001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.reef.wake.examples.join; 020 021import org.apache.reef.wake.rx.Observer; 022import org.apache.reef.wake.rx.StaticObservable; 023 024import java.util.concurrent.ConcurrentSkipListSet; 025 026/** 027 * Blocking join. 028 */ 029public class BlockingJoin implements StaticObservable { 030 private final Observer<TupleEvent> out; 031 private final ConcurrentSkipListSet<TupleEvent> left = new ConcurrentSkipListSet<>(); 032 private boolean leftDone = false; 033 034 public BlockingJoin(final Observer<TupleEvent> out) { 035 this.out = out; 036 } 037 038 private synchronized void tellEveryoneLeftIsDone() { 039 leftDone = true; 040 notifyAll(); 041 } 042 043 private synchronized void waitUntilLeftIsDone() { 044 while (!leftDone) { 045 try { 046 wait(); 047 } catch (final InterruptedException e) { 048 throw new IllegalStateException( 049 "No support for interrupted threads here!", e); 050 } 051 } 052 } 053 054 public Observer<TupleEvent> wireLeft() { 055 return new Observer<TupleEvent>() { 056 057 @Override 058 public void onNext(final TupleEvent value) { 059 left.add(value); 060 } 061 062 @Override 063 public void onError(final Exception error) { 064 065 } 066 067 @Override 068 public void onCompleted() { 069 tellEveryoneLeftIsDone(); 070 } 071 072 }; 073 } 074 075 public Observer<TupleEvent> wireRight() { 076 return new Observer<TupleEvent>() { 077 078 @Override 079 public void onNext(final TupleEvent value) { 080 if (!leftDone) { 081 waitUntilLeftIsDone(); 082 } 083 if (left.contains(value)) { 084 out.onNext(value); 085 } 086 } 087 088 @Override 089 public void onError(final Exception error) { 090 } 091 092 @Override 093 public void onCompleted() { 094 waitUntilLeftIsDone(); 095 out.onCompleted(); 096 } 097 }; 098 } 099}