Asynchronous Google Datastore Client

A modern, feature-rich and tunable Java client library for Google Cloud Datastore.

Features

• Supports a asynchronous (non blocking) design that returns ListenableFutures for all queries and mutations.
• Also supports synchronous alternatives.
• Insulates the consumer from having to deal with Protobuf payloads.
• Includes a simple QueryBuilder to construct natural looking queries.

Overview

The current implementations of Google Datastore Client and Google Cloud Java Client are synchronous, meaning they block when making HTTP calls to their backend. This client uses async-http-client and returns ListenableFutures which can be nicer to work with, especially running at scale.

Usage

Add this to your pom.xml file

<dependency>
  <groupId>com.spotify</groupId>
  <artifactId>async-datastore-client</artifactId>
  <version>3.0.2</version>
</dependency>

NOTE: Version 3.0.0+ depends on Guava 19 which contains breaking changes to Futures.transform. If you require support for Guava version 18 or lower then use async-datastore-client version 2.1.0.

Example: Insert an entity

import com.spotify.asyncdatastoreclient.DatastoreConfig;
import com.spotify.asyncdatastoreclient.Datastore;
import com.spotify.asyncdatastoreclient.QueryBuilder;
import com.spotify.asyncdatastoreclient.Insert;
import com.spotify.asyncdatastoreclient.MutationResult;

import com.google.api.services.datastore.client.DatastoreHelper;
import com.google.common.collect.ImmutableList;
import com.google.common.util.concurrent.ListenableFuture;

final DatastoreConfig config = DatastoreConfig.builder()
    .requestTimeout(1000)
    .requestRetry(3)
    .project(PROJECT_ID)
    .credential(GoogleCredential
        .fromStream(credentialsInputStream)
        .createScoped(DatastoreConfig.SCOPES))
    .build();

final Datastore datastore = Datastore.create(config);

final Insert insert = QueryBuilder.insert("employee", 1234567L)
    .value("fullname", "Fred Blinge")
    .value("age", 40)
    .value("workdays", ImmutableList.of("Monday", "Tuesday", "Friday"));

// for asynchronous call...
final ListenableFuture<MutationResult> resultAsync = datastore.executeAsync(insert);

// ...or for synchronous
final MutationResult result = datastore.execute(insert);

Example: Query entities

import com.spotify.asyncdatastoreclient.QueryBuilder;
import com.spotify.asyncdatastoreclient.Query;

import static com.spotify.asyncdatastoreclient.QueryBuilder.eq;
import static com.spotify.asyncdatastoreclient.QueryBuilder.asc;

final Query query = QueryBuilder.query()
    .kindOf("employee")
    .filterBy(eq("role", "engineer"))
    .orderBy(asc("age"));

// call datastore.executeAsync() to get a ListenableFuture<QueryResult>
for (final Entity entity : datastore.execute(query)) {
  System.out.println("Name: " + entity.getString("fullname));
  ...
}

Building

mvn clean compile

Running tests

By default integration tests are executed against a Local Development Server on port 8080. To run tests, first download the Development Server, at least version 1.4.1 and start the emulator:

gcloud beta emulators datastore start --host-port localhost:8080 --consistency 1.0 --project async-test --data-dir project-test

NOTE: The --consistency=1.0 option is sometimes necessary in order for unit tests to run successful.

All integration tests may by run with maven as follows:

mvn verify

Properties may also be provided to override unit test configuration:

mvn verify -Dhost=https://www.googleapis.com -Dproject=testing -Dkeypath=./my-key.json

License

This software is released under the Apache License 2.0. More information in the file LICENSE distributed with this project.