com.google.gerrit.server.cache.CacheMetrics.java Source code

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Here is the source code for com.google.gerrit.server.cache.CacheMetrics.java

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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.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 (DynamicMap.Entry<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(DynamicMap.Entry<Cache<?, ?>> e) {
        if ("gerrit".equals(e.getPluginName())) {
            return e.getExportName();
        }
        return String.format("plugin/%s/%s", e.getPluginName(), e.getExportName());
    }
}