Add Store+Sync to reading list.

ios/chrome/browser/reading_list/reading_list_store.cc

+// Copyright 2016 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 "ios/chrome/browser/reading_list/reading_list_store.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "components/sync/model/entity_change.h"
+#include "components/sync/model/metadata_batch.h"
+#include "components/sync/model/metadata_change_list.h"
+#include "components/sync/model/model_type_change_processor.h"
+#include "components/sync/model/mutable_data_batch.h"
+#include "components/sync/model/simple_metadata_change_list.h"
+#include "components/sync/protocol/model_type_state.pb.h"
+#include "ios/chrome/browser/reading_list/proto/reading_list.pb.h"
+#include "ios/chrome/browser/reading_list/reading_list_model_impl.h"
+#include "ios/web/public/web_thread.h"
+
+ReadingListStore::ReadingListStore(std::unique_ptr<ReadingListDB> database,
+                                   const base::FilePath& database_dir,
+                                   StoreFactoryFunction create_store_callback)
+    : ModelTypeService(base::Bind(&syncer::ModelTypeChangeProcessor::Create),
+                       syncer::READING_LIST),
+      database_loaded_(false),
+      create_store_callback_(create_store_callback),
+      pending_transaction_(0) {}
+
+ReadingListStore::~ReadingListStore() {
+  DCHECK(pending_transaction_ == 0);
+}
+
+void ReadingListStore::SetReadingListModel(ReadingListModelImpl* model) {
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  model_ = model;
+  create_store_callback_.Run(
+      base::Bind(&ReadingListStore::OnStoreCreated, base::AsWeakPtr(this)));
+}
+
+void ReadingListStore::BeginTransaction() {
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  pending_transaction_++;
+  if (pending_transaction_ == 1) {
+    batch_ = store_->CreateWriteBatch();
+  }
+}
+
+void ReadingListStore::CommitTransaction() {
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  pending_transaction_--;
+  if (pending_transaction_ == 0) {
+    store_->CommitWriteBatch(
+        std::move(batch_),
+        base::Bind(&ReadingListStore::OnDatabaseSave, base::AsWeakPtr(this)));
+    batch_.reset();
+  }
+}
+
+void ReadingListStore::SaveEntry(const ReadingListEntry& entry,
+                                 bool read,
+                                 bool from_sync) {
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  BeginTransaction();

[skym, 2016/11/01 18:27:26]

Aaah, I finally understand why you have multiple transactions, you want to
ensure that you always have a batch_ object when you need it. I kinda wish there
was a more elegant solution out there but it seems fine to me as is.

+
+  std::unique_ptr<reading_list::ReadingListLocal> pb_entry =
+      entry.AsReadingListLocal(read);
+  std::unique_ptr<sync_pb::ReadingListSpecifics> pb_entry_sync =

[skym, 2016/11/01 18:27:26]

I'd personally move this down to below the if(..) {.. return; } block.

[Olivier, 2016/11/02 14:57:11]

Done.

+      entry.AsReadingListSpecifics(read);
+  // Unref the URL before making asynchronous call.

[skym, 2016/11/01 18:27:26]

Is this really needed? I'm having a difficult time understanding why this would
be necessary.

[Olivier, 2016/11/02 14:57:11]

This was part of a fix that revealed to be unrelated. Removed.

+  std::string local_key = entry.URL().spec();
+
+  store_->WriteData(batch_.get(), local_key, pb_entry->SerializeAsString());
+
+  if (!change_processor() || from_sync) {
+    CommitTransaction();
+    return;
+  }
+
+  std::unique_ptr<syncer::MetadataChangeList> metadata_change_list =
+      CreateMetadataChangeList();
+
+  std::unique_ptr<syncer::EntityData> entity_data(new syncer::EntityData());
+  *entity_data->specifics.mutable_reading_list() = *pb_entry_sync;
+  entity_data->non_unique_name = pb_entry_sync->entry_id();
+
+  change_processor()->Put(entry.URL().spec(), std::move(entity_data),
+                          metadata_change_list.get());

[skym, 2016/11/01 18:27:26]

Max/Pavel, this use case of MetadataChangeList could use a pass through
implementation instead of one that holds things in memory! Would remove the
creation and transfer lines in any situation where we have known store_ and
batch_ objects. DeviceInfo has this use case as well.

