com.yammer.metrics.reporting

Class MetricsServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

com.yammer.metrics.reporting.MetricsServlet

All Implemented Interfaces:

MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>, Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class MetricsServlet
extends javax.servlet.http.HttpServlet
implements MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>

An HTTP servlet which outputs the metrics in a MetricsRegistry (and optionally the data provided by VirtualMachineMetrics) in a JSON object. Only responds to GET requests.

If the servlet context has an attribute named com.yammer.metrics.reporting.MetricsServlet.registry which is a MetricsRegistry instance, MetricsServlet will use it instead of Metrics.

MetricsServlet also takes an initialization parameter, show-jvm-metrics, which should be a boolean value (e.g., "true" or "false"). It determines whether or not JVM-level metrics will be included in the JSON output.

GET requests to 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.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	JSON_FACTORY_ATTRIBUTE The attribute name of the JsonFactory instance in the servlet context.
static String	REGISTRY_ATTRIBUTE The attribute name of the MetricsRegistry instance in the servlet context.
static String	SHOW_JVM_METRICS The initialization parameter name which determines whether or not JVM_level metrics will be included in the JSON output.

Constructor Summary

Constructors

Constructor and Description
MetricsServlet() Creates a new MetricsServlet.
MetricsServlet(boolean showJvmMetrics) Creates a new MetricsServlet.
MetricsServlet(Clock clock, VirtualMachineMetrics vm, MetricsRegistry registry, com.fasterxml.jackson.core.JsonFactory factory, boolean showJvmMetrics) Creates a new MetricsServlet.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp)
void	init(javax.servlet.ServletConfig config)
void	processCounter(MetricName name, Counter counter, com.yammer.metrics.reporting.MetricsServlet.Context context)
void	processGauge(MetricName name, Gauge<?> gauge, com.yammer.metrics.reporting.MetricsServlet.Context context)
void	processHistogram(MetricName name, Histogram histogram, com.yammer.metrics.reporting.MetricsServlet.Context context)
void	processMeter(MetricName name, Metered meter, com.yammer.metrics.reporting.MetricsServlet.Context context)
void	processTimer(MetricName name, Timer timer, com.yammer.metrics.reporting.MetricsServlet.Context context)
void	writeRegularMetrics(com.fasterxml.jackson.core.JsonGenerator json, String classPrefix, boolean showFullSamples)

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

REGISTRY_ATTRIBUTE

public static final String REGISTRY_ATTRIBUTE

The attribute name of the MetricsRegistry instance in the servlet context.

JSON_FACTORY_ATTRIBUTE

public static final String JSON_FACTORY_ATTRIBUTE

The attribute name of the JsonFactory instance in the servlet context.

SHOW_JVM_METRICS

public static final String SHOW_JVM_METRICS

The initialization parameter name which determines whether or not JVM_level metrics will be included in the JSON output.

See Also:

Constant Field Values

Constructor Detail

MetricsServlet

public MetricsServlet()

Creates a new MetricsServlet.

MetricsServlet

public MetricsServlet(boolean showJvmMetrics)

Creates a new MetricsServlet.

Parameters:

showJvmMetrics - whether or not JVM-level metrics will be included in the output

MetricsServlet

public MetricsServlet(Clock clock,
              VirtualMachineMetrics vm,
              MetricsRegistry registry,
              com.fasterxml.jackson.core.JsonFactory factory,
              boolean showJvmMetrics)

Creates a new MetricsServlet.

Parameters:

clock - the clock used for the current time

vm - a VirtualMachineMetrics instance

registry - a MetricsRegistry

factory - a JsonFactory

showJvmMetrics - whether or not JVM-level metrics will be included in the output

Method Detail

init

public void init(javax.servlet.ServletConfig config)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

doGet

protected void doGet(javax.servlet.http.HttpServletRequest req,
         javax.servlet.http.HttpServletResponse resp)
              throws javax.servlet.ServletException,
                     IOException

Overrides:

doGet in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

IOException

writeRegularMetrics

public void writeRegularMetrics(com.fasterxml.jackson.core.JsonGenerator json,
                       String classPrefix,
                       boolean showFullSamples)
                         throws IOException

Throws:

IOException

processHistogram

public void processHistogram(MetricName name,
                    Histogram histogram,
                    com.yammer.metrics.reporting.MetricsServlet.Context context)
                      throws Exception

Specified by:

processHistogram in interface MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>

Throws:

Exception

processCounter

public void processCounter(MetricName name,
                  Counter counter,
                  com.yammer.metrics.reporting.MetricsServlet.Context context)
                    throws Exception

Specified by:

processCounter in interface MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>

Throws:

Exception

processGauge

public void processGauge(MetricName name,
                Gauge<?> gauge,
                com.yammer.metrics.reporting.MetricsServlet.Context context)
                  throws Exception

Specified by:

processGauge in interface MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>

Throws:

Exception

processMeter

public void processMeter(MetricName name,
                Metered meter,
                com.yammer.metrics.reporting.MetricsServlet.Context context)
                  throws Exception

Specified by:

processMeter in interface MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>

Throws:

Exception

processTimer

public void processTimer(MetricName name,
                Timer timer,
                com.yammer.metrics.reporting.MetricsServlet.Context context)
                  throws Exception

Specified by:

processTimer in interface MetricProcessor<com.yammer.metrics.reporting.MetricsServlet.Context>

Throws:

Exception