1// Copyright (c) 2006-2009 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 "chrome/browser/sync/engine/process_updates_command.h"
6
7#include <vector>
8
9#include "base/basictypes.h"
10#include "chrome/browser/sync/engine/syncer.h"
11#include "chrome/browser/sync/engine/syncer_proto_util.h"
12#include "chrome/browser/sync/engine/syncer_util.h"
13#include "chrome/browser/sync/engine/syncproto.h"
14#include "chrome/browser/sync/sessions/sync_session.h"
15#include "chrome/browser/sync/syncable/directory_manager.h"
16#include "chrome/browser/sync/syncable/syncable.h"
17
18using std::vector;
19
20namespace browser_sync {
21
22using sessions::SyncSession;
23using sessions::StatusController;
24
25ProcessUpdatesCommand::ProcessUpdatesCommand() {}
26ProcessUpdatesCommand::~ProcessUpdatesCommand() {}
27
28bool ProcessUpdatesCommand::ModelNeutralExecuteImpl(SyncSession* session) {
29  const GetUpdatesResponse& updates =
30      session->status_controller()->updates_response().get_updates();
31  const int update_count = updates.entries_size();
32
33  // Don't bother processing updates if there were none.
34  return update_count != 0;
35}
36
37void ProcessUpdatesCommand::ModelChangingExecuteImpl(SyncSession* session) {
38  syncable::ScopedDirLookup dir(session->context()->directory_manager(),
39                                session->context()->account_name());
40  if (!dir.good()) {
41    LOG(ERROR) << "Scoped dir lookup failed!";
42    return;
43  }
44
45  StatusController* status = session->status_controller();
46
47  const sessions::UpdateProgress& progress(status->update_progress());
48  vector<sessions::VerifiedUpdate>::const_iterator it;
49  for (it = progress.VerifiedUpdatesBegin();
50       it != progress.VerifiedUpdatesEnd();
51       ++it) {
52    const sync_pb::SyncEntity& update = it->second;
53
54    if (it->first != VERIFY_SUCCESS && it->first != VERIFY_UNDELETE)
55      continue;
56    switch (ProcessUpdate(dir, update)) {
57      case SUCCESS_PROCESSED:
58      case SUCCESS_STORED:
59        break;
60      default:
61        NOTREACHED();
62        break;
63    }
64  }
65
66  status->set_num_consecutive_errors(0);
67
68  // TODO(nick): The following line makes no sense to me.
69  status->set_syncing(true);
70  return;
71}
72
73namespace {
74// Returns true if the entry is still ok to process.
75bool ReverifyEntry(syncable::WriteTransaction* trans, const SyncEntity& entry,
76                   syncable::MutableEntry* same_id) {
77
78  const bool deleted = entry.has_deleted() && entry.deleted();
79  const bool is_directory = entry.IsFolder();
80  const syncable::ModelType model_type = entry.GetModelType();
81
82  return VERIFY_SUCCESS == SyncerUtil::VerifyUpdateConsistency(trans,
83                                                               entry,
84                                                               same_id,
85                                                               deleted,
86                                                               is_directory,
87                                                               model_type);
88}
89}  // namespace
90
91// Process a single update. Will avoid touching global state.
92ServerUpdateProcessingResult ProcessUpdatesCommand::ProcessUpdate(
93    const syncable::ScopedDirLookup& dir,
94    const sync_pb::SyncEntity& proto_update) {
95
96  const SyncEntity& update = *static_cast<const SyncEntity*>(&proto_update);
97  using namespace syncable;
98  syncable::Id server_id = update.id();
99  const std::string name = SyncerProtoUtil::NameFromSyncEntity(update);
100
101  WriteTransaction trans(dir, SYNCER, __FILE__, __LINE__);
102
103  // Look to see if there's a local item that should recieve this update,
104  // maybe due to a duplicate client tag or a lost commit response.
105  syncable::Id local_id = SyncerUtil::FindLocalIdToUpdate(&trans, update);
106
107  // FindLocalEntryToUpdate has veto power.
108  if (local_id.IsNull()) {
109    return SUCCESS_PROCESSED;  // The entry has become irrelevant.
110  }
111
112  SyncerUtil::CreateNewEntry(&trans, local_id);
113
114  // We take a two step approach. First we store the entries data in the
115  // server fields of a local entry and then move the data to the local fields
116  MutableEntry target_entry(&trans, GET_BY_ID, local_id);
117
118  // We need to run the Verify checks again; the world could have changed
119  // since VerifyUpdatesCommand.
120  if (!ReverifyEntry(&trans, update, &target_entry)) {
121    return SUCCESS_PROCESSED;  // The entry has become irrelevant.
122  }
123
124  // If we're repurposing an existing local entry with a new server ID,
125  // change the ID now, after we're sure that the update can succeed.
126  if (local_id != server_id) {
127    DCHECK(!update.deleted());
128    SyncerUtil::ChangeEntryIDAndUpdateChildren(&trans, &target_entry,
129        server_id);
130    // When IDs change, versions become irrelevant.  Forcing BASE_VERSION
131    // to zero would ensure that this update gets applied, but would indicate
132    // creation or undeletion if it were committed that way.  Instead, prefer
133    // forcing BASE_VERSION to entry.version() while also forcing
134    // IS_UNAPPLIED_UPDATE to true.  If the item is UNSYNCED, it's committable
135    // from the new state; it may commit before the conflict resolver gets
136    // a crack at it.
137    if (target_entry.Get(IS_UNSYNCED) || target_entry.Get(BASE_VERSION) > 0) {
138      // If either of these conditions are met, then we can expect valid client
139      // fields for this entry.  When BASE_VERSION is positive, consistency is
140      // enforced on the client fields at update-application time.  Otherwise,
141      // we leave the BASE_VERSION field alone; it'll get updated the first time
142      // we successfully apply this update.
143      target_entry.Put(BASE_VERSION, update.version());
144    }
145    // Force application of this update, no matter what.
146    target_entry.Put(IS_UNAPPLIED_UPDATE, true);
147  }
148
149  SyncerUtil::UpdateServerFieldsFromUpdate(&target_entry, update, name);
150
151  if (target_entry.Get(SERVER_VERSION) == target_entry.Get(BASE_VERSION) &&
152      !target_entry.Get(IS_UNSYNCED) &&
153      !target_entry.Get(IS_UNAPPLIED_UPDATE)) {
154    // If these don't match, it means that we have a different view of the
155    // truth from other clients.  That's a sync bug, though we may be able
156    // to recover the next time this item commits.
157    LOG_IF(ERROR, !SyncerUtil::ServerAndLocalEntriesMatch(&target_entry))
158        << target_entry;
159  }
160  return SUCCESS_PROCESSED;
161}
162
163}  // namespace browser_sync
164