sync: Per-type update application

sync/engine/apply_updates_and_resolve_conflicts_command.cc

-// Copyright 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/apply_updates_and_resolve_conflicts_command.h"
-
-#include "base/location.h"
-#include "sync/engine/conflict_resolver.h"
-#include "sync/engine/update_applicator.h"
-#include "sync/sessions/sync_session.h"
-#include "sync/syncable/directory.h"
-#include "sync/syncable/syncable_read_transaction.h"
-#include "sync/syncable/syncable_write_transaction.h"
-
-namespace syncer {
-
-using sessions::SyncSession;
-
-ApplyUpdatesAndResolveConflictsCommand::
-    ApplyUpdatesAndResolveConflictsCommand() {}
-ApplyUpdatesAndResolveConflictsCommand::
-    ~ApplyUpdatesAndResolveConflictsCommand() {}
-
-std::set<ModelSafeGroup>
-ApplyUpdatesAndResolveConflictsCommand::GetGroupsToChange(
-    const sessions::SyncSession& session) const {
-  std::set<ModelSafeGroup> groups_with_unapplied_updates;
-
-  FullModelTypeSet server_types_with_unapplied_updates;
-  {
-    syncable::Directory* dir = session.context()->directory();
-    syncable::ReadTransaction trans(FROM_HERE, dir);
-    server_types_with_unapplied_updates =
-        dir->GetServerTypesWithUnappliedUpdates(&trans);
-  }
-
-  for (FullModelTypeSet::Iterator it =
-           server_types_with_unapplied_updates.First(); it.Good(); it.Inc()) {
-    groups_with_unapplied_updates.insert(
-        GetGroupForModelType(it.Get(), session.context()->routing_info()));
-  }
-
-  return groups_with_unapplied_updates;
-}
-
-SyncerError ApplyUpdatesAndResolveConflictsCommand::ModelChangingExecuteImpl(
-    SyncSession* session) {
-  sessions::StatusController* status = session->mutable_status_controller();
-  syncable::Directory* dir = session->context()->directory();
-  syncable::WriteTransaction trans(FROM_HERE, syncable::SYNCER, dir);
-
-  // Compute server types with unapplied updates that fall under our
-  // group restriction.
-  const FullModelTypeSet server_types_with_unapplied_updates =
-      dir->GetServerTypesWithUnappliedUpdates(&trans);
-  FullModelTypeSet server_type_restriction;
-  for (FullModelTypeSet::Iterator it =
-           server_types_with_unapplied_updates.First(); it.Good(); it.Inc()) {
-    if (GetGroupForModelType(it.Get(), session->context()->routing_info()) ==
-        status->group_restriction()) {
-      server_type_restriction.Put(it.Get());
-    }
-  }
-
-  // Don't process control type updates here.  They will be handled elsewhere.
-  FullModelTypeSet control_types = ToFullModelTypeSet(ControlTypes());
-  server_type_restriction.RemoveAll(control_types);
-
-  std::vector<int64> handles;
-  dir->GetUnappliedUpdateMetaHandles(
-      &trans, server_type_restriction, &handles);
-
-  // First set of update application passes.
-  UpdateApplicator applicator(
-      dir->GetCryptographer(&trans),
-      session->context()->routing_info(),
-      status->group_restriction());
-  applicator.AttemptApplications(&trans, handles);
-  status->increment_num_updates_applied_by(applicator.updates_applied());
-  status->increment_num_hierarchy_conflicts_by(
-      applicator.hierarchy_conflicts());
-  status->increment_num_encryption_conflicts_by(
-      applicator.encryption_conflicts());
-
-  if (applicator.simple_conflict_ids().size() != 0) {
-    // Resolve the simple conflicts we just detected.
-    ConflictResolver resolver;
-    resolver.ResolveConflicts(&trans,
-                              dir->GetCryptographer(&trans),
-                              applicator.simple_conflict_ids(),
-                              status);
-
-    // Conflict resolution sometimes results in more updates to apply.
-    handles.clear();
-    dir->GetUnappliedUpdateMetaHandles(
-        &trans, server_type_restriction, &handles);
-
-    UpdateApplicator conflict_applicator(
-        dir->GetCryptographer(&trans),
-        session->context()->routing_info(),
-        status->group_restriction());
-    conflict_applicator.AttemptApplications(&trans, handles);
-
-    // We count the number of updates from both applicator passes.
-    status->increment_num_updates_applied_by(
-        conflict_applicator.updates_applied());
-
-    // Encryption conflicts should remain unchanged by the resolution of simple
-    // conflicts.  Those can only be solved by updating our nigori key bag.
-    DCHECK_EQ(conflict_applicator.encryption_conflicts(),
-              applicator.encryption_conflicts());
-
-    // Hierarchy conflicts should also remain unchanged, for reasons that are
-    // more subtle.  Hierarchy conflicts exist when the application of a pending
-    // update from the server would make the local folder hierarchy
-    // inconsistent.  The resolution of simple conflicts could never affect the
-    // hierarchy conflicting item directly, because hierarchy conflicts are not
-    // processed by the conflict resolver.  It could, in theory, modify the
-    // local hierarchy on which hierarchy conflict detection depends.  However,
-    // the conflict resolution algorithm currently in use does not allow this.
-    DCHECK_EQ(conflict_applicator.hierarchy_conflicts(),
-              applicator.hierarchy_conflicts());
-
-    // There should be no simple conflicts remaining.  We know this because the
-    // resolver should have resolved all the conflicts we detected last time
-    // and, by the two previous assertions, that no conflicts have been
-    // downgraded from encryption or hierarchy down to simple.
-    DCHECK(conflict_applicator.simple_conflict_ids().empty());
-  }
-
-  return SYNCER_OK;
-}
-
-}  // namespace syncer