Package com.perfino.annotation

Annotation Interface Telemetry

@Retention(CLASS)
@Target(METHOD)
public @interface Telemetry

Create a Devops telemetry from the numeric return value of the annotated static method.

Only public static parameterless methods can be used for creating custom telemetries, annotating instance methods or non-public static methods will not have any effect. The method must return a numeric value, either a primitive value like int or double or a primitive wrapper instance like java.lang.Integer or java.lang.Double.

It is not enough if the class containing the annotated method is present in the classpath. You have to make sure that the class is loaded at runtime, so perfino can intercept the class loading event and set up the custom telemetry.

The method is called periodically on a dedicated thread. This may have implications for the requirements of thread safety in your code. If the numeric value is calculated on the fly, access to the data structures must be made thread-safe by making access to those data structures synchronized. Alternatively, you could calculate a cached value when convenient and save it to a volatile atomic value, like an int or a class from the java.util.concurrent.atomic package.

In the perfino UI, the telemetry is shown in the VM data views under "Custom telemetries" together with the MBean telemetries that are defined in the recording settings. In addition, you can choose custom telemetries as data sources for sparklines in the dashboard or in the VMs view.

For example, the following code snippet defines a custom telemetry with the name "Connection count":

     @Telemetry("Connection count")
     public static int getConnectionCount() {
         return connectionCount;
     }

Multiple lines in a single custom telemetry

If you want to compare several measurements in the same telemetry, you can annotate multiple methods with the same value() for the telemetry name, but with a different line() parameter.

For example:

     @Telemetry(value = "Queries", line = "Successful queries")
     public static int getSuccessCount() {
         return successCount;
     }
     @Telemetry(value = "Queries", line = "Failed queries")
     public static int getErrorCount() {
         return errorCount;
     }

This will create a single custom telemetry with the name "Queries" and two data lines named "Successful queries" and "Failed queries".

Required Element Summary

Required Elements

Modifier and Type	Required Element	Description
String	value	The name of the telemetry.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
TelemetryFormat	format	Optional display options for the telemetry.
String	line	The optional line name of the telemetry.

Element Details

value

String value

The name of the telemetry. Give different names to different telemetries. Reuse the same name when annotating different methods if you are creating a custom telemetry with multiple lines. If only a single line is used, you can omit the "value" parameter name, as in

     @Telemetry("Connection count")

line

String line

The optional line name of the telemetry. Only specify this parameter if you're creating a telemetry with multiple lines. See Telemetry for an example.

Default:

""

format

TelemetryFormat format

Optional display options for the telemetry.

Default:

@com.perfino.annotation.TelemetryFormat