Function invoke_handler 

pub async fn invoke_handler<P, R>(
    function_name: &str,
    payload: P,
    state: &Arc<ExecutionState>,
    op_id: &OperationIdentifier,
    config: &InvokeConfig<P, R>,
    logger: &Arc<dyn Logger>,
) -> Result<R, DurableError>
where
    P: Serialize + DeserializeOwned + Send,
    R: Serialize + DeserializeOwned + Send,

Invokes another durable Lambda function.

This handler implements the invoke semantics:

• Calls the target Lambda function via service client
• Handles timeout configuration
• Checkpoints invocation and result
• Propagates errors from invoked function

Arguments

• function_name - The name or ARN of the Lambda function to invoke
• payload - The payload to send to the function
• state - The execution state for checkpointing
• op_id - The operation identifier
• config - Invoke configuration (timeout, serdes)
• logger - Logger for structured logging

Returns

The result from the invoked function, or an error if invocation fails.