/** removes a parity block in the specified stripe */
private void removeParityBlock(Path filePath, int stripe) throws IOException {
// find parity file
ParityFilePair ppair = ParityFilePair.getParityFile(ErasureCodeType.XOR, filePath, conf);
String parityPathStr = ppair.getPath().toUri().getPath();
LOG.info("parity path: " + parityPathStr);
FileSystem parityFS = ppair.getFileSystem();
if (!(parityFS instanceof DistributedFileSystem)) {
throw new IOException("parity file is not on distributed file system");
}
DistributedFileSystem parityDFS = (DistributedFileSystem) parityFS;
// now corrupt the block corresponding to the stripe selected
FileStatus parityFileStatus = parityDFS.getFileStatus(new Path(parityPathStr));
long parityBlockSize = parityFileStatus.getBlockSize();
long parityFileLength = parityFileStatus.getLen();
long parityFileLengthInBlocks =
(parityFileLength / parityBlockSize)
+ (((parityFileLength % parityBlockSize) == 0) ? 0L : 1L);
if (parityFileLengthInBlocks <= stripe) {
throw new IOException(
"selected stripe "
+ stripe
+ " but parity file only has "
+ parityFileLengthInBlocks
+ " blocks");
}
if (parityBlockSize != BLOCK_SIZE) {
throw new IOException(
"file block size is " + BLOCK_SIZE + " but parity file block size is " + parityBlockSize);
}
LocatedBlocks parityFileBlocks =
parityDFS.getClient().namenode.getBlockLocations(parityPathStr, 0, parityFileLength);
if (parityFileBlocks.locatedBlockCount() != parityFileLengthInBlocks) {
throw new IOException(
"expected "
+ parityFileLengthInBlocks
+ " parity file blocks but got "
+ parityFileBlocks.locatedBlockCount()
+ " blocks");
}
LocatedBlock parityFileBlock = parityFileBlocks.get(stripe);
removeAndReportBlock(parityDFS, new Path(parityPathStr), parityFileBlock);
LOG.info("removed parity file block/stripe " + stripe + " for " + filePath.toString());
}
static {
ParityFilePair.disableCacheUsedInTestOnly();
}
