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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 com.signalfx.shaded.apache.commons.io.input;
import static com.signalfx.shaded.apache.commons.io.IOUtils.EOF;
import java.io.IOException;
import java.io.InputStream;
import java.io.PipedInputStream;
import java.io.PipedOutputStream;
import java.time.Duration;
import java.util.Objects;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import com.signalfx.shaded.apache.commons.io.build.AbstractStreamBuilder;
import com.signalfx.shaded.apache.commons.io.output.QueueOutputStream;
/**
* Simple alternative to JDK {@link java.io.PipedInputStream}; queue input stream provides what's written in queue output stream.
*
* To build an instance, see {@link Builder}.
*
*
* Example usage:
*
*
*
* QueueInputStream inputStream = new QueueInputStream();
* QueueOutputStream outputStream = inputStream.newQueueOutputStream();
*
* outputStream.write("hello world".getBytes(UTF_8));
* inputStream.read();
*
*
* Unlike JDK {@link PipedInputStream} and {@link PipedOutputStream}, queue input/output streams may be used safely in a single thread or multiple threads.
* Also, unlike JDK classes, no special meaning is attached to initial or current thread. Instances can be used longer after initial threads exited.
*
*
* Closing a {@link QueueInputStream} has no effect. The methods in this class can be called after the stream has been closed without generating an
* {@link IOException}.
*
*
* @see QueueOutputStream
* @since 2.9.0
*/
public class QueueInputStream extends InputStream {
/**
* Builds a new {@link QueueInputStream} instance.
*
* For example:
*
*
* {@code
* QueueInputStream s = QueueInputStream.builder()
* .setBlockingQueue(new LinkedBlockingQueue<>())
* .setTimeout(Duration.ZERO)
* .get();}
*
*
* @since 2.12.0
*/
public static class Builder extends AbstractStreamBuilder {
private BlockingQueue blockingQueue = new LinkedBlockingQueue<>();
private Duration timeout = Duration.ZERO;
/**
* Constructs a new instance.
*
* This builder use the aspects BlockingQueue and timeout.
*
*
* @return a new instance.
*/
@Override
public QueueInputStream get() {
return new QueueInputStream(blockingQueue, timeout);
}
/**
* Sets backing queue for the stream.
*
* @param blockingQueue backing queue for the stream.
* @return this
*/
public Builder setBlockingQueue(final BlockingQueue blockingQueue) {
this.blockingQueue = blockingQueue != null ? blockingQueue : new LinkedBlockingQueue<>();
return this;
}
/**
* Sets the polling timeout.
*
* @param timeout the polling timeout.
* @return this.
*/
public Builder setTimeout(final Duration timeout) {
if (timeout != null && timeout.toNanos() < 0) {
throw new IllegalArgumentException("timeout must not be negative");
}
this.timeout = timeout != null ? timeout : Duration.ZERO;
return this;
}
}
/**
* Constructs a new {@link Builder}.
*
* @return a new {@link Builder}.
* @since 2.12.0
*/
public static Builder builder() {
return new Builder();
}
private final BlockingQueue blockingQueue;
private final long timeoutNanos;
/**
* Constructs a new instance with no limit to its internal queue size and zero timeout.
*/
public QueueInputStream() {
this(new LinkedBlockingQueue<>());
}
/**
* Constructs a new instance with given queue and zero timeout.
*
* @param blockingQueue backing queue for the stream.
* @deprecated Use {@link #builder()}, {@link Builder}, and {@link Builder#get()}.
*/
@Deprecated
public QueueInputStream(final BlockingQueue blockingQueue) {
this(blockingQueue, Duration.ZERO);
}
/**
* Constructs a new instance with given queue and timeout.
*
* @param blockingQueue backing queue for the stream.
* @param timeout how long to wait before giving up when polling the queue.
*/
private QueueInputStream(final BlockingQueue blockingQueue, final Duration timeout) {
this.blockingQueue = Objects.requireNonNull(blockingQueue, "blockingQueue");
this.timeoutNanos = Objects.requireNonNull(timeout, "timeout").toNanos();
}
/**
* Gets the blocking queue.
*
* @return the blocking queue.
*/
BlockingQueue getBlockingQueue() {
return blockingQueue;
}
/**
* Gets the timeout duration.
*
* @return the timeout duration.
*/
Duration getTimeout() {
return Duration.ofNanos(timeoutNanos);
}
/**
* Constructs a new QueueOutputStream instance connected to this. Writes to the output stream will be visible to this input stream.
*
* @return QueueOutputStream connected to this stream.
*/
public QueueOutputStream newQueueOutputStream() {
return new QueueOutputStream(blockingQueue);
}
/**
* Reads and returns a single byte.
*
* @return the byte read, or {@code -1} if a timeout occurs before a queue element is available.
* @throws IllegalStateException if thread is interrupted while waiting.
*/
@Override
public int read() {
try {
final Integer value = blockingQueue.poll(timeoutNanos, TimeUnit.NANOSECONDS);
return value == null ? EOF : 0xFF & value;
} catch (final InterruptedException e) {
Thread.currentThread().interrupt();
// throw runtime unchecked exception to maintain signature backward-compatibility of
// this read method, which does not declare IOException
throw new IllegalStateException(e);
}
}
}