+
+  static_cast<syncer::SimpleMetadataChangeList*>(metadata_change_list.get())
+      ->TransferChanges(store_.get(), batch_.get());
+  CommitTransaction();
+}
+
+void ReadingListStore::RemoveEntry(const ReadingListEntry& entry,
+                                   bool from_sync) {
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  BeginTransaction();
+  std::string local_key = entry.URL().spec();

[skym, 2016/11/01 18:27:26]

Same as above.

[Olivier, 2016/11/02 14:57:11]

Done.

+  store_->DeleteData(batch_.get(), local_key);
+  if (!change_processor() || from_sync) {
+    CommitTransaction();
+    return;
+  }
+  std::unique_ptr<syncer::MetadataChangeList> metadata_change_list =
+      CreateMetadataChangeList();
+
+  change_processor()->Delete(local_key, metadata_change_list.get());
+  static_cast<syncer::SimpleMetadataChangeList*>(metadata_change_list.get())
+      ->TransferChanges(store_.get(), batch_.get());
+
+  CommitTransaction();
+}
+
+void ReadingListStore::OnDatabaseLoad(
+    syncer::ModelTypeStore::Result result,
+    std::unique_ptr<syncer::ModelTypeStore::RecordList> entries) {
+  DCHECK_CURRENTLY_ON(web::WebThread::UI);
+  if (result != syncer::ModelTypeStore::Result::SUCCESS) {
+    return;
+  }
+  database_loaded_ = true;
+  auto read = base::MakeUnique<ReadingListEntries>();
+  auto unread = base::MakeUnique<ReadingListEntries>();
+
+  for (const syncer::ModelTypeStore::Record& r : *entries.get()) {
+    // for (const reading_list::ReadingListLocal& pb_entry : *entries) {
+    std::unique_ptr<reading_list::ReadingListLocal> proto =
+        base::MakeUnique<reading_list::ReadingListLocal>();
+    if (!proto->ParseFromString(r.value)) {
+      continue;
+      // TODO(skym, crbug.com/582460): Handle unrecoverable initialization
+      // failure.
+    }
+
+    std::unique_ptr<ReadingListEntry> entry(
+        ReadingListEntry::FromReadingListLocal(*proto));
+    if (!entry) {
+      continue;
+    }
+    if (proto->status() == reading_list::ReadingListLocal::READ) {
+      read->push_back(std::move(*entry));
+    } else {
+      unread->push_back(std::move(*entry));
+    }
+  }
+
+  model_->ModelLoaded(std::move(unread), std::move(read));
+
+  store_->ReadAllMetadata(
+      base::Bind(&ReadingListStore::OnReadAllMetadata, base::AsWeakPtr(this)));
+}
+
+void ReadingListStore::OnReadAllMetadata(
+    syncer::ModelTypeStore::Result result,
+    std::unique_ptr<syncer::ModelTypeStore::RecordList> metadata_records,
+    const std::string& global_metadata) {
+  if (result != syncer::ModelTypeStore::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.
+    return;
+  }
+
+  std::unique_ptr<syncer::MetadataBatch> batch(new syncer::MetadataBatch());
+  sync_pb::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
+    // belong in this service?
+    change_processor()->OnMetadataLoaded(
+        change_processor()->CreateAndUploadError(
+            FROM_HERE, "Failed to deserialize global metadata."),
+        nullptr);
+  }
+  for (const syncer::ModelTypeStore::Record& r : *metadata_records.get()) {
+    sync_pb::EntityMetadata entity_metadata;
+    if (entity_metadata.ParseFromString(r.value)) {
+      batch->AddMetadata(r.id, entity_metadata);
+    } else {
+      // TODO(skym): This really isn't too bad. We just want to regenerate
+      // metadata for this particular entity. Unfortunately there isn't a
+      // convenient way to tell the processor to do this.
+      LOG(WARNING) << "Failed to deserialize entity metadata.";
+    }
+  }
+  change_processor()->OnMetadataLoaded(syncer::SyncError(), std::move(batch));
+}
+
+void ReadingListStore::OnDatabaseSave(syncer::ModelTypeStore::Result result) {
+  return;
+}
+
+void ReadingListStore::OnStoreCreated(
+    syncer::ModelTypeStore::Result result,
+    std::unique_ptr<syncer::ModelTypeStore> store) {
+  store_ = std::move(store);
+  store_->ReadAllData(
+      base::Bind(&ReadingListStore::OnDatabaseLoad, base::AsWeakPtr(this)));
+  return;
+}
+
+syncer::ModelTypeService* ReadingListStore::GetModelTypeService() {
+  return this;
+}
+
+// Creates an object used to communicate changes in the sync metadata to the
+// model type store.
+std::unique_ptr<syncer::MetadataChangeList>
+ReadingListStore::CreateMetadataChangeList() {
+  return base::MakeUnique<syncer::SimpleMetadataChangeList>();
+}
+
+// Perform the initial merge between local and sync data. This should only be
+// called when a data type is first enabled to start syncing, and there is no
+// sync metadata. Best effort should be made to match local and sync data. The
+// keys in the |entity_data_map| will have been created via GetClientTag(...),
+// and if a local and sync data should match/merge but disagree on tags, the
+// service should use the sync data's tag. Any local pieces of data that are
+// not present in sync should immediately be Put(...) to the processor before
+// returning. The same MetadataChangeList that was passed into this function
+// can be passed to Put(...) calls. Delete(...) can also be called but should
+// not be needed for most model types. Durable storage writes, if not able to
+// combine all change atomically, should save the metadata after the data
+// changes, so that this merge will be re-driven by sync if is not completely
+// saved during the current run.
+syncer::SyncError ReadingListStore::MergeSyncData(
+    std::unique_ptr<syncer::MetadataChangeList> metadata_change_list,
+    syncer::EntityDataMap entity_data_map) {
+  // Keep track of the last update of each item.
+  std::map<GURL, int64_t> last_update;
+  std::unique_ptr<ReadingListModel::ScopedReadingListBatchUpdate> batch =
+      model_->BeginBatchUpdates();
+
+  // Merge sync to local data.
+  for (const auto& kv : entity_data_map) {
+    const sync_pb::ReadingListSpecifics& specifics =
+        kv.second.value().specifics.reading_list();
+    std::unique_ptr<ReadingListEntry> entry(
+        ReadingListEntry::FromReadingListSpecifics(specifics));
+    DCHECK(entry->URL().spec() == kv.first);
+    DCHECK(specifics.entry_id() == kv.first);
+    last_update[entry->URL()] = entry->UpdateTime();
+    // This method will update the model and the local store.
+    model_->SyncAddEntry(
+        std::move(entry),
+        specifics.status() == sync_pb::ReadingListSpecifics::READ);
+  }
+
+  int unread_count = model_->unread_size();
+  int read_count = model_->read_size();
+  for (int index = 0; index < unread_count + read_count; index++) {

