Many async optimisations.

* Selectors implementation will now attempt to immediately execute an IO
  operation instead of waiting for a ready notification.
* Removed recursion in asynchttpserver.
* Improved buffered implementation of recvLine in asyncnet.
* Optimised ``respond`` in asynchttpserver removing a possible "Delayed ACK"
  situation.

lib/pure/asyncdispatch.nim

@@ -552,7 +552,18 @@ when defined(windows) or defined(nimdoc):
   initAll()
 else:
   import selectors
-  from posix import EINTR, EAGAIN, EINPROGRESS, EWOULDBLOCK, MSG_PEEK
+  when defined(windows):
+    import winlean
+    const
+      EINTR = WSAEINPROGRESS
+      EINPROGRESS = WSAEINPROGRESS
+      EWOULDBLOCK = WSAEWOULDBLOCK
+      EAGAIN = EINPROGRESS
+      MSG_NOSIGNAL = 0
+  else:
+    from posix import EINTR, EAGAIN, EINPROGRESS, EWOULDBLOCK, MSG_PEEK,
+                      MSG_NOSIGNAL
+  
   type
     TAsyncFD* = distinct cint
     TCallback = proc (sock: TAsyncFD): bool {.closure,gcsafe.}
@@ -693,7 +704,7 @@ else:
 
     proc cb(sock: TAsyncFD): bool =
       result = true
-      let res = recv(sock.TSocketHandle, addr readBuffer[0], size,
+      let res = recv(sock.TSocketHandle, addr readBuffer[0], size.cint,
                      flags.cint)
       #echo("recv cb res: ", res)
       if res < 0:
@@ -708,7 +719,7 @@ else:
       else:
         readBuffer.setLen(res)
         retFuture.complete(readBuffer)
-  
+    if not cb(socket):
       addRead(socket, cb)
     return retFuture
 
@@ -721,7 +732,8 @@ else:
       result = true
       let netSize = data.len-written
       var d = data.cstring
-      let res = send(sock.TSocketHandle, addr d[written], netSize, 0.cint)
+      let res = send(sock.TSocketHandle, addr d[written], netSize.cint,
+                     MSG_NOSIGNAL)
       if res < 0:
         let lastError = osLastError()
         if lastError.int32 notin {EINTR, EWOULDBLOCK, EAGAIN}:
@@ -734,6 +746,7 @@ else:
           result = false # We still have data to send.
         else:
           retFuture.complete()
+    if not cb(socket):
       addWrite(socket, cb)
     return retFuture
 
@@ -756,6 +769,7 @@ else:
       else:
         register(client.TAsyncFD)
         retFuture.complete(($inet_ntoa(sockAddress.sin_addr), client.TAsyncFD))
+    if not cb(socket):
       addRead(socket, cb)
     return retFuture
 

lib/pure/asynchttpserver.nim

@@ -51,10 +51,15 @@ proc `==`*(protocol: tuple[orig: string, major, minor: int],
 proc newAsyncHttpServer*(): PAsyncHttpServer =
   new result
 
-proc sendHeaders*(req: TRequest, headers: PStringTable) {.async.} =
+proc addHeaders(msg: var string, headers: PStringTable) =
-  ## Sends the specified headers to the requesting client.
   for k, v in headers:
-    await req.client.send(k & ": " & v & "\c\L")
+    msg.add(k & ": " & v & "\c\L")
+
+proc sendHeaders*(req: TRequest, headers: PStringTable): PFuture[void] =
+  ## Sends the specified headers to the requesting client.
+  var msg = ""
+  addHeaders(msg, headers)
+  return req.client.send(msg)
 
 proc respond*(req: TRequest, code: THttpCode,
         content: string, headers: PStringTable = newStringTable()) {.async.} =
@@ -64,9 +69,9 @@ proc respond*(req: TRequest, code: THttpCode,
   ## This procedure will **not** close the client socket.
   var customHeaders = headers
   customHeaders["Content-Length"] = $content.len
-  await req.client.send("HTTP/1.1 " & $code & "\c\L")
+  var msg = "HTTP/1.1 " & $code & "\c\L"
-  await sendHeaders(req, headers)
+  msg.addHeaders(customHeaders)
-  await req.client.send("\c\L" & content)
+  await req.client.send(msg & "\c\L" & content)
 
 proc newRequest(): TRequest =
   result.headers = newStringTable(modeCaseInsensitive)
@@ -93,6 +98,7 @@ proc sendStatus(client: PAsyncSocket, status: string): PFuture[void] =
 
 proc processClient(client: PAsyncSocket, address: string,
                  callback: proc (request: TRequest): PFuture[void]) {.async.} =
+  while true:
     # GET /path HTTP/1.1
     # Header: val
     # \n
@@ -174,9 +180,9 @@ proc processClient(client: PAsyncSocket, address: string,
       # header states otherwise.
       # In HTTP 1.0 we assume that the connection should not be persistent.
       # Unless the connection header states otherwise.
-    await processClient(client, address, callback)
     else:
       request.client.close()
+      break
 
 proc serve*(server: PAsyncHttpServer, port: TPort,
             callback: proc (request: TRequest): PFuture[void],

lib/pure/asyncnet.nim

@@ -110,12 +110,10 @@ proc recv*(socket: PAsyncSocket, size: int,
       if socket.currPos >= socket.bufLen:
         if (flags and MSG_PEEK) == MSG_PEEK:
           # We don't want to get another buffer if we're peeking.
-          result.setLen(read)
+          break
-          return
         let res = await socket.readIntoBuf(flags and (not MSG_PEEK))
         if res == 0:
-          result.setLen(read)
+          break
-          return
 
       let chunk = min(socket.bufLen-socket.currPos, size-read)
       copyMem(addr(result[read]), addr(socket.buffer[socket.currPos]), chunk)
@@ -181,11 +179,43 @@ proc recvLine*(socket: PAsyncSocket): PFuture[string] {.async.} =
   ## If the socket is disconnected in the middle of a line (before ``\r\L``
   ## is read) then line will be set to ``""``.
   ## The partial line **will be lost**.
-  
   template addNLIfEmpty(): stmt =
     if result.len == 0:
       result.add("\c\L")
 
+  if socket.isBuffered:
+    result = ""
+    if socket.bufLen == 0:
+      let res = await socket.readIntoBuf(0)
+      if res == 0:
+        return
+
+    var lastR = false
+    while true:
+      if socket.currPos >= socket.bufLen:
+        let res = await socket.readIntoBuf(0)
+        if res == 0:
+          result = ""
+          break
+
+      case socket.buffer[socket.currPos]
+      of '\r':
+        lastR = true
+        addNLIfEmpty()
+      of '\L':
+        addNLIfEmpty()
+        socket.currPos.inc()
+        return
+      else:
+        if lastR:
+          socket.currPos.inc()
+          return
+        else:
+          result.add socket.buffer[socket.currPos]
+      socket.currPos.inc()
+  else:
+    
+
     result = ""
     var c = ""
     while true:

lib/pure/selectors.nim

@@ -163,7 +163,7 @@ elif defined(linux):
   proc newSelector*(): PSelector =
     new result
     result.epollFD = epoll_create(64)
-    result.events = cast[array[64, epoll_event]](alloc0(sizeof(epoll_event)*64))
+    #result.events = cast[array[64, epoll_event]](alloc0(sizeof(epoll_event)*64))
     result.fds = initTable[TSocketHandle, PSelectorKey]()
     if result.epollFD < 0:
       OSError(OSLastError())