Example usage for org.apache.hadoop.hdfs.shortcircuit ShortCircuitCache freeSlot

Introduction

In this page you can find the example usage for org.apache.hadoop.hdfs.shortcircuit ShortCircuitCache freeSlot.

Prototype

public void freeSlot(Slot slot) 

Source Link

Document

Free a slot immediately.

Usage

From source file:BlockReaderFactory.java

License:Apache License

/**
 * Fetch a pair of short-circuit block descriptors from a local DataNode.
 *
 * @return    Null if we could not communicate with the datanode,
 *            a new ShortCircuitReplicaInfo object otherwise.
 *            ShortCircuitReplicaInfo objects may contain either an InvalidToken
 *            exception, or a ShortCircuitReplica object ready to use.
 *///from w  w  w  .j a  va2s. c  o m
@Override
public ShortCircuitReplicaInfo createShortCircuitReplicaInfo() {
    if (createShortCircuitReplicaInfoCallback != null) {
        ShortCircuitReplicaInfo info = createShortCircuitReplicaInfoCallback.createShortCircuitReplicaInfo();
        if (info != null)
            return info;
    }
    if (LOG.isTraceEnabled()) {
        LOG.trace(this + ": trying to create ShortCircuitReplicaInfo.");
    }
    BlockReaderPeer curPeer;
    while (true) {
        curPeer = nextDomainPeer();
        if (curPeer == null)
            break;
        if (curPeer.fromCache)
            remainingCacheTries--;
        DomainPeer peer = (DomainPeer) curPeer.peer;
        Slot slot = null;
        ShortCircuitCache cache = clientContext.getShortCircuitCache();
        try {
            MutableBoolean usedPeer = new MutableBoolean(false);
            slot = cache.allocShmSlot(datanode, peer, usedPeer,
                    new ExtendedBlockId(block.getBlockId(), block.getBlockPoolId()), clientName);
            if (usedPeer.booleanValue()) {
                if (LOG.isTraceEnabled()) {
                    LOG.trace(this + ": allocShmSlot used up our previous socket " + peer.getDomainSocket()
                            + ".  Allocating a new one...");
                }
                curPeer = nextDomainPeer();
                if (curPeer == null)
                    break;
                peer = (DomainPeer) curPeer.peer;
            }
            ShortCircuitReplicaInfo info = requestFileDescriptors(peer, slot);
            clientContext.getPeerCache().put(datanode, peer);
            return info;
        } catch (IOException e) {
            if (slot != null) {
                cache.freeSlot(slot);
            }
            if (curPeer.fromCache) {
                // Handle an I/O error we got when using a cached socket.
                // These are considered less serious, because the socket may be stale.
                if (LOG.isDebugEnabled()) {
                    LOG.debug(this + ": closing stale domain peer " + peer, e);
                }
                IOUtils.cleanup(LOG, peer);
            } else {
                // Handle an I/O error we got when using a newly created socket.
                // We temporarily disable the domain socket path for a few minutes in
                // this case, to prevent wasting more time on it.
                LOG.warn(this + ": I/O error requesting file descriptors.  " + "Disabling domain socket "
                        + peer.getDomainSocket(), e);
                IOUtils.cleanup(LOG, peer);
                clientContext.getDomainSocketFactory().disableDomainSocketPath(pathInfo.getPath());
                return null;
            }
        }
    }
    return null;
}

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