// FatalHandler makes critical errors exit the program
// immediately, much like the log.Fatal* methods from the
// standard log package
func FatalHandler(h log.Handler) log.Handler {
return log.FuncHandler(func(r *log.Record) error {
err := h.Log(r)
if r.Lvl == log.LvlCrit {
os.Exit(1)
}
return err
})
}
// FuncAndLineHandler creates a log handler that adds the calling function's
// name and line number as context.
func FuncAndLineHandler(h log.Handler, lvl log.Lvl) log.Handler {
return log.FuncHandler(func(r *log.Record) error {
if r.Lvl <= lvl {
call := stack.Call(r.CallPC[0])
r.Ctx = append(r.Ctx, "fn", fmt.Sprintf("%+v", call))
r.Ctx = append(r.Ctx, "ln", fmt.Sprint(call))
return h.Log(r)
}
return nil
})
}
// EscalateErrHandler wraps another handler and passes all records through
// unchanged except if the logged context contains a non-nil error
// value in its context. In that case, the record's level is raised
// to LvlError unless it was already more serious (LvlCrit).
//
// This allows you to log the result of all functions for debugging
// and still capture error conditions when in production with a single
// log line. As an example, the following the log record will be written
// out only if there was an error writing a value to redis:
//
// logger := logext.EscalateErrHandler(
// log.LvlFilterHandler(log.LvlInfo, log.StdoutHandler))
//
// reply, err := redisConn.Do("SET", "foo", "bar")
// logger.Debug("Wrote value to redis", "reply", reply, "err", err)
// if err != nil {
// return err
// }
//
func EscalateErrHandler(h log.Handler) log.Handler {
return log.FuncHandler(func(r *log.Record) error {
if r.Lvl > log.LvlError {
for i := 1; i < len(r.Ctx); i++ {
if v, ok := r.Ctx[i].(error); ok && v != nil {
r.Lvl = log.LvlError
break
}
}
}
return h.Log(r)
})
}
func errorMultiHandler(normalHandler, errorHandler log.Handler) log.Handler {
return log.FuncHandler(func(r *log.Record) error {
if len(r.Ctx) > 1 {
_, ok := r.Ctx[1].(error)
if ok {
r.Ctx = r.Ctx[2:]
errorHandler.Log(r)
} else {
normalHandler.Log(r)
}
} else {
normalHandler.Log(r)
}
return nil
})
}