Re: [RFC spice-gtk 2/5] qos: introduce quality of service to channels

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When we have overall notion of available bandwidth and the bandwidth is
constrained, we should be able to adjust Opus settings accordingly:
https://opus-codec.org/examples/#bitrate-scalability

The QoS may be as important for uplinks as is for downlinks because
many last-mile connections have asymmetrical bandwidth/latency/jitter.

David

On Fri, 2017-04-07 at 15:19 +0200, Victor Toso wrote:
> From: Victor Toso <me@xxxxxxxxxxxxxx>
> 
> The QOS over spice channels is splitted in a few patches in order to
> easy review.
> 
> This patch introduces 4 new functions that are only internally
> exposed
> to SpiceChannels, they are:
> 
> * spice_session_qos_can_channel_write()
> * spice_session_qos_can_channel_read()
> * spice_session_qos_channel_has_write_nbytes()
> * spice_session_qos_channel_has_read_nbytes()
> 
> Prior to each read or write, the SpiceChannel should query if it is
> allowed to perform the IO with spice_session_qos_can_channel_write
> (or
> read).
> 
> After each successful read or write, the SpiceChannel should inform
> the QOS system how many bytes it has write/read.
> 
> These functions should perform as fast as possible to not introduce
> delays in each IO.
> 
> The logic behind QOS will be introduced in follow up patches.
> 
> Related: https://bugs.freedesktop.org/show_bug.cgi?id=96598
> 
> Signed-off-by: Victor Toso <victortoso@xxxxxxxxxx>
> ---
>  src/spice-channel.c      |  28 ++++++++++++
>  src/spice-option.c       |   5 ++
>  src/spice-session-priv.h |   5 ++
>  src/spice-session.c      | 117
> +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 155 insertions(+)
> 
> diff --git a/src/spice-channel.c b/src/spice-channel.c
> index b3fd521..f49950d 100644
> --- a/src/spice-channel.c
> +++ b/src/spice-channel.c
> @@ -837,6 +837,13 @@ static gint
> spice_channel_flush_wire_nonblocking(SpiceChannel *channel,
>      return ret;
>  }
>  
> +static gboolean wait_qos_can_flush(gpointer data)
> +{
> +    SpiceChannel *channel = SPICE_CHANNEL(data);
> +    SpiceChannelPrivate *c = channel->priv;
> +    return spice_session_qos_can_channel_write(c->session, channel);
> +}
> +
>  /*
>   * Write all 'data' of length 'datalen' bytes out to
>   * the wire
> @@ -856,6 +863,12 @@ static void
> spice_channel_flush_wire(SpiceChannel *channel,
>  
>          if (c->has_error) return;
>  
> +        if (!g_coroutine_condition_wait(&c->coroutine,
> wait_qos_can_flush, channel)) {
> +            CHANNEL_DEBUG(channel, "Closing the channel:
> spice_channel_flush failed qos");
> +            c->has_error = TRUE;
> +            return;
> +        }
> +
>          ret = spice_channel_flush_wire_nonblocking(channel,
> ptr+offset, datalen-offset, &cond);
>          if (ret == -1) {
>              if (cond != 0) {
> @@ -875,6 +888,7 @@ static void spice_channel_flush_wire(SpiceChannel
> *channel,
>          }
>          offset += ret;
>          c->total_write_bytes += ret;
> +        spice_session_qos_channel_has_write_nbytes(c->session,
> channel, ret);
>      }
>  }
>  
> @@ -1063,6 +1077,13 @@ static int
> spice_channel_read_wire_nonblocking(SpiceChannel *channel,
>      return ret;
>  }
>  
> +static gboolean wait_qos_can_read(gpointer data)
> +{
> +    SpiceChannel *channel = SPICE_CHANNEL(data);
> +    SpiceChannelPrivate *c = channel->priv;
> +    return spice_session_qos_can_channel_read(c->session, channel);
> +}
> +
>  /*
>   * Read at least 1 more byte of data straight off the wire
>   * into the requested buffer.
