com.datastax.driver.core.ThreadLocalMonotonicTimestampGenerator Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of cassandra-driver Show documentation
Show all versions of cassandra-driver Show documentation
Shaded version of DataStax Java Driver for Apache Cassandra
/*
* Copyright (C) 2012-2015 DataStax Inc.
*
* 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 com.datastax.driver.core;
import java.util.concurrent.TimeUnit;
/**
* A timestamp generator that guarantees monotonically increasing timestamps on a per-thread basis, and logs warnings
* when timestamps drift in the future.
*
* Beware that there is a risk of timestamp collision with this generator when accessed
* by more than one thread at a time; only use it when threads are not in direct competition
* for timestamp ties (i.e., they are executing independent statements).
*
* @see AbstractMonotonicTimestampGenerator
*/
public class ThreadLocalMonotonicTimestampGenerator extends LoggingMonotonicTimestampGenerator {
// We're deliberately avoiding an anonymous subclass with initialValue(), because this can introduce
// classloader leaks in managed environments like Tomcat
private final ThreadLocal lastRef = new ThreadLocal();
/**
* Creates a new instance with a warning threshold and warning interval of one second.
*
* @see #ThreadLocalMonotonicTimestampGenerator(long, TimeUnit, long, TimeUnit)
*/
public ThreadLocalMonotonicTimestampGenerator() {
this(1, TimeUnit.SECONDS, 1, TimeUnit.SECONDS);
}
/**
* Creates a new instance.
*
* @param warningThreshold how far in the future timestamps are allowed to drift before a warning is logged.
* @param warningThresholdUnit the unit for {@code warningThreshold}.
* @param warningInterval how often the warning will be logged if timestamps keep drifting above the threshold.
* @param warningIntervalUnit the unit for {@code warningIntervalUnit}.
*/
public ThreadLocalMonotonicTimestampGenerator(long warningThreshold, TimeUnit warningThresholdUnit,
long warningInterval, TimeUnit warningIntervalUnit) {
super(warningThreshold, warningThresholdUnit, warningInterval, warningIntervalUnit);
}
@Override
public long next() {
Long last = this.lastRef.get();
if (last == null)
last = 0L;
long next = computeNext(last);
this.lastRef.set(next);
return next;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy