fastcgi: Optimize FastCGI transport (#4978)

* break up code and use lazy reading and pool bufio.Writer

* close underlying connection when operation failed

* allocate bufWriter and streamWriter only once

* refactor record writing

* rebase from master

* handle err

* Fix type assertion

Also reduce some duplication

* Refactor client and clientCloser for logging

Should reduce allocations

* Minor cosmetic adjustments; apply Apache license

* Appease the linter

Co-authored-by: Matthew Holt <mholt@users.noreply.github.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/modules/caddyhttp/reverseproxy/fastcgi/record.go b/modules/caddyhttp/reverseproxy/fastcgi/record.go
new file mode 100644
index 0000000..46c1f17
--- /dev/null
+++ b/modules/caddyhttp/reverseproxy/fastcgi/record.go
@@ -0,0 +1,58 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package fastcgi
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+)
+
+type record struct {
+	h       header
+	lr      io.LimitedReader
+	padding int64
+}
+
+func (rec *record) fill(r io.Reader) (err error) {
+	rec.lr.N = rec.padding
+	rec.lr.R = r
+	if _, err = io.Copy(io.Discard, rec); err != nil {
+		return
+	}
+
+	if err = binary.Read(r, binary.BigEndian, &rec.h); err != nil {
+		return
+	}
+	if rec.h.Version != 1 {
+		err = errors.New("fcgi: invalid header version")
+		return
+	}
+	if rec.h.Type == EndRequest {
+		err = io.EOF
+		return
+	}
+	rec.lr.N = int64(rec.h.ContentLength)
+	rec.padding = int64(rec.h.PaddingLength)
+	return
+}
+
+func (rec *record) Read(p []byte) (n int, err error) {
+	return rec.lr.Read(p)
+}
+
+func (rec *record) hasMore() bool {
+	return rec.lr.N > 0
+}