Re: [Qemu-devel] [PATCH v2 1/3] net: asynchronous send/receive infrastructure for net/socket.c

[ronnie sahlberg]

In
net_socket_update_fd_handler()

shouldnt you call qemu_notify_event() if any of the handlers have
changed from NULL to non-NULL ?
or else it might take a while before the change takes effect.


regards
ronnie sahlberg

On Wed, Aug 22, 2012 at 1:52 AM, Stefan Hajnoczi
<address@hidden> wrote:
> The net/socket.c net client is not truly asynchronous.  This patch
> borrows the qemu_set_fd_handler2() code from net/tap.c as the basis for
> proper asynchronous send/receive.
>
> Only read packets from the socket when the peer is able to receive.
> This avoids needless queuing.
>
> Later patches implement asynchronous send.
>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
>  net/socket.c |   58 
> ++++++++++++++++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 52 insertions(+), 6 deletions(-)
>
> diff --git a/net/socket.c b/net/socket.c
> index c172c24..54e32f0 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -42,9 +42,51 @@ typedef struct NetSocketState {
>      unsigned int packet_len;
>      uint8_t buf[4096];
>      struct sockaddr_in dgram_dst; /* contains inet host and port destination 
> iff connectionless (SOCK_DGRAM) */
> +    IOHandler *send_fn;           /* differs between SOCK_STREAM/SOCK_DGRAM 
> */
> +    bool read_poll;               /* waiting to receive data? */
> +    bool write_poll;              /* waiting to transmit data? */
>  } NetSocketState;
>
>  static void net_socket_accept(void *opaque);
> +static void net_socket_writable(void *opaque);
> +
> +/* Only read packets from socket when peer can receive them */
> +static int net_socket_can_send(void *opaque)
> +{
> +    NetSocketState *s = opaque;
> +
> +    return qemu_can_send_packet(&s->nc);
> +}
> +
> +static void net_socket_update_fd_handler(NetSocketState *s)
> +{
> +    qemu_set_fd_handler2(s->fd,
> +                         s->read_poll  ? net_socket_can_send : NULL,
> +                         s->read_poll  ? s->send_fn : NULL,
> +                         s->write_poll ? net_socket_writable : NULL,
> +                         s);
> +}
> +
> +static void net_socket_read_poll(NetSocketState *s, bool enable)
> +{
> +    s->read_poll = enable;
> +    net_socket_update_fd_handler(s);
> +}
> +
> +static void net_socket_write_poll(NetSocketState *s, bool enable)
> +{
> +    s->write_poll = enable;
> +    net_socket_update_fd_handler(s);
> +}
> +
> +static void net_socket_writable(void *opaque)
> +{
> +    NetSocketState *s = opaque;
> +
> +    net_socket_write_poll(s, false);
> +
> +    qemu_flush_queued_packets(&s->nc);
> +}
>
>  /* XXX: we consider we can send the whole packet without blocking */
>  static ssize_t net_socket_receive(NetClientState *nc, const uint8_t *buf, 
> size_t size)
> @@ -81,7 +123,8 @@ static void net_socket_send(void *opaque)
>      } else if (size == 0) {
>          /* end of connection */
>      eoc:
> -        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
> +        net_socket_read_poll(s, false);
> +        net_socket_write_poll(s, false);
>          if (s->listen_fd != -1) {
>              qemu_set_fd_handler(s->listen_fd, net_socket_accept, NULL, s);
>          }
> @@ -152,7 +195,8 @@ static void net_socket_send_dgram(void *opaque)
>          return;
>      if (size == 0) {
>          /* end of connection */
> -        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
> +        net_socket_read_poll(s, false);
> +        net_socket_write_poll(s, false);
>          return;
>      }
>      qemu_send_packet(&s->nc, s->buf, size);
> @@ -243,7 +287,8 @@ static void net_socket_cleanup(NetClientState *nc)
>  {
>      NetSocketState *s = DO_UPCAST(NetSocketState, nc, nc);
>      if (s->fd != -1) {
> -        qemu_set_fd_handler(s->fd, NULL, NULL, NULL);
> +        net_socket_read_poll(s, false);
> +        net_socket_write_poll(s, false);
>          close(s->fd);
>          s->fd = -1;
>      }
> @@ -314,8 +359,8 @@ static NetSocketState 
> *net_socket_fd_init_dgram(NetClientState *peer,
>
>      s->fd = fd;
>      s->listen_fd = -1;
> -
> -    qemu_set_fd_handler(s->fd, net_socket_send_dgram, NULL, s);
> +    s->send_fn = net_socket_send_dgram;
> +    net_socket_read_poll(s, true);
>
>      /* mcast: save bound address as dst */
>      if (is_connected) {
> @@ -332,7 +377,8 @@ err:
>  static void net_socket_connect(void *opaque)
>  {
>      NetSocketState *s = opaque;
> -    qemu_set_fd_handler(s->fd, net_socket_send, NULL, s);
> +    s->send_fn = net_socket_send;
> +    net_socket_read_poll(s, true);
>  }
>
>  static NetClientInfo net_socket_info = {
> --
> 1.7.10.4
>
>