Add Store+Sync to reading list.

ios/chrome/browser/reading_list/reading_list_store.cc

Index: ios/chrome/browser/reading_list/reading_list_store.cc
diff --git a/ios/chrome/browser/reading_list/reading_list_store.cc b/ios/chrome/browser/reading_list/reading_list_store.cc
new file mode 100644
index 0000000000000000000000000000000000000000..410b984709c710536fd4ca22c38b75aa554a64d3
--- /dev/null
+++ b/ios/chrome/browser/reading_list/reading_list_store.cc
@@ -0,0 +1,457 @@
+// 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/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_impl/accumulating_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(
+    StoreFactoryFunction create_store_callback,
+    const ChangeProcessorFactory& change_processor_factory)
+    : ModelTypeSyncBridge(change_processor_factory, syncer::READING_LIST),
+      create_store_callback_(create_store_callback),
+      pending_transaction_count_(0) {}
+
+ReadingListStore::~ReadingListStore() {
+  DCHECK(pending_transaction_count_ == 0);
+}
+
+void ReadingListStore::SetReadingListModel(ReadingListModel* model,
+                                           ReadingListStoreDelegate* delegate) {
+  DCHECK(CalledOnValidThread());
+  model_ = model;
+  delegate_ = delegate;
+  create_store_callback_.Run(
+      base::Bind(&ReadingListStore::OnStoreCreated, base::AsWeakPtr(this)));
+}
+
+std::unique_ptr<ReadingListModelStorage::ScopedBatchUpdate>
+ReadingListStore::EnsureBatchCreated() {
+  return base::WrapUnique<ReadingListModelStorage::ScopedBatchUpdate>(
+      new ScopedBatchUpdate(this));
+}
+
+ReadingListStore::ScopedBatchUpdate::ScopedBatchUpdate(ReadingListStore* store)
+    : store_(store) {
+  store_->BeginTransaction();
+}
+
+ReadingListStore::ScopedBatchUpdate::~ScopedBatchUpdate() {
+  store_->CommitTransaction();
+}
+
+void ReadingListStore::BeginTransaction() {
+  DCHECK(CalledOnValidThread());
+  pending_transaction_count_++;
+  if (pending_transaction_count_ == 1) {
+    batch_ = store_->CreateWriteBatch();
+  }
+}
+
+void ReadingListStore::CommitTransaction() {
+  DCHECK(CalledOnValidThread());
+  pending_transaction_count_--;
+  if (pending_transaction_count_ == 0) {
+    store_->CommitWriteBatch(
+        std::move(batch_),
+        base::Bind(&ReadingListStore::OnDatabaseSave, base::AsWeakPtr(this)));
+    batch_.reset();
+  }
+}
+
+void ReadingListStore::SaveEntry(const ReadingListEntry& entry, bool read) {
+  DCHECK(CalledOnValidThread());
+  auto token = EnsureBatchCreated();
+
+  std::unique_ptr<reading_list::ReadingListLocal> pb_entry =
+      entry.AsReadingListLocal(read);
+
+  batch_->WriteData(entry.URL().spec(), pb_entry->SerializeAsString());
+
+  if (!change_processor()->IsTrackingMetadata()) {
+    return;
+  }
+  std::unique_ptr<sync_pb::ReadingListSpecifics> pb_entry_sync =
+      entry.AsReadingListSpecifics(read);
+
+  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());
+  batch_->TransferMetadataChanges(std::move(metadata_change_list));
+}
+
+void ReadingListStore::RemoveEntry(const ReadingListEntry& entry) {
+  DCHECK(CalledOnValidThread());
+  auto token = EnsureBatchCreated();
+
+  batch_->DeleteData(entry.URL().spec());
+  if (!change_processor()->IsTrackingMetadata()) {
+    return;
+  }
+  std::unique_ptr<syncer::MetadataChangeList> metadata_change_list =
+      CreateMetadataChangeList();
+
+  change_processor()->Delete(entry.URL().spec(), metadata_change_list.get());
+  batch_->TransferMetadataChanges(std::move(metadata_change_list));
+}
+
+void ReadingListStore::OnDatabaseLoad(
+    syncer::ModelTypeStore::Result result,
+    std::unique_ptr<syncer::ModelTypeStore::RecordList> entries) {
+  DCHECK(CalledOnValidThread());
+  if (result != syncer::ModelTypeStore::Result::SUCCESS) {
+    change_processor()->OnMetadataLoaded(
+        change_processor()->CreateAndUploadError(
+            FROM_HERE, "Cannot load Reading List Database."),
+        nullptr);
+    return;
+  }
