[Sync] Services can now always assume processor exists.

components/sync/device_info/device_info_service.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/sync/device_info/device_info_service.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 49 matching lines @@
 
 std::unique_ptr<MetadataChangeList>
 DeviceInfoService::CreateMetadataChangeList() {
   return base::MakeUnique<SimpleMetadataChangeList>();
 }
 
 SyncError DeviceInfoService::MergeSyncData(
     std::unique_ptr<MetadataChangeList> metadata_change_list,
     EntityDataMap entity_data_map) {
   DCHECK(has_provider_initialized_);
-  DCHECK(has_metadata_loaded_);
-  DCHECK(change_processor());
+  DCHECK(change_processor()->IsTrackingMetadata());
 
   // Local data should typically be near empty, with the only possible value
   // corresponding to this device. This is because on signout all device info
   // data is blown away. However, this simplification is being ignored here and
   // a full difference is going to be calculated to explore what other service
   // implementations may look like.
   std::set<std::string> local_guids_to_put;
   for (const auto& kv : all_data_) {
     local_guids_to_put.insert(kv.first);
   }
@@ skipping 33 matching lines @@
 
   CommitAndNotify(std::move(batch), std::move(metadata_change_list),
                   has_changes);
   return SyncError();
 }
 
 SyncError DeviceInfoService::ApplySyncChanges(
     std::unique_ptr<MetadataChangeList> metadata_change_list,
     EntityChangeList entity_changes) {
   DCHECK(has_provider_initialized_);
-  DCHECK(has_metadata_loaded_);
 
   std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();
   bool has_changes = false;
   for (EntityChange& change : entity_changes) {
     const std::string guid = change.storage_key();
     // Each device is the authoritative source for itself, ignore any remote
     // changes that have our local cache guid.
     if (guid == local_device_info_provider_->GetLocalDeviceInfo()->guid()) {
       continue;
     }
@@ skipping 10 matching lines @@
     }
   }
 
   CommitAndNotify(std::move(batch), std::move(metadata_change_list),
                   has_changes);
   return SyncError();
 }
 
 void DeviceInfoService::GetData(StorageKeyList storage_keys,
                                 DataCallback callback) {
-  DCHECK(has_metadata_loaded_);
-
   std::unique_ptr<DataBatchImpl> batch(new DataBatchImpl());
   for (const auto& key : storage_keys) {
     const auto& iter = all_data_.find(key);
     if (iter != all_data_.end()) {
       DCHECK_EQ(key, iter->second->cache_guid());
       batch->Put(key, CopyToEntityData(*iter->second));
     }
   }
-
   callback.Run(SyncError(), std::move(batch));
 }
 
 void DeviceInfoService::GetAllData(DataCallback callback) {
-  DCHECK(has_metadata_loaded_);
-
   std::unique_ptr<DataBatchImpl> batch(new DataBatchImpl());
   for (const auto& kv : all_data_) {
     batch->Put(kv.first, CopyToEntityData(*kv.second));
   }
-
   callback.Run(SyncError(), std::move(batch));
 }
 
 std::string DeviceInfoService::GetClientTag(const EntityData& entity_data) {
   DCHECK(entity_data.specifics.has_device_info());
   return DeviceInfoUtil::SpecificsToTag(entity_data.specifics.device_info());
 }
 
 std::string DeviceInfoService::GetStorageKey(const EntityData& entity_data) {
   DCHECK(entity_data.specifics.has_device_info());
   return entity_data.specifics.device_info().cache_guid();
 }
 
-void DeviceInfoService::OnChangeProcessorSet() {
-  // We've recieved a new processor that needs metadata. If we're still in the
-  // process of loading data and/or metadata, then |has_metadata_loaded_| is
-  // false and we'll wait for those async reads to happen. If we've already
-  // loaded metadata and then subsequently we get a new processor, we must not
-  // have created the processor ourselves because we had no metadata. So there
-  // must not be any metadata on disk.
-  if (has_metadata_loaded_) {
-    change_processor()->OnMetadataLoaded(SyncError(),
-                                         base::MakeUnique<MetadataBatch>());
-    ReconcileLocalAndStored();
-  }
-}
-
 bool DeviceInfoService::IsSyncing() const {
   return !all_data_.empty();
 }
 
 std::unique_ptr<DeviceInfo> DeviceInfoService::GetDeviceInfo(
     const std::string& client_id) const {
   const ClientIdToSpecifics::const_iterator iter = all_data_.find(client_id);
   if (iter == all_data_.end()) {
     return std::unique_ptr<DeviceInfo>();
   }
-
   return CopyToModel(*iter->second);
 }
 
 std::vector<std::unique_ptr<DeviceInfo>> DeviceInfoService::GetAllDeviceInfo()
     const {
   std::vector<std::unique_ptr<DeviceInfo>> list;
-
   for (ClientIdToSpecifics::const_iterator iter = all_data_.begin();
        iter != all_data_.end(); ++iter) {
     list.push_back(CopyToModel(*iter->second));
   }
-
   return list;
 }
 
 void DeviceInfoService::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }
 
 void DeviceInfoService::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
@@ skipping 109 matching lines @@
   if (has_data_loaded_ && has_provider_initialized_) {
     store_->ReadAllMetadata(base::Bind(&DeviceInfoService::OnReadAllMetadata,
                                        base::AsWeakPtr(this)));
   }
 }
 
 void DeviceInfoService::OnReadAllMetadata(
     Result result,
     std::unique_ptr<RecordList> metadata_records,
     const std::string& global_metadata) {
-  DCHECK(!has_metadata_loaded_);
-
   if (result != Result::SUCCESS) {
     // Store has encountered some serious error. We should still be able to
     // continue as a read only service, since if we got this far we must have
     // loaded all data out succesfully.
     ReportStartupErrorToSync("Load of metadata completely failed.");
     return;
   }
 
