com.yammer.metrics.reporting.MetricsServlet Maven / Gradle / Ivy
package com.yammer.metrics.reporting;
import com.yammer.metrics.Metrics;
import com.yammer.metrics.core.*;
import com.yammer.metrics.stats.Snapshot;
import org.codehaus.jackson.JsonEncoding;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.map.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Map;
import java.util.SortedMap;
import java.util.concurrent.TimeUnit;
/**
* An HTTP servlet which outputs the metrics in a {@link MetricsRegistry} (and optionally the data
* provided by {@link VirtualMachineMetrics}) in a JSON object. Only responds to {@code GET}
* requests.
*
* If the servlet context has an attribute named
* {@code com.yammer.metrics.reporting.MetricsServlet.registry} which is a
* {@link MetricsRegistry} instance, {@link MetricsServlet} will use it instead of {@link Metrics}.
*
* {@link MetricsServlet} also takes an initialization parameter, {@code show-jvm-metrics}, which
* should be a boolean value (e.g., {@code "true"} or {@code "false"}). It determines whether or not
* JVM-level metrics will be included in the JSON output.
*
* {@code GET} requests to {@link MetricsServlet} can make use of the following query-string
* parameters:
*
* /metrics?class=com.example.service-
*
class is a string used to filter the metrics in the JSON by metric name. In
* the given example, only metrics for classes whose canonical name starts with
* com.example.service would be shown. You can also use jvm for
* just the JVM-level metrics.
*
*
* /metrics?pretty=true-
*
pretty determines whether or not the JSON which is returned is printed with
* indented whitespace or not. If you're looking at the JSON in the browser, use this.
*
*
* /metrics?full-samples=true-
*
full-samples determines whether or not the JSON which is returned will
* include the full content of histograms' and timers' reservoir samples. If you're
* aggregating across hosts, you may want to do this to allow for more accurate quantile
* calculations.
*
*
*/
public class MetricsServlet extends HttpServlet implements MetricProcessor {
/**
* The attribute name of the {@link MetricsRegistry} instance in the servlet context.
*/
public static final String REGISTRY_ATTRIBUTE = MetricsServlet.class.getName() + ".registry";
/**
* The attribute name of the {@link JsonFactory} instance in the servlet context.
*/
public static final String JSON_FACTORY_ATTRIBUTE = JsonFactory.class.getCanonicalName();
/**
* The initialization parameter name which determines whether or not JVM_level metrics will be
* included in the JSON output.
*/
public static final String SHOW_JVM_METRICS = "show-jvm-metrics";
static final class Context {
final boolean showFullSamples;
final JsonGenerator json;
Context(JsonGenerator json, boolean showFullSamples) {
this.json = json;
this.showFullSamples = showFullSamples;
}
}
private static final JsonFactory DEFAULT_JSON_FACTORY = new JsonFactory(new ObjectMapper());
private static final Logger LOGGER = LoggerFactory.getLogger(MetricsServlet.class);
private static final String CONTENT_TYPE = "application/json";
private final Clock clock;
private final VirtualMachineMetrics vm;
private MetricsRegistry registry;
private JsonFactory factory;
private boolean showJvmMetrics;
/**
* Creates a new {@link MetricsServlet}.
*/
public MetricsServlet() {
this(Clock.defaultClock(), VirtualMachineMetrics.getInstance(),
Metrics.defaultRegistry(), DEFAULT_JSON_FACTORY, true);
}
/**
* Creates a new {@link MetricsServlet}.
*
* @param showJvmMetrics whether or not JVM-level metrics will be included in the output
*/
public MetricsServlet(boolean showJvmMetrics) {
this(Clock.defaultClock(), VirtualMachineMetrics.getInstance(),
Metrics.defaultRegistry(), DEFAULT_JSON_FACTORY, showJvmMetrics);
}
/**
* Creates a new {@link MetricsServlet}.
