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[](https://godoc.org/github.com/jacobsa/reqtrace)
reqtrace is a package for simple request tracing. It requires nothing of its
user except:
* They must use [golang.org/x/net/context][context].
* They must add a single line to each function they want to be visible in
traces.
[context]: http://godoc.org/golang.org/x/net/context
In particular, reqtrace is console-based and doesn't require an HTTP server.
**Warning**: This package is still barebones and in its early days. I reserve
the right to make backwards-incompatible changes to its API. But if it's useful
to you in your current form, have at it.
## Use
Call reqtrace.Trace anywhere you want to start a new root trace. (This is
probably where you create your root context.) This returns a new context that
you should pass to child operations, and a reporting function that you must use
to inform reqtrace when the trace is complete.
For example:
```Go
func HandleRequest(r *someRequest) (err error) {
ctx, report := reqtrace.Trace(context.Background(), "HandleRequest")
defer func() { report(err) }()
// Do two things for this request.
DoSomething(ctx, r)
DoSomethingElse(ctx, r)
}
```
Within other functions that you want to show up in the trace, you
reqtrace.StartSpan (or its more convenient sibling reqtrace.StartSpanWithError):
```Go
func DoSomething(ctx context.Context, r *someRequest) (err error) {
defer reqtrace.StartSpanWithError(&ctx, &err, "DoSomething")()
// Process the request somehow using ctx. If downstream code also annotes
// using reqtrace, reqtrace will know that its spans are descendants of
// this one.
CallAnotherLibrary(ctx, r.Param)
}
```
When `--reqtrace.enable` is set, the completion of a trace will cause helpful
ASCII art to be spit out.
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