sync: Gracefully handle very early shutdown

sync/engine/sync_scheduler_impl.cc

 // Copyright (c) 2012 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 "sync/engine/sync_scheduler_impl.h"
 
 #include <algorithm>
 #include <cstring>
 
 #include "base/auto_reset.h"
@@ skipping 155 matching lines @@
       mode_(NORMAL_MODE),
       delay_provider_(delay_provider),
       syncer_(syncer),
       session_context_(context),
       no_scheduling_allowed_(false),
       do_poll_after_credentials_updated_(false) {
 }
 
 SyncSchedulerImpl::~SyncSchedulerImpl() {
   DCHECK(CalledOnValidThread());
-  StopImpl();
+  Stop();
 }
 
 void SyncSchedulerImpl::OnCredentialsUpdated() {
   DCHECK(CalledOnValidThread());
 
   if (HttpResponse::SYNC_AUTH_ERROR ==
       session_context_->connection_manager()->server_status()) {
     OnServerConnectionErrorFixed();
   }
 }
@@ skipping 450 matching lines @@
                    weak_ptr_factory_.GetWeakPtr()));
   } else {
     pending_wakeup_timer_.Start(
         FROM_HERE,
         wait_interval_->length,
         base::Bind(&SyncSchedulerImpl::ExponentialBackoffRetry,
                    weak_ptr_factory_.GetWeakPtr()));
   }
 }
 
-void SyncSchedulerImpl::RequestStop() {
-  syncer_->RequestEarlyExit();  // Safe to call from any thread.
-  DCHECK(weak_handle_this_.IsInitialized());
-  SDVLOG(3) << "Posting StopImpl";
-  weak_handle_this_.Call(FROM_HERE,
-                         &SyncSchedulerImpl::StopImpl);
-}
-
-void SyncSchedulerImpl::StopImpl() {
+void SyncSchedulerImpl::Stop() {
   DCHECK(CalledOnValidThread());
-  SDVLOG(2) << "StopImpl called";
+  SDVLOG(2) << "Stop called";
 
   // Kill any in-flight method calls.
   weak_ptr_factory_.InvalidateWeakPtrs();
   wait_interval_.reset();
   NotifyRetryTime(base::Time());
   poll_timer_.Stop();
   pending_wakeup_timer_.Stop();
   pending_configure_params_.reset();
   if (started_)
     started_ = false;
@@ skipping 187 matching lines @@
 void SyncSchedulerImpl::OnReceivedClientInvalidationHintBufferSize(int size) {
   if (size > 0)
     nudge_tracker_.SetHintBufferSize(size);
   else
     NOTREACHED() << "Hint buffer size should be > 0.";
 }
 
 void SyncSchedulerImpl::OnShouldStopSyncingPermanently() {
   DCHECK(CalledOnValidThread());
   SDVLOG(2) << "OnShouldStopSyncingPermanently";
-  syncer_->RequestEarlyExit();  // Thread-safe.
+  Stop();
   Notify(SyncEngineEvent::STOP_SYNCING_PERMANENTLY);
 }
 
 void SyncSchedulerImpl::OnActionableError(
     const sessions::SyncSessionSnapshot& snap) {
   DCHECK(CalledOnValidThread());
   SDVLOG(2) << "OnActionableError";
   SyncEngineEvent event(SyncEngineEvent::ACTIONABLE_ERROR);
   event.snapshot = snap;
   session_context_->NotifyListeners(event);
 }
 
 void SyncSchedulerImpl::OnSyncProtocolError(
     const sessions::SyncSessionSnapshot& snapshot) {
   DCHECK(CalledOnValidThread());
   if (ShouldRequestEarlyExit(
           snapshot.model_neutral_state().sync_protocol_error)) {
     SDVLOG(2) << "Sync Scheduler requesting early exit.";
-    syncer_->RequestEarlyExit();  // Thread-safe.
+    Stop();
   }
   if (IsActionableError(snapshot.model_neutral_state().sync_protocol_error))
     OnActionableError(snapshot);
 }
 
 void SyncSchedulerImpl::SetNotificationsEnabled(bool notifications_enabled) {
   DCHECK(CalledOnValidThread());
   session_context_->set_notifications_enabled(notifications_enabled);
   if (notifications_enabled)
     nudge_tracker_.OnInvalidationsEnabled();
   else
     nudge_tracker_.OnInvalidationsDisabled();
 }
 
 base::TimeDelta SyncSchedulerImpl::GetSessionsCommitDelay() const {
   DCHECK(CalledOnValidThread());
   return sessions_commit_delay_;
 }
 
 #undef SDVLOG_LOC
 
 #undef SDVLOG
 
 #undef SLOG
 
 #undef ENUM_CASE
 
 }  // namespace syncer