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// Copyright (C) 2015 The Android Open Source Project
//
// 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.google.gerrit.metrics.dropwizard;
import com.codahale.metrics.Gauge;
import com.codahale.metrics.Metric;
import com.codahale.metrics.MetricRegistry;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Maps;
import com.google.gerrit.metrics.Description;
import com.google.gerrit.metrics.Field;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/** Abstract callback metric broken down into buckets. */
abstract class BucketedCallback<V> implements BucketedMetric {
private final DropWizardMetricMaker metrics;
private final MetricRegistry registry;
private final String name;
private final Description.FieldOrdering ordering;
protected final Field<?>[] fields;
private final V zero;
private final Map<Object, ValueGauge> cells;
protected volatile Runnable trigger;
private final Object lock = new Object();
BucketedCallback(
DropWizardMetricMaker metrics,
MetricRegistry registry,
String name,
Class<V> valueType,
Description desc,
Field<?>... fields) {
this.metrics = metrics;
this.registry = registry;
this.name = name;
this.ordering = desc.getFieldOrdering();
this.fields = fields;
this.zero = CallbackMetricImpl0.zeroFor(valueType);
this.cells = new ConcurrentHashMap<>();
}
void doRemove() {
for (Object key : cells.keySet()) {
registry.remove(submetric(key));
}
metrics.remove(name);
}
void doBeginSet() {
for (ValueGauge g : cells.values()) {
g.set = false;
}
}
void doPrune() {
Iterator<Map.Entry<Object, ValueGauge>> i = cells.entrySet().iterator();
while (i.hasNext()) {
if (!i.next().getValue().set) {
i.remove();
}
}
}
void doEndSet() {
for (ValueGauge g : cells.values()) {
if (!g.set) {
g.value = zero;
}
}
}
ValueGauge getOrCreate(Object f1, Object f2) {
return getOrCreate(ImmutableList.of(f1, f2));
}
ValueGauge getOrCreate(Object f1, Object f2, Object f3) {
return getOrCreate(ImmutableList.of(f1, f2, f3));
}
ValueGauge getOrCreate(Object key) {
ValueGauge c = cells.get(key);
if (c != null) {
return c;
}
synchronized (lock) {
c = cells.get(key);
if (c == null) {
c = new ValueGauge();
registry.register(submetric(key), c);
cells.put(key, c);
}
return c;
}
}
private String submetric(Object key) {
return DropWizardMetricMaker.name(ordering, name, name(key));
}
abstract String name(Object key);
@Override
public Metric getTotal() {
return null;
}
@Override
public Field<?>[] getFields() {
return fields;
}
@Override
public Map<Object, Metric> getCells() {
return Maps.transformValues(cells, in -> (Metric) in);
}
final class ValueGauge implements Gauge<V> {
volatile V value = zero;
boolean set;
@Override
public V getValue() {
Runnable t = trigger;
if (t != null) {
t.run();
}
return value;
}
}
}