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Work on #403, removed dependency on async method invocation module, added more tests

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This commit is contained in:
Narendra Pathai
2016-07-22 16:47:52 +05:30
parent 4bd1f14cfb
commit 2b945ca27f
5 changed files with 275 additions and 76 deletions
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26
promise/src/main/java/com/iluwatar/promise/App.java
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@@ -1,6 +1,9 @@
package com.iluwatar.promise;
import com.iluwatar.async.method.invocation.ThreadAsyncExecutor;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
*
@@ -12,10 +15,19 @@ public class App {
* Program entry point
* @param args arguments
* @throws InterruptedException if main thread is interruped.
* @throws ExecutionException
*/
public static void main(String[] args) throws InterruptedException {
ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
public static void main(String[] args) throws InterruptedException, ExecutionException {
ExecutorService executor = Executors.newSingleThreadExecutor();
try {
promiseUsage(executor);
} finally {
executor.shutdownNow();
}
}
private static void promiseUsage(Executor executor)
throws InterruptedException, ExecutionException {
Promise<Integer> consumedPromise = new Promise<>();
consumedPromise.fulfillInAsync(() -> {
Thread.sleep(1000);
@@ -29,10 +41,10 @@ public class App {
Thread.sleep(1000);
return "10";
}, executor).then(value -> { return Integer.parseInt(value); }).then(value -> {
System.out.println(value);
System.out.println("Consumed transformed int value: " + value);
});
consumedPromise.await();
transformedPromise.await();
consumedPromise.get();
transformedPromise.get();
}
}

