new DataOutputStream(new BufferedOutputStream(
peer.getOutputStream()));
new Sender(out).requestShortCircuitFds(block, blockToken, 1);
DataInputStream in =
new DataInputStream(peer.getInputStream());
BlockOpResponseProto resp = BlockOpResponseProto.parseFrom(
PBHelper.vintPrefixed(in));
DomainSocket sock = peer.getDomainSocket();
switch (resp.getStatus()) {
case SUCCESS:
BlockReaderLocal reader = null;
byte buf[] = new byte[1];
FileInputStream fis[] = new FileInputStream[2];
sock.recvFileInputStreams(fis, buf, 0, buf.length);
try {
reader = new BlockReaderLocal.Builder(conf).
setFilename(file).
setBlock(block).
setStartOffset(startOffset).
setStreams(fis).
setDatanodeID(datanodeID).
setVerifyChecksum(verifyChecksum).
setBlockMetadataHeader(
BlockMetadataHeader.preadHeader(fis[1].getChannel())).
setFileInputStreamCache(fisCache).
setCachingStrategy(cachingStrategy).
build();
} finally {
if (reader == null) {
IOUtils.cleanup(DFSClient.LOG, fis[0], fis[1]);
}
}
return reader;
case ERROR_UNSUPPORTED:
if (!resp.hasShortCircuitAccessVersion()) {
DFSClient.LOG.warn("short-circuit read access is disabled for " +
"DataNode " + datanodeID + ". reason: " + resp.getMessage());
domSockFactory.disableShortCircuitForPath(sock.getPath());
} else {
DFSClient.LOG.warn("short-circuit read access for the file " +
file + " is disabled for DataNode " + datanodeID +
". reason: " + resp.getMessage());
}
return null;
case ERROR_ACCESS_TOKEN:
String msg = "access control error while " +
"attempting to set up short-circuit access to " +
file + resp.getMessage();
DFSClient.LOG.debug(msg);
throw new InvalidBlockTokenException(msg);
default:
DFSClient.LOG.warn("error while attempting to set up short-circuit " +
"access to " + file + ": " + resp.getMessage());
domSockFactory.disableShortCircuitForPath(sock.getPath());
return null;
}
}