Revert of Add SyncScheduler for scheduling CryptAuth enrollments and syncing devices.

components/proximity_auth/cryptauth/sync_scheduler_impl.cc

-// 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.
-
-#include "components/proximity_auth/cryptauth/sync_scheduler_impl.h"
-
-#include <algorithm>
-#include <cmath>
-#include <limits>
-
-#include "base/bind.h"
-#include "base/numerics/safe_conversions.h"
-#include "base/rand_util.h"
-#include "base/strings/stringprintf.h"
-#include "components/proximity_auth/logging/logging.h"
-
-namespace proximity_auth {
-
-namespace {
-
-// Returns a human readable string given a |time_delta|.
-std::string TimeDeltaToString(const base::TimeDelta& time_delta) {
-  if (time_delta.InDays() > 0)
-    return base::StringPrintf("%d days", time_delta.InDays());
-
-  if (time_delta.InHours() > 0)
-    return base::StringPrintf("%d hours", time_delta.InHours());
-
-  if (time_delta.InMinutes() > 0)
-    return base::StringPrintf("%d minutes", time_delta.InMinutes());
-
-  return base::StringPrintf("%d seconds",
-                            base::saturated_cast<int>(time_delta.InSeconds()));
-}
-
-}  // namespace
-
-SyncSchedulerImpl::SyncSchedulerImpl(Delegate* delegate,
-                                     base::TimeDelta refresh_period,
-                                     base::TimeDelta base_recovery_period,
-                                     double max_jitter_ratio,
-                                     const std::string& scheduler_name)
-    : delegate_(delegate),
-      refresh_period_(refresh_period),
-      base_recovery_period_(base_recovery_period),
-      max_jitter_ratio_(max_jitter_ratio),
-      scheduler_name_(scheduler_name),
-      strategy_(Strategy::PERIODIC_REFRESH),
-      sync_state_(SyncState::NOT_STARTED),
-      weak_ptr_factory_(this) {
-}
-
-SyncSchedulerImpl::~SyncSchedulerImpl() {
-}
-
-void SyncSchedulerImpl::Start(
-    const base::TimeDelta& elapsed_time_since_last_sync,
-    Strategy strategy) {
-  strategy_ = strategy;
-  sync_state_ = SyncState::WAITING_FOR_REFRESH;
-  // We reset the failure backoff when the scheduler is started again, as the
-  // configuration that caused the previous attempts to fail most likely won't
-  // be present after a restart.
-  if (strategy_ == Strategy::AGGRESSIVE_RECOVERY)
-    failure_count_ = 1;
-
-  // To take into account the time waited when the system is powered off, we
-  // subtract the time elapsed with a normal sync period to the initial time
-  // to wait.
-  base::TimeDelta sync_delta =
-      GetJitteredPeriod() - elapsed_time_since_last_sync;
-  if (sync_delta < base::TimeDelta::FromSeconds(0))
-    sync_delta = base::TimeDelta::FromSeconds(0);
-
-  ScheduleNextSync(sync_delta);
-}
-
-void SyncSchedulerImpl::ForceSync() {
-  OnTimerFired();
-}
-
-base::TimeDelta SyncSchedulerImpl::GetTimeToNextSync() const {
-  if (!timer_)
-    return base::TimeDelta::FromSeconds(0);
-  return timer_->GetCurrentDelay();
-}
-
-SyncScheduler::Strategy SyncSchedulerImpl::GetStrategy() const {
-  return strategy_;
-}
-
-SyncScheduler::SyncState SyncSchedulerImpl::GetSyncState() const {
-  return sync_state_;
-}
-
-void SyncSchedulerImpl::OnTimerFired() {
-  timer_.reset();
-  if (strategy_ == Strategy::PERIODIC_REFRESH) {
-    PA_LOG(INFO) << "Timer fired for periodic refresh, making request...";
-    sync_state_ = SyncState::SYNC_IN_PROGRESS;
-  } else if (strategy_ == Strategy::AGGRESSIVE_RECOVERY) {
-    PA_LOG(INFO) << "Timer fired for aggressive recovery, making request...";
