public synchronized StoredBlock get(Sha256Hash hash) throws BlockStoreException {
ensureOpen();
// Check the memory cache first.
StoredBlock fromMem = blockCache.get(hash);
if (fromMem != null) {
return fromMem;
}
if (notFoundCache.get(hash) == notFoundMarker) {
return null;
}
try {
Record fromDisk = getRecord(hash);
StoredBlock block = null;
if (fromDisk == null) {
notFoundCache.put(hash, notFoundMarker);
} else {
block = fromDisk.toStoredBlock(params);
blockCache.put(hash, block);
}
return block;
} catch (IOException e) {
throw new BlockStoreException(e);
} catch (ProtocolException e) {
throw new BlockStoreException(e);
}
}
private Record getRecord(Sha256Hash hash) throws IOException, ProtocolException {
long startPos = channel.position();
// Use our own file pointer within the tight loop as updating channel positions is really
// expensive.
long pos = startPos;
Record record = new Record();
int numMoves = 0;
long startTime = new Date().getTime();
do {
if (!record.read(channel, pos, buf)) throw new IOException("Failed to read buffer");
if (record.getHeader(params).getHash().equals(hash)) {
// Found it. Update file position for next time.
channel.position(pos);
long endTime = new Date().getTime();
if (endTime - startTime > 100) {
log.info(
"Spent {} seconds doing {} backwards seeks",
(endTime - startTime) / 1000.0,
numMoves);
}
return record;
}
// Did not find it.
if (pos == 1 + 32) {
// At the start so wrap around to the end.
pos = channel.size() - Record.SIZE;
} else {
// Move backwards.
pos = pos - Record.SIZE;
checkState(pos >= 1 + 32, pos);
}
numMoves++;
} while (pos != startPos);
// Was never stored.
channel.position(pos);
long endTime = new Date().getTime();
if (endTime - startTime > 1000) {
log.info(
"Spent {} seconds doing {} backwards seeks", (endTime - startTime) / 1000.0, numMoves);
}
return null;
}
public synchronized void put(StoredBlock block) throws BlockStoreException {
ensureOpen();
try {
Sha256Hash hash = block.getHeader().getHash();
// Append to the end of the file.
Record.write(channel, block);
blockCache.put(hash, block);
} catch (IOException e) {
throw new BlockStoreException(e);
}
}