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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.curator.recipes;
import com.yahoo.path.Path;
import com.yahoo.vespa.curator.Curator;
import org.apache.curator.framework.recipes.atomic.AtomicValue;
import org.apache.curator.framework.recipes.atomic.DistributedAtomicLong;
/**
* A distributed atomic counter.
*
* @author Ulf Lilleengen
*/
public class CuratorCounter {
private final DistributedAtomicLong counter;
private final Path counterPath;
public CuratorCounter(Curator curator, Path counterPath) {
this.counter = curator.createAtomicCounter(counterPath.getAbsolute());
this.counterPath = counterPath;
}
/** Convenience method for {@link #add(long)} with 1 */
public long next() {
return add(1L);
}
/** Convenience method for {@link #add(long)} with -1 */
public long previous() {
return add(-1L);
}
/**
* Atomically add and return resulting value.
*
* @param delta value to add, may be negative
* @return the resulting value
* @throws IllegalStateException if addition fails
*/
public synchronized long add(long delta) {
try {
AtomicValue<Long> value = counter.add(delta);
if (!value.succeeded()) {
throw new IllegalStateException("Add did not succeed");
}
return value.postValue();
} catch (Exception e) {
throw new IllegalStateException("Unable to add value", e);
}
}
public synchronized void set(long current) {
try {
counter.trySet(current);
} catch (Exception e) {
throw new IllegalStateException("Unable to set value", e);
}
}
public long get() {
try {
AtomicValue<Long> value = counter.get();
if (!value.succeeded()) {
throw new RuntimeException("Get did not succeed");
}
return value.postValue();
} catch (Exception e) {
throw new RuntimeException("Unable to get value", e);
}
}
public void initialize(long value) {
try {
counter.initialize(value);
} catch (Exception e) {
throw new IllegalStateException("Error initializing atomic counter", e);
}
}
@Override
public String toString() {
return "curator counter " + counterPath;
}
}
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