com.datastax.driver.core.LoggingMonotonicTimestampGenerator Maven / Gradle / Ivy
/*
* Copyright DataStax, Inc.
*
* This software can be used solely with DataStax Enterprise. Please consult the license at
* http://www.datastax.com/terms/datastax-dse-driver-license-terms
*/
package com.datastax.driver.core;
import static java.util.concurrent.TimeUnit.MICROSECONDS;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A monotonic timestamp generator that logs warnings when timestamps drift in the future (see this
* class's constructors and {@link #onDrift(long, long)} for more information).
*/
public abstract class LoggingMonotonicTimestampGenerator
extends AbstractMonotonicTimestampGenerator {
private static final Logger LOGGER = LoggerFactory.getLogger(TimestampGenerator.class);
private final long warningThresholdMicros;
private final long warningIntervalMillis;
private final AtomicLong lastDriftWarning = new AtomicLong(Long.MIN_VALUE);
/**
* 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}.
*/
protected LoggingMonotonicTimestampGenerator(
long warningThreshold,
TimeUnit warningThresholdUnit,
long warningInterval,
TimeUnit warningIntervalUnit) {
this.warningThresholdMicros = MICROSECONDS.convert(warningThreshold, warningThresholdUnit);
this.warningIntervalMillis = MILLISECONDS.convert(warningInterval, warningIntervalUnit);
}
/**
* {@inheritDoc}
*
* This implementation logs a warning at regular intervals when timestamps drift more than a
* specified threshold in the future. These messages are emitted at {@code WARN} level in the
* category {@code com.datastax.driver.core.TimestampGenerator}.
*
* @param currentTick the current clock tick.
* @param lastTimestamp the last timestamp that was generated.
*/
protected void onDrift(long currentTick, long lastTimestamp) {
if (LOGGER.isWarnEnabled()
&& warningThresholdMicros >= 0
&& lastTimestamp > currentTick + warningThresholdMicros) {
long now = System.currentTimeMillis();
long lastWarning = lastDriftWarning.get();
if (now > lastWarning + warningIntervalMillis
&& lastDriftWarning.compareAndSet(lastWarning, now)) {
LOGGER.warn(
"Clock skew detected: current tick ({}) was {} microseconds behind the last generated timestamp ({}), "
+ "returned timestamps will be artificially incremented to guarantee monotonicity.",
currentTick,
lastTimestamp - currentTick,
lastTimestamp);
}
}
}
}