Example usage for org.apache.hadoop.hdfs.protocol ClientDatanodeProtocol getReplicaVisibleLength

Introduction

In this page you can find the example usage for org.apache.hadoop.hdfs.protocol ClientDatanodeProtocol getReplicaVisibleLength.

Prototype

long getReplicaVisibleLength(ExtendedBlock b) throws IOException;

Source Link

Document

Return the visible length of a replica.

Usage

From source file:com.mellanox.r4h.DFSInputStream.java

License:Apache License

/** Read the block length from one of the datanodes. */
private long readBlockLength(LocatedBlock locatedblock) throws IOException {
    assert locatedblock != null : "LocatedBlock cannot be null";
    int replicaNotFoundCount = locatedblock.getLocations().length;

    for (DatanodeInfo datanode : locatedblock.getLocations()) {
        ClientDatanodeProtocol cdp = null;

        try {//  w  w  w  .  j  a v  a 2 s.  co m
            cdp = DFSUtil.createClientDatanodeProtocolProxy(datanode, dfsClient.getConfiguration(),
                    dfsClient.getConf().getSocketTimeout(), dfsClient.getConf().getConnectToDnViaHostname(),
                    locatedblock);

            final long n = cdp.getReplicaVisibleLength(locatedblock.getBlock());

            if (n >= 0) {
                return n;
            }
        } catch (IOException ioe) {
            if (ioe instanceof RemoteException
                    && (((RemoteException) ioe).unwrapRemoteException() instanceof ReplicaNotFoundException)) {
                // special case : replica might not be on the DN, treat as 0 length
                replicaNotFoundCount--;
            }

            if (DFSClient.LOG.isDebugEnabled()) {
                DFSClient.LOG.debug("Failed to getReplicaVisibleLength from datanode " + datanode
                        + " for block " + locatedblock.getBlock(), ioe);
            }
        } finally {
            if (cdp != null) {
                RPC.stopProxy(cdp);
            }
        }
    }

    // Namenode told us about these locations, but none know about the replica
    // means that we hit the race between pipeline creation start and end.
    // we require all 3 because some other exception could have happened
    // on a DN that has it. we want to report that error
    if (replicaNotFoundCount == 0) {
        return 0;
    }

    throw new IOException("Cannot obtain block length for " + locatedblock);
}

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