By Jochen Voss, last updated 2013-07-16
The trace package provides a simple tracing framework for
the excellent Go programming language.
Code using this framework can emit diagnostic messages using the
trace.T() function. In normal operation, calls to
trace.T() have no effect and are very fast. When tracing is
enabled, in order to track down a problem or to explore the inner workings
of a program, listeners can be attached to record and display all trace
messages.
Main features:
To download the trace package, simply use the
go get command as follows:
go get github.com/seehuhn/trace
The source code is available at github.com/seehuhn/trace.
Detailed usage instructions are available via the package's online help, either on godoc.org or on the command line:
go doc github.com/seehuhn/trace
A short summary can be found below.
trace.T("a/b/c", trace.PrioError,
"failed to connect to server %q, using offline mode", serverName)
The first argument in this call is a path which gives information about
the origin of the message, the second argument indicates the importance of
the message. Both, the path and the priority are used to decide which
listeners receive the correponding message. The following arguments, a
format string and additional optional arguments, are passed to
fmt.Sprintf to compose the message reported to the listeners
registered for the given message path.
Listeners can subscribe to messages, either for a given path or for all
paths, using the Register() method. A minimum priority for
messages to be delivered can be used. Example:
func MyListener(t time.Time, path string, prio Priority, msg string) {
log.Println(msg)
}
func main() {
listener := trace.Register(MyListener, "a/b", trace.PrioAll)
// ... code which calls trace.T()
listener.Unregister()
}
This code installs MyListener as a handler which receives all messages sent for the path "a/b" and its sub-paths.
Copyright © 2013, Jochen Voss. All content on this website (including text, pictures, and any other original works), unless otherwise noted, is licensed under a Creative Commons Attribution-Share Alike 3.0 License.