Jesque

Jesque is an implementation of Resque in Java. It is fully-interoperable with the Ruby and Node.js (Coffee-Resque) implementations.

Jesque is a Maven project and depends on Jedis to connect to Redis, Jackson to map to/from JSON and SLF4J for logging.

The project contains a client implementation as well as a worker implementation that supports listeners.

NOTE: Jesque's delayed jobs implementation is not compatible with resque-scheduler

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How do I use it?

Jesque requires Java 7+. Download the latest source at:

https://github.com/gresrun/jesque Or, to use it in your Maven project, add it as a dependency:

<dependency>
  <groupId>net.greghaines</groupId>
  <artifactId>jesque</artifactId>
  <version>2.2.0</version>
</dependency>

Quickstart:

// Configuration
final Config config = new ConfigBuilder().build();

// Add a job to the queue
final Job job = new Job("TestAction",
  new Object[]{ 1, 2.3, true, "test", Arrays.asList("inner", 4.5)});
final Client client = new ClientImpl(config);
client.enqueue("foo", job);
client.end();

// Start a worker to run jobs from the queue
final Worker worker = new WorkerImpl(config,
  Arrays.asList("foo"), new MapBasedJobFactory(map(entry("TestAction", TestAction.class))));
  
final Thread workerThread = new Thread(worker);
workerThread.start();

// Enqueue more jobs, etc.

// Shutdown the worker when finished
worker.end(true);
try { workerThread.join(); } catch (Exception e){ e.printStackTrace(); }

If enqueueing multiple jobs at the same time, there is client.batchEnqueue(String queue, List<Job> jobs) which does it in an optimized way.

Delayed jobs

Delayed jobs can be executed at sometime in the future.

final long delay = 10; // in seconds
final long future = System.currentTimeMillis() + (delay * 1000); // timestamp

client.delayedEnqueue("fooDelay", job, future);

Recurring Jobs

Recurring jobs can start at a specific time and execute at specified intervals.

final long delay = 10; // in seconds
final long future = System.currentTimeMillis() + (delay * 1000); // timestamp
final long frequency = 60; // in seconds

client.recurringEnqueue("fooRecur", job, future, (frequency * 1000));

Cancelling jobs

Delayed and recurring jobs can be cancelled.

client.removeDelayedEnqueue("fooDelay", job);
client.removeRecurringEnqueue("fooRecur", job);

Using a ClientPool

ClientPool is useful in multi threaded apps,

final Client jesqueClientPool = new ClientPoolImpl(config, PoolUtils.createJedisPool(config));
jesqueClientPool.enqueue("foo", job);

Listeners

You can execute custom callbacks during specific Worker events.

int myVar = 0;
worker.getWorkerEventEmitter().addListener(new WorkerListener(){
   public void onEvent(WorkerEvent event, Worker worker, String queue, Job job, 
					   Object runner, Object result, Throwable t) {
    if (runner instanceof TestAction) {
        ((TestAction) runner).setSomeVariable(myVar);
    }
  }
}, WorkerEvent.JOB_EXECUTE);

Available Worker Events

• WORKER_START Finished starting up and is about to start running.
• WORKER_POLL Polling the queue.
• JOB_PROCESS Processing a Job.
• JOB_EXECUTE About to execute a materialized Job.
• JOB_SUCCESS Successfully executed a materialized Job.
• JOB_FAILURE Caught an Exception during the execution of a materialized Job.
• WORKER_ERROR Caught an Exception during normal operation.
• WORKER_STOP Finished running and is about to shutdown.

For more usage examples check the tests. The tests require that Redis is running on localhost:6379.

Use the resque-web application to see the status of your jobs and workers or, if you prefer Java, try Jesque-Web.

Redis Configuration

As mentioned Jesque depends on Jedis to connect to Redis.

You can configure Jesque to connect to Redis given a URL in a system property (as used in Heroku + RedisToGo) with the following snippet:

final ConfigBuilder configBuilder = new ConfigBuilder();
try {
  URI redisUrl = new URI(System.getProperty("REDIS_PROVIDER", "127.0.0.1"));
  String redisHost = redisUrl.getHost();
  int redisPort = redisUrl.getPort();
  String redisUserInfo = redisUrl.getUserInfo();
  if (redisHost != null) {
    configBuilder.withHost(redisHost);
  }
  if (redisPort > -1) {
    configBuilder.withPort(redisPort);
  }
  if (redisUserInfo != null) {
    configBuilder.withPassword(redisUserInfo.split(":",2)[1]);
  }
} catch (URISyntaxException use) {
  // Handle error
}
final Config config = configBuilder.build();

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Design Decisions

• I chose to implement the jobs as classes that implement java.lang.Runnable or java.util.concurrent.Callable. If the job requires arguments (most do), there must be a constructor that matches the supplied arguments. I felt this was the most flexible option and didn't require the jobs to inherit or implement a special Jesque class. Because of this, the jobs don't even need to know about Jesque at all. Furthermore, the client need not have the job's Class in its VM, it only needs to know the classname and all the parameters' Classes on its classpath. Only the workers realize the job and then run them.
• I chose to use Jedis because:
  1. It is simple to use
  2. Fully supports Redis 2.0 and uses the new unified protocol
  3. No dependencies
• I chose to use Jackson because:
  1. I was already familiar with it
  2. It performs great and does what it says on the tin
  3. No dependencies
• I chose to use SLF4J because:
  1. It lets the application choose how to log
  2. No dependencies

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Misc.

If you are on Mac OS X, I highly recommend using the fantasic Homebrew package manager. It makes installing and maintaining libraries, tools and applications a cinch. E.g.:

brew install redis
brew install git
brew install maven

Boom! Ready to go!

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License

Copyright 2021 Greg Haines

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.