Tweaks in the data types to improve inlining and garbage collection.

pkg/log/data.go

@@ -47,8 +47,6 @@ nonprintable(enum VSL_tag_e tag)
 */
 import "C"
 
-import "fmt"
-
 // TxType is a classifier for a log transaction, indicating if it is
 // the log of a client or backend request/response, a Varnish session,
 // or a raw transaction.
@@ -89,7 +87,7 @@ func (txtype TxType) String() string {
 	case TxRaw:
 		return "Record"
 	default:
-		panic("invalid transaction type")
+		return "invalid transaction type"
 	}
 }
 
@@ -154,7 +152,7 @@ func (reason Reason) String() string {
 	case Pipe:
 		return "pipe"
 	default:
-		panic("invalid reason")
+		return "invalid reason"
 	}
 }
 
@@ -225,54 +223,77 @@ const (
 
 // String returns "b", "c" or "-".
 func (rt RecordType) String() string {
-	return string(rt)
+	switch rt {
+	case Client:
+		return "c"
+	case Backend:
+		return "b"
+	case None:
+		return "-"
+	default:
+		return "invalid RecordType"
+	}
 }
 
-func initTags() []string {
-	var tags []string
+// TagData contains metadata about log tags, particularly their string
+// form, since a tag appears as a number in a Record. The type of the
+// Tags variable is TagData[]; for a tag t, use TagData[t] to get its
+// metadata.
+//
+// String is the Tag name that appears in the second column of default
+// varnishlog output, such as "ReqHeader" for a client request header,
+// or "BerespHeader" for a backend response header.
+//
+// If Tags[t].Legal is false, then there is no legal tag for t. No
+// such tag is generated from log reads for a live instance of
+// Varnish. You may encounter such a tag when reading from a binary
+// log that was generated by a version of Varnish that is different
+// from the version with which the Go client is currently linked.
+//
+// NonPrintable is true if log payloads of the type indicated by the
+// tag may contain non-printable characters. If NonPrintable is false
+// (which is the case for most tags), you can assume that the log
+// payload contains only printable ASCII characters.
+type TagData struct {
+	String       string
+	Legal        bool
+	NonPrintable bool
+}
+
+func initTags() []TagData {
+	var tags []TagData
 	if uint8(C.slt_max()) > ^uint8(0) {
 		panic("SLT__MAX > max uint8")
 	}
 	max := int(C.slt_max())
 	for i := 0; i < max; i++ {
-		if C.VSL_tags[i] == nil {
-			tags = append(tags, fmt.Sprintf("%d", i))
-			continue
+		tagdata := TagData{}
+		if C.VSL_tags[i] != nil {
+			tagdata.String = C.GoString(C.VSL_tags[i])
+			tagdata.Legal = true
+			tagdata.NonPrintable = C.nonprintable(uint32(i)) != 0
 		}
-		tags = append(tags, C.GoString(C.VSL_tags[i]))
+		tags = append(tags, tagdata)
 	}
 	return tags
 }
 
-var tags = initTags()
+// Tags has the type []TagData -- for a tag t in a Record, Tags[t]
+// contains its metadata.
+var Tags = initTags()
 
 // A Tag is a classifier for the contents of a Record's payload,
 // corresponding to the second column of default varnishlog
-// output. For a Tag t, t.String() may be "ReqURL" for a client
+// output. For a Tag t, Tags[t].String may be "ReqURL" for a client
 // request URL, "BerespStatus" for the HTTP status of a backend
 // response, and so forth.
 type Tag uint8
 
-// String returns the Tag name that appears in the second column of
-// default varnishlog output, such as "ReqHeader" for a client request
-// header, or "BerespHeader" for a backend response header.
-//
-// If t.String() returns the numeric value of t as a string, then
-// there is no legal tag for t. No such tag is generated from log
-// reads for a live instance of Varnish. You may encounter such a tag
-// when reading from a binary log that was generated by a version of
-// Varnish that is different from the version with which the Go client
-// is currently linked.
+// String returns the string form for a tag (the value in
+// Tags[tag].String). This makes it easy to get the string form with
+// the %s or %v verbs for a formatter in package fmt.
 func (tag Tag) String() string {
-	return tags[tag]
-}
-
-// Nonprintable returns true if log payloads of the type indicated by
-// the tag may contain non-printable characters. If Nonprintable()
-// returns false (which is the case for most tags), you can assume
-// that the log payload contains only printable ASCII characters.
-func (tag Tag) Nonprintable() bool {
-	return C.nonprintable(uint32(tag)) != 0
+	return Tags[tag].String
 }
 
 // Payload is the type of the message contained in a Record -- the
@@ -413,7 +434,7 @@ func (status Status) String() string {
 	case More:
 		return "More log transactions are pending"
 	default:
-		panic("invalid status")
+		return "invalid status"
 	}
 }
 

pkg/log/log_test.go

@@ -30,6 +30,20 @@ package log
 
 import "testing"
 
+func TestTags(t *testing.T) {
+	for i, tag := range Tags {
+		if Tag(i).String() != tag.String {
+			t.Errorf("Tag %d string mismatch .String()=%v "+
+				"Tags[%d].String=%v", i, Tag(i).String(),
+				i, Tags[i].String)
+		}
+		if !tag.Legal && tag.String != "" {
+			t.Errorf("Non-empty String for illegal Tag %d: %s", i,
+				tag.String)
+		}
+	}
+}
+
 var expTxTypeStr = map[TxType]string{
 	TxUnknown: "Unknown",
 	Sess:      "Session",