com.google.apphosting.runtime.DatastoreSessionStore Maven / Gradle / Ivy

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/*
 * Copyright 2021 Google LLC
 *
 * 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
 *
 *     https://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.apphosting.runtime;

import static com.google.apphosting.runtime.SessionManagerUtil.deserialize;
import static com.google.apphosting.runtime.SessionManagerUtil.serialize;

import com.google.appengine.api.NamespaceManager;
import com.google.appengine.api.datastore.Blob;
import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.DatastoreTimeoutException;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.EntityNotFoundException;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;
import com.google.common.flogger.GoogleLogger;
import java.util.Map;

/**
 * A {@link SessionStore} implementation on top of the datastore.
 *
 */
public class DatastoreSessionStore implements SessionStore {

  private static final GoogleLogger logger = GoogleLogger.forEnclosingClass();

  static final String SESSION_ENTITY_TYPE = "_ah_SESSION";
  static final String EXPIRES_PROP = "_expires";
  static final String VALUES_PROP = "_values";

  private final DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();

  /**
   * Return a {@link Key} for the given session "key" string
   * ({@link SessionManager#SESSION_PREFIX} + sessionId) in the empty namespace.
   */
  static Key createKeyForSession(String key) {
    String originalNamespace = NamespaceManager.get();
    try {
      NamespaceManager.set("");
      return KeyFactory.createKey(SESSION_ENTITY_TYPE, key);
    } finally {
      NamespaceManager.set(originalNamespace);
    }
  }

  static SessionData createSessionFromEntity(Entity entity) {
    SessionData data = new SessionData();
    data.setExpirationTime((Long) entity.getProperty(EXPIRES_PROP));

    Blob valueBlob = (Blob) entity.getProperty(VALUES_PROP);
    @SuppressWarnings("unchecked")
    Map valueMap = (Map) deserialize(valueBlob.getBytes());
    data.setValueMap(valueMap);
    return data;
  }

  /**
   * Return an {@link Entity} for the given key and data in the empty
   * namespace.
   */
  static Entity createEntityForSession(String key, SessionData data) {
    String originalNamespace = NamespaceManager.get();
    try {
      NamespaceManager.set("");
      Entity entity = new Entity(SESSION_ENTITY_TYPE, key);
      entity.setProperty(EXPIRES_PROP, data.getExpirationTime());
      entity.setProperty(VALUES_PROP, new Blob(serialize(data.getValueMap())));
      return entity;
    } finally {
      NamespaceManager.set(originalNamespace);
    }
  }

  @Override
  public SessionData getSession(String key) {
    try {
      Entity entity = datastore.get(createKeyForSession(key));
      logger.atFinest().log("Loaded session %s from datastore.", key);
      return createSessionFromEntity(entity);
    } catch (EntityNotFoundException ex) {
      logger.atFine().log("Unable to find specified session %s", key);
    }
    return null;
  }

  @Override
  public void saveSession(String key, SessionData data) throws Retryable {
    try {
      datastore.put(createEntityForSession(key, data));
    } catch (DatastoreTimeoutException e) {
      throw new Retryable(e);
    }
  }

  @Override
  public void deleteSession(String key) {
    datastore.delete(createKeyForSession(key));
  }
}