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| package com.tools.demo.forker;
import org.apache.commons.collections.map.HashedMap;
import java.util.*;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* 并发方式在同一个流上执行多种操作
*/
public class StreamForker<T> {
private final Stream<T> stream;
private final Map<Object,Function<Stream<T>,?>> forks = new HashedMap();
public StreamForker(Stream<T> stream){
this.stream = stream;
}
public StreamForker<T> forker(Object key,Function<Stream<T>,?> f){
forks.put(key,f);
return this;
}
public Results getResult(){
ForkingStreamComsumer<T> comsumer = build();
try {
stream.sequential().forEach(comsumer);
}finally {
comsumer.finish();
}
return comsumer;
}
public static interface Results{
public <R> R get(Object key);
}
private ForkingStreamComsumer<T> build(){
List<BlockingQueue<T>> queues = new ArrayList<>();
Map<Object,Future<?>> actions = forks.entrySet().stream().reduce(
new HashMap<Object,Future<?>>(),
(map,e)->{
map.put(e.getKey(),getOperationResult(queues,e.getValue()));
return map;
},
(m1,m2)->{
m1.putAll(m2);
return m1;
});
return new ForkingStreamComsumer<>(queues,actions);
}
private Future<?> getOperationResult(List<BlockingQueue<T>> queues, Function<Stream<T>, ?> f) {
BlockingQueue<T> queue = new LinkedBlockingDeque<>();
queues.add(queue);
Spliterator<T> spliterator = new BlockingQueueSpliterator<>(queue);
Stream<T> source = StreamSupport.stream(spliterator, false);
return CompletableFuture.supplyAsync(()->f.apply(source));
}
static class ForkingStreamComsumer<T> implements Consumer<T>,Results {
static final Object END_OF_STREAM = new Object();
private final List<BlockingQueue<T>> queues;
private final Map<Object,Future<?>> actions;
ForkingStreamComsumer(List<BlockingQueue<T>> queues,Map<Object,Future<?>> actions){
this.queues=queues;
this.actions=actions;
}
void finish(){
accept((T)END_OF_STREAM);
}
@Override
public <R> R get(Object key) {
try {
return ((Future<R>) actions.get(key)).get();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
@Override
public void accept(T t) {
queues.forEach(q->q.add(t));
}
}
class BlockingQueueSpliterator<T> implements Spliterator<T>{
private final BlockingQueue<T> q;
public BlockingQueueSpliterator(BlockingQueue<T> q) {
this.q = q;
}
@Override
public boolean tryAdvance(Consumer<? super T> action) {
T t;
while (true){
try {
t = q.take();
break;
}catch (Exception e){}
}
if(t != ForkingStreamComsumer.END_OF_STREAM){
action.accept(t);
return true;
}
return false;
}
@Override
public Spliterator<T> trySplit() {
return null;
}
@Override
public long estimateSize() {
return 0;
}
@Override
public int characteristics() {
return 0;
}
}
public static void main(String[] args) {
}
}
|