Part 1: Optimize using compiler's inliner (#2687)

* optimized functions for inlining

* added note regarding ResponseWriterWrapper

* optimzed browseWrite* methods for FileServer

* created benchmarks for comparison

* creating browseListing instance in each function

* created benchmarks for openResponseWriter

* removed benchmarks of old implementations

* implemented sync.Pool for byte buffers

* using global sync.Pool for writing JSON/HTML

1 files changed, 10 insertions, 2 deletions

diff --git a/caddy.go b/caddy.go
index 5a5349e99..c30eccf77 100644
--- a/caddy.go
+++ b/caddy.go
@@ -208,8 +208,16 @@ func (d *Duration) UnmarshalJSON(b []byte) error {
 // If no version information is available, a non-nil
 // value will still be returned, but with an
 // unknown version.
-func GoModule() debug.Module {
-	mod := debug.Module{Version: "unknown"}
+func GoModule() *debug.Module {
+	var mod debug.Module
+	return goModule(&mod)
+}
+
+// goModule holds the actual implementation of GoModule.
+// Allocating debug.Module in GoModule() and passing a
+// reference to goModule enables mid-stack inlining.
+func goModule(mod *debug.Module) *debug.Module {
+	mod.Version = "unknown"
 	bi, ok := debug.ReadBuildInfo()
 	if ok {
 		mod.Path = bi.Main.Path