场景一
有几个同学约好一起去食堂吃饭，各自都从各自的宿舍出发，然后到宿舍楼下集合。当所有的人都到了宿舍楼下之后，再一起从宿舍楼下出发前往食堂吃饭。
public static void main(String[] args) {
Map<String, Boolean> stringMap = new HashMap<String, Boolean>();
stringMap.put("111", Boolean.TRUE);
stringMap.put("112", Boolean.TRUE);
stringMap.put("113", Boolean.TRUE);
stringMap.put("114", Boolean.TRUE);
stringMap.put("115", Boolean.TRUE);
Boolean aBoolean = testMoreThread(stringMap);
if (aBoolean) {
System.out.println("大家都到达了宿舍楼下，一起出发吧。。。");
} else {
System.out.println("都回宿舍了？？？？？？？");
}
}
处理结果
114开始从宿舍出发。。。
114到达楼下。。。
115开始从宿舍出发。。。
115到达楼下。。。
112开始从宿舍出发。。。
112到达楼下。。。
113开始从宿舍出发。。。
113到达楼下。。。
111开始从宿舍出发。。。
111到达楼下。。。
大家都到达了宿舍楼下，一起出发吧。。。
114开始从宿舍楼下出发。。。
114到达食堂。。。
115开始从宿舍楼下出发。。。
115到达食堂。。。
112开始从宿舍楼下出发。。。
112到达食堂。。。
111开始从宿舍楼下出发。。。
111到达食堂。。。
113开始从宿舍楼下出发。。。
113到达食堂。。。
Process finished with exit code 0
场景二：
有几个同学约好一起去食堂吃饭，各自都从各自的宿舍出发，然后到宿舍楼下集合。有个同学到达楼下后突然想点外卖，然后大家都回宿舍
public static void main(String[] args) {
Map<String, Boolean> stringMap = new HashMap<String, Boolean>();
stringMap.put("111", Boolean.TRUE);
stringMap.put("112", Boolean.TRUE);
stringMap.put("113", Boolean.TRUE);
stringMap.put("114", Boolean.TRUE);
stringMap.put("115", Boolean.FALSE);
Boolean aBoolean = testMoreThread(stringMap);
if (aBoolean) {
System.out.println("大家都到达了宿舍楼下，一起出发吧。。。");
} else {
System.out.println("都回宿舍了？？？？？？？");
}
}
处理结果
114开始从宿舍出发。。。
114到达楼下。。。
115开始从宿舍出发。。。
115到达楼下。。。突然想叫外卖，回宿舍。。。
112开始从宿舍出发。。。
112到达楼下。。。
113开始从宿舍出发。。。
113到达楼下。。。
111开始从宿舍出发。。。
111到达楼下。。。
111回宿舍。。。
113回宿舍。。。
114回宿舍。。。
112回宿舍。。。
都回宿舍了？？？？？？？
Process finished with exit code 0
多线程处理实现
public static Boolean testMoreThread(Map<String, Boolean> stringMap) {
CyclicBarrierDemo sCyclicBarrier = new CyclicBarrierDemo(stringMap.size()+1, new Runnable() {
@Override
public void run() {
}
});
try {
for (String key : stringMap.keySet()) {
Worker worker = new Worker(key, 5000, sCyclicBarrier, stringMap.get(key));
worker.start();
}
Thread.sleep(1000);
sCyclicBarrier.await();//工人完成工作，计数器减一
} catch (Exception e) {
return Boolean.FALSE;
}
return Boolean.TRUE;
}
public static class Worker extends Thread {
String workerName;
int workTime;
CyclicBarrierDemo sCyclicBarrier;
Boolean workValue;
public Worker(String workerName, int workTime, CyclicBarrierDemo sCyclicBarrier, Boolean workValue) {
this.workerName = workerName;
this.workTime = workTime;
this.sCyclicBarrier = sCyclicBarrier;
this.workValue = workValue;
}
public void run() {
System.out.println(workerName + "开始从宿舍出发。。。");
try {
if (workValue) {
System.out.println(workerName + "到达楼下。。。");
sCyclicBarrier.await();//等待别的同学
System.out.println(workerName + "开始从宿舍楼下出发。。。");
System.out.println(workerName + "到达食堂。。。");
} else {
System.out.println(workerName + "到达楼下。。。突然想叫外卖，回宿舍。。。");
sCyclicBarrier.out();
}
} catch (Throwable e) {
ExceptionUtil.printStackTrace(e);
System.out.println(workerName + "回宿舍。。。");
sCyclicBarrier.out();
}
}
}
package com.self.ddyoung.daily.plugin;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
/**
* @author <a href="mailto:sanbian@pamirs.top">Sanbian</a>
* @version 1.0
* @since 17/2/21 下午8:05
*/
public class CyclicBarrierDemo{
/**
* Each use of the barrier is represented as a generation instance.
