[SyncFS] Count added/removed DB entries in building/deleteing indexes.

BUG=347425
TEST=./unit_tests --gtest_filter="MetadataDatabaseIndexOn*"

Review URL: https://codereview.chromium.org/455263003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289783 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 53 insertions, 5 deletions

diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.cc
index a5b7163..ae40a2b 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.cc
@@ -680,7 +680,9 @@ MetadataDatabaseIndexOnDisk::GetAllMetadataIDs() const {
   return file_ids;
 }
 
-void MetadataDatabaseIndexOnDisk::BuildTrackerIndexes() {
+int64 MetadataDatabaseIndexOnDisk::BuildTrackerIndexes() {
+  int64 num_puts_before = db_->num_puts();
+
   scoped_ptr<LevelDBWrapper::Iterator> itr(db_->NewIterator());
   for (itr->Seek(kFileTrackerKeyPrefix); itr->Valid(); itr->Next()) {
     if (!RemovePrefix(itr->key().ToString(), kFileTrackerKeyPrefix, NULL))
@@ -698,6 +700,23 @@ void MetadataDatabaseIndexOnDisk::BuildTrackerIndexes() {
     AddToPathIndexes(tracker);
     AddToDirtyTrackerIndexes(tracker);
   }
+
+  return db_->num_puts() - num_puts_before;
+}
+
+int64 MetadataDatabaseIndexOnDisk::DeleteTrackerIndexes() {
+  const char* kIndexPrefixes[] = {
+    kAppRootIDByAppIDKeyPrefix, kActiveTrackerIDByFileIDKeyPrefix,
+    kTrackerIDByFileIDKeyPrefix, kMultiTrackerByFileIDKeyPrefix,
+    kActiveTrackerIDByParentAndTitleKeyPrefix,
+    kTrackerIDByParentAndTitleKeyPrefix, kMultiBackingParentAndTitleKeyPrefix,
+    kDirtyIDKeyPrefix, kDemotedDirtyIDKeyPrefix
+  };
+
+  int64 num_deletes_before = db_->num_deletes();
+  for (size_t i = 0; i < arraysize(kIndexPrefixes); ++i)
+    DeleteKeyStartsWith(kIndexPrefixes[i]);
+  return db_->num_deletes() - num_deletes_before;
 }
 
 LevelDBWrapper* MetadataDatabaseIndexOnDisk::GetDBForTesting() {
@@ -772,8 +791,7 @@ void MetadataDatabaseIndexOnDisk::AddToFileIDIndexes(
   DVLOG(1) << "  Add to trackers by file ID: " << file_id;
   const std::string prefix = GenerateTrackerIDByFileIDKeyPrefix(file_id);
   AddToTrackerIDSetWithPrefix(
-      GenerateActiveTrackerIDByFileIDKey(file_id),
-      prefix, new_tracker);
+      GenerateActiveTrackerIDByFileIDKey(file_id), prefix, new_tracker);
 
   const std::string multi_tracker_key = GenerateMultiTrackerKey(file_id);
   if (!DBHasKey(multi_tracker_key) &&
@@ -1125,5 +1143,16 @@ MetadataDatabaseIndexOnDisk::CountWithPrefix(
   return count == 0 ? NONE : SINGLE;
 }
 
+void MetadataDatabaseIndexOnDisk::DeleteKeyStartsWith(
+    const std::string& prefix) {
+  scoped_ptr<LevelDBWrapper::Iterator> itr(db_->NewIterator());
+  for (itr->Seek(prefix); itr->Valid();) {
+    const std::string key = itr->key().ToString();
+    if (!StartsWithASCII(key, prefix, true))
+      break;
+    itr->Delete();
+  }
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.h b/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.h
index 12f757a..8dae9ce 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.h
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk.h
@@ -69,7 +69,12 @@ class MetadataDatabaseIndexOnDisk : public MetadataDatabaseIndexInterface {
   virtual std::vector<std::string> GetAllMetadataIDs() const OVERRIDE;
 
   // Builds on-disk indexes from FileTracker entries on disk.
-  void BuildTrackerIndexes();
+  // Returns the number of newly added entries for indexing.
+  int64 BuildTrackerIndexes();
+
+  // Deletes entries used for indexes on on-disk database.
+  // Returns the number of the deleted entries.
+  int64 DeleteTrackerIndexes();
 
   LevelDBWrapper* GetDBForTesting();
 
@@ -150,6 +155,9 @@ class MetadataDatabaseIndexOnDisk : public MetadataDatabaseIndexInterface {
   // Entries for |ignored_id| are not counted in.
   NumEntries CountWithPrefix(const std::string& prefix, int64 ignored_id);
 
+  // Deletes entries whose keys start from |prefix|.
+  void DeleteKeyStartsWith(const std::string& prefix);
+
   LevelDBWrapper* db_;  // Not owned.
   scoped_ptr<ServiceMetadata> service_metadata_;
 
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk_unittest.cc b/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk_unittest.cc
index f40e6f2..1ce143f 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk_unittest.cc
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database_index_on_disk_unittest.cc
@@ -237,7 +237,7 @@ TEST_F(MetadataDatabaseIndexOnDiskTest, BuildIndexTest) {
   EXPECT_TRUE(tracker_ids.empty());
   EXPECT_EQ(0U, index()->CountDirtyTracker());
 
-  index()->BuildTrackerIndexes();
+  EXPECT_EQ(16, index()->BuildTrackerIndexes());
   WriteToDB();
 
   // After building indexes, we should have correct indexes.
@@ -252,6 +252,17 @@ TEST_F(MetadataDatabaseIndexOnDiskTest, BuildIndexTest) {
   EXPECT_EQ(1U, index()->CountDirtyTracker());
 }
 
+TEST_F(MetadataDatabaseIndexOnDiskTest, BuildAndDeleteIndexTest) {
+  CreateTestDatabase(false, NULL);
+  int64 answer = index()->BuildTrackerIndexes();
+  WriteToDB();
+  ASSERT_EQ(16, answer);
+  EXPECT_EQ(answer, index()->DeleteTrackerIndexes());
+  WriteToDB();
+  EXPECT_EQ(answer, index()->BuildTrackerIndexes());
+  WriteToDB();
+}
+
 TEST_F(MetadataDatabaseIndexOnDiskTest, AllEntriesTest) {
   CreateTestDatabase(true, NULL);