package com.codahale.metrics.jvm;
import com.codahale.metrics.JmxAttributeGauge;
import com.codahale.metrics.Metric;
import com.codahale.metrics.MetricSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.management.JMException;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import static com.codahale.metrics.MetricRegistry.name;
/**
* A set of gauges for the count, usage, and capacity of the JVM's direct and mapped buffer pools.
* <p>
* These JMX objects are only available on Java 7 and above.
*/
public class BufferPoolMetricSet implements MetricSet {
private static final Logger LOGGER = LoggerFactory.getLogger(BufferPoolMetricSet.class);
private static final String[] ATTRIBUTES = { "Count", "MemoryUsed", "TotalCapacity" };
private static final String[] NAMES = { "count", "used", "capacity" };
private static final String[] POOLS = { "direct", "mapped" };
private final MBeanServer mBeanServer;
public BufferPoolMetricSet(MBeanServer mBeanServer) {
this.mBeanServer = mBeanServer;
}
@Override
public Map<String, Metric> getMetrics() {
final Map<String, Metric> gauges = new HashMap<String, Metric>();
for (String pool : POOLS) {
for (int i = 0; i < ATTRIBUTES.length; i++) {
final String attribute = ATTRIBUTES[i];
final String name = NAMES[i];
try {
final ObjectName on = new ObjectName("java.nio:type=BufferPool,name=" + pool);
mBeanServer.getMBeanInfo(on);
gauges.put(name(pool, name),
new JmxAttributeGauge(mBeanServer, on, attribute));
} catch (JMException ignored) {
LOGGER.debug("Unable to load buffer pool MBeans, possibly running on Java 6");
}
}
}
return Collections.unmodifiableMap(gauges);
}
}