org.glowroot.agent.util.Tickers Maven / Gradle / Ivy
/*
* Copyright 2015 the original author or authors.
*
* 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 org.glowroot.agent.util;
import org.glowroot.agent.shaded.com.google.common.annotations.VisibleForTesting;
import org.glowroot.agent.shaded.com.google.common.base.Ticker;
public class Tickers {
private static final boolean USE_DUMMY_TICKER =
Boolean.getBoolean("glowroot.internal.dummyTicker");
private Tickers() {}
// normally Ticker should be injected, but in some memory sensitive classes it can be cached
// in a static field
public static Ticker getTicker() {
return getTicker(USE_DUMMY_TICKER);
}
// Nano times roll over every 292 years, so it is important to test differences between nano
// times instead of direct comparison (e.g. nano2 - nano1 >= 0, not nano1 <= nano2)
// (see http://java.sun.com/javase/7/docs/api/java/lang/System.html#nanoTime())
public static boolean lessThanOrEqual(long tick1, long tick2) {
return tick2 - tick1 >= 0;
}
@VisibleForTesting
static Ticker getTicker(boolean dummyTicker) {
if (dummyTicker) {
return new DummyTicker();
} else {
return Ticker.systemTicker();
}
}
private static class DummyTicker extends Ticker {
@Override
public long read() {
return 0;
}
}
}