Merge pull request #3648 from FedericoCeratto/reuse_port

Add SO_REUSEPORT support

lib/posix/posix.nim

@@ -1575,6 +1575,8 @@ var
     ## Receive timeout.
   SO_REUSEADDR* {.importc, header: "<sys/socket.h>".}: cint
     ## Reuse of local addresses is supported.
+  SO_REUSEPORT* {.importc, header: "<sys/socket.h>".}: cint
+    ## Multiple binding: load balancing on incoming TCP connections or UDP packets. (Requires Linux kernel > 3.9)
   SO_SNDBUF* {.importc, header: "<sys/socket.h>".}: cint
     ## Send buffer size.
   SO_SNDLOWAT* {.importc, header: "<sys/socket.h>".}: cint

lib/pure/asynchttpserver.nim

@@ -39,6 +39,7 @@ type
   AsyncHttpServer* = ref object
     socket: AsyncSocket
     reuseAddr: bool
+    reusePort: bool
 
   HttpCode* = enum
     Http100 = "100 Continue",
@@ -99,10 +100,11 @@ proc `==`*(protocol: tuple[orig: string, major, minor: int],
     of HttpVer10: 0
   result = protocol.major == major and protocol.minor == minor
 
-proc newAsyncHttpServer*(reuseAddr = true): AsyncHttpServer =
+proc newAsyncHttpServer*(reuseAddr = true, reusePort = false): AsyncHttpServer =
   ## Creates a new ``AsyncHttpServer`` instance.
   new result
   result.reuseAddr = reuseAddr
+  result.reusePort = reusePort
 
 proc addHeaders(msg: var string, headers: StringTableRef) =
   for k, v in headers:
@@ -264,6 +266,8 @@ proc serve*(server: AsyncHttpServer, port: Port,
   server.socket = newAsyncSocket()
   if server.reuseAddr:
     server.socket.setSockOpt(OptReuseAddr, true)
+  if server.reusePort:
+    server.socket.setSockOpt(OptReusePort, true)
   server.socket.bindAddr(port, address)
   server.socket.listen()
 

lib/pure/nativesockets.nim

@@ -38,7 +38,7 @@ export
   SOL_SOCKET,
   SOMAXCONN,
   SO_ACCEPTCONN, SO_BROADCAST, SO_DEBUG, SO_DONTROUTE,
-  SO_KEEPALIVE, SO_OOBINLINE, SO_REUSEADDR,
+  SO_KEEPALIVE, SO_OOBINLINE, SO_REUSEADDR, SO_REUSEPORT,
   MSG_PEEK
 
 when defined(macosx) and not defined(nimdoc):

lib/pure/net.nim

@@ -129,7 +129,7 @@ type
 
   SOBool* = enum ## Boolean socket options.
     OptAcceptConn, OptBroadcast, OptDebug, OptDontRoute, OptKeepAlive,
-    OptOOBInline, OptReuseAddr
+    OptOOBInline, OptReuseAddr, OptReusePort
 
   ReadLineResult* = enum ## result for readLineAsync
     ReadFullLine, ReadPartialLine, ReadDisconnected, ReadNone
@@ -579,6 +579,7 @@ proc toCInt*(opt: SOBool): cint =
   of OptKeepAlive: SO_KEEPALIVE
   of OptOOBInline: SO_OOBINLINE
   of OptReuseAddr: SO_REUSEADDR
+  of OptReusePort: SO_REUSEPORT
 
 proc getSockOpt*(socket: Socket, opt: SOBool, level = SOL_SOCKET): bool {.
   tags: [ReadIOEffect].} =