/**
* Creates a new entry if not yet present. Adds the fragment. If all fragements for a given
* message have been received, an entire message is reassembled and returned. Otherwise null is
* returned.
*
* @param id - the message ID, unique for a sender
* @param frag_id the index of this fragmentation (0..tot_frags-1)
* @param tot_frags the total number of fragmentations expected
* @param fragment - the byte buffer for this fragment
*/
public synchronized byte[] add(long id, int frag_id, int tot_frags, byte[] fragment) {
byte[] retval = null; // initialize the return value to default not complete
FragEntry e = table.get(id);
if (e == null) { // Create new entry if not yet present
e = new FragEntry(id, tot_frags);
table.put(id, e);
}
e.set(frag_id, fragment);
if (e.isComplete()) {
retval = e.assembleBuffer();
table.remove(id);
}
return retval;
}
