opt: make use of the inheritance of file status flags on BSD-like OS

acceptor_bsd.go

@@ -0,0 +1,25 @@
+// Copyright (c) 2023 The Gnet Authors. All rights reserved.
+//
+// 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.
+
+//go:build freebsd || dragonfly || darwin
+// +build freebsd dragonfly darwin
+
+package gnet
+
+// The canonical BSD sockets implementation will inherit file status flags
+// from the listening socket, so we don't need to set the non-blocking flag
+// for the accepted sockets explicitly.
+func setNonBlock(_ int, _ bool) error {
+	return nil
+}

acceptor_linux.go

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2023 The Gnet Authors. All rights reserved.
+ *
+ * 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 gnet
+
+import "golang.org/x/sys/unix"
+
+func setNonBlock(fd int, nonBlocking bool) error {
+	return unix.SetNonblock(fd, nonBlocking)
+}

acceptor_unix.go

@@ -44,7 +44,7 @@ func (eng *engine) accept(fd int, _ netpoll.IOEvent) error {
 		}
 	}
 
-	if err = os.NewSyscallError("fcntl nonblock", unix.SetNonblock(nfd, true)); err != nil {
+	if err = os.NewSyscallError("fcntl nonblock", setNonBlock(nfd, true)); err != nil {
 		return err
 	}
 	remoteAddr := socket.SockaddrToTCPOrUnixAddr(sa)
@@ -83,7 +83,7 @@ func (el *eventloop) accept(fd int, ev netpoll.IOEvent) error {
 		}
 	}
 
-	if err = os.NewSyscallError("fcntl nonblock", unix.SetNonblock(nfd, true)); err != nil {
+	if err = os.NewSyscallError("fcntl nonblock", setNonBlock(nfd, true)); err != nil {
 		return err
 	}
 	remoteAddr := socket.SockaddrToTCPOrUnixAddr(sa)