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/*
* =========================================================================================
* Copyright © 2013-2014 the kamon project <http://kamon.io/>
*
* 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 kamon.util
/**
* This class implements an extremely efficient, thread-safe way to generate a
* incrementing sequence of Longs with a simple Long overflow protection.
*/
class Sequencer {
private val CloseToOverflow = Long.MaxValue - 1000000000
private val sequenceNumber = new PaddedAtomicLong(1L)
def next(): Long = {
val current = sequenceNumber.getAndIncrement
// check if this value is getting close to overflow?
if (current > CloseToOverflow) {
sequenceNumber.set(current - CloseToOverflow) // we need maintain the order
}
current
}
}
object Sequencer {
def apply(): Sequencer = new Sequencer()
}
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