io.opentelemetry.javaagent.bootstrap.CallDepth Maven / Gradle / Ivy
Show all versions of opentelemetry-javaagent-extension-api Show documentation
/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/
package io.opentelemetry.javaagent.bootstrap;
/**
* A utility to track nested calls in an instrumentation.
*
* For example, this can be used to track nested calls to {@code super()} in constructors by
* calling {@link #getAndIncrement()} at the beginning of each constructor.
*
*
This works the following way: when you enter some method that you want to track, you call
* {@link #getAndIncrement()} method. If returned number is larger than 0, then you have already
* been in this method and are in recursive call now. When you then leave the method, you call
* {@link #decrementAndGet()} method. If returned number is larger than 0, then you have already
* been in this method and are in recursive call now.
*
*
In short, the semantic of both methods is the same: they will return value 0 if and only if
* current method invocation is the first one for the current call stack.
*/
public final class CallDepth {
private int depth;
CallDepth() {
this.depth = 0;
}
/**
* Return the current call depth for a given class (not method; we want to be able to track calls
* between different methods in a class).
*
*
The returned instance is unique per given class and per thread.
*/
public static CallDepth forClass(Class cls) {
return CallDepthThreadLocalMap.getCallDepth(cls);
}
/**
* Increment the current call depth and return the previous value. This method will always return
* 0 if it's the first (outermost) call.
*/
public int getAndIncrement() {
return this.depth++;
}
/**
* Decrement the current call depth and return the current value. This method will always return 0
* if it's the last (outermost) call.
*/
public int decrementAndGet() {
return --this.depth;
}
}