* The generation changes whenever the barrier is tripped, or
* is reset. There can be many generations associated with threads
* using the barrier - due to the non-deterministic way the lock
* may be allocated to waiting threads - but only one of these
* can be active at a time (the one to which <tt>count</tt> applies)
* and all the rest are either broken or tripped.
* There need not be an active generation if there has been a break
* but no subsequent reset.
*/
private static class Generation {
boolean broken = false;
}
/** The lock for guarding barrier entry */
private final ReentrantLock lock = new ReentrantLock();
/** Condition to wait on until tripped */
private final Condition trip = lock.newCondition();
/** The number of parties */
private final int parties;
/* The command to run when tripped */
private final Runnable barrierCommand;
/** The current generation */
private CyclicBarrierDemo.Generation generation = new CyclicBarrierDemo.Generation();
/**
* Number of parties still waiting. Counts down from parties to 0
* on each generation. It is reset to parties on each new
* generation or when broken.
*/
private int count;
/**
* Updates state on barrier trip and wakes up everyone.
* Called only while holding lock.
*/
private void nextGeneration() {
// signal completion of last generation
trip.signalAll();
// set up next generation
count = parties;
generation = new CyclicBarrierDemo.Generation();
}
/**
* Sets current barrier generation as broken and wakes up everyone.
* Called only while holding lock.
*/
private void breakBarrier() {
generation.broken = true;
count = parties;
trip.signalAll();
}
AtomicBoolean out = new AtomicBoolean(false
);
public void out(){
out.getAndSet(true);
}
/**
* Main barrier code, covering the various policies.
*/
private int dowait(boolean timed, long nanos)
throws InterruptedException, BrokenBarrierException,
TimeoutException {
final ReentrantLock lock = this.lock;
lock.lock();
try {
final CyclicBarrierDemo.Generation g = generation;
if (g.broken)
throw new BrokenBarrierException();
if (Thread.interrupted()) {
breakBarrier();
throw new InterruptedException();
}
int index = --count;
if (index == 0) { // tripped
boolean ranAction = false;
try {
final Runnable command = barrierCommand;
if (command != null)
command.run();
ranAction = true;
nextGeneration();
return 0;
} finally {
if (!ranAction)
breakBarrier();
}
}
// loop until tripped, broken, interrupted, or timed out
for (;;) {
if(out.get()){
Thread.currentThread().interrupt();
}
try {
if (!timed) {
// if(out.get()){
// Thread.currentThread().interrupt();
// }
// System.out.print("awaitNanos(100)");
trip.awaitNanos(100);
// Thread.sleep(100L);
}
else if (nanos > 0L)
nanos = trip.awaitNanos(nanos);
} catch (InterruptedException ie) {
if (g == generation && ! g.broken) {
breakBarrier();
throw ie;
} else {
// We're about to finish waiting even if we had not
// been interrupted, so this interrupt is deemed to
// "belong" to subsequent execution.
