Macro tracing_facade::trace_begin

macro_rules! trace_begin {
    ($name: expr) => { ... };
    ($name: expr, $($metadata: tt)+) => { ... };
}

Records the end of a synchronous duration.

Accepts an expression of a type that implements [Into<Cow>], with optional metadata following. Uses of trace_begin and trace_end must be balanced; in most cases, trace_scoped should be used instead.

The behavior of Metadata specification depends on the implementation of Tracer being used. Chromium's trace event format will merge metadata from beginning and end, preferring values from the end in the case of conflict.

Example

trace_begin!("foo");
trace_begin!("bar", "value": 42);
trace_end!("bar", "value": 123, "values": [1, 2, 3]);
trace_end!("foo");