Remove globals from heffalump/*, add NewDefault{Heffalump,MarkovMap}()

This removes globals from `heffalumpt/`, which are hard to reason about,
easy to get wrong, and should not be created if they are never used.

A possible drawbacks is if you would create multiple new defaults,
but this should never be the case.

heffalump/heffalump.go

@@ -14,11 +14,7 @@ import (
 
 var log = config.GetLogger()
 
-// DefaultHeffalump represents a Heffalump type
-var (
-	DefaultHeffalump *Heffalump
-	DefaultBuffSize  int = 100 * 1 << 10
-)
+const DefaultBuffSize = 100 * 1 << 10
 
 // Heffalump represents our buffer pool and markov map from Heffalump
 type Heffalump struct {
@@ -39,6 +35,12 @@ func NewHeffalump(mm MarkovMap, buffsize int) *Heffalump {
 	}
 }
 
+// NewDefaultHeffalump instantiates a new default Heffalump from a MarkovMap created using
+// using the default source text.
+func NewDefaultHeffalump() *Heffalump {
+	return NewHeffalump(NewDefaultMarkovMap(), DefaultBuffSize)
+}
+
 // WriteHell writes markov chain heffalump hell to the provided io.Writer
 func (h *Heffalump) WriteHell(bw *bufio.Writer) (int64, error) {
 	var n int64

heffalump/markov.go

@@ -11,10 +11,8 @@ import (
 	"git.tcp.direct/kayos/common/squish"
 )
 
-var DefaultMarkovMap MarkovMap
-
-func init() {
-	// DefaultMarkovMap is a Markov chain based on src.
+// NewDefaultMarkovMap creates a new MarkovMap from the default source text.
+func NewDefaultMarkovMap() MarkovMap {
 	src, err := squish.UnpackStr(srcGz)
 	if err != nil {
 		panic(err)
@@ -23,8 +21,7 @@ func init() {
 		panic("failed to unpack source")
 	}
 
-	DefaultMarkovMap = MakeMarkovMap(strings.NewReader(src))
-	DefaultHeffalump = NewHeffalump(DefaultMarkovMap, DefaultBuffSize)
+	return MakeMarkovMap(strings.NewReader(src))
 }
 
 // ScanHTML is a basic split function for a Scanner that returns each

internal/http/router.go

@@ -19,7 +19,7 @@ import (
 
 var (
 	log              *zerolog.Logger
-	hellpotHeffalump = heffalump.DefaultHeffalump
+	hellpotHeffalump *heffalump.Heffalump
 )
 
 func getRealRemote(ctx *fasthttp.RequestCtx) string {
@@ -139,6 +139,9 @@ func Serve() error {
 
 		markovMap := heffalump.MakeMarkovMap(strings.NewReader(src))
 		hellpotHeffalump = heffalump.NewHeffalump(markovMap, heffalump.DefaultBuffSize)
+	} else {
+		log.Info().Msg("Using default source text")
+		hellpotHeffalump = heffalump.NewDefaultHeffalump()
 	}
 
 	l := config.HTTPBind + ":" + config.HTTPPort