src/main/java/com/google/android/libraries/feed/feedstore/JournalStorageDirectImpl.java

// Copyright 2018 The Feed Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.android.libraries.feed.feedstore;

import com.google.android.libraries.feed.api.host.storage.CommitResult;
import com.google.android.libraries.feed.api.host.storage.JournalMutation;
import com.google.android.libraries.feed.api.host.storage.JournalStorage;
import com.google.android.libraries.feed.api.host.storage.JournalStorageDirect;
import com.google.android.libraries.feed.common.Result;
import com.google.android.libraries.feed.common.concurrent.MainThreadCaller;
import com.google.android.libraries.feed.common.concurrent.MainThreadRunner;
import java.util.List;

/**
 * An implementation of {@link JournalStorageDirect} which converts {@link JournalStorage} to a
 * synchronized implementation. This acts as a wrapper class over JournalStorage. It will provide a
 * consumer calling on the main thread and waiting on a Future to complete to return the consumer
 * results.
 */
public final class JournalStorageDirectImpl extends MainThreadCaller
    implements JournalStorageDirect {
  private static final String LOCATION = "JournalStorage.";
  private final JournalStorage journalStorage;

  public JournalStorageDirectImpl(
      JournalStorage journalStorage, MainThreadRunner mainThreadRunner) {
    super(mainThreadRunner);
    this.journalStorage = journalStorage;
  }

  @Override
  public Result<List<byte[]>> read(String journalName) {
    return mainThreadCaller(
        LOCATION + "read",
        (consumer) -> journalStorage.read(journalName, consumer),
        Result.failure());
  }

  @Override
  public CommitResult commit(JournalMutation mutation) {
    return mainThreadCaller(
        LOCATION + "commit",
        (consumer) -> journalStorage.commit(mutation, consumer),
        CommitResult.FAILURE);
  }

  @Override
  public Result<Boolean> exists(String journalName) {
    return mainThreadCaller(
        LOCATION + "exists",
        (consumer) -> journalStorage.exists(journalName, consumer),
        Result.failure());
  }

  @Override
  public Result<List<String>> getAllJournals() {
    return mainThreadCaller(
        LOCATION + "getAllJournals", journalStorage::getAllJournals, Result.failure());
  }

  @Override
  public CommitResult deleteAll() {
    return mainThreadCaller(
        LOCATION + "deleteAll", journalStorage::deleteAll, CommitResult.FAILURE);
  }
}