169
promise/src/main/java/com/iluwatar/promise/Promise.java
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@@ -2,17 +2,18 @@ package com.iluwatar.promise;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Consumer;
import java.util.function.Function;
import com.iluwatar.async.method.invocation.AsyncExecutor;
import com.iluwatar.async.method.invocation.internal.CompletableResult;
/**
* Implements the promise pattern.
* @param <T> type of result.
*/
public class Promise<T> extends CompletableResult<T> {
public class Promise<T> extends PromiseSupport<T> {
private Runnable fulfillmentAction;
@@ -20,31 +21,30 @@ public class Promise<T> extends CompletableResult<T> {
* Creates a promise that will be fulfilled in future.
*/
public Promise() {
super(null);
}
/**
* Fulfills the promise with the provided value.
* @param value the fulfilled value that can be accessed using {@link #getValue()}.
* @param value the fulfilled value that can be accessed using {@link #get()}.
*/
@Override
public void setValue(T value) {
super.setValue(value);
postComplete();
public void fulfill(T value) {
super.fulfill(value);
postFulfillment();
}
/**
* Fulfills the promise with exception due to error in execution.
* @param exception the exception will be wrapped in {@link ExecutionException}
* when accessing the value using {@link #getValue()}.
* when accessing the value using {@link #get()}.
*/
@Override
public void setException(Exception exception) {
super.setException(exception);
postComplete();
public void fulfillExceptionally(Exception exception) {
super.fulfillExceptionally(exception);
postFulfillment();
}
void postComplete() {
void postFulfillment() {
if (fulfillmentAction == null) {
return;
}
@@ -59,13 +59,12 @@ public class Promise<T> extends CompletableResult<T> {
* @param executor the executor in which the task should be run.
* @return a promise that represents the result of running the task provided.
*/
public Promise<T> fulfillInAsync(final Callable<T> task, AsyncExecutor executor) {
executor.startProcess(new Callable<Void>() {
@Override
public Void call() throws Exception {
setValue(task.call());
return null;
public Promise<T> fulfillInAsync(final Callable<T> task, Executor executor) {
executor.execute(() -> {
try {
fulfill(task.call());
} catch (Exception e) {
fulfillExceptionally(e);
}
});
return this;
@@ -91,18 +90,22 @@ public class Promise<T> extends CompletableResult<T> {
*/
public <V> Promise<V> then(Function<? super T, V> func) {
Promise<V> dest = new Promise<>();
fulfillmentAction = new FunctionAction<V>(this, dest, func);
fulfillmentAction = new TransformAction<V>(this, dest, func);
return dest;
}
/**
* A consume action provides the action, the value from source promise and fulfills the
* destination promise.
*/
private class ConsumeAction implements Runnable {
private Promise<T> current;
private Promise<T> src;
private Promise<Void> dest;
private Consumer<? super T> action;
public ConsumeAction(Promise<T> current, Promise<Void> dest, Consumer<? super T> action) {
this.current = current;
ConsumeAction(Promise<T> src, Promise<Void> dest, Consumer<? super T> action) {
this.src = src;
this.dest = dest;
this.action = action;
}
@@ -110,22 +113,26 @@ public class Promise<T> extends CompletableResult<T> {
@Override
public void run() {
try {
action.accept(current.getValue());
dest.setValue(null);
action.accept(src.get());
dest.fulfill(null);
} catch (Throwable e) {
dest.setException((Exception) e.getCause());
dest.fulfillExceptionally((Exception) e.getCause());
}
}
}
private class FunctionAction<V> implements Runnable {
/**
* A function action provides transformation function, value from source promise and fulfills the
* destination promise with the transformed value.
*/
private class TransformAction<V> implements Runnable {
private Promise<T> current;
private Promise<T> src;
private Promise<V> dest;
private Function<? super T, V> func;
public FunctionAction(Promise<T> current, Promise<V> dest, Function<? super T, V> func) {
this.current = current;
TransformAction(Promise<T> src, Promise<V> dest, Function<? super T, V> func) {
this.src = src;
this.dest = dest;
this.func = func;
}
@@ -133,11 +140,103 @@ public class Promise<T> extends CompletableResult<T> {
@Override
public void run() {
try {
V result = func.apply(current.getValue());
dest.setValue(result);
V result = func.apply(src.get());
dest.fulfill(result);
} catch (Throwable e) {
dest.setException((Exception) e.getCause());
dest.fulfillExceptionally((Exception) e.getCause());
}
}
}
}
/**
* A really simplified implementation of future that allows completing it successfully with a value
* or exceptionally with an exception.
*/
class PromiseSupport<T> implements Future<T> {
static final int RUNNING = 1;
static final int FAILED = 2;
static final int COMPLETED = 3;
final Object lock;
volatile int state = RUNNING;
T value;
Exception exception;
PromiseSupport() {
this.lock = new Object();
}
void fulfill(T value) {
this.value = value;
this.state = COMPLETED;
synchronized (lock) {
lock.notifyAll();
}
}
void fulfillExceptionally(Exception exception) {
this.exception = exception;
this.state = FAILED;
synchronized (lock) {
lock.notifyAll();
}
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
return false;
}
@Override
public boolean isCancelled() {
return false;
}
@Override
public boolean isDone() {
return state > RUNNING;
}
@Override
public T get() throws InterruptedException, ExecutionException {
if (state == COMPLETED) {
return value;
} else if (state == FAILED) {
throw new ExecutionException(exception);
} else {
synchronized (lock) {
lock.wait();
if (state == COMPLETED) {
return value;
} else {
throw new ExecutionException(exception);
}
}
}
}
@Override
public T get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
if (state == COMPLETED) {
return value;
} else if (state == FAILED) {
throw new ExecutionException(exception);
} else {
synchronized (lock) {
lock.wait(unit.toMillis(timeout));
if (state == COMPLETED) {
return value;
} else if (state == FAILED) {
throw new ExecutionException(exception);
} else {
throw new TimeoutException();
}
}
}
}
}

4
promise/src/test/java/com/iluwatar/promise/AppTest.java
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@@ -1,5 +1,7 @@
package com.iluwatar.promise;
import java.util.concurrent.ExecutionException;
import org.junit.Test;
/**
@@ -9,7 +11,7 @@ import org.junit.Test;
public class AppTest {
@Test
public void testApp() throws InterruptedException {
public void testApp() throws InterruptedException, ExecutionException {
App.main(null);
}
}

