync operation.
class Delegate {
public:
virtual ~Delegate() {}
// Called when the scheduler fires and requests a sync attempt. The delegate
// should call sync_request->Complete() when the request finishes.
virtual void OnSyncRequested(std::unique_ptr<SyncRequest> sync_request) = 0;
};
virtual ~SyncScheduler() {}
// Starts the scheduler with an aggressive recovery strategy if
// |strategy| is true; otherwise, it will be started with
// periodic refresh.
//
// |elapsed_time_since_last_sync| is the time since the last successful sync,
// so we can determine the duration of the first sync period. For example, the
// scheduler will immediately issue a sync request if the elapsed time is
// greater than the refresh period.
virtual void Start(const base::TimeDelta& elapsed_time_since_last_sync,
Strategy strategy) = 0;
// Cancels the current scheduled sync, and forces a sync immediately. Note
// that if this sync fails, the scheduler will adopt the AGGRESSIVE_RECOVERY
// strategy.
virtual void ForceSync() = 0;
// Returns the time until the next scheduled sync operation. If no sync is
// scheduled, a TimeDelta of zero will be returned.
virtual base::TimeDelta GetTimeToNextSync() const = 0;
// Returns the current sync strategy.
virtual Strategy GetStrategy() const = 0;
// Returns the current state of the scheduler.
virtual SyncState GetSyncState() const = 0;
protected:
// Called by SyncRequest instances when the sync completes.
virtual void OnSyncCompleted(bool success) = 0;
};
} // namespace cryptauth
#endif // COMPONENTS_CRYPTAUTH_SYNC_SCHEDULER_H_
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