io.helidon.security.jersey.InputStreamPublisher Maven / Gradle / Ivy
/*
* Copyright (c) 2018 Oracle and/or its affiliates. All rights reserved.
*
* 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.
*/
package io.helidon.security.jersey;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.atomic.AtomicBoolean;
import io.helidon.common.reactive.Flow;
/**
* Publisher that reads data from an input stream and publishes them as {@link ByteBuffer} events.
*/
@SuppressWarnings("Duplicates")
class InputStreamPublisher implements Flow.Publisher {
private final InputStream inputStream;
private final byte[] buffer;
private final SingleSubscriberHolder subscriber = new SingleSubscriberHolder<>();
private final RequestedCounter requested = new RequestedCounter();
private final AtomicBoolean publishing = new AtomicBoolean(false);
/**
* Create new input stream publisher that reads data from a supplied input stream and publishes them a single subscriber.
*
* Note that this implementation does not rely on any asynchronous processing and its business logic is always invoked
* on the subscriber thread (as part of {@link #subscribe(Flow.Subscriber)} and {@link Flow.Subscription#request(long)}
* method calls).
*
* @param inputStream underlying input stream to be used to read the data tu be published as events.
* @param bufferSize maximum published event data buffer size.
*/
InputStreamPublisher(InputStream inputStream, int bufferSize) {
this.inputStream = inputStream;
this.buffer = new byte[bufferSize];
}
@Override
public void subscribe(Flow.Subscriber subscriberParam) {
if (subscriber.register(subscriberParam)) {
publishing.set(true); // prevent onNext from inside of onSubscribe
try {
subscriberParam.onSubscribe(new Flow.Subscription() {
@Override
public void request(long n) {
requested.increment(n, t -> tryComplete(t));
tryPublish();
}
@Override
public void cancel() {
}
});
} finally {
publishing.set(false);
}
tryPublish(); // give onNext a chance in case request has been invoked in onSubscribe
}
}
private void tryPublish() {
while (!subscriber.isClosed() && (requested.get() > 0) && publishing.compareAndSet(false, true)) {
try {
final Flow.Subscriber sub = this.subscriber.get(); // blocking retrieval
while (!subscriber.isClosed() && requested.tryDecrement()) {
int len = inputStream.read(buffer);
if (len >= 0) {
sub.onNext(ByteBuffer.wrap(buffer, 0, len));
} else {
tryComplete();
}
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
tryComplete(e);
} catch (IOException | ExecutionException e) {
tryComplete(e);
} finally {
publishing.set(false); // give a chance to some other thread to publish
}
}
}
private void tryComplete() {
subscriber.close(Flow.Subscriber::onComplete);
}
private void tryComplete(Throwable t) {
subscriber.close(sub -> sub.onError(t));
}
}