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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.server.cache;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheStats;
import com.google.common.collect.ImmutableSet;
import com.google.gerrit.extensions.registration.DynamicMap;
import com.google.gerrit.extensions.registration.Extension;
import com.google.gerrit.extensions.registration.PluginName;
import com.google.gerrit.metrics.CallbackMetric;
import com.google.gerrit.metrics.CallbackMetric1;
import com.google.gerrit.metrics.Description;
import com.google.gerrit.metrics.Field;
import com.google.gerrit.metrics.MetricMaker;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.util.Set;
@Singleton
public class CacheMetrics {
@Inject
public CacheMetrics(MetricMaker metrics, DynamicMap<Cache<?, ?>> cacheMap) {
Field<String> F_NAME = Field.ofString("cache_name");
CallbackMetric1<String, Long> memEnt =
metrics.newCallbackMetric(
"caches/memory_cached",
Long.class,
new Description("Memory entries").setGauge().setUnit("entries"),
F_NAME);
CallbackMetric1<String, Double> memHit =
metrics.newCallbackMetric(
"caches/memory_hit_ratio",
Double.class,
new Description("Memory hit ratio").setGauge().setUnit("percent"),
F_NAME);
CallbackMetric1<String, Long> memEvict =
metrics.newCallbackMetric(
"caches/memory_eviction_count",
Long.class,
new Description("Memory eviction count").setGauge().setUnit("evicted entries"),
F_NAME);
CallbackMetric1<String, Long> perDiskEnt =
metrics.newCallbackMetric(
"caches/disk_cached",
Long.class,
new Description("Disk entries used by persistent cache").setGauge().setUnit("entries"),
F_NAME);
CallbackMetric1<String, Double> perDiskHit =
metrics.newCallbackMetric(
"caches/disk_hit_ratio",
Double.class,
new Description("Disk hit ratio for persistent cache").setGauge().setUnit("percent"),
F_NAME);
Set<CallbackMetric<?>> cacheMetrics =
ImmutableSet.<CallbackMetric<?>>of(memEnt, memHit, memEvict, perDiskEnt, perDiskHit);
metrics.newTrigger(
cacheMetrics,
() -> {
for (Extension<Cache<?, ?>> e : cacheMap) {
Cache<?, ?> c = e.getProvider().get();
String name = metricNameOf(e);
CacheStats cstats = c.stats();
memEnt.set(name, c.size());
memHit.set(name, cstats.hitRate() * 100);
memEvict.set(name, cstats.evictionCount());
if (c instanceof PersistentCache) {
PersistentCache.DiskStats d = ((PersistentCache) c).diskStats();
perDiskEnt.set(name, d.size());
perDiskHit.set(name, hitRatio(d));
}
}
cacheMetrics.forEach(CallbackMetric::prune);
});
}
private static double hitRatio(PersistentCache.DiskStats d) {
if (d.requestCount() <= 0) {
return 100;
}
return ((double) d.hitCount() / d.requestCount() * 100);
}
private static String metricNameOf(Extension<Cache<?, ?>> e) {
if (PluginName.GERRIT.equals(e.getPluginName())) {
return e.getExportName();
}
return String.format("plugin/%s/%s", e.getPluginName(), e.getExportName());
}
}
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