sync/engine/apply_updates_and_resolve_conflicts_command.cc

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "sync/engine/apply_updates_and_resolve_conflicts_command.h"
   6
   7 #include "base/location.h"
   8 #include "sync/engine/conflict_resolver.h"
   9 #include "sync/engine/update_applicator.h"
  10 #include "sync/sessions/sync_session.h"
  11 #include "sync/syncable/directory.h"
  12 #include "sync/syncable/syncable_read_transaction.h"
  13 #include "sync/syncable/syncable_write_transaction.h"
  14
  15 namespace syncer {
  16
  17 using sessions::SyncSession;
  18
  19 ApplyUpdatesAndResolveConflictsCommand::
  20     ApplyUpdatesAndResolveConflictsCommand() {}
  21 ApplyUpdatesAndResolveConflictsCommand::
  22     ~ApplyUpdatesAndResolveConflictsCommand() {}
  23
  24 std::set<ModelSafeGroup>
  25 ApplyUpdatesAndResolveConflictsCommand::GetGroupsToChange(
  26     const sessions::SyncSession& session) const {
  27   std::set<ModelSafeGroup> groups_with_unapplied_updates;
  28
  29   FullModelTypeSet server_types_with_unapplied_updates;
  30   {
  31     syncable::Directory* dir = session.context()->directory();
  32     syncable::ReadTransaction trans(FROM_HERE, dir);
  33     server_types_with_unapplied_updates =
  34         dir->GetServerTypesWithUnappliedUpdates(&trans);
  35   }
  36
  37   for (FullModelTypeSet::Iterator it =
  38            server_types_with_unapplied_updates.First(); it.Good(); it.Inc()) {
  39     groups_with_unapplied_updates.insert(
  40         GetGroupForModelType(it.Get(), session.context()->routing_info()));
  41   }
  42
  43   return groups_with_unapplied_updates;
  44 }
  45
  46 SyncerError ApplyUpdatesAndResolveConflictsCommand::ModelChangingExecuteImpl(
  47     SyncSession* session) {
  48   sessions::StatusController* status = session->mutable_status_controller();
  49   syncable::Directory* dir = session->context()->directory();
  50   syncable::WriteTransaction trans(FROM_HERE, syncable::SYNCER, dir);
  51
  52   // Compute server types with unapplied updates that fall under our
  53   // group restriction.
  54   const FullModelTypeSet server_types_with_unapplied_updates =
  55       dir->GetServerTypesWithUnappliedUpdates(&trans);
  56   FullModelTypeSet server_type_restriction;
  57   for (FullModelTypeSet::Iterator it =
  58            server_types_with_unapplied_updates.First(); it.Good(); it.Inc()) {
  59     if (GetGroupForModelType(it.Get(), session->context()->routing_info()) ==
  60         status->group_restriction()) {
  61       server_type_restriction.Put(it.Get());
  62     }
  63   }
  64
  65   // Don't process control type updates here.  They will be handled elsewhere.
  66   FullModelTypeSet control_types = ToFullModelTypeSet(ControlTypes());
  67   server_type_restriction.RemoveAll(control_types);
  68
  69   std::vector<int64> handles;
  70   dir->GetUnappliedUpdateMetaHandles(
  71       &trans, server_type_restriction, &handles);
  72
  73   // First set of update application passes.
  74   UpdateApplicator applicator(
  75       dir->GetCryptographer(&trans),
  76       session->context()->routing_info(),
  77       status->group_restriction());
  78   applicator.AttemptApplications(&trans, handles);
  79   status->increment_num_updates_applied_by(applicator.updates_applied());
  80   status->increment_num_hierarchy_conflicts_by(
  81       applicator.hierarchy_conflicts());
  82   status->increment_num_encryption_conflicts_by(
  83       applicator.encryption_conflicts());
  84
  85   if (applicator.simple_conflict_ids().size() != 0) {
  86     // Resolve the simple conflicts we just detected.
  87     ConflictResolver resolver;
  88     resolver.ResolveConflicts(&trans,
  89                               dir->GetCryptographer(&trans),
  90                               applicator.simple_conflict_ids(),
  91                               status);
  92
  93     // Conflict resolution sometimes results in more updates to apply.
  94     handles.clear();
  95     dir->GetUnappliedUpdateMetaHandles(
  96         &trans, server_type_restriction, &handles);
  97
  98     UpdateApplicator conflict_applicator(
  99         dir->GetCryptographer(&trans),
 100         session->context()->routing_info(),
 101         status->group_restriction());
 102     conflict_applicator.AttemptApplications(&trans, handles);
 103
 104     // We count the number of updates from both applicator passes.
 105     status->increment_num_updates_applied_by(
 106         conflict_applicator.updates_applied());
 107
 108     // Encryption conflicts should remain unchanged by the resolution of simple
 109     // conflicts.  Those can only be solved by updating our nigori key bag.
 110     DCHECK_EQ(conflict_applicator.encryption_conflicts(),
 111               applicator.encryption_conflicts());
 112
 113     // Hierarchy conflicts should also remain unchanged, for reasons that are
 114     // more subtle.  Hierarchy conflicts exist when the application of a pending
 115     // update from the server would make the local folder hierarchy
 116     // inconsistent.  The resolution of simple conflicts could never affect the
 117     // hierarchy conflicting item directly, because hierarchy conflicts are not
 118     // processed by the conflict resolver.  It could, in theory, modify the
 119     // local hierarchy on which hierarchy conflict detection depends.  However,
 120     // the conflict resolution algorithm currently in use does not allow this.
 121     DCHECK_EQ(conflict_applicator.hierarchy_conflicts(),
 122               applicator.hierarchy_conflicts());
 123
 124     // There should be no simple conflicts remaining.  We know this because the
 125     // resolver should have resolved all the conflicts we detected last time
 126     // and, by the two previous assertions, that no conflicts have been
 127     // downgraded from encryption or hierarchy down to simple.
 128     DCHECK(conflict_applicator.simple_conflict_ids().empty());
 129   }
 130
 131   return SYNCER_OK;
 132 }
 133
 134 }  // namespace syncer