[skym, 2016/11/01 18:27:26]

This is a lot of complexity to just iterate over all the entries model_ is
hanging onto. Though I don't have a better solution. :/

+    bool read = index >= unread_count;
+    const ReadingListEntry& entry =
+        read ? model_->GetReadEntryAtIndex(index - unread_count)
+             : model_->GetUnreadEntryAtIndex(index);
+    if (last_update.count(entry.URL()) &&
+        last_update[entry.URL()] >= entry.UpdateTime()) {
+      // The synced entry is up to date.
+      continue;
+    }
+    std::unique_ptr<sync_pb::ReadingListSpecifics> entry_pb =
+        entry.AsReadingListSpecifics(read);
+
+    std::unique_ptr<syncer::EntityData> entity_data(new syncer::EntityData());

[skym, 2016/11/01 18:27:26]

auto and base::MakeUnique?

[Olivier, 2016/11/02 14:57:11]

Done.

+    *(entity_data->specifics.mutable_reading_list()) = *entry_pb;
+    entity_data->non_unique_name = entry_pb->entry_id();
+
+    static_cast<syncer::SimpleMetadataChangeList*>(metadata_change_list.get())
+        ->TransferChanges(store_.get(), batch_.get());
+    change_processor()->Put(entry_pb->entry_id(), std::move(entity_data),
+                            metadata_change_list.get());
+  }
+  return syncer::SyncError();
+}
+
+// Apply changes from the sync server locally.
+// Please note that |entity_changes| might have fewer entries than
+// |metadata_change_list| in case when some of the data changes are filtered
+// out, or even be empty in case when a commit confirmation is processed and
+// only the metadata needs to persisted.
+syncer::SyncError ReadingListStore::ApplySyncChanges(
+    std::unique_ptr<syncer::MetadataChangeList> metadata_change_list,
+    syncer::EntityChangeList entity_changes) {
+  std::unique_ptr<ReadingListModel::ScopedReadingListBatchUpdate> batch =
+      model_->BeginBatchUpdates();
+  for (syncer::EntityChange& change : entity_changes) {
+    const sync_pb::ReadingListSpecifics& specifics =
+        change.data().specifics.reading_list();
+    if (change.type() == syncer::EntityChange::ACTION_DELETE) {
+      model_->SyncRemoveEntry(GURL(specifics.url()));
+      continue;
+    }
+
+    std::unique_ptr<ReadingListEntry> entry(
+        ReadingListEntry::FromReadingListSpecifics(specifics));
+    model_->SyncAddEntry(
+        std::move(entry),
+        specifics.status() == sync_pb::ReadingListSpecifics::READ);
+  }