+  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) {
+    reading_list::ReadingListLocal proto;
+    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));
+    }
+  }
+
+  delegate_->StoreLoaded(std::move(unread), std::move(read));
+
+  store_->ReadAllMetadata(
+      base::Bind(&ReadingListStore::OnReadAllMetadata, base::AsWeakPtr(this)));
+}
+
+void ReadingListStore::OnReadAllMetadata(
+    syncer::SyncError sync_error,
+    std::unique_ptr<syncer::MetadataBatch> metadata_batch) {
+  DCHECK(CalledOnValidThread());
+  change_processor()->OnMetadataLoaded(sync_error, std::move(metadata_batch));
+}
+
+void ReadingListStore::OnDatabaseSave(syncer::ModelTypeStore::Result result) {
+  return;
+}
+
+void ReadingListStore::OnStoreCreated(
+    syncer::ModelTypeStore::Result result,
+    std::unique_ptr<syncer::ModelTypeStore> store) {
+  DCHECK(CalledOnValidThread());
+  if (result != syncer::ModelTypeStore::Result::SUCCESS) {
+    // TODO(crbug.com/664926): handle store creation error.
+    return;
+  }
+  store_ = std::move(store);
+  store_->ReadAllData(
+      base::Bind(&ReadingListStore::OnDatabaseLoad, base::AsWeakPtr(this)));
+  return;
+}
+
+syncer::ModelTypeSyncBridge* ReadingListStore::GetModelTypeSyncBridge() {
+  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 syncer::ModelTypeStore::WriteBatch::CreateMetadataChangeList();
+}
+
+// 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) {
+  DCHECK(CalledOnValidThread());
+  auto token = EnsureBatchCreated();
+  // Keep track of the last update of each item.
+  std::set<std::string> synced_entries;
+  std::unique_ptr<ReadingListModel::ScopedReadingListBatchUpdate>
+      model_batch_updates = model_->BeginBatchUpdates();
+
+  // Merge sync to local data.
+  for (const auto& kv : entity_data_map) {
+    synced_entries.insert(kv.first);
+    const sync_pb::ReadingListSpecifics& specifics =
+        kv.second.value().specifics.reading_list();
+    // Deserialize entry.
+    bool read = specifics.status() == sync_pb::ReadingListSpecifics::READ;
+    std::unique_ptr<ReadingListEntry> entry(
+        ReadingListEntry::FromReadingListSpecifics(specifics));
+
+    bool was_read;
+    const ReadingListEntry* existing_entry =
+        model_->GetEntryFromURL(entry->URL(), &was_read);
+
+    if (!existing_entry) {
+      // This entry is new. Add it to the store and model.
+      // Convert to local store format and write to store.
+      std::unique_ptr<reading_list::ReadingListLocal> entry_pb =
+          entry->AsReadingListLocal(read);
+      batch_->WriteData(entry->URL().spec(), entry_pb->SerializeAsString());
+
+      // Notify model about updated entry.
+      delegate_->SyncAddEntry(std::move(entry), read);
+    } else if (existing_entry->UpdateTime() < entry->UpdateTime()) {
+      // The entry from sync is more recent.
+      // Merge the local data to it and store it.
+      ReadingListEntry* merged_entry =
+          delegate_->SyncMergeEntry(std::move(entry), read);
+
+      // Write to the store.
+      std::unique_ptr<reading_list::ReadingListLocal> entry_local_pb =
+          merged_entry->AsReadingListLocal(read);
+      batch_->WriteData(entry->URL().spec(),
+                        entry_local_pb->SerializeAsString());
+
+      // Send to sync
+      std::unique_ptr<sync_pb::ReadingListSpecifics> entry_sync_pb =
+          merged_entry->AsReadingListSpecifics(read);
+      auto entity_data = base::MakeUnique<syncer::EntityData>();
+      *(entity_data->specifics.mutable_reading_list()) = *entry_sync_pb;
+      entity_data->non_unique_name = entry_sync_pb->entry_id();
+
+      change_processor()->Put(entry_sync_pb->entry_id(), std::move(entity_data),
+                              metadata_change_list.get());
+
+    } else {
+      // The entry from sync is out of date.
+      // Send back the local more recent entry.
+      // No need to update
+      std::unique_ptr<sync_pb::ReadingListSpecifics> entry_pb =