> @@ -1081,6 +1102,12 @@ static int
> spice_channel_read_wire(SpiceChannel *channel, void *data, size_t len
>              return 0;
>          }
>  
> +        if (!g_coroutine_condition_wait(&c->coroutine,
> wait_qos_can_read, channel)) {
> +            CHANNEL_DEBUG(channel, "Closing the channel:
> spice_channel_read failed qos");
> +            c->has_error = TRUE;
> +            return 0;
> +        }
> +
>          ret = spice_channel_read_wire_nonblocking(channel, data,
> len, &cond);
>  
>          if (ret == -1) {
> @@ -1099,6 +1126,7 @@ static int spice_channel_read_wire(SpiceChannel
> *channel, void *data, size_t len
>              return 0;
>          }
>  
> +        spice_session_qos_channel_has_read_nbytes(c->session,
> channel, ret);
>          return ret;
>      }
>  }
> diff --git a/src/spice-option.c b/src/spice-option.c
> index c04e978..bf81dea 100644
> --- a/src/spice-option.c
> +++ b/src/spice-option.c
> @@ -36,6 +36,7 @@ static char *usbredir_redirect_on_connect = NULL;
>  static gboolean smartcard = FALSE;
>  static gboolean disable_audio = FALSE;
>  static gboolean disable_usbredir = FALSE;
> +static gboolean disable_qos = FALSE;
>  static gint cache_size = 0;
>  static gint glz_window_size = 0;
>  static gchar *secure_channels = NULL;
> @@ -203,6 +204,8 @@ GOptionGroup* spice_get_option_group(void)
>            N_("Subject of the host certificate (field=value pairs
> separated by commas)"), N_("<host-subject>") },
>          { "spice-disable-audio", '\0', 0, G_OPTION_ARG_NONE,
> &disable_audio,
>            N_("Disable audio support"), NULL },
> +        { "spice-disable-qos", '\0', 0, G_OPTION_ARG_NONE,
> &disable_qos,
> +          N_("Disable quality of service"), NULL },
>          { "spice-smartcard", '\0', 0, G_OPTION_ARG_NONE, &smartcard,
>            N_("Enable smartcard support"), NULL },
>          { "spice-smartcard-certificates", '\0', 0,
> G_OPTION_ARG_STRING, &smartcard_certificates,
> @@ -312,6 +315,8 @@ void spice_set_session_option(SpiceSession
> *session)
>          g_object_set(session, "enable-usbredir", FALSE, NULL);
>      if (disable_audio)
>          g_object_set(session, "enable-audio", FALSE, NULL);
> +    if (disable_qos)
> +        g_object_set(session, "enable-qos", FALSE, NULL);
>      if (cache_size)
>          g_object_set(session, "cache-size", cache_size, NULL);
>      if (glz_window_size)
> diff --git a/src/spice-session-priv.h b/src/spice-session-priv.h
> index 03005aa..a65a7c0 100644
> --- a/src/spice-session-priv.h
> +++ b/src/spice-session-priv.h
> @@ -100,6 +100,11 @@ void spice_session_set_main_channel(SpiceSession
> *session, SpiceChannel *channel
>  gboolean spice_session_set_migration_session(SpiceSession *session,
> SpiceSession *mig_session);
>  SpiceAudio *spice_audio_get(SpiceSession *session, GMainContext
> *context);
>  const gchar* spice_audio_data_mode_to_string(gint mode);
> +
> +gboolean spice_session_qos_can_channel_write(SpiceSession *session,
> SpiceChannel *channel);
> +gboolean spice_session_qos_can_channel_read(SpiceSession *session,
> SpiceChannel *channel);
> +void spice_session_qos_channel_has_write_nbytes(SpiceSession
> *session, SpiceChannel *channel, gssize nbytes);
> +void spice_session_qos_channel_has_read_nbytes(SpiceSession
