test/unit/org/apache/cassandra/metrics/CassandraMetricsRegistryTest.java

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 * 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
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 *   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cassandra.metrics;

import java.lang.management.ManagementFactory;
import java.util.Collection;

import org.junit.Test;

import com.codahale.metrics.jvm.BufferPoolMetricSet;
import com.codahale.metrics.jvm.GarbageCollectorMetricSet;
import com.codahale.metrics.jvm.MemoryUsageGaugeSet;
import org.apache.cassandra.metrics.CassandraMetricsRegistry.MetricName;

import static org.junit.Assert.*;


public class CassandraMetricsRegistryTest
{
    // A class with a name ending in '$'
    private static class StrangeName$
    {
    }

    @Test
    public void testChooseType()
    {
        assertEquals("StrangeName", MetricName.chooseType(null, StrangeName$.class));
        assertEquals("StrangeName", MetricName.chooseType("", StrangeName$.class));
        assertEquals("String", MetricName.chooseType(null, String.class));
        assertEquals("String", MetricName.chooseType("", String.class));

        assertEquals("a", MetricName.chooseType("a", StrangeName$.class));
        assertEquals("b", MetricName.chooseType("b", String.class));
    }

    @Test
    public void testMetricName()
    {
        MetricName name = new MetricName(StrangeName$.class, "NaMe", "ScOpE");
        assertEquals("StrangeName", name.getType());
    }

    @Test
    public void testJvmMetricsRegistration()
    {
        CassandraMetricsRegistry registry = CassandraMetricsRegistry.Metrics;

        // Same registration as CassandraDaemon
        registry.register("jvm.buffers", new BufferPoolMetricSet(ManagementFactory.getPlatformMBeanServer()));
        registry.register("jvm.gc", new GarbageCollectorMetricSet());
        registry.register("jvm.memory", new MemoryUsageGaugeSet());

        Collection<String> names = registry.getNames();

        // No metric with ".." in name
        assertTrue(names.stream()
                        .filter(name -> name.contains(".."))
                        .count()
                   == 0);

        // There should be several metrics within each category
        for (String category : new String[]{"jvm.buffers","jvm.gc","jvm.memory"})
        {
            assertTrue(names.stream()
                            .filter(name -> name.startsWith(category+'.'))
                            .count() > 1);
        }
    }

}