Example usage for org.apache.hadoop.hdfs.server.datanode.fsdataset FsDatasetSpi getBlockInputStream

Introduction

In this page you can find the example usage for org.apache.hadoop.hdfs.server.datanode.fsdataset FsDatasetSpi getBlockInputStream.

Prototype

InputStream getBlockInputStream(ExtendedBlock b, long seekOffset) throws IOException;

Source Link

Document

Returns an input stream at specified offset of the specified block.

Usage

From source file:backup.datanode.DataNodeBackupProcessor.java

License:Apache License

@Override
protected long doBackup(ExtendedBlock extendedBlock, boolean force) throws Exception {
    if (!force) {
        long blockId = extendedBlock.getBlockId();
        DatanodeUuids result;//from  w w w  .jav a 2 s.  co m
        try {
            result = _nameNodeClient.getDatanodeUuids(blockId);
        } catch (Exception e) {
            if (LOG.isDebugEnabled()) {
                LOG.error("datanode UUID lookup failed " + e.getCause(), e);
            } else {
                LOG.error("datanode UUID lookup failed {}", e.getCause());
            }
            result = new DatanodeUuids();
        }
        List<String> datanodeUuids = result.getDatanodeUuids();
        if (!datanodeUuids.isEmpty()) {
            LOG.debug("datanode UUIDs for block id {} {}", blockId, datanodeUuids);
            List<String> orderedDataNodeUuids = getOrderDataNodeUuids(datanodeUuids, blockId);
            String datanodeUuid = _datanode.getDatanodeUuid();
            int binarySearch = Collections.binarySearch(orderedDataNodeUuids, datanodeUuid);
            if (binarySearch == 0) {
                LOG.debug("datanode UUID {} first in list {} for block id {}, performing backup", datanodeUuid,
                        datanodeUuids, blockId);
            } else if (binarySearch > 0) {
                return binarySearch * _retryDelay;
            } else {
                LOG.debug("datanode UUID {} not found in list {} for block id {}, forcing backup", datanodeUuid,
                        datanodeUuids, blockId);
            }
        } else {
            LOG.debug("datanode UUIDs for block id {} empty, forcing backup", blockId);
        }
    }

    if (_backupStore.hasBlock(extendedBlock)) {
        LOG.debug("block {} already backed up", extendedBlock);
        return 0;
    }

    FsDatasetSpi<?> fsDataset = _datanode.getFSDataset();

    org.apache.hadoop.hdfs.protocol.ExtendedBlock heb = BackupUtil.toHadoop(extendedBlock);
    if (!fsDataset.isValidBlock(heb)) {
        return 0;
    }
    BlockLocalPathInfo info = fsDataset.getBlockLocalPathInfo(heb);
    String blockPath = info.getBlockPath();
    if (Files.isSymbolicLink(new File(blockPath).toPath())) {
        LOG.debug("block {} is symbolic link, not backing up", extendedBlock);
        return 0;
    }

    LOG.info("performing block {}", extendedBlock);
    long numBytes = heb.getNumBytes();
    try (LengthInputStream data = new LengthInputStream(trackThroughPut(fsDataset.getBlockInputStream(heb, 0)),
            numBytes)) {
        org.apache.hadoop.hdfs.server.datanode.fsdataset.LengthInputStream tmeta;
        tmeta = fsDataset.getMetaDataInputStream(heb);
        try (LengthInputStream meta = new LengthInputStream(trackThroughPut(tmeta), tmeta.getLength())) {
            _backupStore.backupBlock(extendedBlock, data, meta);
            return 0;
        }
    } catch (IOException e) {
        if (LOG.isDebugEnabled() || !e.getMessage().contains("is not valid")) {
            LOG.error(e.getMessage(), e);
        } else {
            LOG.debug("block {} has been removed {}", extendedBlock);
        }
        return 0;
    }
}

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