package org.apache.hadoop.raid;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.HarFileSystem;
import org.apache.hadoop.fs.Path;
public class ParityFilePair {
final private Path path;
final private FileStatus stat;
final private FileSystem fs;
private ParityFilePair(Path path, FileStatus stat, FileSystem fs) {
this.path = path;
this.stat = stat;
this.fs = fs;
}
public Path getPath() {
return this.path;
}
public FileStatus getFileStatus() {
return this.stat;
}
public FileSystem getFileSystem() {
return this.fs;
}
/**
* Return whether if parity file of the source file exists or not
*
* @param src The FileStatus of the source file.
* @param codec The Codec of the parity to check
* @param conf
* @return
* @throws IOException
*/
public static boolean parityExists(FileStatus src, Codec codec,
Configuration conf) throws IOException {
return ParityFilePair.getParityFile(codec, src.getPath(), conf) != null;
}
/**
* Returns the Path to the parity file of a given file / directory
*
* @param codec The Codec of the parity
* @param srcPath Path to the original source file
* @return ParityFilePair representing the parity file of the source
* @throws IOException
*/
public static ParityFilePair getParityFile(Codec codec, Path srcPath,
Configuration conf) throws IOException {
FileSystem fsSrc = srcPath.getFileSystem(conf);
if (codec.isDirRaid) {
FileStatus stat = null;
try {
stat = fsSrc.getFileStatus(srcPath);
} catch (java.io.FileNotFoundException e) {
return null;
}
if (!stat.isDir()) {
// directory raid needs a directory to get parity file
srcPath = srcPath.getParent();
}
}
Path srcParent = srcPath.getParent();
//We assume that parity file and source file live in the same cluster
FileSystem fsDest = fsSrc;
Path destPathPrefix = fsDest.makeQualified(new Path(
codec.parityDirectory));
FileStatus srcStatus = null;
try {
srcStatus = fsSrc.getFileStatus(srcPath);
} catch (java.io.FileNotFoundException e) {
return null;
}
Path outDir = destPathPrefix;
if (srcParent != null) {
if (srcParent.getParent() == null) {
outDir = destPathPrefix;
} else {
outDir = new Path(destPathPrefix, RaidNode.makeRelative(srcParent));
}
}
//CASE 1: CHECK HAR - Must be checked first because har is created after
// parity file and returning the parity file could result in error while
// reading it.
Path outPath = RaidNode.getOriginalParityFile(destPathPrefix, srcPath);
String harDirName = srcParent.getName() + RaidNode.HAR_SUFFIX;
Path HarPath = new Path(outDir,harDirName);
if (fsDest.exists(HarPath)) {
URI HarPathUri = HarPath.toUri();
Path inHarPath = new Path("har://",HarPathUri.getPath()+"/"+outPath.toUri().getPath());
FileSystem fsHar = new HarFileSystem(fsDest);
fsHar.initialize(inHarPath.toUri(), conf);
FileStatus inHar = FileStatusCache.get(fsHar, inHarPath);
if (inHar != null) {
if (verifyParity(srcStatus, inHar, codec, conf)) {
return new ParityFilePair(inHarPath, inHar, fsHar);
}
}
}
//CASE 2: CHECK PARITY
try {
FileStatus outHar = fsDest.getFileStatus(outPath);
if (verifyParity(srcStatus, outHar, codec, conf)) {
return new ParityFilePair(outPath, outHar, fsDest);
}
} catch (java.io.FileNotFoundException e) {
}
return null; // NULL if no parity file
}
static boolean verifyParity(FileStatus src, FileStatus parity,
Codec codec, Configuration conf) throws IOException {
if (parity.getModificationTime() != src.getModificationTime()) {
return false;
}
int stripeLength = codec.stripeLength;
int parityLegnth = codec.parityLength;
long expectedSize = 0;
if (codec.isDirRaid) {
FileSystem srcFs = src.getPath().getFileSystem(conf);
List<FileStatus> lfs = RaidNode.listDirectoryRaidFileStatus(conf, srcFs,
src.getPath());
if (lfs == null) {
return false;
}
long blockNum = DirectoryStripeReader.getBlockNum(lfs);
long parityBlockSize = DirectoryStripeReader.getParityBlockSize(conf,
lfs);
int parityBlocks = (int)Math.ceil(
((double)blockNum) / stripeLength) * parityLegnth;
expectedSize = parityBlocks * parityBlockSize;
} else {
double sourceBlocks = Math.ceil(
((double)src.getLen()) / src.getBlockSize());
int parityBlocks = (int)Math.ceil(
sourceBlocks / stripeLength) * parityLegnth;
expectedSize = parityBlocks * src.getBlockSize();
}
if (parity.getLen() != expectedSize) {
RaidNode.LOG.error("Bad parity file:" + parity.getPath() +
" File size doen't match. parity:" + parity.getLen() +
" expected:" + expectedSize);
return false;
}
return true;
}
/**
* Caches the listStatus result in a thread local cache. This greatly
* increases the speed of repeatedly calling getParityFile() from
* the same thread.
*/
static class FileStatusCache {
private static final long CACHE_STALE_PERIOD = 60 * 1000L;
// The threadlocal stores a separate cache for each thread
private static ThreadLocal<Map<Path, FileStatusWithTime>> tLocalCaches =
new ThreadLocal<Map<Path, FileStatusWithTime>>();
/**
* Do getFileStatus with caching
* @param fs FileSystem
* @param file The path to do getFileStatus
* @return FileStatus of the file
* @throws IOException
*/
static FileStatus get(FileSystem fs, Path file) throws IOException {
long now = RaidNode.now();
Map<Path, FileStatusWithTime> cache = tLocalCaches.get();
// If the current thread do not have a cache, create one.
if (cache == null || !useCache) {
cache = new HashMap<Path, FileStatusWithTime>();
tLocalCaches.set(cache);
}
FileStatusWithTime fileStatusWithTime = cache.get(file);
if (fileStatusWithTime != null) {
if (now - fileStatusWithTime.time > CACHE_STALE_PERIOD) {
cache.remove(file);
} else {
return fileStatusWithTime.fileStatus;
}
}
Path parent = file.getParent();
// We cache the FileStatus in one directory. When move to a different
// directory, the cache is cleared.
cache.clear();
FileStatus[] files = null;
try {
files = fs.listStatus(parent);
} catch (FileNotFoundException e) {
}
if (files == null) {
return null;
}
for (FileStatus status : files) {
cache.put(status.getPath(), new FileStatusWithTime(status, now));
}
if (cache.containsKey(file)) {
return cache.get(file).fileStatus;
} else {
return null;
}
}
}
private static class FileStatusWithTime {
final FileStatus fileStatus;
final long time;
FileStatusWithTime(FileStatus fileStatus, long time) {
this.fileStatus = fileStatus;
this.time = time;
}
}
private static boolean useCache = true;
/**
* Disable the cache of FileStatus
* SHOULD NOT BE USED BY ANY PRODUCTION CODE
*/
public static void disableCacheUsedInTestOnly() {
useCache = false;
}
}