Java Code Examples for org.apache.curator.framework.recipes.atomic.AtomicValue#postValue()

@Override
public void startQuery() throws Exception {
    // increment the zookeeper query file
    clientLock.lock();
    try {
        DistributedAtomicLong atomicLong = getLong();
        AtomicValue<Long> longValue = atomicLong.increment();
        if (!longValue.succeeded()) {
            throw new ZookeeperLockException("Unable to start query");
        }
        if (log.isTraceEnabled()) {
            long preValue = longValue.preValue();
            long postValue = longValue.postValue();
            log.trace("Updated value for " + getQueryFile() + " from " + preValue + " to " + postValue);
        }
    } finally {
        clientLock.unlock();
    }
}
 

public void stopQuery() throws Exception {
    // decrement the zookeeper query file and delete if 0
    clientLock.lock();
    try {
        DistributedAtomicLong atomicLong = getLong();
        AtomicValue<Long> longValue = atomicLong.decrement();
        if (!longValue.succeeded()) {
            throw new ZookeeperLockException("Unable to stop query");
        }
        long postValue = longValue.postValue();
        if (log.isTraceEnabled()) {
            long preValue = longValue.preValue();
            log.trace("Updated value for " + getQueryFile() + " from " + preValue + " to " + postValue);
        }
        if (postValue == 0) {
            client.delete().forPath(getQueryFile());
        }
    } finally {
        clientLock.unlock();
    }
}
 

@Override
public boolean isQueryRunning() {
    // check existence of the query file
    clientLock.lock();
    try {
        DistributedAtomicLong atomicLong = getLong();
        AtomicValue<Long> longValue = atomicLong.get();
        if (!longValue.succeeded()) {
            throw new ZookeeperLockException("Unable to get query lock count");
        }
        long postValue = longValue.postValue();
        if (log.isTraceEnabled()) {
            log.trace("Got value for " + getQueryFile() + " to be " + postValue);
        }
        return postValue > 0;
    } catch (Exception e) {
        log.error("Unable to determine if zookeeper lock exists", e);
        // assume the query is still running for now
        return true;
    } finally {
        clientLock.unlock();
    }
}
 

@Override
public void updateMaxTimestamp(long previousMaxTimestamp, long newMaxTimestamp) throws IOException {

    if (newMaxTimestamp < 0) {
        LOG.error("Negative value received for maxTimestamp: {}", newMaxTimestamp);
        throw new IllegalArgumentException();
    }
    if (newMaxTimestamp <= previousMaxTimestamp) {
        LOG.error("maxTimestamp {} <= previousMaxTimesamp: {}", newMaxTimestamp, previousMaxTimestamp);
        throw new IllegalArgumentException();
    }
    AtomicValue<Long> compareAndSet;
    try {
        compareAndSet = timestamp.compareAndSet(previousMaxTimestamp, newMaxTimestamp);
    } catch (Exception e) {
        throw new IOException("Problem setting timestamp in ZK", e);
    }
    if (!compareAndSet.succeeded()) { // We have to explicitly check for success (See Curator doc)
        throw new IOException("GetAndSet operation for storing timestamp in ZK did not succeed "
                + compareAndSet.preValue() + " " + compareAndSet.postValue());
    }

}
 

/**
 * 获得ZK中的当前值,如果不存在，抛出异常
 *
 * @param path
 * @return
 * @throws Exception
 */
private long currentValueFromZk(String path) throws Exception {
    if (isExists(path)) {
        DistributedAtomicLong count = new DistributedAtomicLong(client, path, new RetryNTimes(10, 1000));
        AtomicValue<Long> val = count.get();
        return val.postValue();
    } else {
        throw new RuntimeException("Path is not existed! Call nextValue firstly!");
    }
}
 

/**
 * 获得分布式自增变量
 *
 * @param path
 * @return
 * @throws Exception
 */
public Long getIncrementValue(String path) throws Exception {
    DistributedAtomicLong atomicId = new DistributedAtomicLong(client, path, new RetryNTimes(32, 1000));
    AtomicValue<Long> rc = atomicId.get();
    if (rc.succeeded()) {
        logger.debug("getIncrementValue({}) success! get: {}.", path, rc.postValue());
    } else {
        logger.warn("getIncrementValue({}) failed! get: {}.", path, rc.postValue());
    }
    return rc.postValue();
}
 

/**
 * 自增并获得，自增后的变量
 *
 * @param path
 * @return
 * @throws Exception
 */
public Long incrementAndGetValue(String path) throws Exception {
    DistributedAtomicLong atomicId = new DistributedAtomicLong(client, path, new RetryNTimes(32, 1000));
    AtomicValue<Long> rc = atomicId.increment();
    if (rc.succeeded()) {
        logger.info("incrementAndGetValue({}) success! before: {}, after: {}.", path, rc.preValue(), rc.postValue());
    } else {
        logger.warn("incrementAndGetValue({}) failed! before: {}, after: {}.", path, rc.preValue(), rc.postValue());
    }
    return rc.postValue();
}
 

@Override
public long getMaxTimestamp() throws IOException {

    AtomicValue<Long> atomicValue;
    try {
        atomicValue = timestamp.get();
    } catch (Exception e) {
        throw new IOException("Problem getting data from ZK", e);
    }
    if (!atomicValue.succeeded()) { // We have to explicitly check for success (See Curator doc)
        throw new IOException("Get operation to obtain timestamp from ZK did not succeed");
    }
    return atomicValue.postValue();

}
 

/**
 * 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 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);
    }
}
 

private static Long createID(CuratorFramework curator) {
  try {
    DistributedAtomicLong counter = new DistributedAtomicLong(curator,
        ZookeeperPath.TRANSACTOR_COUNT, new ExponentialBackoffRetry(1000, 10));
    AtomicValue<Long> nextId = counter.increment();
    while (nextId.succeeded() == false) {
      nextId = counter.increment();
    }
    return nextId.postValue();
  } catch (Exception e) {
    throw new IllegalStateException(e);
  }
}