blob: b8bc043987ee985ffd8555882b55bc37b73d418a [file] [log] [blame]
// 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/verify_updates_command.h"
#include <string>
#include "base/location.h"
#include "sync/engine/syncer.h"
#include "sync/engine/syncer_proto_util.h"
#include "sync/engine/syncer_types.h"
#include "sync/engine/syncer_util.h"
#include "sync/internal_api/public/engine/model_safe_worker.h"
#include "sync/protocol/bookmark_specifics.pb.h"
#include "sync/protocol/sync.pb.h"
#include "sync/syncable/entry.h"
#include "sync/syncable/mutable_entry.h"
#include "sync/syncable/syncable_proto_util.h"
#include "sync/syncable/write_transaction.h"
namespace syncer {
using syncable::GET_BY_ID;
using syncable::SYNCER;
using syncable::WriteTransaction;
namespace {
// This function attempts to determine whether or not this update is genuinely
// new, or if it is a reflection of one of our own commits.
// There is a known inaccuracy in its implementation. If this update ends up
// being applied to a local item with a different ID, we will count the change
// as being a non-reflection update. Fortunately, the server usually updates
// our IDs correctly in its commit response, so a new ID during GetUpdate should
// be rare.
// The only secnarios I can think of where this might happen are:
// - We commit a new item to the server, but we don't persist the
// server-returned new ID to the database before we shut down. On the GetUpdate
// following the next restart, we will receive an update from the server that
// updates its local ID.
// - When two attempts to create an item with identical UNIQUE_CLIENT_TAG values
// collide at the server. I have seen this in testing. When it happens, the
// test server will send one of the clients a response to upate its local ID so
// that both clients will refer to the item using the same ID going forward. In
// this case, we're right to assume that the update is not a reflection.
// For more information, see FindLocalIdToUpdate().
bool UpdateContainsNewVersion(syncable::BaseTransaction *trans,
const sync_pb::SyncEntity &update) {
int64 existing_version = -1; // The server always sends positive versions.
syncable::Entry existing_entry(trans, GET_BY_ID,
if (existing_entry.good())
existing_version = existing_entry.Get(syncable::BASE_VERSION);
if (!existing_entry.good() && update.deleted()) {
// There are several possible explanations for this. The most common cases
// will be first time sync and the redelivery of deletions we've already
// synced, accepted, and purged from our database. In either case, the
// update is useless to us. Let's count them all as "not new", even though
// that may not always be entirely accurate.
return false;
if (existing_entry.good() &&
!existing_entry.Get(syncable::UNIQUE_CLIENT_TAG).empty() &&
existing_entry.Get(syncable::IS_DEL) &&
update.deleted()) {
// Unique client tags will have their version set to zero when they're
// deleted. The usual version comparison logic won't be able to detect
// reflections of these items. Instead, we assume any received tombstones
// are reflections. That should be correct most of the time.
return false;
return existing_version < update.version();
// In the event that IDs match, but tags differ AttemptReuniteClient tag
// will have refused to unify the update.
// We should not attempt to apply it at all since it violates consistency
// rules.
VerifyResult VerifyTagConsistency(const sync_pb::SyncEntity& entry,
const syncable::MutableEntry& same_id) {
if (entry.has_client_defined_unique_tag() &&
entry.client_defined_unique_tag() !=
same_id.Get(syncable::UNIQUE_CLIENT_TAG)) {
} // namespace
VerifyUpdatesCommand::VerifyUpdatesCommand() {}
VerifyUpdatesCommand::~VerifyUpdatesCommand() {}
std::set<ModelSafeGroup> VerifyUpdatesCommand::GetGroupsToChange(
const sessions::SyncSession& session) const {
std::set<ModelSafeGroup> groups_with_updates;
const sync_pb::GetUpdatesResponse& updates =
for (int i = 0; i < updates.entries().size(); i++) {
return groups_with_updates;
SyncerError VerifyUpdatesCommand::ModelChangingExecuteImpl(
sessions::SyncSession* session) {
DVLOG(1) << "Beginning Update Verification";
syncable::Directory* dir = session->context()->directory();
WriteTransaction trans(FROM_HERE, SYNCER, dir);
sessions::StatusController* status = session->mutable_status_controller();
const sync_pb::GetUpdatesResponse& updates =
int update_count = updates.entries().size();
ModelTypeSet requested_types = GetRoutingInfoTypes(
DVLOG(1) << update_count << " entries to verify";
for (int i = 0; i < update_count; i++) {
const sync_pb::SyncEntity& update = updates.entries(i);
ModelSafeGroup g = GetGroupForModelType(GetModelType(update),
if (g != status->group_restriction())
VerifyUpdateResult result = VerifyUpdate(&trans, update,
status->mutable_update_progress()->AddVerifyResult(result.value, update);
if (!UpdateContainsNewVersion(&trans, update))
if (update.deleted())
return SYNCER_OK;
VerifyUpdatesCommand::VerifyUpdateResult VerifyUpdatesCommand::VerifyUpdate(
syncable::WriteTransaction* trans, const sync_pb::SyncEntity& entry,
ModelTypeSet requested_types,
const ModelSafeRoutingInfo& routes) {
syncable::Id id = SyncableIdFromProto(entry.id_string());
VerifyUpdateResult result = {VERIFY_FAIL, GROUP_PASSIVE};
const bool deleted = entry.has_deleted() && entry.deleted();
const bool is_directory = IsFolder(entry);
const ModelType model_type = GetModelType(entry);
if (!id.ServerKnows()) {
LOG(ERROR) << "Illegal negative id in received updates";
return result;
const std::string name = SyncerProtoUtil::NameFromSyncEntity(entry);
if (name.empty() && !deleted) {
LOG(ERROR) << "Zero length name in non-deleted update";
return result;
syncable::MutableEntry same_id(trans, GET_BY_ID, id);
result.value = VerifyNewEntry(entry, &same_id, deleted);
ModelType placement_type = !deleted ? GetModelType(entry)
: same_id.good() ? same_id.GetModelType() : UNSPECIFIED;
result.placement = GetGroupForModelType(placement_type, routes);
if (VERIFY_UNDECIDED == result.value) {
result.value = VerifyTagConsistency(entry, same_id);
if (VERIFY_UNDECIDED == result.value) {
if (deleted) {
// For deletes the server could send tombostones for items that
// the client did not request. If so ignore those items.
if (IsRealDataType(placement_type) &&
!requested_types.Has(placement_type)) {
result.value = VERIFY_SKIP;
} else {
result.value = VERIFY_SUCCESS;
// If we have an existing entry, we check here for updates that break
// consistency rules.
if (VERIFY_UNDECIDED == result.value) {
result.value = VerifyUpdateConsistency(trans, entry, &same_id,
deleted, is_directory, model_type);
if (VERIFY_UNDECIDED == result.value)
result.value = VERIFY_SUCCESS; // No news is good news.
return result; // This might be VERIFY_SUCCESS as well
} // namespace syncer