-    sync_state_ = SyncState::SYNC_IN_PROGRESS;
-  } else {
-    NOTREACHED();
-    return;
-  }
-
-  delegate_->OnSyncRequested(
-      make_scoped_ptr(new SyncRequest(weak_ptr_factory_.GetWeakPtr())));
-}
-
-scoped_ptr<base::Timer> SyncSchedulerImpl::CreateTimer() {
-  bool retain_user_task = false;
-  bool is_repeating = false;
-  return make_scoped_ptr(new base::Timer(retain_user_task, is_repeating));
-}
-
-void SyncSchedulerImpl::ScheduleNextSync(const base::TimeDelta& sync_delta) {
-  if (sync_state_ != SyncState::WAITING_FOR_REFRESH) {
-    PA_LOG(ERROR) << "Unexpected state when scheduling next sync: sync_state="
-                  << static_cast<int>(sync_state_);
-    return;
-  }
-
-  bool is_aggressive_recovery = (strategy_ == Strategy::AGGRESSIVE_RECOVERY);
-  PA_LOG(INFO) << "Scheduling next sync for " << scheduler_name_ << ":\n"
-               << "    Strategy: " << (is_aggressive_recovery
-                                           ? "Aggressive Recovery"
-                                           : "Periodic Refresh") << "\n"
-               << "    Time Delta: " << TimeDeltaToString(sync_delta)
-               << (is_aggressive_recovery
-                       ? base::StringPrintf(
-                             "\n    Previous Failures: %d",
-                             base::saturated_cast<int>(failure_count_))
-                       : "");
-
-  timer_ = CreateTimer();
-  timer_->Start(FROM_HERE, sync_delta,
-                base::Bind(&SyncSchedulerImpl::OnTimerFired,
-                           weak_ptr_factory_.GetWeakPtr()));
-}
-
-void SyncSchedulerImpl::OnSyncCompleted(bool success) {
-  if (sync_state_ != SyncState::SYNC_IN_PROGRESS) {
-    PA_LOG(ERROR) << "Unexpected state when sync completed: sync_state="
-                  << static_cast<int>(sync_state_)
-                  << ", strategy_=" << static_cast<int>(strategy_);
-    return;
-  }
-  sync_state_ = SyncState::WAITING_FOR_REFRESH;
-
-  if (success) {
-    strategy_ = Strategy::PERIODIC_REFRESH;
-    failure_count_ = 0;
-  } else {
-    strategy_ = Strategy::AGGRESSIVE_RECOVERY;
-    ++failure_count_;
-  }
-
-  ScheduleNextSync(GetJitteredPeriod());
-}
-
-base::TimeDelta SyncSchedulerImpl::GetJitteredPeriod() {
-  double jitter = 2 * max_jitter_ratio_ * (base::RandDouble() - 0.5);
-  base::TimeDelta period = GetPeriod();
-  base::TimeDelta jittered_time_delta = period + (period * jitter);
-  if (jittered_time_delta.InMilliseconds() < 0)
-    jittered_time_delta = base::TimeDelta::FromMilliseconds(0);
-  return jittered_time_delta;
-}
-
-base::TimeDelta SyncSchedulerImpl::GetPeriod() {
-  if (strategy_ == Strategy::PERIODIC_REFRESH) {
-    return refresh_period_;
-  } else if (strategy_ == Strategy::AGGRESSIVE_RECOVERY && failure_count_ > 0) {
-    // The backoff for each consecutive failure is exponentially doubled until
-    // it is equal to the normal refresh period.
-    // Note: |backoff_factor| may evaulate to INF if |failure_count_| is large,
-    // but multiplication operations for TimeDelta objects are saturated.
-    double backoff_factor = pow(2, failure_count_ - 1);
-    base::TimeDelta backoff_period = base_recovery_period_ * backoff_factor;
-    return backoff_period < refresh_period_ ? backoff_period : refresh_period_;
-  } else {
-    PA_LOG(ERROR) << "Error getting period for strategy: "
-                  << static_cast<int>(strategy_);
-    return base::TimeDelta();
-  }
-}
-
-}  // namespace proximity_auth