+          existing_entry->AsReadingListSpecifics(was_read);
+      auto entity_data = base::MakeUnique<syncer::EntityData>();
+      *(entity_data->specifics.mutable_reading_list()) = *entry_pb;
+      entity_data->non_unique_name = entry_pb->entry_id();
+
+      change_processor()->Put(entry_pb->entry_id(), std::move(entity_data),
+                              metadata_change_list.get());
+    }
+  }
+
+  // Commit local only entries to server.
+  int unread_count = model_->unread_size();
+  int read_count = model_->read_size();
+  for (int index = 0; index < unread_count + read_count; index++) {
+    bool read = index >= unread_count;
+    const ReadingListEntry& entry =
+        read ? model_->GetReadEntryAtIndex(index - unread_count)
+             : model_->GetUnreadEntryAtIndex(index);
+    if (synced_entries.count(entry.URL().spec())) {
+      // Entry already exists and has been merged above.
+      continue;
+    }
+
+    // Local entry has later timestamp. It should be committed to server.
+    std::unique_ptr<sync_pb::ReadingListSpecifics> entry_pb =
+        entry.AsReadingListSpecifics(read);
+
+    auto entity_data = base::MakeUnique<syncer::EntityData>();
+    *(entity_data->specifics.mutable_reading_list()) = *entry_pb;
+    entity_data->non_unique_name = entry_pb->entry_id();
+
+    change_processor()->Put(entry_pb->entry_id(), std::move(entity_data),
+                            metadata_change_list.get());
+  }
+  batch_->TransferMetadataChanges(std::move(metadata_change_list));
+
+  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) {
+  DCHECK(CalledOnValidThread());
+  std::unique_ptr<ReadingListModel::ScopedReadingListBatchUpdate> batch =
+      model_->BeginBatchUpdates();
+  auto token = EnsureBatchCreated();
+
+  for (syncer::EntityChange& change : entity_changes) {
+    if (change.type() == syncer::EntityChange::ACTION_DELETE) {
+      batch_->DeleteData(change.storage_key());
+      // Need to notify model that entry is deleted.
+      delegate_->SyncRemoveEntry(GURL(change.storage_key()));
+    } else {
+      // Deserialize entry.
+      const sync_pb::ReadingListSpecifics& specifics =
+          change.data().specifics.reading_list();
+      bool read = specifics.status() == sync_pb::ReadingListSpecifics::READ;
+      std::unique_ptr<ReadingListEntry> entry(
+          ReadingListEntry::FromReadingListSpecifics(specifics));
+
+      bool was_read;
+      const ReadingListEntry* existing_entry =
+          model_->GetEntryFromURL(entry->URL(), &was_read);
+
+      if (!existing_entry) {
+        // This entry is new. Add it to the store and model.
+        // Convert to local store format and write to store.
+        std::unique_ptr<reading_list::ReadingListLocal> entry_pb =
+            entry->AsReadingListLocal(read);
+        batch_->WriteData(entry->URL().spec(), entry_pb->SerializeAsString());
+
+        // Notify model about updated entry.
+        delegate_->SyncAddEntry(std::move(entry), read);
+      } else if (existing_entry->UpdateTime() < entry->UpdateTime()) {
+        // The entry from sync is more recent.
+        // Merge the local data to it and store it.
+        ReadingListEntry* merged_entry =
+            delegate_->SyncMergeEntry(std::move(entry), read);
+
+        // Write to the store.
+        std::unique_ptr<reading_list::ReadingListLocal> entry_local_pb =
+            merged_entry->AsReadingListLocal(read);
+        batch_->WriteData(merged_entry->URL().spec(),
+                          entry_local_pb->SerializeAsString());
+
+        // Send to sync
+        std::unique_ptr<sync_pb::ReadingListSpecifics> entry_sync_pb =
+            merged_entry->AsReadingListSpecifics(read);
+        auto entity_data = base::MakeUnique<syncer::EntityData>();
+        *(entity_data->specifics.mutable_reading_list()) = *entry_sync_pb;
+        entity_data->non_unique_name = entry_sync_pb->entry_id();
+
+        change_processor()->Put(entry_sync_pb->entry_id(),

