zipkin2.Annotation Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 zipkin2;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.io.StreamCorruptedException;
/**
* Associates an event that explains latency with a timestamp.
*
* Unlike log statements, annotations are often codes: Ex. {@code cache.miss}.
*/
//@Immutable
public final class Annotation implements Comparable, Serializable { // for Spark jobs
private static final long serialVersionUID = 0L;
public static Annotation create(long timestamp, String value) {
if (value == null) throw new NullPointerException("value == null");
return new Annotation(timestamp, value);
}
/**
* Microseconds from epoch.
*
* This value should be set directly by instrumentation, using the most precise value possible.
* For example, {@code gettimeofday} or multiplying {@link System#currentTimeMillis} by 1000.
*/
public long timestamp() {
return timestamp;
}
/**
* Usually a short tag indicating an event, like {@code cache.miss} or {@code error}
*/
public String value() {
return value;
}
/** Compares by {@link #timestamp}, then {@link #value}. */
@Override public int compareTo(Annotation that) {
if (this == that) return 0;
int byTimestamp = timestamp() < that.timestamp() ? -1 : timestamp() == that.timestamp() ? 0 : 1;
if (byTimestamp != 0) return byTimestamp;
return value().compareTo(that.value());
}
// clutter below mainly due to difficulty working with Kryo which cannot handle AutoValue subclass
// See https://github.com/apache/incubator-zipkin/issues/1879
final long timestamp;
final String value;
Annotation(long timestamp, String value) {
this.timestamp = timestamp;
this.value = value;
}
@Override public String toString() {
return "Annotation{"
+ "timestamp=" + timestamp + ", "
+ "value=" + value
+ "}";
}
@Override public boolean equals(Object o) {
if (o == this) return true;
if (!(o instanceof Annotation)) return false;
Annotation that = (Annotation) o;
return timestamp == that.timestamp() && value.equals(that.value());
}
@Override public int hashCode() {
int h = 1;
h *= 1000003;
h ^= (int) ((timestamp >>> 32) ^ timestamp);
h *= 1000003;
h ^= value.hashCode();
return h;
}
// As this is an immutable object (no default constructor), defer to a serialization proxy.
final Object writeReplace() throws ObjectStreamException {
return new SerializedForm(this);
}
private static final class SerializedForm implements Serializable {
static final long serialVersionUID = 0L;
final long timestamp;
final String value;
SerializedForm(Annotation annotation) {
timestamp = annotation.timestamp;
value = annotation.value;
}
Object readResolve() throws ObjectStreamException {
try {
return Annotation.create(timestamp, value);
} catch (IllegalArgumentException e) {
throw new StreamCorruptedException(e.getMessage());
}
}
}
}