header.go Referer() optimize (#1313)

* args.go GetBool(): use switch with string casting

This should be optimized by Go compiler itself so the b2s() call is not needed.

It was previously done by this but changed in
1e7885eb56cdf4c6f550e143b0dbd3acc82a4137

* header.go Referer() optimize

Use direct peekArgBytes() instead of PeekBytes() that will check for special headers

* header_timing_test.go BenchmarkRequestHeaderPeekBytesSpecialHeader

The old BenchmarkRequestHeaderPeekBytesCanonical and BenchmarkRequestHeaderPeekBytesNonCanonical are in fact just measured the header normalization.
But it's anyway is benchmarked separately.
Results was almost the same: 1.5 ns/op.

Instead, let's reuse the benches to find a difference between peeking of special (Host, CT) and custom headers.

1 files changed, 39 insertions, 7 deletions

diff --git a/header_timing_test.go b/header_timing_test.go
index 0d7ab67..81ff7fb 100644
--- a/header_timing_test.go
+++ b/header_timing_test.go
@@ -12,6 +12,9 @@ import (
 
 var strFoobar = []byte("foobar.com")
 
+// it has the same length as Content-Type
+var strNonSpecialHeader = []byte("Dontent-Type")
+
 type benchReadBuf struct {
 	s []byte
 	n int
@@ -96,12 +99,13 @@ func BenchmarkResponseHeaderWrite(b *testing.B) {
 	})
 }
 
-func BenchmarkRequestHeaderPeekBytesCanonical(b *testing.B) {
+// Result: 2.2 ns/op
+func BenchmarkRequestHeaderPeekBytesSpecialHeader(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		var h RequestHeader
-		h.SetBytesV("Host", strFoobar)
+		h.SetContentTypeBytes(strFoobar)
 		for pb.Next() {
-			v := h.PeekBytes(strHost)
+			v := h.PeekBytes(strContentType)
 			if !bytes.Equal(v, strFoobar) {
 				b.Fatalf("unexpected result: %q. Expected %q", v, strFoobar)
 			}
@@ -109,13 +113,41 @@ func BenchmarkRequestHeaderPeekBytesCanonical(b *testing.B) {
 	})
 }
 
-func BenchmarkRequestHeaderPeekBytesNonCanonical(b *testing.B) {
+// Result: 2.9 ns/op
+func BenchmarkRequestHeaderPeekBytesNonSpecialHeader(b *testing.B) {
 	b.RunParallel(func(pb *testing.PB) {
 		var h RequestHeader
-		h.SetBytesV("Host", strFoobar)
-		hostBytes := []byte("HOST")
+		h.SetBytesKV(strNonSpecialHeader, strFoobar)
+		for pb.Next() {
+			v := h.PeekBytes(strNonSpecialHeader)
+			if !bytes.Equal(v, strFoobar) {
+				b.Fatalf("unexpected result: %q. Expected %q", v, strFoobar)
+			}
+		}
+	})
+}
+
+// Result: 2.3 ns/op
+func BenchmarkResponseHeaderPeekBytesSpecialHeader(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		var h ResponseHeader
+		h.SetContentTypeBytes(strFoobar)
+		for pb.Next() {
+			v := h.PeekBytes(strContentType)
+			if !bytes.Equal(v, strFoobar) {
+				b.Fatalf("unexpected result: %q. Expected %q", v, strFoobar)
+			}
+		}
+	})
+}
+
+// Result: 2.9 ns/op
+func BenchmarkResponseHeaderPeekBytesNonSpecialHeader(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		var h ResponseHeader
+		h.SetBytesKV(strNonSpecialHeader, strFoobar)
 		for pb.Next() {
-			v := h.PeekBytes(hostBytes)
+			v := h.PeekBytes(strNonSpecialHeader)
 			if !bytes.Equal(v, strFoobar) {
 				b.Fatalf("unexpected result: %q. Expected %q", v, strFoobar)
 			}