// Read up to 'len' bytes of Value. Value should already be persisted to
// disk. A racing delete can trigger a failure where we get a null return,
// but no crash (although one could argue that a racing load&delete is a bug
// no matter what).
@Override
public byte[] load(Value v) {
long skip = 0;
Key k = v._key;
// Convert an arraylet chunk into a long-offset from the base file.
if (k._kb[0] == Key.ARRAYLET_CHUNK) {
skip = ValueArray.getChunkOffset(k); // The offset
k = ValueArray.getArrayKey(k); // From the base file key
}
if (k._kb[0] == Key.DVEC) {
skip = water.fvec.NFSFileVec.chunkOffset(k); // The offset
}
try {
FileInputStream s = null;
try {
s = new FileInputStream(getFileForKey(k));
FileChannel fc = s.getChannel();
fc.position(skip);
AutoBuffer ab = new AutoBuffer(fc, true, Value.NFS);
byte[] b = ab.getA1(v._max);
ab.close();
assert v.isPersisted();
return b;
} finally {
if (s != null) s.close();
}
} catch (IOException e) { // Broken disk / short-file???
H2O.ignore(e);
return null;
}
}
@Override
public byte[] load(final Value v) {
final byte[] b = MemoryManager.malloc1(v._max);
long skip = 0;
Key k = v._key;
if (k._kb[0] == Key.ARRAYLET_CHUNK) {
skip = ValueArray.getChunkOffset(k); // The offset
k = ValueArray.getArrayKey(k); // From the base file key
} else if (k._kb[0] == Key.DVEC) {
skip = water.fvec.NFSFileVec.chunkOffset(k); // The offset
}
final Path p =
_iceRoot == null ? new Path(getPathForKey(k)) : new Path(_iceRoot, getIceName(v));
final long skip_ = skip;
run(
new Callable() {
@Override
public Object call() throws Exception {
FileSystem fs = FileSystem.get(p.toUri(), CONF);
FSDataInputStream s = null;
try {
s = fs.open(p);
// NOTE:
// The following line degrades performance of HDFS load from S3 API:
// s.readFully(skip,b,0,b.length);
// Google API's simple seek has better performance
// Load of 300MB file via Google API ~ 14sec, via s.readFully ~ 5min (under the same
// condition)
ByteStreams.skipFully(s, skip_);
ByteStreams.readFully(s, b);
assert v.isPersisted();
} finally {
Utils.close(s);
}
return null;
}
},
true,
v._max);
return b;
}