Example usage for org.apache.hadoop.hdfs BlockReader readAll

Introduction

In this page you can find the example usage for org.apache.hadoop.hdfs BlockReader readAll.

Prototype

int readAll(byte[] buf, int offset, int len) throws IOException;

Source Link

Document

Similar to #readFully(byte[],int,int) except that it will not throw an exception on EOF.

Usage

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

License:Apache License

private void actualGetFromOneDataNode(final DNAddrPair datanode, LocatedBlock block, final long start,
        final long end, byte[] buf, int offset, Map<ExtendedBlock, Set<DatanodeInfo>> corruptedBlockMap)
        throws IOException {
    DFSClientFaultInjector.get().startFetchFromDatanode();
    int refetchToken = 1; // only need to get a new access token once
    int refetchEncryptionKey = 1; // only need to get a new encryption key once

    while (true) {
        // cached block locations may have been updated by chooseDataNode()
        // or fetchBlockAt(). Always get the latest list of locations at the
        // start of the loop.
        CachingStrategy curCachingStrategy;
        boolean allowShortCircuitLocalReads;
        block = getBlockAt(block.getStartOffset());
        synchronized (infoLock) {
            curCachingStrategy = cachingStrategy;
            allowShortCircuitLocalReads = !shortCircuitForbidden();
        }/*from w  w  w .  java  2 s  .  com*/
        DatanodeInfo chosenNode = datanode.info;
        InetSocketAddress targetAddr = datanode.addr;
        StorageType storageType = datanode.storageType;
        BlockReader reader = null;

        try {
            DFSClientFaultInjector.get().fetchFromDatanodeException();
            Token<BlockTokenIdentifier> blockToken = block.getBlockToken();
            int len = (int) (end - start + 1);
            reader = new BlockReaderFactory(dfsClient.getConf()).setInetSocketAddress(targetAddr)
                    .setRemotePeerFactory(dfsClient).setDatanodeInfo(chosenNode).setStorageType(storageType)
                    .setFileName(src).setBlock(block.getBlock()).setBlockToken(blockToken).setStartOffset(start)
                    .setVerifyChecksum(verifyChecksum).setClientName(dfsClient.clientName).setLength(len)
                    .setCachingStrategy(curCachingStrategy)
                    .setAllowShortCircuitLocalReads(allowShortCircuitLocalReads)
                    .setClientCacheContext(dfsClient.getClientContext()).setUserGroupInformation(dfsClient.ugi)
                    .setConfiguration(dfsClient.getConfiguration()).build();
            int nread = reader.readAll(buf, offset, len);
            updateReadStatistics(readStatistics, nread, reader);

            if (nread != len) {
                throw new IOException(
                        "truncated return from reader.read(): " + "excpected " + len + ", got " + nread);
            }
            DFSClientFaultInjector.get().readFromDatanodeDelay();
            return;
        } catch (ChecksumException e) {
            String msg = "fetchBlockByteRange(). Got a checksum exception for " + src + " at "
                    + block.getBlock() + ":" + e.getPos() + " from " + chosenNode;
            DFSClient.LOG.warn(msg);
            // we want to remember what we have tried
            addIntoCorruptedBlockMap(block.getBlock(), chosenNode, corruptedBlockMap);
            addToDeadNodes(chosenNode);
            throw new IOException(msg);
        } catch (IOException e) {
            if (e instanceof InvalidEncryptionKeyException && refetchEncryptionKey > 0) {
                DFSClient.LOG.info("Will fetch a new encryption key and retry, "
                        + "encryption key was invalid when connecting to " + targetAddr + " : " + e);
                // The encryption key used is invalid.
                refetchEncryptionKey--;
                dfsClient.clearDataEncryptionKey();
                continue;
            } else if (refetchToken > 0 && tokenRefetchNeeded(e, targetAddr)) {
                refetchToken--;
                try {
                    fetchBlockAt(block.getStartOffset());
                } catch (IOException fbae) {
                    // ignore IOE, since we can retry it later in a loop
                }
                continue;
            } else {
                String msg = "Failed to connect to " + targetAddr + " for file " + src + " for block "
                        + block.getBlock() + ":" + e;
                DFSClient.LOG.warn("Connection failure: " + msg, e);
                addToDeadNodes(chosenNode);
                throw new IOException(msg);
            }
        } finally {
            if (reader != null) {
                reader.close();
            }
        }
    }
}

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