BTrace Annotations

BTrace annotations

Stable probes use org.openjdk.btrace.core.annotations:

import org.openjdk.btrace.core.annotations.*;

Common annotations

Annotation	Purpose
@BTrace	Marks a Java probe class.
@OnMethod	Instruments a matching class and method.
@OnTimer	Runs a handler periodically.
@OnEvent	Runs a handler for a client or probe event.
@OnExit	Runs when the probe exits.
@Sampled	Samples handler execution.
@Level	Enables handlers at selected instrumentation levels.
@ProbeClassName / @ProbeMethodName	Injects the matched class or method name.
@Duration / @Return	Injects return duration or value at return/error locations.
@Self / @TargetInstance	Injects the current or called instance where supported.

For the complete annotation reference, locations, filters, and argument rules, see the stable-release documentation.

Example

@BTrace
public class SlowMethods {
  @OnMethod(
      clazz = "com.example.OrderService",
      method = "*",
      location = @Location(Kind.RETURN))
  public static void onReturn(
      @ProbeMethodName String method, @Duration long duration) {
    if (duration > 200_000_000L) {
      println(method);
    }
  }
}