move conn acquire release to wrapper func accepting callback

src/config.go

@@ -6,6 +6,8 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"hash/crc32"
+	"io"
 	"log"
 	"net"
 	"os"
@@ -102,3 +104,27 @@ func (c Config) Close() {
 		}
 	}
 }
+
+func (c Config) WithConn(hashKey string, foo func(net.Conn) error) error {
+	hash := int(crc32.ChecksumIEEE([]byte(hashKey)))
+	hashIdx := hash % len(c.forwards)
+	forward := c.forwards[hashIdx]
+
+	log.Printf("acquire conn %v", hashIdx)
+	forwardCon := forward.Get()
+	if forwardCon == nil {
+		log.Printf("got a nil conn to %v", hashIdx)
+		return io.EOF
+	}
+	forwardConn := forwardCon.(net.Conn)
+
+	if err := foo(forwardConn); err != nil {
+		log.Printf("errored with conn %v: %v", hashIdx, err)
+		forwardConn.Close()
+		return err
+	}
+
+	log.Printf("release conn %v", hashIdx)
+	forward.Put(forwardConn)
+	return nil
+}