[pavely, 2016/11/17 06:39:23]

Important consideration about passing accepted sync change back to
change_processor is to avoid ping-pong type scenarios:
1. Client A makes change
2. Client B receives it from server, accepts it, but passes it to
change_processor
3. This change gets committed to server and client A does the same thing
4. Repeat from step 2.

If the entry passed to change_processor is the same that was just received then
change_processor will notice that specifics hash didn't change and will not
schedule change for syncing, thus avoiding above situation.

[Olivier, 2016/11/17 08:54:34]

Added a todo

+                                std::move(entity_data),
+                                metadata_change_list.get());
+
+      } else {
+        // The entry from sync is out of date.
+        // Send back the local more recent entry.
+        // No need to update
+        std::unique_ptr<sync_pb::ReadingListSpecifics> entry_pb =
+            existing_entry->AsReadingListSpecifics(was_read);
+        auto entity_data = base::MakeUnique<syncer::EntityData>();
+        *(entity_data->specifics.mutable_reading_list()) = *entry_pb;
+        entity_data->non_unique_name = entry_pb->entry_id();
+
+        change_processor()->Put(entry_pb->entry_id(), std::move(entity_data),
+                                metadata_change_list.get());
+      }
+    }
+  }
+
+  batch_->TransferMetadataChanges(std::move(metadata_change_list));
+  return syncer::SyncError();
+}
+
+void ReadingListStore::GetData(StorageKeyList storage_keys,
+                               DataCallback callback) {
+  DCHECK(CalledOnValidThread());
+  auto batch = base::MakeUnique<syncer::MutableDataBatch>();
+  for (std::string url_string : storage_keys) {
+    bool read;
+    const ReadingListEntry* entry =
+        model_->GetEntryFromURL(GURL(url_string), &read);
+    if (entry) {
+      AddEntryToBatch(batch.get(), *entry, read);
+    }
+  }
+
+  callback.Run(syncer::SyncError(), std::move(batch));
+}
+
+void ReadingListStore::GetAllData(DataCallback callback) {
+  DCHECK(CalledOnValidThread());
+  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++) {
+    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) {
+  DCHECK(CalledOnValidThread());
+  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) {
+  DCHECK(CalledOnValidThread());
+  return GetStorageKey(entity_data);
+}
+
+// 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) {
+  DCHECK(CalledOnValidThread());
+  return entity_data.specifics.reading_list().entry_id();
+}