*
* @param clock the clock used for the current time
* @param vm a {@link VirtualMachineMetrics} instance
* @param registry a {@link MetricsRegistry}
* @param factory a {@link JsonFactory}
* @param showJvmMetrics whether or not JVM-level metrics will be included in the output
*/
public MetricsServlet(Clock clock,
VirtualMachineMetrics vm,
MetricsRegistry registry,
JsonFactory factory,
boolean showJvmMetrics) {
this.clock = clock;
this.vm = vm;
this.registry = registry;
this.factory = factory;
this.showJvmMetrics = showJvmMetrics;
}
@Override
public void init(ServletConfig config) throws ServletException {
final Object factory = config.getServletContext()
.getAttribute(JSON_FACTORY_ATTRIBUTE);
if (factory instanceof JsonFactory) {
this.factory = (JsonFactory) factory;
}
final Object o = config.getServletContext().getAttribute(REGISTRY_ATTRIBUTE);
if (o instanceof MetricsRegistry) {
this.registry = (MetricsRegistry) o;
}
final String showJvmMetricsParam = config.getInitParameter(SHOW_JVM_METRICS);
if (showJvmMetricsParam != null) {
this.showJvmMetrics = Boolean.parseBoolean(showJvmMetricsParam);
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
final String classPrefix = req.getParameter("class");
final boolean pretty = Boolean.parseBoolean(req.getParameter("pretty"));
final boolean showFullSamples = Boolean.parseBoolean(req.getParameter("full-samples"));
resp.setStatus(HttpServletResponse.SC_OK);
resp.setContentType(CONTENT_TYPE);
final OutputStream output = resp.getOutputStream();
final JsonGenerator json = factory.createJsonGenerator(output, JsonEncoding.UTF8);
if (pretty) {
json.useDefaultPrettyPrinter();
}
json.writeStartObject();
{
if (showJvmMetrics && ("jvm".equals(classPrefix) || classPrefix == null)) {
writeVmMetrics(json);
}
writeRegularMetrics(json, classPrefix, showFullSamples);
}
json.writeEndObject();
json.close();
}
private void writeVmMetrics(JsonGenerator json) throws IOException {
json.writeFieldName("jvm");
json.writeStartObject();
{
json.writeFieldName("vm");
json.writeStartObject();
{
json.writeStringField("name", vm.name());
json.writeStringField("version", vm.version());
}
json.writeEndObject();
json.writeFieldName("memory");
json.writeStartObject();
{
json.writeNumberField("totalInit", vm.totalInit());
json.writeNumberField("totalUsed", vm.totalUsed());
json.writeNumberField("totalMax", vm.totalMax());
json.writeNumberField("totalCommitted", vm.totalCommitted());
json.writeNumberField("heapInit", vm.heapInit());
json.writeNumberField("heapUsed", vm.heapUsed());
json.writeNumberField("heapMax", vm.heapMax());
json.writeNumberField("heapCommitted", vm.heapCommitted());
json.writeNumberField("heap_usage", vm.heapUsage());
json.writeNumberField("non_heap_usage", vm.nonHeapUsage());
json.writeFieldName("memory_pool_usages");
json.writeStartObject();
{
for (Map.Entry pool : vm.memoryPoolUsage().entrySet()) {
json.writeNumberField(pool.getKey(), pool.getValue());
}
}
json.writeEndObject();
}
json.writeEndObject();
final Map bufferPoolStats = vm.getBufferPoolStats();
if (!bufferPoolStats.isEmpty()) {
json.writeFieldName("buffers");
json.writeStartObject();
{
json.writeFieldName("direct");
json.writeStartObject();
{
json.writeNumberField("count", bufferPoolStats.get("direct").getCount());
json.writeNumberField("memoryUsed", bufferPoolStats.get("direct").getMemoryUsed());
json.writeNumberField("totalCapacity", bufferPoolStats.get("direct").getTotalCapacity());
}
json.writeEndObject();
json.writeFieldName("mapped");
json.writeStartObject();
{
json.writeNumberField("count", bufferPoolStats.get("mapped").getCount());
json.writeNumberField("memoryUsed", bufferPoolStats.get("mapped").getMemoryUsed());
json.writeNumberField("totalCapacity", bufferPoolStats.get("mapped").getTotalCapacity());
}
json.writeEndObject();
}
json.writeEndObject();
}
json.writeNumberField("daemon_thread_count", vm.daemonThreadCount());
json.writeNumberField("thread_count", vm.threadCount());
json.writeNumberField("current_time", clock.time());
json.writeNumberField("uptime", vm.uptime());
json.writeNumberField("fd_usage", vm.fileDescriptorUsage());
json.writeFieldName("thread-states");
json.writeStartObject();
{
for (Map.Entry entry : vm.threadStatePercentages()
.entrySet()) {
json.writeNumberField(entry.getKey().toString().toLowerCase(),
entry.getValue());
}
}
json.writeEndObject();
json.writeFieldName("garbage-collectors");
json.writeStartObject();
{
for (Map.Entry entry : vm.garbageCollectors()
.entrySet()) {