[pavely, 2016/11/01 06:14:10]

metadata_change_list contains metadata updates and progress marker corresponding
to updates in entity_changes. This function should transfer them to batch_ and
commit all changes as part of the same transaction.

The same is true for MergeSyncData (see Sky's comments).

[Olivier, 2016/11/02 14:57:11]

Done.

+  return syncer::SyncError();
+}
+
+// Asynchronously retrieve the corresponding sync data for |storage_keys|.

[skym, 2016/11/01 18:27:26]

This implementation is not async.

[Olivier, 2016/11/02 14:57:11]

Done.

+void ReadingListStore::GetData(StorageKeyList storage_keys,
+                               DataCallback callback) {
+  auto batch = base::MakeUnique<syncer::MutableDataBatch>();
+  for (std::string url_string : storage_keys) {
+    auto add_to_batch_callback =
+        base::Bind(&ReadingListStore::AddEntryToBatch, base::Unretained(this),
+                   batch.get());
+    model_->CallbackEntryReadStatusURL(GURL(url_string), add_to_batch_callback);
+  }
+
+  callback.Run(syncer::SyncError(), std::move(batch));
+}
+
+// Asynchronously retrieve all of the local sync data.

[skym, 2016/11/01 18:27:26]

This implementation is not async.

[Olivier, 2016/11/02 14:57:10]

Done.

+void ReadingListStore::GetAllData(DataCallback callback) {
+  auto batch = base::MakeUnique<syncer::MutableDataBatch>();
+  int unread_count = model_->unread_size();
+  int read_count = model_->read_size();
+  for (int index = 0; index < unread_count + read_count; index++) {

[skym, 2016/11/01 18:27:26]

I feel like I've seen this logic before! :)

+    bool read = index >= unread_count;
+    const ReadingListEntry& entry =
+        read ? model_->GetReadEntryAtIndex(index - unread_count)
+             : model_->GetUnreadEntryAtIndex(index);
+    AddEntryToBatch(batch.get(), entry, read);
+  }
+
+  callback.Run(syncer::SyncError(), std::move(batch));
+}
+
+void ReadingListStore::AddEntryToBatch(syncer::MutableDataBatch* batch,
+                                       const ReadingListEntry& entry,
+                                       bool read) {
+  std::unique_ptr<sync_pb::ReadingListSpecifics> entry_pb =
+      entry.AsReadingListSpecifics(read);
+
+  std::unique_ptr<syncer::EntityData> entity_data(new syncer::EntityData());
+  *(entity_data->specifics.mutable_reading_list()) = *entry_pb;
+  entity_data->non_unique_name = entry_pb->entry_id();
+
+  batch->Put(entry_pb->entry_id(), std::move(entity_data));
+}
+
+// Get or generate a client tag for |entity_data|. This must be the same tag
+// that was/would have been generated in the SyncableService/Directory world
+// for backward compatibility with pre-USS clients. The only time this
+// theoretically needs to be called is on the creation of local data, however
+// it is also used to verify the hash of remote data. If a data type was never
+// launched pre-USS, then method does not need to be different from
+// GetStorageKey().
+std::string ReadingListStore::GetClientTag(
+    const syncer::EntityData& entity_data) {
+  return entity_data.specifics.reading_list().entry_id();
+}
+
+// Get or generate a storage key for |entity_data|. This will only ever be
+// called once when first encountering a remote entity. Local changes will
+// provide their storage keys directly to Put instead of using this method.
+// Theoretically this function doesn't need to be stable across multiple calls
+// on the same or different clients, but to keep things simple, it probably
+// should be.
+std::string ReadingListStore::GetStorageKey(
+    const syncer::EntityData& entity_data) {
+  return entity_data.specifics.reading_list().entry_id();
+}