Reflective version of #305 (#341)

Author: marcust

simpleclient_hotspot/src/main/java/io/prometheus/client/hotspot/BufferPoolsExports.java

@@ -0,0 +1,122 @@
+package io.prometheus.client.hotspot;
+
+import io.prometheus.client.Collector;
+import io.prometheus.client.GaugeMetricFamily;
+
+import java.lang.management.ManagementFactory;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.logging.Logger;
+
+/**
+ * Exports metrics about JVM buffers.
+ *
+ * Can be replaced with a simple access once JDK 1.7 compatibility is baseline.
+ *
+ */
+public class BufferPoolsExports extends Collector {
+
+    private static final Logger LOGGER = Logger.getLogger(BufferPoolsExports.class.getName());
+
+    private final List<Object> bufferPoolMXBeans = new ArrayList<Object>();
+    private Method getName;
+    private Method getMemoryUsed;
+    private Method getTotalCapacity;
+    private Method getCount;
+
+    public BufferPoolsExports() {
+        try {
+            final Class<?> bufferPoolMXBeanClass = Class.forName("java.lang.management.BufferPoolMXBean");
+            bufferPoolMXBeans.addAll(accessBufferPoolMXBeans(bufferPoolMXBeanClass));
+
+            getName = bufferPoolMXBeanClass.getMethod("getName");
+            getMemoryUsed = bufferPoolMXBeanClass.getMethod("getMemoryUsed");
+            getTotalCapacity = bufferPoolMXBeanClass.getMethod("getTotalCapacity");
+            getCount = bufferPoolMXBeanClass.getMethod("getCount");
+
+        } catch (ClassNotFoundException e) {
+            LOGGER.fine("BufferPoolMXBean not available, no metrics for buffer pools will be exported");
+        } catch (NoSuchMethodException e) {
+            LOGGER.fine("Can not get necessary accessor from BufferPoolMXBean: " + e.getMessage());
+        }
+    }
+
+    private static List<Object> accessBufferPoolMXBeans(final Class<?> bufferPoolMXBeanClass) {
+        try {
+            final Method getPlatformMXBeansMethod = ManagementFactory.class.getMethod("getPlatformMXBeans", Class.class);
+            final Object listOfBufferPoolMXBeanInstances = getPlatformMXBeansMethod.invoke(null, bufferPoolMXBeanClass);
+
+            return (List<Object>) listOfBufferPoolMXBeanInstances;
+
+        } catch (NoSuchMethodException e) {
+            LOGGER.fine("ManagementFactory.getPlatformMXBeans not available, no metrics for buffer pools will be exported");
+            return Collections.emptyList();
+        } catch (IllegalAccessException e) {
+            LOGGER.fine("ManagementFactory.getPlatformMXBeans not accessible, no metrics for buffer pools will be exported");
+            return Collections.emptyList();
+        } catch (InvocationTargetException e) {
+            LOGGER.warning("ManagementFactory.getPlatformMXBeans could not be invoked, no metrics for buffer pools will be exported");
+            return Collections.emptyList();
+        }
+    }
+
+    @Override
+    public List<MetricFamilySamples> collect() {
+        List<MetricFamilySamples> mfs = new ArrayList<MetricFamilySamples>();
+        GaugeMetricFamily used = new GaugeMetricFamily(
+                "jvm_buffer_pool_used_bytes",
+                "Used bytes of a given JVM buffer pool.",
+                Collections.singletonList("pool"));
+        mfs.add(used);
+        GaugeMetricFamily capacity = new GaugeMetricFamily(
+                "jvm_buffer_pool_capacity_bytes",
+                "Bytes capacity of a given JVM buffer pool.",
+                Collections.singletonList("pool"));
+        mfs.add(capacity);
+        GaugeMetricFamily buffers = new GaugeMetricFamily(
+                "jvm_buffer_pool_used_buffers",
+                "Used buffers of a given JVM buffer pool.",
+                Collections.singletonList("pool"));
+        mfs.add(buffers);
+        for (final Object pool : bufferPoolMXBeans) {
+            used.addMetric(
+                    Collections.singletonList(getName(pool)),
+                    callLongMethond(getMemoryUsed,pool));
+            capacity.addMetric(
+                    Collections.singletonList(getName(pool)),
+                    callLongMethond(getTotalCapacity,pool));
+            buffers.addMetric(
+                    Collections.singletonList(getName(pool)),
+                    callLongMethond(getCount,pool));
+        }
+        return mfs;
+    }
+
+    private long callLongMethond(final Method method, final Object pool) {
+        try {
+            return (Long)method.invoke(pool);
+        } catch (IllegalAccessException e) {
+            LOGGER.fine("Couldn't call " + method.getName() + ": " + e.getMessage());
+        } catch (InvocationTargetException e) {
+            LOGGER.fine("Couldn't call " + method.getName() + ": " + e.getMessage());
+        }
+        return 0L;
+    }
+
+    private String getName(final Object pool) {
+        try {
+            return (String)getName.invoke(pool);
+        } catch (IllegalAccessException e) {
+            LOGGER.fine("Couldn't call getName " + e.getMessage());
+        } catch (InvocationTargetException e) {
+            LOGGER.fine("Couldn't call getName " + e.getMessage());
+        }
+        return "<unknown>";
+    }
+
+
+
+}

simpleclient_hotspot/src/main/java/io/prometheus/client/hotspot/DefaultExports.java

@@ -22,6 +22,7 @@ public static synchronized void initialize() {
     if (!initialized) {
       new StandardExports().register();
       new MemoryPoolsExports().register();
+      new BufferPoolsExports().register();
       new GarbageCollectorExports().register();
       new ThreadExports().register();
       new ClassLoadingExports().register();