FunctionInvocationWrapper.wrapped flag never resets when a function invocation throws

Start in SimpleFunctionRegistry.java at SimpleFunctionRegistry.FunctionInvocationWrapper.apply(), especially the wrapped reset around doApply(). Trace the error path and the ObservationFunctionAroundWrapper interaction. Done means repeated failing invocations continue to be observed and spring_cloud_function_seconds_count increments for each error.

Bug

In SimpleFunctionRegistry.FunctionInvocationWrapper.apply(), the FunctionInvocationWrapper.wrapped flag is set to true before delegating to doApply() (to prevent re-entrant wrapping). It is reset to false afterwards — but not in a finally block:

Object result = this.doApply(input, targetFunction);
targetFunction.wrapped = false; // ← skipped if doApply throws
return result;

When a function invocation throws, wrapped stays true forever. Every subsequent message finds wrapped = true and bypasses the ObservationFunctionAroundWrapper entirely.

This means ObservationFunctionAroundWrapper — and therefore the spring_cloud_function_seconds Micrometer timer — only records the very first message invocation which leads to an error. Every subsequent message bypasses the observation entirely.

Symptom

spring_cloud_function_seconds_count with an error is permanently stuck at 1 regardless of how many more messages result in an error. Confirmed with OTLP cumulative temporality (default), no pod restarts.

Expected behaviour

spring_cloud_function_seconds_count increments on every function invocation which leads to an error.

Actual behaviour

spring_cloud_function_seconds_count is always 1 after the first invocation which led to an error — further invocations are not observed.

Versions

• spring-cloud-function-context:4.3.0
• Also confirmed present in main branch (same lines 622–623 in SimpleFunctionRegistry.java)

Suggested fix

Reset this.wrapped = false after the wrapper call returns, e.g. in a finally block:

    this.wrapped = true;
    try {
        result = functionAroundWrapper.apply(input, this);
    }
    finally {
        this.wrapped = false;
    }
}