JobChainingUsingTaskDataMain.java

/*
 * Copyright (C) Gustav Karlsson
 *
 * <p>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
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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.github.kagkarlsson.examples;

import com.github.kagkarlsson.examples.helpers.Example;
import com.github.kagkarlsson.scheduler.Scheduler;
import com.github.kagkarlsson.scheduler.task.CompletionHandler;
import com.github.kagkarlsson.scheduler.task.helper.CustomTask;
import com.github.kagkarlsson.scheduler.task.helper.Tasks;
import java.io.Serializable;
import java.time.Duration;
import java.time.Instant;
import javax.sql.DataSource;

public class JobChainingUsingTaskDataMain extends Example {

  public static void main(String[] args) {
    new JobChainingUsingTaskDataMain().runWithDatasource();
  }

  @Override
  public void run(DataSource dataSource) {

    final CustomTask<JobState> chainingTask =
        Tasks.custom("job-chain-poc", JobState.class)
            .execute(
                (taskInstance, executionContext) -> {

                  // For illustration, can be made less verbose using suitable abstractions etc
                  if (taskInstance.getData().currentStep == Step.STEP1) {
                    System.out.println("Step1 ran. Job: " + taskInstance.getData());
                    return (executionComplete, executionOperations) -> {
                      JobState nextJobState = taskInstance.getData().nextStep(Step.STEP2);
                      executionOperations.reschedule(
                          executionComplete, Instant.now(), nextJobState);
                      // Feature: Optionally expose a method
                      // executionContext.triggerCheckForDueExecutions() to hint at immediate
                      // execution
                    };

                  } else if (taskInstance.getData().currentStep == Step.STEP2) {
                    System.out.println("Step2 ran. Job: " + taskInstance.getData());
                    return (executionComplete, executionOperations) -> {
                      JobState nextJobState = taskInstance.getData().nextStep(Step.STEP3);
                      executionOperations.reschedule(
                          executionComplete, Instant.now(), nextJobState);
                    };

                  } else if (taskInstance.getData().currentStep == Step.STEP3) {
                    System.out.println(
                        "Step3 ran. Removing multistep-job. Job: " + taskInstance.getData());
                    return new CompletionHandler.OnCompleteRemove<>();

                  } else {
                    throw new RuntimeException("Unknown step: " + taskInstance.getData());
                  }
                });

    final Scheduler scheduler =
        Scheduler.create(dataSource, chainingTask)
            .enableImmediateExecution() // Bug: currently no effect, only works when using
            // schedulerClient
            .pollingInterval(Duration.ofSeconds(1))
            .build();

    scheduler.start();

    sleep(1_000);

    // Schedule a multistep job. Simulate some instance-specific data, id=507
    scheduler.schedule(
        chainingTask.instance("job-507", JobState.newJob(507)), Instant.now().plusSeconds(1));
  }

  public enum Step {
    STEP1,
    STEP2,
    STEP3
  }

  public static class JobState implements Serializable {
    private static long serialVersionUID = 1L;
    public Step currentStep;
    public int id;

    public JobState(int id, Step currentStep) {
      this.id = id;
      this.currentStep = currentStep;
    }

    public static JobState newJob(int id) {
      return new JobState(id, Step.STEP1);
    }

    public JobState nextStep(Step nextStep) {
      return new JobState(id, nextStep);
    }

    @Override
    public String toString() {
      return "JobState{" + "currentStep=" + currentStep + ", id=" + id + '}';
    }
  }
}