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, 26 insertions, 0 deletions

diff --git a/modules/caddyhttp/reverseproxy/fastcgi/pool.go b/modules/caddyhttp/reverseproxy/fastcgi/pool.go
new file mode 100644
index 0000000..29017f1
--- /dev/null
+++ b/modules/caddyhttp/reverseproxy/fastcgi/pool.go
@@ -0,0 +1,26 @@
+// 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 (
+	"bytes"
+	"sync"
+)
+
+var bufPool = sync.Pool{
+	New: func() any {
+		return new(bytes.Buffer)
+	},
+}