Macro trace_future_args

macro_rules! trace_future_args {
    ($category:expr, $name:expr $(, $key:expr => $val:expr)*) => { ... };
    ($category:expr, $name:expr, $flow_id:expr $(, $key:expr => $val:expr)*) => { ... };
}

Macro for constructing TraceFutureArgs. The trace arguments won’t be constructed if the category is not enabled. If the category becomes enabled while the TraceFuture is still alive then the duration events will still be written but without the trace arguments.

Example:

async move {
    ....
}.trace(trace_future_args!(c"category", c"name", "x" => 5, "y" => 10)).await;