Example usage for java.util.concurrent DelayQueue offer

Introduction

In this page you can find the example usage for java.util.concurrent DelayQueue offer.

Prototype

public boolean offer(E e) 

Source Link

Document

Inserts the specified element into this delay queue.

Usage

From source file:org.apache.hawq.pxf.service.UGICache.java

/**
 * If a UGI for the given session exists in the cache, returns it. Otherwise, creates a new
 * proxy UGI. In either case this method increments the reference count of the UGI. This method
 * also destroys expired, unreferenced UGIs for the same segmentId as the given session.
 *
 * @param session The user from the session is impersonated by the proxy UGI.
 * @return the proxy UGI for the given session.
 *//*from  w w  w . j  av  a2 s  .  c o  m*/
public UserGroupInformation getUserGroupInformation(SessionId session) throws IOException {
    Integer segmentId = session.getSegmentId();
    String user = session.getUser();
    DelayQueue<Entry> delayQueue = getExpirationQueue(segmentId);
    synchronized (delayQueue) {
        // Use the opportunity to cleanup any expired entries
        cleanup(delayQueue);
        Entry entry = cache.get(session);
        if (entry == null) {
            if (LOG.isDebugEnabled()) {
                LOG.debug(session + " Creating proxy user = " + user);
            }
            entry = new Entry(ticker, ugiProvider.createProxyUGI(user), session);
            delayQueue.offer(entry);
            cache.put(session, entry);
        }
        entry.incrementRefCount();
        return entry.getUGI();
    }
}

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From source file:org.apache.hawq.pxf.service.UGICache.java

/**
 * Decrement reference count for the given session's UGI. Resets the time at which the UGI will
 * expire to UGI_CACHE_EXPIRY milliseconds in the future.
 *
 * @param session                  the session for which we want to release the UGI.
 * @param cleanImmediatelyIfNoRefs if true, destroys the UGI for the given session (only if it
 *                                 is now unreferenced).
 */// w w w  . j  a  v  a2 s  . c o m
public void release(SessionId session, boolean cleanImmediatelyIfNoRefs) {

    Entry entry = cache.get(session);

    if (entry == null) {
        throw new IllegalStateException("Cannot release UGI for this session; it is not cached: " + session);
    }

    DelayQueue<Entry> expirationQueue = getExpirationQueue(session.getSegmentId());

    synchronized (expirationQueue) {
        entry.decrementRefCount();
        expirationQueue.remove(entry);
        if (cleanImmediatelyIfNoRefs && entry.isNotInUse()) {
            closeUGI(entry);
        } else {
            // Reset expiration time and put it back in the queue
            // only when we don't close the UGI
            entry.resetTime();
            expirationQueue.offer(entry);
        }
    }
}

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From source file:org.apache.hawq.pxf.service.UGICache.java

/**
 * Iterate through all the entries in the queue and close expired {@link UserGroupInformation},
 * otherwise it resets the timer for every non-expired entry.
 *
 * @param expirationQueue//from  w w  w .jav a  2 s.com
 */
private void cleanup(DelayQueue<Entry> expirationQueue) {

    Entry expiredUGI;
    while ((expiredUGI = expirationQueue.poll()) != null) {
        if (expiredUGI.isNotInUse()) {
            closeUGI(expiredUGI);
        } else {
            // The UGI object is still being used by another thread
            String fsMsg = "FileSystem for proxy user = " + expiredUGI.getSession().getUser();
            if (LOG.isDebugEnabled()) {
                LOG.debug(expiredUGI.getSession().toString() + " Skipping close of " + fsMsg);
            }
            // Place it back in the queue if still in use and was not closed
            expiredUGI.resetTime();
            expirationQueue.offer(expiredUGI);
        }
        if (LOG.isDebugEnabled()) {
            LOG.debug("Delay Queue Size for segment " + expiredUGI.getSession().getSegmentId() + " = "
                    + expirationQueue.size());
        }
    }
}

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