json.writeFieldName(entry.getKey());
json.writeStartObject();
{
final VirtualMachineMetrics.GarbageCollectorStats gc = entry.getValue();
json.writeNumberField("runs", gc.getRuns());
json.writeNumberField("time", gc.getTime(TimeUnit.MILLISECONDS));
}
json.writeEndObject();
}
}
json.writeEndObject();
}
json.writeEndObject();
}
public void writeRegularMetrics(JsonGenerator json, String classPrefix, boolean showFullSamples) throws IOException {
for (Map.Entry> entry : registry.groupedMetrics().entrySet()) {
if (classPrefix == null || entry.getKey().startsWith(classPrefix)) {
json.writeFieldName(entry.getKey());
json.writeStartObject();
{
for (Map.Entry subEntry : entry.getValue().entrySet()) {
json.writeFieldName(subEntry.getKey().getName());
try {
subEntry.getValue()
.processWith(this,
subEntry.getKey(),
new Context(json, showFullSamples));
} catch (Exception e) {
LOGGER.warn("Error writing out {}", subEntry.getKey(), e);
}
}
}
json.writeEndObject();
}
}
}
@Override
public void processHistogram(MetricName name, Histogram histogram, Context context) throws Exception {
final JsonGenerator json = context.json;
json.writeStartObject();
{
json.writeStringField("type", "histogram");
json.writeNumberField("count", histogram.count());
writeSummarizable(histogram, json);
writeSampling(histogram, json);
if (context.showFullSamples) {
json.writeObjectField("values", histogram.getSnapshot().getValues());
}
}
json.writeEndObject();
}
@Override
public void processCounter(MetricName name, Counter counter, Context context) throws Exception {
final JsonGenerator json = context.json;
json.writeStartObject();
{
json.writeStringField("type", "counter");
json.writeNumberField("count", counter.count());
}
json.writeEndObject();
}
@Override
public void processGauge(MetricName name, Gauge gauge, Context context) throws Exception {
final JsonGenerator json = context.json;
json.writeStartObject();
{
json.writeStringField("type", "gauge");
json.writeObjectField("value", evaluateGauge(gauge));
}
json.writeEndObject();
}
@Override
public void processMeter(MetricName name, Metered meter, Context context) throws Exception {
final JsonGenerator json = context.json;
json.writeStartObject();
{
json.writeStringField("type", "meter");
json.writeStringField("event_type", meter.eventType());
writeMeteredFields(meter, json);
}
json.writeEndObject();
}
@Override
public void processTimer(MetricName name, Timer timer, Context context) throws Exception {
final JsonGenerator json = context.json;
json.writeStartObject();
{
json.writeStringField("type", "timer");
json.writeFieldName("duration");
json.writeStartObject();
{
json.writeStringField("unit", timer.durationUnit().toString().toLowerCase());
writeSummarizable(timer, json);
writeSampling(timer, json);
if (context.showFullSamples) {
json.writeObjectField("values", timer.getSnapshot().getValues());
}
}
json.writeEndObject();
json.writeFieldName("rate");
json.writeStartObject();
{
writeMeteredFields(timer, json);
}
json.writeEndObject();
}
json.writeEndObject();
}
private static Object evaluateGauge(Gauge gauge) {
try {
return gauge.value();
} catch (RuntimeException e) {
LOGGER.warn("Error evaluating gauge", e);
return "error reading gauge: " + e.getMessage();
}
}
private static void writeSummarizable(Summarizable metric, JsonGenerator json) throws IOException {
json.writeNumberField("min", metric.min());
json.writeNumberField("max", metric.max());
json.writeNumberField("mean", metric.mean());
json.writeNumberField("std_dev", metric.stdDev());
}
private static void writeSampling(Sampling metric, JsonGenerator json) throws IOException {
final Snapshot snapshot = metric.getSnapshot();
json.writeNumberField("median", snapshot.getMedian());
json.writeNumberField("p75", snapshot.get75thPercentile());
json.writeNumberField("p95", snapshot.get95thPercentile());
json.writeNumberField("p98", snapshot.get98thPercentile());
json.writeNumberField("p99", snapshot.get99thPercentile());
json.writeNumberField("p999", snapshot.get999thPercentile());
}
private static void writeMeteredFields(Metered metered, JsonGenerator json) throws IOException {
json.writeStringField("unit", metered.rateUnit().toString().toLowerCase());
json.writeNumberField("count", metered.count());
json.writeNumberField("mean", metered.meanRate());
json.writeNumberField("m1", metered.oneMinuteRate());
json.writeNumberField("m5", metered.fiveMinuteRate());
json.writeNumberField("m15", metered.fifteenMinuteRate());
}
}
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