/**
* @param ref The ref.
* @return The offset to list record pointer; list record is created if it doesn't exist.
*/
private long createOrGetListRecord(long ref) {
if (Ref.hasList(ref)) {
// LOG.info("Found list record at " + writeBuffers.getReadPoint());
return writeBuffers.getReadPoint(); // Assumes we are here after key compare.
}
long firstTailOffset = Ref.getOffset(ref);
// LOG.info("First tail offset to create list record is " + firstTailOffset);
// Determine the length of storage for value and key lengths of the first record.
writeBuffers.setReadPoint(firstTailOffset);
writeBuffers.skipVLong();
writeBuffers.skipVLong();
int lengthsLength = (int) (writeBuffers.getReadPoint() - firstTailOffset);
// Create the list record, copy first record value/key lengths there.
writeBuffers.writeBytes(firstTailOffset, lengthsLength);
long lrPtrOffset = writeBuffers.getWritePoint();
// LOG.info("Creating list record: copying " + lengthsLength + ", lrPtrOffset " + lrPtrOffset);
// Reserve 5 bytes for writeValueRecord to fill. There might be junk there so null them.
writeBuffers.write(FIVE_ZEROES);
// Link the list record to the first element.
writeBuffers.writeFiveByteULong(firstTailOffset, lrPtrOffset - lengthsLength - firstTailOffset);
return lrPtrOffset;
}
/**
* Adds a newly-written record to existing list.
*
* @param lrPtrOffset List record pointer offset.
* @param tailOffset New record offset.
*/
private void addRecordToList(long lrPtrOffset, long tailOffset) {
// Now, insert this record into the list.
long prevHeadOffset = writeBuffers.readNByteLong(lrPtrOffset, 5);
// LOG.info("Reading offset " + prevHeadOffset + " at " + lrPtrOffset);
assert prevHeadOffset < tailOffset; // We replace an earlier element, must have lower offset.
writeBuffers.writeFiveByteULong(lrPtrOffset, tailOffset);
// LOG.info("Writing offset " + tailOffset + " at " + lrPtrOffset);
writeBuffers.writeVLong(prevHeadOffset == 0 ? 0 : (tailOffset - prevHeadOffset));
}