> *session, SpiceChannel *channel, gssize nbytes);
>  G_END_DECLS
>  
>  #endif /* __SPICE_CLIENT_SESSION_PRIV_H__ */
> diff --git a/src/spice-session.c b/src/spice-session.c
> index 6f8cf5e..f7c35b4 100644
> --- a/src/spice-session.c
> +++ b/src/spice-session.c
> @@ -68,6 +68,9 @@ struct _SpiceSessionPrivate {
>      /* whether to enable smartcard event forwarding to the server */
>      gboolean          smartcard;
>  
> +    /* whether to enable quality of service */
> +    gboolean          qos_enabled;
> +
>      /* list of certificates to use for the software smartcard reader
> if
>       * enabled. For now, it has to contain exactly 3 certificates
> for
>       * the software reader to be functional
> @@ -123,8 +126,15 @@ struct _SpiceSessionPrivate {
>      SpiceUsbDeviceManager *usb_manager;
>      SpicePlaybackChannel *playback_channel;
>      PhodavServer      *webdav;
> +
> +    /* QoS */
> +    GHashTable        *qos_table;
>  };
>  
> +typedef struct session_channel_qos {
> +    bool throttling_write_enabled;
> +    bool throttling_read_enabled;
> +} session_channel_qos;
>  
>  /**
>   * SECTION:spice-session
> @@ -204,6 +214,7 @@ enum {
>      PROP_USERNAME,
>      PROP_UNIX_PATH,
>      PROP_PREF_COMPRESSION,
> +    PROP_QOS,
>  };
>  
>  /* signals */
> @@ -295,6 +306,7 @@ static void spice_session_init(SpiceSession
> *session)
>      s->glz_window = glz_decoder_window_new();
>      update_proxy(session, NULL);
>  
> +    s->qos_table = g_hash_table_new_full(g_direct_hash,
> g_direct_equal, NULL, g_free);
>      s->usb_manager = spice_usb_device_manager_get(session, &err);
>      if (err != NULL) {
>          SPICE_DEBUG("Could not initialize SpiceUsbDeviceManager -
> %s", err->message);
> @@ -382,6 +394,7 @@ spice_session_finalize(GObject *gobject)
>  
>      g_clear_pointer(&s->pubkey, g_byte_array_unref);
>      g_clear_pointer(&s->ca, g_byte_array_unref);
> +    g_clear_pointer(&s->qos_table, g_hash_table_unref);
>  
>      /* Chain up to the parent class */
>      if (G_OBJECT_CLASS(spice_session_parent_class)->finalize)
> @@ -696,6 +709,9 @@ static void
> spice_session_get_property(GObject    *gobject,
>      case PROP_PREF_COMPRESSION:
>          g_value_set_enum(value, s->preferred_compression);
>          break;
> +    case PROP_QOS:
> +        g_value_set_boolean(value, s->qos_enabled);
> +        break;
>      default:
>  	G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, prop_id, pspec);
>  	break;
> @@ -835,6 +851,9 @@ static void
> spice_session_set_property(GObject      *gobject,
>      case PROP_PREF_COMPRESSION:
>          s->preferred_compression = g_value_get_enum(value);
>          break;
> +    case PROP_QOS:
> +        s->qos_enabled = g_value_get_boolean(value);
> +        break;
>      default:
>          G_OBJECT_WARN_INVALID_PROPERTY_ID(gobject, prop_id, pspec);
>          break;
> @@ -1260,6 +1279,22 @@ static void
> spice_session_class_init(SpiceSessionClass *klass)
>                               G_PARAM_READWRITE |
>                               G_PARAM_STATIC_STRINGS));
>  
> +    /**
> +     * SpiceSession:enable-qos:
> +     *
> +     * If set to TRUE, the quality of service for channels will be
> enabled.
