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fengyuan.wan
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lock
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4 files changed

+225
-10
lines changed

4 files changed

+225
-10
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‎03concurrency/0301/src/main/java/java0/conc0302/threadpool/ConditionTest.java‎

Lines changed: 71 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,71 @@
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package java0.conc0302.threadpool;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.locks.Condition;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReentrantLock;
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/**
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* @Desc
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* @Author wfy
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* @Date 2021/2/4 10:38
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*/
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public class ConditionTest {
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static Lock lock = new ReentrantLock(true);
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static Condition fullCondition = lock.newCondition();
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static Condition emptyCondition = lock.newCondition();
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static int size = 0;
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static int capacity = 10;
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//空了才入队。 满了才出队。
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public static void main(String[] args) {
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enqueue();
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dequeue();
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}
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public static void enqueue() {
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new Thread(() -> {
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lock.lock();
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try {
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while (true) {
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if (size < capacity) {
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TimeUnit.MILLISECONDS.sleep(100);
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++size;
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System.out.println("enqueue " + size);
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} else {
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emptyCondition.signalAll();
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fullCondition.await();
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}
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}
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} catch (Exception e) {
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} finally {
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lock.unlock();
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}
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}).start();
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}
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public static void dequeue() {
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new Thread(() -> {
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lock.lock();
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try {
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while (true) {
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if (size > 0) {
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TimeUnit.MILLISECONDS.sleep(100);
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--size;
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System.out.println("dequeue " + size);
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} else {
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fullCondition.signalAll();
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emptyCondition.await();
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}
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}
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} catch (Exception e) {
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} finally {
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lock.unlock();
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}
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}).start();
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}
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}

‎03concurrency/0301/src/main/java/java0/conc0302/threadpool/Mutex.java‎

Lines changed: 82 additions & 0 deletions
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package java0.conc0302.threadpool;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.locks.AbstractQueuedSynchronizer;
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import java.util.concurrent.locks.Condition;
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import java.util.concurrent.locks.Lock;
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class Mutex implements Lock {
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// 静态内部类，自定义同步器
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private static class Sync extends AbstractQueuedSynchronizer {
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// 是否处于占用状态
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@Override
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protected boolean isHeldExclusively() {
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return getState() == 1;
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}
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// 当状态为0的时候获取锁
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@Override
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public boolean tryAcquire(int acquires) {
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if (compareAndSetState(0, 1)) {
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setExclusiveOwnerThread(Thread.currentThread());
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return true;
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}
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return false;
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}
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// 释放锁，将状态设置为0
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@Override
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protected boolean tryRelease(int releases) {
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if (getState() == 0) throw new IllegalMonitorStateException();
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setExclusiveOwnerThread(null);
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setState(0);
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return true;
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}
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// 返回一个Condition，每个condition都包含了一个condition队列
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Condition newCondition() {
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return new ConditionObject();
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}
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}
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// 仅需要将操作代理到Sync上即可
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private final Sync sync = new Sync();
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@Override
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public void lock() {
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sync.acquire(1);
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}
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@Override
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public boolean tryLock() {
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return sync.tryAcquire(1);
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}
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@Override
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public void unlock() {
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sync.release(1);
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}
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@Override
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public Condition newCondition() {
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return sync.newCondition();
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}
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public boolean isLocked() {
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return sync.isHeldExclusively();
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}
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public boolean hasQueuedThreads() {
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return sync.hasQueuedThreads();
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}
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@Override
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public void lockInterruptibly() throws InterruptedException {
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sync.acquireInterruptibly(1);
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}
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@Override
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public boolean tryLock(long timeout, TimeUnit unit) throws InterruptedException {
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return sync.tryAcquireNanos(1, unit.toNanos(timeout));
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}
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}

‎03concurrency/0301/src/main/java/java0/conc0302/threadpool/ReentrantLockTest.java‎

Lines changed: 29 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,7 @@
11
package java0.conc0302.threadpool;
22

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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.locks.Condition;
35
import java.util.concurrent.locks.Lock;
46
import java.util.concurrent.locks.ReentrantLock;
57

@@ -13,22 +15,39 @@ public class ReentrantLockTest {
1315
static int count = 0;
1416

1517
public static void main(String[] args) {
16-
for (int i = 0; i < 10; i++) {
17-
new Thread(ReentrantLockTest::incr).start();
18+
Thread interT = null;
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for (int i = 0; i < 2; i++) {
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Thread t = new Thread(ReentrantLockTest::incr);
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t.start();
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if (i == 1) {
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interT = t;
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}
1825
}
19-
26+
// try {
27+
// TimeUnit.SECONDS.sleep(1);
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// } catch (InterruptedException e) {
29+
// e.printStackTrace();
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// }
2031
}
2132

2233
public static void incr() {
23-
lock.lock();
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boolean locked = false;
2435
try {
25-
for (int i = 0; i < 10000; i++) {
26-
count++;
27-
System.out.println(count);
36+
locked = lock.tryLock(10, TimeUnit.MILLISECONDS);
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} catch (InterruptedException e) {
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System.out.println("error");
39+
e.printStackTrace();
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}
41+
if (locked) {
42+
Condition c = lock.newCondition();
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try {
44+
for (int i = 0; i < 100000; i++) {
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count++;
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System.out.println(count);
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}
48+
} finally {
49+
lock.unlock();
2850
}
29-
} finally {
30-
lock.unlock();
3151
}
32-
3352
}
3453
}

‎03concurrency/0301/src/main/java/java0/conc0302/threadpool/ReentrantLockTest01.java‎

Lines changed: 43 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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package java0.conc0302.threadpool;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.locks.Condition;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReentrantLock;
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8+
/**
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* @Desc
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* @Author wfy
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* @Date 2021/2/3 18:05
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*/
13+
public class ReentrantLockTest01 {
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static ReentrantLock lock = new ReentrantLock(true);
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static int count = 0;
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17+
public static void main(String[] args) {
18+
for (int i = 0; i < 1; i++) {
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Thread t = new Thread(ReentrantLockTest01::incr);
20+
t.start();
21+
}
22+
// try {
23+
// TimeUnit.SECONDS.sleep(1);
24+
// } catch (InterruptedException e) {
25+
// e.printStackTrace();
26+
// }
27+
}
28+
29+
public static void incr() {
30+
System.out.println(lock.getHoldCount());
31+
lock.lock();
32+
lock.lock();
33+
lock.lock();
34+
try {
35+
System.out.println(lock.getHoldCount());
36+
} finally {
37+
lock.unlock();
38+
lock.unlock();
39+
lock.unlock();
40+
}
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System.out.println(lock.getHoldCount());
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}
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}

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