Package com.netflix.spectator.api

Primary interfaces for working with spectator.

See: Description

Interface Summary

Interface	Description
Clock	A timing source that can be used to access the current wall time as well as a high resolution monotonic time to measuring elapsed times.
Counter	Measures the rate of change based on calls to increment.
DistributionSummary	Track the sample distribution of events.
Gauge	A meter with a single value that can only be sampled at a point in time.
Id	Identifier for a meter or measurement.
LongTaskTimer	Timer intended to track a small number of long running tasks.
Meter	A device for collecting a set of measurements.
Registry	Registry to manage a set of meters.
RegistryConfig	Configuration settings for the registry.
Tag	Key/value pair used to classify and drill into measurements.
TagList	Base type for a collection of tags.
Timer	Timer intended to track a large number of short running events.

Class Summary

Class	Description
AbstractMeter<T>	Helper base class for meters that maintains a weak reference to the object being measured.
AbstractRegistry	Base class to make it easier to implement a simple registry that only needs to customise the types returned for Counter, DistributionSummary, and Timer calls.
AbstractTimer	Base class to simplify implementing a Timer.
BasicTag	Immutable implementation of Tag.
CompositeRegistry	Maps calls to zero or more sub-registries.
DefaultRegistry	Default implementation of registry.
DoubleFunction<T extends java.lang.Number>	Function to extract a double value from an object.
ExtendedRegistry	Deprecated This class was used prior to java 8 for adding extension methods to the registry without breaking all classes implementing the interface.
Functions	Common functions for use with gauges.
ManualClock	Clock implementation that allows the user to explicitly control the time.
Measurement	A measurement sampled from a meter.
NoopRegistry	Registry implementation that does nothing.
Spectator	Static factory used to access the main global registry.
Utils	Helper functions for working with a sequence of measurements.

Enum Summary

Enum	Description
Statistic	The valid set of statistics that can be reported by timers and distribution summaries.

Package com.netflix.spectator.api Description

Primary interfaces for working with spectator. To get started, here is a small code sample:

 Server s = new Server(new DefaultRegistry());

 class Server {
   private final Registry registry;
   private final Id requestCountId;
   private final Timer requestLatency;
   private final DistributionSummary responseSizes;

   public Server(Registry registry) {
     this.registry = registry;
     requestCountId = registry.createId("server.requestCount");
     requestLatency = registry.timer("server.requestLatency");
     responseSizes = registry.distributionSummary("server.responseSizes");
     registry.gauge("server.numConnections", this, Server::getNumConnections);
   }

   public Response handle(Request req) {
     final long s = System.nanoTime();
     try {
       Response res = doSomething(req);

       final Id cntId = requestCountId
         .withTag("country", req.country())
         .withTag("status", res.status());
       registry.counter(cntId).increment();

       responseSizes.record(res.body().size());

       return res;
     } catch (Exception e) {
       final Id cntId = requestCountId
         .withTag("country", req.country())
         .withTag("status", "exception")
         .withTag("error", e.getClass().getSimpleName());
       registry.counter(cntId).increment();
       throw e;
     } finally {
       requestLatency.record(System.nanoTime() - s, TimeUnit.NANOSECONDS);
     }
   }

   public int getNumConnections() {
     // however we determine the current number of connections on the server
   }
 }
 

The main classes you will need to understand:

• Spectator: static entrypoint to access the registry.
• Registry: registry class used to create meters.
• Counter: meter type for measuring a rate of change.
• Timer: meter type for measuring the time for many short events.
• LongTaskTimer: meter type for measuring the time for a few long events.
• DistributionSummary: meter type for measuring the sample distribution of some type of events.