break socket send into chunks

Author: elcritch

src/nesper/servers/rpc/rpcsocket_queue_mpack.nim

@@ -35,6 +35,15 @@ proc sendChunks*(sourceClient: Socket, rmsg: string) =
     sourceClient.send(move sl)
     i = j
 
+proc sendLength*(sourceClient: Socket, rmsg: string) =
+  var rmsgN: int = rmsg.len()
+  var rmsgSz = newString(4)
+  for i in 0..3:
+    rmsgSz[i] = char(rmsgN and 0xFF)
+    rmsgN = rmsgN shr 8
+
+  sourceClient.send(move rmsgSz)
+
 proc rpcMsgPackQueueWriteHandler*(srv: TcpServerInfo[RpcQueueHandle], result: ReadyKey, sourceClient: Socket, qh: RpcQueueHandle) =
   raise newException(OSError, "the request to the OS failed")
 
@@ -56,12 +65,8 @@ proc rpcMsgPackQueueReadHandler*(srv: TcpServerInfo[RpcQueueHandle], result: Rea
         continue
 
       var rmsg: string = msgpack2json.fromJsonNode(res)
-      var rmsgN: int = rmsg.len()
-      var rmsgSz = newString(4)
-      for i in 0..3:
-        rmsgSz[i] = char(rmsgN and 0xFF)
-        rmsgN = rmsgN shr 8
 
+      sourceClient.sendLength(rmsg)
       sourceClient.sendChunks(rmsg)
 
   except TimeoutError: