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Examples 4.1 Scheduling
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‎tests/java/itrx/chapter4/scheduling/ObserveOnTest.java‎

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package itrx.chapter4.scheduling;
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import static org.junit.Assert.*;
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import org.junit.Assert;
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import org.junit.Test;
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import rx.Observable;
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import rx.schedulers.Schedulers;
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public class ObserveOnTest {
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public void exampleObserveOn() {
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Observable.create(o -> {
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System.out.println("Created on " + Thread.currentThread().getId());
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o.onNext(1);
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o.onNext(2);
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o.onCompleted();
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})
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.observeOn(Schedulers.newThread())
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.subscribe(i ->
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System.out.println("Received " + i + " on " + Thread.currentThread().getId()));
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// Created on 1
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// Received 1 on 13
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// Received 2 on 13
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}
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public void exampleObserveOnBeforeAfter() {
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Observable.create(o -> {
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System.out.println("Created on " + Thread.currentThread().getId());
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o.onNext(1);
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o.onNext(2);
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o.onCompleted();
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})
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.doOnNext(i ->
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System.out.println("Before " + i + " on " + Thread.currentThread().getId()))
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.observeOn(Schedulers.newThread())
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.doOnNext(i ->
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System.out.println("After " + i + " on " + Thread.currentThread().getId()))
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.subscribe();
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// Created on 1
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// Before 1 on 1
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// Before 2 on 1
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// After 1 on 13
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// After 2 on 13
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}
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//
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// Test
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//
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@Test
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public void testObserveOn() {
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long[] threads = {0, 0};
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Observable.create(o -> {
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threads[0] = Thread.currentThread().getId();
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o.onNext(1);
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o.onNext(2);
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o.onCompleted();
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})
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.observeOn(Schedulers.newThread())
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.subscribe(i -> threads[1] = Thread.currentThread().getId());
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Assert.assertNotEquals("Create and receive on different threads", threads[0], threads[1]);
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}
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@Test
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public void testObserveOnBeforeAfter() {
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long[] threads = {0, 0, 0, 0, 0};
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threads[0] = Thread.currentThread().getId();
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Observable.create(o -> {
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threads[1] = Thread.currentThread().getId();
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o.onNext(1);
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o.onNext(2);
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o.onCompleted();
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})
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.doOnNext(i -> threads[2] = Thread.currentThread().getId())
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.observeOn(Schedulers.newThread())
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.doOnNext(i -> threads[3] = Thread.currentThread().getId())
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.subscribe(i -> threads[4] = Thread.currentThread().getId());
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assertEquals("Create on main thread", threads[0], threads[1]);
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assertEquals("Synchronous before observeOn", threads[1], threads[2]);
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assertEquals("Synchronous after observeOn", threads[3], threads[4]);
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assertNotEquals("Before and after observeOn on different threads", threads[2], threads[3]);
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}
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}

‎tests/java/itrx/chapter4/scheduling/SchedulerTest.java‎

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package itrx.chapter4.scheduling;
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import static org.junit.Assert.*;
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import java.lang.Thread.State;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.concurrent.TimeUnit;
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import org.junit.Test;
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import rx.Scheduler;
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import rx.schedulers.Schedulers;
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import rx.schedulers.TestScheduler;
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public class SchedulerTest {
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public void exampleSchedule() {
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Scheduler scheduler = Schedulers.immediate();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(
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() -> System.out.println("Action"));
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}
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public void exampleScheduleFuture() {
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Scheduler scheduler = Schedulers.newThread();
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long start = System.currentTimeMillis();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(
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() -> System.out.println(System.currentTimeMillis()-start),
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5, TimeUnit.SECONDS);
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worker.schedule(
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() -> System.out.println(System.currentTimeMillis()-start),
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5, TimeUnit.SECONDS);
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// 5033
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// 5035
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}
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public void exampleCancelWork() {
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Scheduler scheduler = Schedulers.newThread();
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long start = System.currentTimeMillis();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(
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() -> {
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System.out.println(System.currentTimeMillis()-start);
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worker.unsubscribe();
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},
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5, TimeUnit.SECONDS);
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worker.schedule(
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() -> System.out.println(System.currentTimeMillis()-start),
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5, TimeUnit.SECONDS);
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// 5032
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}
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public void exampleCancelWithInterrupt() throws InterruptedException {
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Scheduler scheduler = Schedulers.newThread();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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try {
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Thread.sleep(2000);
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System.out.println("Action completed");
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} catch (InterruptedException e) {
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System.out.println("Action interrupted");
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}
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});
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Thread.sleep(500);
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worker.unsubscribe();
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// Action interrupted
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}
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//
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// Test
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//
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@Test
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public void testSchedule() {
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List<Boolean> executed = new ArrayList<>();
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Scheduler scheduler = Schedulers.immediate();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(
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() -> executed.add(true));
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assertEquals(Arrays.asList(new Boolean(true)), executed);
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}
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@Test
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public void testScheduleFuture() {
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long[] executionTimes = {0, 0};
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TestScheduler scheduler = Schedulers.test();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(
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() -> executionTimes[0] = scheduler.now(),
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5, TimeUnit.SECONDS);
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worker.schedule(
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() -> executionTimes[1] = scheduler.now(),
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5, TimeUnit.SECONDS);
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scheduler.advanceTimeTo(5000, TimeUnit.MILLISECONDS);
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assertEquals("First task executed on time", 5000, executionTimes[0]);
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assertEquals("Second task executed on time", 5000, executionTimes[1]);
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}
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@Test
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public void testCancelWork() {
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long[] executionTimes = {0, 0};
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TestScheduler scheduler = Schedulers.test();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(
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() -> {
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executionTimes[0] = scheduler.now();
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worker.unsubscribe();
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},
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5, TimeUnit.SECONDS);
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worker.schedule(
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() -> executionTimes[1] = scheduler.now(),
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5, TimeUnit.SECONDS);
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scheduler.advanceTimeTo(5000, TimeUnit.MILLISECONDS);
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assertEquals("First task executed on time", 5000, executionTimes[0]);
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assertEquals("Second task never executed", 0, executionTimes[1]);
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}
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@Test
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public void testCancelWithInterrupt() throws InterruptedException {
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Scheduler scheduler = Schedulers.newThread();
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Scheduler.Worker worker = scheduler.createWorker();
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Thread[] workerThread = {null};
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Boolean[] interrupted = {false};
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worker.schedule(() -> {
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try {
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workerThread[0] = Thread.currentThread();
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Thread.sleep(100);
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} catch (InterruptedException e) {
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interrupted[0] = true;
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}
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});
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while (workerThread[0] == null ||
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workerThread[0].getState() != State.TIMED_WAITING)
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Thread.sleep(1); // Wait for task to sleep
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worker.unsubscribe();
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workerThread[0].join();
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assertTrue("Task must be interrupted before completing", interrupted[0]);
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}
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}

