cloudpods/vendor/github.com/lestrrat-go/pdebug/README.md

go-pdebug

Utilities for my print debugging fun. YMMV

Synopsis

Description

Building with pdebug declares a constant, pdebug.Enabled which you can use to easily compile in/out depending on the presence of a build tag.

func Foo() {
  // will only be available if you compile with `-tags debug`
  if pdebug.Enabled {
    pdebug.Printf("Starting Foo()!
  }
}

Note that using github.com/lestrrat-go/pdebug and -tags debug only compiles in the code. In order to actually show the debug trace, you need to specify an environment variable:

# For example, to show debug code during testing:
PDEBUG_TRACE=1 go test -tags debug

If you want to forcefully show the trace (which is handy when you're debugging/testing), you can use the debug0 tag instead:

go test -tags debug0

Markers

When you want to print debug a chain of function calls, you can use the Marker functions:

func Foo() {
  if pdebug.Enabled {
    g := pdebug.Marker("Foo")
    defer g.End()
  }

  pdebug.Printf("Inside Foo()!")
}

This will cause all of the Printf calls to automatically indent the output so it's visually easier to see where a certain trace log is being generated.

By default it will print something like:

|DEBUG| START Foo
|DEBUG|   Inside Foo()!
|DEBUG| END Foo (1.23μs)

If you want to automatically show the error value you are returning (but only if there is an error), you can use the BindError method:

func Foo() (err error) {
  if pdebug.Enabled {
    g := pdebug.Marker("Foo").BindError(&err)
    defer g.End()
  }

  pdebug.Printf("Inside Foo()!")

  return errors.New("boo")
}

This will print something like:

|DEBUG| START Foo
|DEBUG|   Inside Foo()!
|DEBUG| END Foo (1.23μs): ERROR boo