-  // If we have no metadata then we don't want to create a processor. The idea
-  // is that by not having a processor, the services will suffer less of a
-  // performance hit. This isn't terribly applicable for this model type, but
-  // we want this class to be as similar to other services as possible so follow
-  // the convention.
-  if (metadata_records->size() > 0 || !global_metadata.empty()) {
-    CreateChangeProcessor();
-  }
-
-  // Set this after OnChangeProcessorSet so that we can correctly avoid giving
-  // the processor empty metadata. We always want to set |has_metadata_loaded_|
-  // at this point so that we'll know to give a processor empty metadata if it
-  // is created later.
-  has_metadata_loaded_ = true;
-
-  if (!change_processor()) {
-    // This means we haven't been told to start syncing and we don't have any
-    // local metadata.
-    return;
-  }
-
   std::unique_ptr<MetadataBatch> batch(new MetadataBatch());
   ModelTypeState state;
   if (state.ParseFromString(global_metadata)) {
     batch->SetModelTypeState(state);
   } else {
     // TODO(skym): How bad is this scenario? We may be able to just give an
     // empty batch to the processor and we'll treat corrupted data type state
     // as no data type state at all. The question is do we want to add any of
     // the entity metadata to the batch or completely skip that step? We're
     // going to have to perform a merge shortly. Does this decision/logic even
@@ skipping 25 matching lines @@
 }
 
 void DeviceInfoService::ReconcileLocalAndStored() {
   // On initial syncing we will have a change processor here, but it will not be
   // tracking changes. We need to persist a copy of our local device info to
   // disk, but the Put call to the processor will be ignored. That should be
   // fine however, as the discrepancy will be picked up later in merge. We don't
   // bother trying to track this case and act intelligently because simply not
   // much of a benefit in doing so.
   DCHECK(has_provider_initialized_);
-  DCHECK(has_metadata_loaded_);
-  DCHECK(change_processor());
+
   const DeviceInfo* current_info =
       local_device_info_provider_->GetLocalDeviceInfo();
   auto iter = all_data_.find(current_info->guid());
 
   // Convert to DeviceInfo for Equals function.
   if (iter != all_data_.end() &&
       current_info->Equals(*CopyToModel(*iter->second))) {
     const TimeDelta pulse_delay(DeviceInfoUtil::CalculatePulseDelay(
         GetLastUpdateTime(*iter->second), Time::Now()));
     if (!pulse_delay.is_zero()) {
       pulse_timer_.Start(FROM_HERE, pulse_delay,
                          base::Bind(&DeviceInfoService::SendLocalData,
                                     base::Unretained(this)));
       return;
     }
   }
   SendLocalData();
 }
 
 void DeviceInfoService::SendLocalData() {
   DCHECK(has_provider_initialized_);
-  // TODO(skym): Handle disconnecting and reconnecting, this will currently halt
-  // the pulse timer and never restart it.
-  if (!change_processor()) {
-    return;
-  }
 
   std::unique_ptr<DeviceInfoSpecifics> specifics =
       CopyToSpecifics(*local_device_info_provider_->GetLocalDeviceInfo());
   specifics->set_last_updated_timestamp(TimeToProtoTime(Time::Now()));
 
   std::unique_ptr<MetadataChangeList> metadata_change_list =
       CreateMetadataChangeList();
-  change_processor()->Put(specifics->cache_guid(), CopyToEntityData(*specifics),
-                          metadata_change_list.get());
+  if (change_processor()->IsTrackingMetadata()) {
+    change_processor()->Put(specifics->cache_guid(),
+                            CopyToEntityData(*specifics),
+                            metadata_change_list.get());
+  }
 
   std::unique_ptr<WriteBatch> batch = store_->CreateWriteBatch();
   StoreSpecifics(std::move(specifics), batch.get());
 
   CommitAndNotify(std::move(batch), std::move(metadata_change_list), true);
   pulse_timer_.Start(
       FROM_HERE, DeviceInfoUtil::kPulseInterval,
       base::Bind(&DeviceInfoService::SendLocalData, base::Unretained(this)));
 }
 
@@ skipping 13 matching lines @@
 
 int DeviceInfoService::CountActiveDevices(const Time now) const {
   return std::count_if(all_data_.begin(), all_data_.end(),
                        [now](ClientIdToSpecifics::const_reference pair) {
                          return DeviceInfoUtil::IsActive(
                              GetLastUpdateTime(*pair.second), now);
                        });
 }
 
 void DeviceInfoService::ReportStartupErrorToSync(const std::string& msg) {
-  DCHECK(!has_metadata_loaded_);
+  // TODO(skym): Shouldn't need to log this here, reporting should always log.
   LOG(WARNING) << msg;
-
-  // Create a processor and give it the error in case sync tries to start.
-  if (!change_processor()) {
-    CreateChangeProcessor();
-  }
   change_processor()->OnMetadataLoaded(
       change_processor()->CreateAndUploadError(FROM_HERE, msg), nullptr);
 }
 
 // static
 Time DeviceInfoService::GetLastUpdateTime(
     const DeviceInfoSpecifics& specifics) {
   if (specifics.has_last_updated_timestamp()) {
     return ProtoTimeToTime(specifics.last_updated_timestamp());
   } else {
     return Time();
   }
 }
 
 }  // namespace syncer