‎tests/java/itrx/chapter4/scheduling/SchedulersTest.java‎

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package itrx.chapter4.scheduling;
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import static org.junit.Assert.*;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.concurrent.Semaphore;
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import org.junit.Test;
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import rx.Scheduler;
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import rx.schedulers.Schedulers;
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public class SchedulersTest {
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public static void printThread(String message) {
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System.out.println(message + " on " + Thread.currentThread().getId());
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}
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public void exampleImmediate() {
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Scheduler scheduler = Schedulers.immediate();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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System.out.println("Start");
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worker.schedule(() -> System.out.println("Inner"));
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System.out.println("End");
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});
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// Start
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// Inner
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// End
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}
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public void exampleTrampoline() {
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Scheduler scheduler = Schedulers.trampoline();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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System.out.println("Start");
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worker.schedule(() -> System.out.println("Inner"));
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System.out.println("End");
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});
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// Start
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// End
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// Inner
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}
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public void exampleNewThread() throws InterruptedException {
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printThread("Main");
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Scheduler scheduler = Schedulers.newThread();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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printThread("Start");
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worker.schedule(() -> printThread("Inner"));
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printThread("End");
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});
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Thread.sleep(500);
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worker.schedule(() -> printThread("Again"));
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// Main on 1
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// Start on 11
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// End on 11
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// Inner on 11
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// Again on 11
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}
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//
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// Test
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//
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@Test
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public void testImmediate() {
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List<String> execution = new ArrayList<>();
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Scheduler scheduler = Schedulers.immediate();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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execution.add("Start");
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worker.schedule(() -> execution.add("Inner"));
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execution.add("End");
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});
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assertEquals(Arrays.asList("Start", "Inner", "End"), execution);
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}
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@Test
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public void testTrampoline() {
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List<String> execution = new ArrayList<>();
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Scheduler scheduler = Schedulers.trampoline();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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execution.add("Start");
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worker.schedule(() -> execution.add("Inner"));
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execution.add("End");
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});
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assertEquals(Arrays.asList("Start", "End", "Inner"), execution);
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}
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@Test
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public void testNewThread() throws InterruptedException {
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List<String> execution = new ArrayList<>();
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List<Thread> threads = new ArrayList<>();
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Semaphore workfinished = new Semaphore(-2);
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Scheduler scheduler = Schedulers.newThread();
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Scheduler.Worker worker = scheduler.createWorker();
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worker.schedule(() -> {
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threads.add(Thread.currentThread());
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execution.add("Start");
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worker.schedule(() -> {
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execution.add("Inner");
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workfinished.release();
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});
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execution.add("End");
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workfinished.release();
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});
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worker.schedule(() -> {
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threads.add(Thread.currentThread());
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workfinished.release();
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});
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workfinished.acquire();
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assertEquals("Same worker schedules on the same thread",
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threads.get(0),
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threads.get(1));
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assertEquals("New thread used as trampoline",
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Arrays.asList("Start", "End", "Inner"),
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execution);
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}
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}

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