Thread.currentThread().interrupt();
}
}
if (g.broken)
throw new BrokenBarrierException();
if (g != generation)
return index;
if (timed && nanos <= 0L) {
breakBarrier();
throw new TimeoutException();
}
}
} finally {
lock.unlock();
}
}
/**
* Creates a new <tt>CyclicBarrier</tt> that will trip when the
* given number of parties (threads) are waiting upon it, and which
* will execute the given barrier action when the barrier is tripped,
* performed by the last thread entering the barrier.
*
* @param parties the number of threads that must invoke {@link #await}
* before the barrier is tripped
* @param barrierAction the command to execute when the barrier is
* tripped, or {@code null} if there is no action
* @throws IllegalArgumentException if {@code parties} is less than 1
*/
public CyclicBarrierDemo(int parties, Runnable barrierAction) {
if (parties <= 0) throw new IllegalArgumentException();
this.parties = parties;
this.count = parties;
this.barrierCommand = barrierAction;
}
/**
* Creates a new <tt>CyclicBarrier</tt> that will trip when the
* given number of parties (threads) are waiting upon it, and
* does not perform a predefined action when the barrier is tripped.
*
* @param parties the number of threads that must invoke {@link #await}
* before the barrier is tripped
* @throws IllegalArgumentException if {@code parties} is less than 1
*/
public CyclicBarrierDemo(int parties) {
this(parties, null);
}
/**
* Returns the number of parties required to trip this barrier.
*
* @return the number of parties required to trip this barrier
*/
public int getParties() {
return parties;
}
/**
* Waits until all {@linkplain #getParties parties} have invoked
* <tt>await</tt> on this barrier.
*
* <p>If the current thread is not the last to arrive then it is
* disabled for thread scheduling purposes and lies dormant until
* one of the following things happens:
* <ul>
* <li>The last thread arrives; or
* <li>Some other thread {@linkplain Thread#interrupt interrupts}
* the current thread; or
* <li>Some other thread {@linkplain Thread#interrupt interrupts}
* one of the other waiting threads; or
* <li>Some other thread times out while waiting for barrier; or
* <li>Some other thread invokes {@link #reset} on this barrier.
* </ul>
*
* <p>If the current thread:
* <ul>
* <li>has its interrupted status set on entry to this method; or
* <li>is {@linkplain Thread#interrupt interrupted} while waiting
* </ul>
* then {@link InterruptedException} is thrown and the current thread's
* interrupted status is cleared.
*
* <p>If the barrier is {@link #reset} while any thread is waiting,
* or if the barrier {@linkplain #isBroken is broken} when
* <tt>await</tt> is invoked, or while any thread is waiting, then
* {@link BrokenBarrierException} is thrown.
*
* <p>If any thread is {@linkplain Thread#interrupt interrupted} while waiting,
* then all other waiting threads will throw
* {@link BrokenBarrierException} and the barrier is placed in the broken
* state.
*
* <p>If the current thread is the last thread to arrive, and a
* non-null barrier action was supplied in the constructor, then the
* current thread runs the action before allowing the other threads to
* continue.
* If an exception occurs during the barrier action then that exception
* will be propagated in the current thread and the barrier is placed in
* the broken state.
*
* @return the arrival index of the current thread, where index
* <tt>{@link #getParties()} - 1</tt> indicates the first
* to arrive and zero indicates the last to arrive
* @throws InterruptedException if the current thread was interrupted
* while waiting
* @throws BrokenBarrierException if <em>another</em> thread was
* interrupted or timed out while the current thread was
* waiting, or the barrier was reset, or the barrier was
* broken when {@code await} was called, or the barrier
* action (if present) failed due an exception.
*/
public int await() throws InterruptedException, BrokenBarrierException {
try {
return dowait(false, 0L);
} catch (TimeoutException toe) {
throw new Error(toe); // cannot happen;
}
}
/**
* Waits until all {@linkplain #getParties parties} have invoked
* <tt>await</tt> on this barrier, or the specified waiting time elapses.
