54 lines
1.4 KiB
Java
54 lines
1.4 KiB
Java
package org.warp.commonutils.locks;
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import java.util.concurrent.Semaphore;
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import java.util.concurrent.atomic.AtomicInteger;
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public class TransitLock {
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private final FlexibleCountDownLatch unfinishedTransits = new FlexibleCountDownLatch(0);
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private final Semaphore permits = new Semaphore(Integer.MAX_VALUE);
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private final AtomicInteger allowedTransits = new AtomicInteger(1);
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private final Object synchronization = new Object();
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public TransitLock() {
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}
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public void allowTransit() {
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var allowedTransits = this.allowedTransits.incrementAndGet();
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if (allowedTransits == 1) {
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var permitsToRelease = Math.max(0, Integer.MAX_VALUE - (permits.availablePermits() + 10000));
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permits.release(permitsToRelease);
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} else if (allowedTransits > 1) {
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throw new IllegalStateException("Already allowed transit!");
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}
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}
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public void disallowTransit() {
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synchronized (synchronization) {
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var allowedTransits = this.allowedTransits.decrementAndGet();
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if (allowedTransits == 0) {
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unfinishedTransits.await();
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permits.drainPermits();
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} else if (allowedTransits > 0) {
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throw new IllegalStateException("Transits are still allowed for an unknown reason!");
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}
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}
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}
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public void transit() {
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startTransit();
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endTransit();
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}
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public void startTransit() {
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synchronized (synchronization) {
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unfinishedTransits.grow();
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permits.acquireUninterruptibly();
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}
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}
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public void endTransit() {
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unfinishedTransits.countDown();
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}
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}
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