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/*
* Copyright (C) 2015 SoftIndex LLC.
*
* 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.datakernel.stream;
import io.datakernel.async.AsyncGetter;
import io.datakernel.async.ResultCallback;
import io.datakernel.eventloop.Eventloop;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
public class StreamConsumers {
private StreamConsumers() {
}
public static Idle idle(Eventloop eventloop) {
return new Idle<>(eventloop);
}
public static Closing closing(Eventloop eventloop) {
return new Closing<>(eventloop);
}
public static ClosingWithError closingWithError(Eventloop eventloop, Exception exception) {
return new ClosingWithError<>(eventloop, exception);
}
/**
* Returns {@link ToList} which saves received items in list
*
* @param eventloop event loop in which will run it
* @param list list with received items
* @param type of item
*/
public static ToList toList(Eventloop eventloop, List list) {
return new ToList<>(eventloop, list);
}
/**
* Returns {@link ToList} which saves received items in empty list
*
* @param eventloop event loop in which will run it
* @param type of item
*/
public static ToList toList(Eventloop eventloop) {
return toList(eventloop, new ArrayList());
}
/**
* Returns {@link ToList} which suspends after each receiving data with saving it to list.
*
* @param eventloop event loop in which will run it
* @param list list with received items
* @param type of item
*/
public static ToList toListOneByOne(Eventloop eventloop, List list) {
return new ToList(eventloop, list) {
@Override
public void onData(T item) {
super.onData(item);
upstreamProducer.suspend();
this.eventloop.post(new Runnable() {
@Override
public void run() {
upstreamProducer.resume();
}
});
}
};
}
/**
* Returns {@link ToList} which suspends after each receiving data with saving it to empty list.
*
* @param eventloop event loop in which will run it
* @param type of item
*/
public static ToList toListOneByOne(Eventloop eventloop) {
return toListOneByOne(eventloop, new ArrayList());
}
/**
* Returns {@link ToList} which suspends after some random receiving data with saving it to list from
* argument.
* Useful for unit testing purposes - to make sure upstream producer handles onSuspend and onResume events properly
*
* @param eventloop event loop in which will run it
* @param list list with received items
* @param random for generate random values of boolean
* @param type of item
*/
public static ToList toListRandomlySuspending(Eventloop eventloop, List list, final Random random) {
return new ToList(eventloop, list) {
@Override
public void onData(T item) {
super.onData(item);
if (random.nextBoolean()) {
suspendUpstream();
this.eventloop.post(new Runnable() {
@Override
public void run() {
resumeUpstream();
}
});
}
}
};
}
/**
* Returns {@link ToList} which suspends after default random receiving data with saving it to list
* from argument.
*
* @param eventloop event loop in which will run it
* @param list list with received items
* @param type of item
*/
public static ToList toListRandomlySuspending(Eventloop eventloop, List list) {
return toListRandomlySuspending(eventloop, list, new Random());
}
/**
* Returns {@link ToList} which suspends after default random receiving data with saving it to empty list.
*
* @param eventloop event loop in which will run it
* @param type of item
*/
public static ToList toListRandomlySuspending(Eventloop eventloop) {
return toListRandomlySuspending(eventloop, new ArrayList(), new Random());
}
public static StreamConsumer asynchronouslyResolving(final Eventloop eventloop, final AsyncGetter> consumerGetter) {
final StreamForwarder forwarder = new StreamForwarder<>(eventloop);
eventloop.post(new Runnable() {
@Override
public void run() {
consumerGetter.get(new ResultCallback>() {
@Override
public void onResult(StreamConsumer result) {
forwarder.streamTo(result);
}
@Override
public void onException(Exception exception) {
forwarder.streamTo(new ClosingWithError(eventloop, exception));
}
});
}
});
return forwarder;
}
/**
* Represents a simple {@link AbstractStreamConsumer} which with changing producer sets its status as complete.
*
* @param type of received data
*/
public static class Closing extends AbstractStreamConsumer implements StreamDataReceiver {
public Closing(Eventloop eventloop) {
super(eventloop);
}
/**
* With changing producer sets its status as complete.
*/
@Override
public void onConsumerStarted() {
upstreamProducer.close();
}
@Override
public StreamDataReceiver getDataReceiver() {
return this;
}
@Override
public void onData(T item) {
// do nothing
}
@Override
public void onEndOfStream() {
}
}
public static class ClosingWithError extends AbstractStreamConsumer implements StreamDataReceiver {
private final Exception exception;
public ClosingWithError(Eventloop eventloop, Exception exception) {
super(eventloop);
this.exception = exception;
}
@Override
public void onConsumerStarted() {
upstreamProducer.closeWithError(exception);
}
@Override
public StreamDataReceiver getDataReceiver() {
return this;
}
@Override
public void onData(T item) {
// do nothing
}
@Override
public void onEndOfStream() {
}
}
/**
* Represents a simple {@link AbstractStreamConsumer} which with changing producer sets its status as complete.
*
* @param type of received data
*/
public static class Idle extends AbstractStreamConsumer implements StreamDataReceiver {
public Idle(Eventloop eventloop) {
super(eventloop);
}
@Override
public StreamDataReceiver getDataReceiver() {
return this;
}
@Override
public void onData(T item) {
// do nothing
}
@Override
public void onEndOfStream() {
upstreamProducer.close();
}
}
/**
* Represents a {@link AbstractStreamConsumer} which adds each item of received data to List.
*
* @param type of received data
*/
public static class ToList extends AbstractStreamConsumer implements StreamDataReceiver {
private final List list;
/**
* Creates a new instance of ConsumerToList with empty list and event loop from argument, in which
* this customer will run
*/
public ToList(Eventloop eventloop) {
this(eventloop, new ArrayList());
}
/**
* Creates a new instance of ConsumerToList with
*
* @param eventloop event loop in which this customer will run
* @param list list for adding received items
*/
public ToList(Eventloop eventloop, List list) {
super(eventloop);
checkNotNull(list);
this.list = list;
}
/**
* Returns list with received items
*/
public final List getList() {
checkState(upstreamProducer.getError() == null, "Upstream error %s: %s", upstreamProducer, upstreamProducer.getError());
checkState(upstreamProducer.getStatus() == StreamProducer.CLOSED, "Upstream %s is not closed", upstreamProducer);
return list;
}
@Override
public StreamDataReceiver getDataReceiver() {
return this;
}
/**
* Processes received item and adds it to list
*
* @param item received item
*/
@Override
public void onData(T item) {
list.add(item);
}
/**
* Sets the flag complete as true
*/
@Override
public void onEndOfStream() {
upstreamProducer.close();
}
}
}