Token<BlockTokenIdentifier> token, DatanodeInfo node,
long startOffset, long length) throws IOException {
LocalDatanodeInfo localDatanodeInfo = getLocalDatanodeInfo(node
.getIpcPort());
// check the cache first
BlockLocalPathInfo pathinfo = localDatanodeInfo.getBlockLocalPathInfo(blk);
if (pathinfo == null) {
if (userGroupInformation == null) {
userGroupInformation = UserGroupInformation.getCurrentUser();
}
pathinfo = getBlockPathInfo(userGroupInformation, blk, node,
configuration, conf.hdfsTimeout, token,
conf.connectToDnViaHostname);
}
// check to see if the file exists. It may so happen that the
// HDFS file has been deleted and this block-lookup is occurring
// on behalf of a new HDFS file. This time, the block file could
// be residing in a different portion of the fs.data.dir directory.
// In this case, we remove this entry from the cache. The next
// call to this method will re-populate the cache.
FileInputStream dataIn = null;
FileInputStream checksumIn = null;
BlockReaderLocalLegacy localBlockReader = null;
boolean skipChecksumCheck = conf.skipShortCircuitChecksums;
try {
// get a local file system
File blkfile = new File(pathinfo.getBlockPath());
dataIn = new FileInputStream(blkfile);
if (LOG.isDebugEnabled()) {
LOG.debug("New BlockReaderLocalLegacy for file " + blkfile + " of size "
+ blkfile.length() + " startOffset " + startOffset + " length "
+ length + " short circuit checksum " + !skipChecksumCheck);
}
if (!skipChecksumCheck) {
// get the metadata file
File metafile = new File(pathinfo.getMetaPath());
checksumIn = new FileInputStream(metafile);
// read and handle the common header here. For now just a version
BlockMetadataHeader header = BlockMetadataHeader
.readHeader(new DataInputStream(checksumIn));
short version = header.getVersion();
if (version != BlockMetadataHeader.VERSION) {
LOG.warn("Wrong version (" + version + ") for metadata file for "
+ blk + " ignoring ...");
}
DataChecksum checksum = header.getChecksum();
long firstChunkOffset = startOffset
- (startOffset % checksum.getBytesPerChecksum());
localBlockReader = new BlockReaderLocalLegacy(conf, file, blk, token,
startOffset, length, pathinfo, checksum, true, dataIn,
firstChunkOffset, checksumIn);
} else {
localBlockReader = new BlockReaderLocalLegacy(conf, file, blk, token,
startOffset, length, pathinfo, dataIn);
}
} catch (IOException e) {
// remove from cache
localDatanodeInfo.removeBlockLocalPathInfo(blk);
DFSClient.LOG.warn("BlockReaderLocalLegacy: Removing " + blk
+ " from cache because local file " + pathinfo.getBlockPath()
+ " could not be opened.");
throw e;
} finally {
if (localBlockReader == null) {
if (dataIn != null) {