drive: Delete unused ID entries from an already updated DB

BUG=374648
TEST=unit_tests

Review URL: https://codereview.chromium.org/299623012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272495 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/drive/resource_metadata_storage.cc

@@ -285,8 +285,34 @@ bool ResourceMetadataStorage::UpgradeOldDB(
   UMA_HISTOGRAM_SPARSE_SLOWLY("Drive.MetadataDBVersionBeforeUpgradeCheck",
                               header.version());
 
-  if (header.version() == kDBVersion) {  // Nothing to do.
-    return true;
+  if (header.version() == kDBVersion) {
+    // Before r272134, UpgradeOldDB() was not deleting unused ID entries.
+    // Delete unused ID entries to fix crbug.com/374648.
+    std::set<std::string> used_ids;
+
+    scoped_ptr<leveldb::Iterator> it(
+        resource_map->NewIterator(leveldb::ReadOptions()));
+    it->Seek(leveldb::Slice(GetHeaderDBKey()));
+    it->Next();
+    for (; it->Valid(); it->Next()) {
+      if (IsCacheEntryKey(it->key())) {
+        used_ids.insert(GetIdFromCacheEntryKey(it->key()));
+      } else if (!IsChildEntryKey(it->key()) && !IsIdEntryKey(it->key())) {
+        used_ids.insert(it->key().ToString());
+      }
+    }
+    if (!it->status().ok())
+      return false;
+
+    leveldb::WriteBatch batch;
+    for (it->SeekToFirst(); it->Valid(); it->Next()) {
+      if (IsIdEntryKey(it->key()) && !used_ids.count(it->value().ToString()))
+        batch.Delete(it->key());
+    }
+    if (!it->status().ok())
+      return false;
+
+    return resource_map->Write(leveldb::WriteOptions(), &batch).ok();
   } else if (header.version() < 6) {  // Too old, nothing can be done.
     return false;
   } else if (header.version() < 11) {  // Cache entries can be reused.

chrome/browser/chromeos/drive/resource_metadata_storage_unittest.cc

@@ -402,6 +402,48 @@ TEST_F(ResourceMetadataStorageTest, IncompatibleDB_Unknown) {
   EXPECT_EQ(FILE_ERROR_NOT_FOUND, storage_->GetEntry(key1, &entry));
 }
 
+TEST_F(ResourceMetadataStorageTest, DeleteUnusedIDEntries) {
+  leveldb::WriteBatch batch;
+
+  // Put an ID entry with a corresponding ResourceEntry.
+  ResourceEntry entry;
+  entry.set_local_id("id1");
+  entry.set_resource_id("resource_id1");
+
+  std::string serialized_entry;
+  EXPECT_TRUE(entry.SerializeToString(&serialized_entry));
+  batch.Put("id1", serialized_entry);
+  batch.Put('\0' + std::string("ID") + '\0' + "resource_id1", "id1");
+
+  // Put an ID entry with a corresponding FileCacheEntry.
+  FileCacheEntry cache_entry;
+  EXPECT_TRUE(cache_entry.SerializeToString(&serialized_entry));
+  batch.Put(std::string("id2") + '\0' + "CACHE", serialized_entry);
+  batch.Put('\0' + std::string("ID") + '\0' + "resource_id2", "id2");
+
+  // Put an ID entry without any corresponding entries.
+  batch.Put('\0' + std::string("ID") + '\0' + "resource_id3", "id3");
+
+  EXPECT_TRUE(resource_map()->Write(leveldb::WriteOptions(), &batch).ok());
+
+  // Upgrade and reopen.
+  storage_.reset();
+  EXPECT_TRUE(ResourceMetadataStorage::UpgradeOldDB(
+      temp_dir_.path(), base::Bind(&util::CanonicalizeResourceId)));
+  storage_.reset(new ResourceMetadataStorage(
+      temp_dir_.path(), base::MessageLoopProxy::current().get()));
+  ASSERT_TRUE(storage_->Initialize());
+
+  // Only the unused entry is deleted.
+  std::string id;
+  EXPECT_EQ(FILE_ERROR_OK, storage_->GetIdByResourceId("resource_id1", &id));
+  EXPECT_EQ("id1", id);
+  EXPECT_EQ(FILE_ERROR_OK, storage_->GetIdByResourceId("resource_id2", &id));
+  EXPECT_EQ("id2", id);
+  EXPECT_EQ(FILE_ERROR_NOT_FOUND,
+            storage_->GetIdByResourceId("resource_id3", &id));
+}
+
 TEST_F(ResourceMetadataStorageTest, WrongPath) {
   // Create a file.
   base::FilePath path;