// 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;
}
}
private static void ignoreAndWait(final Exception e, boolean printException) {
H2O.ignore(e, "Hit HDFS reset problem, retrying...", printException);
try {
Thread.sleep(500);
} catch (InterruptedException ie) {
}
}
// Store Value v to disk.
@Override
public void store(Value v) {
// Only the home node does persistence on NFS
if (!v._key.home()) return;
// A perhaps useless cutout: the upper layers should test this first.
if (v.isPersisted()) return;
// Never store arraylets on NFS, instead we'll store the entire array.
assert !v.isArray();
try {
File f = getFileForKey(v._key);
f.mkdirs();
FileOutputStream s = new FileOutputStream(f);
try {
byte[] m = v.memOrLoad();
assert (m == null || m.length == v._max); // Assert not saving partial files
if (m != null) new AutoBuffer(s.getChannel(), false, Value.NFS).putA1(m, m.length).close();
v.setdsk(); // Set as write-complete to disk
} finally {
s.close();
}
} catch (IOException e) {
H2O.ignore(e);
}
}