> +     *
> +     * Since: 0.34
> +     **/
> +    g_object_class_install_property
> +        (gobject_class, PROP_QOS,
> +         g_param_spec_boolean("enable-qos",
> +                          "Enable quality of service",
> +                          "Enable quality of service",
> +                          TRUE,
> +                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT |
> +                          G_PARAM_STATIC_STRINGS));
> +
>  
>      /**
>       * SpiceSession::channel-new:
> @@ -1529,6 +1564,7 @@ SpiceSession
> *spice_session_new_from_session(SpiceSession *session)
>                   "enable-smartcard", &c->smartcard,
>                   "enable-audio", &c->audio,
>                   "enable-usbredir", &c->usbredir,
> +                 "enable-qos", &c->qos_enabled,
>                   "ca", &c->ca,
>                   NULL);
>  
> @@ -2226,12 +2262,17 @@ void spice_session_channel_new(SpiceSession
> *session, SpiceChannel *channel)
>  
>      SpiceSessionPrivate *s = session->priv;
>      struct channel *item;
> +    session_channel_qos *qos;
>  
>  
>      item = g_new0(struct channel, 1);
>      item->channel = channel;
>      ring_add(&s->channels, &item->link);
>  
> +    qos = g_new0(session_channel_qos, 1);
> +    qos->throttling_write_enabled = qos->throttling_read_enabled =
> false;
> +    g_hash_table_insert(s->qos_table, channel, qos);
> +
>      if (SPICE_IS_MAIN_CHANNEL(channel)) {
>          gboolean all = spice_strv_contains(s->disable_effects,
> "all");
>  
> @@ -2805,3 +2846,79 @@ gboolean
> spice_session_set_migration_session(SpiceSession *session,
> SpiceSession
>  
>      return TRUE;
>  }
> +
> +G_GNUC_INTERNAL
> +gboolean spice_session_qos_can_channel_write(SpiceSession *session,
> +                                             SpiceChannel *channel)
> +{
> +    session_channel_qos *qos;
> +    SpiceSessionPrivate *s;
> +
> +    g_return_val_if_fail(SPICE_IS_SESSION(session), FALSE);
> +    g_return_val_if_fail(SPICE_IS_CHANNEL(channel), FALSE);
> +
> +    s = session->priv;
> +    if (!s->qos_enabled)
> +        return true;
> +
> +    qos = g_hash_table_lookup(s->qos_table, channel);
> +    g_return_val_if_fail(qos != NULL, FALSE);
> +
> +    return !qos->throttling_write_enabled;
> +}
> +
> +G_GNUC_INTERNAL
> +gboolean spice_session_qos_can_channel_read(SpiceSession *session,
> +                                            SpiceChannel *channel)
> +{
> +    session_channel_qos *qos;
> +    SpiceSessionPrivate *s;
> +
> +    g_return_val_if_fail(SPICE_IS_SESSION(session), FALSE);
> +    g_return_val_if_fail(SPICE_IS_CHANNEL(channel), FALSE);
> +
> +    s = session->priv;
> +    if (!s->qos_enabled)
> +        return true;
> +
> +    qos = g_hash_table_lookup(s->qos_table, channel);
> +    g_return_val_if_fail(qos != NULL, FALSE);
> +
> +    return !qos->throttling_read_enabled;
> +}
> +
> +G_GNUC_INTERNAL
> +void spice_session_qos_channel_has_read_nbytes(SpiceSession
> *session,
> +                                               SpiceChannel
> *channel,
> +                                               gssize nbytes)
> +{
> +    SpiceSessionPrivate *s;
> +
> +    g_return_if_fail(SPICE_IS_SESSION(session));
> +    g_return_if_fail(SPICE_IS_CHANNEL(channel));
> +
> +    s = session->priv;
> +    if (!s->qos_enabled)
> +        return;
> +
> +    /* TODO */
> +    return;
> +}
> +
> +G_GNUC_INTERNAL
> +void spice_session_qos_channel_has_write_nbytes(SpiceSession
> *session,
> +                                                SpiceChannel
> *channel,
> +                                                gssize nbytes)
> +{
> +    SpiceSessionPrivate *s;
> +
> +    g_return_if_fail(SPICE_IS_SESSION(session));
> +    g_return_if_fail(SPICE_IS_CHANNEL(channel));
> +
> +    s = session->priv;
> +    if (!s->qos_enabled)
> +        return;
> +
> +    /* TODO */
> +    return;
> +}
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