/**
* Removes a message whose seqno is equal to <code>next_to_remove</code>, increments the latter. Returns message
* that was removed, or null, if no message can be removed. Messages are thus removed in order.
*/
public Message remove() {
long next=next_to_remove.get();
Segment segment=current_remove_segment;
if(segment == null || !segment.contains(next)) {
segment=findSegment(next);
if(segment != null)
current_remove_segment=segment;
}
if(segment == null)
return null;
Message retval=segment.remove(next);
if(retval != null) {
next_to_remove.compareAndSet(next, next +1);
if(segment.allRemoved())
segments.remove(next / segment_capacity);
}
return retval;
}
/**
* Removes as many messages as possible (in sequence, without gaps)
* @param max Max number of messages to be removed
* @return Tuple<List<Message>,Long>: a tuple of the message list and the highest seqno removed
*/
public Tuple<List<Message>,Long> removeMany(final int max) {
List<Message> list=null; // we remove msgs.size() messages *max*
Tuple<List<Message>,Long> retval=null;
int count=0;
boolean looping=true;
while(count < max && looping) {
long next=next_to_remove.get();
Segment segment=current_remove_segment;
if(segment == null || !segment.contains(next)) {
segment=findSegment(next);
if(segment != null)
current_remove_segment=segment;
}
if(segment == null)
return retval;
long segment_id=next;
long end=segment.getEndIndex();
while(next < end && count < max) {
Message msg=segment.remove(next);
if(msg == null) {
looping=false;
break;
}
if(list == null) {
list=new LinkedList<Message>(); // we remove msgs.size() messages *max*
retval=new Tuple<List<Message>,Long>(list, 0L);
}
list.add(msg);
count++;
retval.setVal2(next);
next_to_remove.compareAndSet(next, ++next);
if(segment.allRemoved())
segments.remove(segment_id / segment_capacity);
}
}
return retval;
}