*
* <p>If the current thread is not the last to arrive then it is
* disabled for thread scheduling purposes and lies dormant until
* one of the following things happens:
* <ul>
* <li>The last thread arrives; or
* <li>The specified timeout elapses; or
* <li>Some other thread {@linkplain Thread#interrupt interrupts}
* the current thread; or
* <li>Some other thread {@linkplain Thread#interrupt interrupts}
* one of the other waiting threads; or
* <li>Some other thread times out while waiting for barrier; or
* <li>Some other thread invokes {@link #reset} on this barrier.
* </ul>
*
* <p>If the current thread:
* <ul>
* <li>has its interrupted status set on entry to this method; or
* <li>is {@linkplain Thread#interrupt interrupted} while waiting
* </ul>
* then {@link InterruptedException} is thrown and the current thread's
* interrupted status is cleared.
*
* <p>If the specified waiting time elapses then {@link TimeoutException}
* is thrown. If the time is less than or equal to zero, the
* method will not wait at all.
*
* <p>If the barrier is {@link #reset} while any thread is waiting,
* or if the barrier {@linkplain #isBroken is broken} when
* <tt>await</tt> is invoked, or while any thread is waiting, then
* {@link BrokenBarrierException} is thrown.
*
* <p>If any thread is {@linkplain Thread#interrupt interrupted} while
* waiting, then all other waiting threads will throw {@link
* BrokenBarrierException} and the barrier is placed in the broken
* state.
*
* <p>If the current thread is the last thread to arrive, and a
* non-null barrier action was supplied in the constructor, then the
* current thread runs the action before allowing the other threads to
* continue.
* If an exception occurs during the barrier action then that exception
* will be propagated in the current thread and the barrier is placed in
* the broken state.
*
* @param timeout the time to wait for the barrier
* @param unit the time unit of the timeout parameter
* @return the arrival index of the current thread, where index
* <tt>{@link #getParties()} - 1</tt> indicates the first
* to arrive and zero indicates the last to arrive
* @throws InterruptedException if the current thread was interrupted
* while waiting
* @throws TimeoutException if the specified timeout elapses
* @throws BrokenBarrierException if <em>another</em> thread was
* interrupted or timed out while the current thread was
* waiting, or the barrier was reset, or the barrier was broken
* when {@code await} was called, or the barrier action (if
* present) failed due an exception
*/
public int await(long timeout, TimeUnit unit)
throws InterruptedException,
BrokenBarrierException,
TimeoutException {
return dowait(true, unit.toNanos(timeout));
}
/**
* Queries if this barrier is in a broken state.
*
* @return {@code true} if one or more parties broke out of this
* barrier due to interruption or timeout since
* construction or the last reset, or a barrier action
* failed due to an exception; {@code false} otherwise.
*/
public boolean isBroken() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return generation.broken;
} finally {
lock.unlock();
}
}
/**
* Resets the barrier to its initial state. If any parties are
* currently waiting at the barrier, they will return with a
* {@link BrokenBarrierException}. Note that resets <em>after</em>
* a breakage has occurred for other reasons can be complicated to
* carry out; threads need to re-synchronize in some other way,
* and choose one to perform the reset. It may be preferable to
* instead create a new barrier for subsequent use.
*/
public void reset() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
breakBarrier(); // break the current generation
nextGeneration(); // start a new generation
} finally {
lock.unlock();
}
}
/**
* Returns the number of parties currently waiting at the barrier.
* This method is primarily useful for debugging and assertions.
*
* @return the number of parties currently blocked in {@link #await}
*/
public int getNumberWaiting() {
final ReentrantLock lock = this.lock;
lock.lock();
try {
return parties - count;
} finally {
lock.unlock();
}
}
}
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