001/* 002 * (C) Copyright 2017 Nuxeo SA (http://nuxeo.com/) and others. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 * 016 * Contributors: 017 * bdelbosc 018 */ 019package org.nuxeo.lib.stream.pattern.consumer.internals; 020 021import static java.util.concurrent.Executors.newFixedThreadPool; 022 023import java.util.ArrayList; 024import java.util.List; 025import java.util.concurrent.Callable; 026import java.util.concurrent.CompletableFuture; 027import java.util.concurrent.ExecutionException; 028import java.util.concurrent.ExecutorService; 029import java.util.concurrent.Executors; 030import java.util.concurrent.ThreadFactory; 031import java.util.concurrent.atomic.AtomicInteger; 032 033import org.apache.commons.logging.Log; 034import org.apache.commons.logging.LogFactory; 035 036/** 037 * Execute a pool of callables. 038 * 039 * @since 9.1 040 */ 041public abstract class AbstractCallablePool<T> implements AutoCloseable { 042 private static final Log log = LogFactory.getLog(AbstractCallablePool.class); 043 044 protected final short nbThreads; 045 046 protected ExecutorService threadPool; 047 048 protected ExecutorService supplyThreadPool; 049 050 public AbstractCallablePool(short nbThreads) { 051 this.nbThreads = nbThreads; 052 } 053 054 /** 055 * Value to return when there was an exception during execution 056 */ 057 protected abstract T getErrorStatus(); 058 059 protected abstract Callable<T> getCallable(int i); 060 061 protected abstract String getThreadPrefix(); 062 063 protected abstract void afterCall(List<T> ret); 064 065 public int getNbThreads() { 066 return nbThreads; 067 } 068 069 public CompletableFuture<List<T>> start() { 070 supplyThreadPool = Executors.newSingleThreadExecutor(new NamedThreadFactory(getThreadPrefix() + "Pool")); 071 CompletableFuture<List<T>> ret = new CompletableFuture<>(); 072 CompletableFuture.supplyAsync(() -> { 073 try { 074 ret.complete(runPool()); 075 } catch (InterruptedException e) { 076 Thread.currentThread().interrupt(); 077 ret.completeExceptionally(e); 078 } catch (Exception e) { 079 log.error("Exception catch in pool: " + e.getMessage(), e); 080 ret.completeExceptionally(e); 081 } 082 return ret; 083 }, supplyThreadPool); 084 // the threadpool will shutdown once the task is done 085 supplyThreadPool.shutdown(); 086 return ret; 087 } 088 089 protected List<T> runPool() throws InterruptedException { 090 threadPool = newFixedThreadPool(nbThreads, new NamedThreadFactory(getThreadPrefix())); 091 log.warn("Start " + getThreadPrefix() + " Pool on " + nbThreads + " thread(s)."); 092 List<CompletableFuture<T>> futures = new ArrayList<>(nbThreads); 093 094 for (int i = 0; i < nbThreads; i++) { 095 Callable<T> callable = getCallable(i); 096 CompletableFuture<T> future = new CompletableFuture<>(); 097 CompletableFuture.supplyAsync(() -> { 098 try { 099 future.complete(callable.call()); 100 } catch (InterruptedException e) { 101 Thread.currentThread().interrupt(); 102 future.completeExceptionally(e); 103 } catch (Throwable e) { // NOSONAR 104 // Throwable is needed to catch all kind of problem that can happen in custom code 105 // when using future the UncaughtExceptionHandler is not reporting all errors. 106 // A LinkageError will stop silently the thread resulting in a hang during future.get 107 log.error("Exception catch in runner: " + e.getMessage(), e); 108 future.completeExceptionally(e); 109 } 110 return future; 111 }, threadPool); 112 futures.add(future); 113 } 114 log.info("Pool is up and running"); 115 threadPool.shutdown(); 116 // We may return here and wait only in the get impl, but the sync cost should be cheap here 117 List<T> ret = new ArrayList<>(nbThreads); 118 for (CompletableFuture<T> future : futures) { 119 T status; 120 try { 121 status = future.get(); 122 } catch (InterruptedException e) { 123 Thread.currentThread().interrupt(); 124 log.error("End of consumer interrupted."); 125 status = getErrorStatus(); 126 } catch (ExecutionException e) { 127 log.error("End of consumer in error: " + e.getMessage() + future.toString()); 128 status = getErrorStatus(); 129 } 130 ret.add(status); 131 } 132 afterCall(ret); 133 return ret; 134 } 135 136 @Override 137 public void close() { 138 supplyThreadPool.shutdownNow(); 139 threadPool.shutdownNow(); 140 } 141 142 protected static class NamedThreadFactory implements ThreadFactory { 143 protected final AtomicInteger count = new AtomicInteger(0); 144 145 protected final String prefix; 146 147 public NamedThreadFactory(String prefix) { 148 this.prefix = prefix; 149 } 150 151 @SuppressWarnings("NullableProblems") 152 @Override 153 public Thread newThread(Runnable r) { 154 Thread t = new Thread(r, String.format("%s-%02d", prefix, count.getAndIncrement())); 155 t.setUncaughtExceptionHandler((t1, e) -> log.error("Uncaught exception: " + e.getMessage(), e)); 156 return t; 157 } 158 } 159 160}