147
promise/src/test/java/com/iluwatar/promise/PromiseTest.java
View File

@@ -1,9 +1,16 @@
package com.iluwatar.promise;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Consumer;
import java.util.function.Function;
@@ -12,20 +19,18 @@ import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;
import com.iluwatar.async.method.invocation.ThreadAsyncExecutor;
/**
* Tests Promise class.
*/
public class PromiseTest {
private ThreadAsyncExecutor executor;
private Executor executor;
private Promise<Integer> promise;
@Rule public ExpectedException exception = ExpectedException.none();
@Before
public void setUp() {
executor = new ThreadAsyncExecutor();
executor = Executors.newSingleThreadExecutor();
promise = new Promise<>();
}
@@ -34,10 +39,70 @@ public class PromiseTest {
throws InterruptedException, ExecutionException {
promise.fulfillInAsync(new NumberCrunchingTask(), executor);
// await fulfillment
promise.await();
assertEquals(NumberCrunchingTask.CRUNCHED_NUMBER, promise.get());
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
@Test
public void promiseIsFulfilledWithAnExceptionIfTaskThrowsAnException()
throws InterruptedException, ExecutionException, TimeoutException {
testWaitingForeverForPromiseToBeFulfilled();
testWaitingSomeTimeForPromiseToBeFulfilled();
}
assertEquals(NumberCrunchingTask.CRUNCHED_NUMBER, promise.getValue());
private void testWaitingForeverForPromiseToBeFulfilled() throws InterruptedException, TimeoutException {
Promise<Integer> promise = new Promise<>();
promise.fulfillInAsync(new Callable<Integer>() {
@Override
public Integer call() throws Exception {
throw new RuntimeException("Barf!");
}}, executor);
try {
promise.get();
fail("Fetching promise should result in exception if the task threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
try {
promise.get(1000, TimeUnit.SECONDS);
fail("Fetching promise should result in exception if the task threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
}
private void testWaitingSomeTimeForPromiseToBeFulfilled()
throws InterruptedException, TimeoutException {
Promise<Integer> promise = new Promise<>();
promise.fulfillInAsync(new Callable<Integer>() {
@Override
public Integer call() throws Exception {
throw new RuntimeException("Barf!");
}}, executor);
try {
promise.get(1000, TimeUnit.SECONDS);
fail("Fetching promise should result in exception if the task threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
try {
promise.get();
fail("Fetching promise should result in exception if the task threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
}
@Test
@@ -50,13 +115,14 @@ public class PromiseTest {
});
// await fulfillment
dependentPromise.await();
dependentPromise.get();
assertTrue(dependentPromise.isDone());
assertFalse(dependentPromise.isCancelled());
}
@Test
public void dependentPromiseIsFulfilledWithAnExceptionIfConsumerThrowsAnException()
throws InterruptedException, ExecutionException {
throws InterruptedException, ExecutionException, TimeoutException {
Promise<Void> dependentPromise = promise
.fulfillInAsync(new NumberCrunchingTask(), executor)
.then(new Consumer<Integer>() {
@@ -67,13 +133,21 @@ public class PromiseTest {
}
});
// await fulfillment
dependentPromise.await();
exception.expect(ExecutionException.class);
dependentPromise.getValue();
try {
dependentPromise.get();
fail("Fetching dependent promise should result in exception if the action threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
try {
dependentPromise.get(1000, TimeUnit.SECONDS);
fail("Fetching dependent promise should result in exception if the action threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
}
@Test
@@ -87,15 +161,14 @@ public class PromiseTest {
});
// await fulfillment
dependentPromise.await();
assertEquals(String.valueOf(NumberCrunchingTask.CRUNCHED_NUMBER), dependentPromise.getValue());
assertEquals(String.valueOf(NumberCrunchingTask.CRUNCHED_NUMBER), dependentPromise.get());
assertTrue(dependentPromise.isDone());
assertFalse(dependentPromise.isCancelled());
}
@Test
public void dependentPromiseIsFulfilledWithAnExceptionIfTheFunctionThrowsException()
throws InterruptedException, ExecutionException {
throws InterruptedException, ExecutionException, TimeoutException {
Promise<String> dependentPromise = promise
.fulfillInAsync(new NumberCrunchingTask(), executor)
.then(new Function<Integer, String>() {
@@ -106,12 +179,30 @@ public class PromiseTest {
}
});
// await fulfillment
dependentPromise.await();
exception.expect(ExecutionException.class);
dependentPromise.getValue();
try {
dependentPromise.get();
fail("Fetching dependent promise should result in exception if the function threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
try {
dependentPromise.get(1000, TimeUnit.SECONDS);
fail("Fetching dependent promise should result in exception if the function threw an exception");
} catch (ExecutionException ex) {
assertTrue(promise.isDone());
assertFalse(promise.isCancelled());
}
}
@Test
public void fetchingAnAlreadyFulfilledPromiseReturnsTheFulfilledValueImmediately()
throws InterruptedException, ExecutionException, TimeoutException {
Promise<Integer> promise = new Promise<>();
promise.fulfill(NumberCrunchingTask.CRUNCHED_NUMBER);
promise.get(1000, TimeUnit.SECONDS);
}
private static class NumberCrunchingTask implements Callable<Integer> {