net.openhft.chronicle.wire.Sequence Maven / Gradle / Ivy
/*
* Copyright 2016-2020 chronicle.software
*
* https://chronicle.software
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.openhft.chronicle.wire;
/**
* This is used in Chronicle-Queue to map a position to a sequence number.
*/
public interface Sequence {
long NOT_FOUND_RETRY = Long.MIN_VALUE;
long NOT_FOUND = -1;
/**
* gets the sequence for a writePosition
*
* This method will only return a valid sequence number of the write position if the write position is the
* last write position in the queue. YOU CAN NOT USE THIS METHOD TO LOOK UP RANDOM SEQUENCES FOR ANY WRITE POSITION.
* NOT_FOUND_RETRY will be return if a sequence number can not be found ( so retry )
* or NOT_FOUND if you should not retry
*
* @param forWritePosition the last write position, expected to be the end of queue
* @return NOT_FOUND_RETRY if the sequence for this write position can not be found (you can retry), or
* NOT_FOUND if it can't be found and there is no point in retrying
*/
long getSequence(long forWritePosition);
/**
* sets the sequence number for a writePosition
*
* @param sequence the sequence number
* @param position the write position
*/
void setSequence(long sequence, long position);
long toIndex(long headerNumber, long sequence);
long toSequenceNumber(long index);
}