Class Gauge

All Implemented Interfaces:
Collector.Describable

public class Gauge extends SimpleCollector<Gauge.Child> implements Collector.Describable
Gauge metric, to report instantaneous values.

Examples of Gauges include:

  • Inprogress requests
  • Number of items in a queue
  • Free memory
  • Total memory
  • Temperature
Gauges can go both up and down.

An example Gauge:

 
   class YourClass {
     static final Gauge inprogressRequests = Gauge.build()
         .name("inprogress_requests").help("Inprogress requests.").register();

     void processRequest() {
        inprogressRequests.inc();
        // Your code here.
        inprogressRequests.dec();
     }
   }
 
 

You can also use labels to track different types of metric:

 
   class YourClass {
     static final Gauge inprogressRequests = Gauge.build()
         .name("inprogress_requests").help("Inprogress requests.")
         .labelNames("method").register();

     void processGetRequest() {
        inprogressRequests.labels("get").inc();
        // Your code here.
        inprogressRequests.labels("get").dec();
     }
     void processPostRequest() {
        inprogressRequests.labels("post").inc();
        // Your code here.
        inprogressRequests.labels("post").dec();
     }
   }
 
 

These can be aggregated and processed together much more easily in the Prometheus server than individual metrics for each labelset.

  • Constructor Details

  • Method Details

    • build

      public static Gauge.Builder build(String name, String help)
      Return a Builder to allow configuration of a new Gauge. Ensures required fields are provided.
      Parameters:
      name - The name of the metric
      help - The help string of the metric
    • build

      public static Gauge.Builder build()
      Return a Builder to allow configuration of a new Gauge.
    • newChild

      protected Gauge.Child newChild()
      Description copied from class: SimpleCollector
      Return a new child, workaround for Java generics limitations.
      Specified by:
      newChild in class SimpleCollector<Gauge.Child>
    • inc

      public void inc()
      Increment the gauge with no labels by 1.
    • inc

      public void inc(double amt)
      Increment the gauge with no labels by the given amount.
    • dec

      public void dec()
      Decrement the gauge with no labels by 1.
    • dec

      public void dec(double amt)
      Decrement the gauge with no labels by the given amount.
    • set

      public void set(double val)
      Set the gauge with no labels to the given value.
    • setToCurrentTime

      public void setToCurrentTime()
      Set the gauge with no labels to the current unixtime.
    • startTimer

      public Gauge.Timer startTimer()
      Start a timer to track a duration, for the gauge with no labels.

      This is primarily useful for tracking the durations of major steps of batch jobs, which are then pushed to a PushGateway. For tracking other durations/latencies you should usually use a Summary.

      Call Gauge.Timer.setDuration() at the end of what you want to measure the duration of.

    • setToTime

      public double setToTime(Runnable timeable)
      Executes runnable code (e.g. a Java 8 Lambda) and observes a duration of how long it took to run.
      Parameters:
      timeable - Code that is being timed
      Returns:
      Measured duration in seconds for timeable to complete.
    • setToTime

      public <E> E setToTime(Callable<E> timeable)
      Executes callable code (e.g. a Java 8 Lambda) and observes a duration of how long it took to run.
      Parameters:
      timeable - Code that is being timed
      Returns:
      Result returned by callable.
    • get

      public double get()
      Get the value of the gauge.
    • collect

      Description copied from class: Collector
      Return all of the metrics of this Collector.
      Specified by:
      collect in class Collector
    • describe

      public List<Collector.MetricFamilySamples> describe()
      Description copied from interface: Collector.Describable
      Provide a list of metric families this Collector is expected to return. These should exclude the samples. This is used by the registry to detect collisions and duplicate registrations. Usually custom collectors do not have to implement Describable. If Describable is not implemented and the CollectorRegistry was created with auto describe enabled (which is the case for the default registry) then Collector.collect() will be called at registration time instead of describe. If this could cause problems, either implement a proper describe, or if that's not practical have describe return an empty list.
      Specified by:
      describe in interface Collector.Describable