[Spice-devel] [spice-gtk PATCH v3] Usbredir: enable lz4 compression

Victor Toso lists at victortoso.com
Sat Apr 30 08:48:33 UTC 2016


Hi,

On Wed, Apr 27, 2016 at 07:00:43PM +0300, Snir Sheriber wrote:
> Compressed message type is CompressedData which contains compression
> type (1 byte) followed by the uncompressed data size (4 bytes) followed
> by the compressed data size (4 bytes) followed by the compressed data
> 
> If SPICE_SPICEVMC_CAP_DATA_COMPRESS_LZ4 capability is available &&
> data_size > COMPRESS_THRESHOLD data will be sent compressed otherwise
> data will be sent uncompressed (as well if compression has failed)
> ---
>  src/channel-usbredir.c | 131 ++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 124 insertions(+), 7 deletions(-)
> 
> diff --git a/src/channel-usbredir.c b/src/channel-usbredir.c
> index c8a2da9..c14d1c7 100644
> --- a/src/channel-usbredir.c
> +++ b/src/channel-usbredir.c
> @@ -24,6 +24,9 @@
>  #ifdef USE_USBREDIR
>  #include <glib/gi18n.h>
>  #include <usbredirhost.h>
> +#ifdef USE_LZ4
> +#include <lz4.h>
> +#endif
>  #ifdef USE_POLKIT
>  #include "usb-acl-helper.h"
>  #endif
> @@ -32,6 +35,7 @@
>  #include "usbutil.h"
>  #endif
>  
> +#include "common/log.h"
>  #include "spice-client.h"
>  #include "spice-common.h"
>  
> @@ -51,6 +55,7 @@
>  
>  #ifdef USE_USBREDIR
>  
> +#define COMPRESS_THRESHOLD 1000
>  #define SPICE_USBREDIR_CHANNEL_GET_PRIVATE(obj)                                  \
>      (G_TYPE_INSTANCE_GET_PRIVATE((obj), SPICE_TYPE_USBREDIR_CHANNEL, SpiceUsbredirChannelPrivate))
>  
> @@ -233,6 +238,8 @@ static void channel_set_handlers(SpiceChannelClass *klass)
>  {
>      static const spice_msg_handler handlers[] = {
>          [ SPICE_MSG_SPICEVMC_DATA ] = usbredir_handle_msg,
> +        [ SPICE_MSG_SPICEVMC_COMPRESSED_DATA ] = usbredir_handle_msg,
> +
>      };
>  
>      spice_channel_set_handlers(klass, handlers, G_N_ELEMENTS(handlers));
> @@ -267,7 +274,11 @@ void spice_usbredir_channel_set_context(SpiceUsbredirChannel *channel,
>          g_error("Out of memory allocating usbredirhost");
>  
>  #if USBREDIR_VERSION >= 0x000701
> -    usbredirhost_set_buffered_output_size_cb(priv->host, usbredir_buffered_output_size_callback);
> +    usbredirhost_set_buffered_output_size_cb(priv->host,
> +                                             usbredir_buffered_output_size_callback);

Indentation above is not necessary

> +#endif
> +#ifdef USE_LZ4
> +    spice_channel_set_capability(channel, SPICE_SPICEVMC_CAP_DATA_COMPRESS_LZ4);
>  #endif
>  }
>
> @@ -632,11 +643,73 @@ static void usbredir_free_write_cb_data(uint8_t *data, void *user_data)
>      usbredirhost_free_write_buffer(priv->host, data);
>  }
>
> +#ifdef USE_LZ4
> +static void usbredir_free_write_cb_compressed_data(uint8_t *data, void *user_data)
> +{
> +    SpiceUsbredirChannel *channel = user_data;
> +    SpiceUsbredirChannelPrivate *priv = channel->priv;
> +
> +    usbredirhost_free_write_buffer(priv->host,
> +                                (uint8_t*)SPICE_CONTAINEROF(data, SpiceMsgCompressedData, compressed_data));
> +}
> +
> +static int try_write_compress_LZ4(SpiceUsbredirChannel *channel, uint8_t *data, int count) {
> +    SpiceMsgOut *msg_out_compressed;
> +    int bound;
> +
> +    if (count <= COMPRESS_THRESHOLD) {
> +        /* Not enough data to compress */
> +        return FALSE;
> +    }
> +    if (!spice_channel_test_capability(SPICE_CHANNEL(channel),
> +                                       SPICE_SPICEVMC_CAP_DATA_COMPRESS_LZ4)) {
> +        /*No server compressing capability - data will not be compressed*/
> +        return FALSE;
> +    }
> +    bound = LZ4_compressBound(count);
> +    if (bound == 0) {
> +        /*Invalid bound - data will not be compressed*/
> +        return FALSE;
> +    }

Thanks for the early returns here. As Marc-Andre suggested, another situation
that we don't want to compress this data is when host and client machine are the
same. The check that he metioned should be enough [0]

[0]
 if (g_socket_get_family(c->sock) == G_SOCKET_FAMILY_UNIX) {
   /* Don't compress data in local case */
   return FALSE;
 }

> +    int compressed_data_count;
> +    SpiceMsgCompressedData *compressed_data_msg;

In spice-gtk we try to keep the declaration of the variables in the begin of the
block when possible (together with bound/msg_out_compressed in this case).

> +
> +    compressed_data_msg = (SpiceMsgCompressedData*)spice_malloc(sizeof(SpiceMsgCompressedData) + bound);
> +    compressed_data_msg->uncompressed_size = count;
> +    compressed_data_msg->type = SPICE_DATA_COMPRESSION_TYPE_LZ4;
> +    compressed_data_count = LZ4_compress_default((char*)data,
> +                                                 (char*)compressed_data_msg->compressed_data,
> +                                                 count,
> +                                                 bound);
> +    if (compressed_data_count > 0) {
> +        compressed_data_msg->compressed_size = compressed_data_count;
> +        msg_out_compressed = spice_msg_out_new(SPICE_CHANNEL(channel),
> +                                               SPICE_MSGC_SPICEVMC_COMPRESSED_DATA);
> +        msg_out_compressed->marshallers->msg_SpiceMsgCompressedData(msg_out_compressed->marshaller,
> +                                                                    compressed_data_msg);
> +        spice_marshaller_add_ref_full(msg_out_compressed->marshaller,
> +                                      compressed_data_msg->compressed_data,
> +                                      compressed_data_count,
> +                                      usbredir_free_write_cb_compressed_data,
> +                                      channel);
> +        spice_msg_out_send(msg_out_compressed);
> +        return TRUE;
> +    } else {/* free & fallback to sending the message uncompressed */

You can remove the else above.

> +        free(compressed_data_msg);
> +        return FALSE;
> +    }
> +}
> +#endif
> +
>  static int usbredir_write_callback(void *user_data, uint8_t *data, int count)
>  {
>      SpiceUsbredirChannel *channel = user_data;
>      SpiceMsgOut *msg_out;
>
> +#ifdef USE_LZ4
> +    if(try_write_compress_LZ4(channel, data, count))
> +        return count;
> +#endif
>      msg_out = spice_msg_out_new(SPICE_CHANNEL(channel),
>                                  SPICE_MSGC_SPICEVMC_DATA);
>      spice_marshaller_add_ref_full(msg_out->marshaller, data, count,
> @@ -724,11 +797,45 @@ static void spice_usbredir_channel_up(SpiceChannel *c)
>      usbredirhost_write_guest_data(priv->host);
>  }
>
> +static int try_handle_compressed_msg(SpiceMsgCompressedData *compressed_data_msg,
> +                                     uint8_t **buf,
> +                                     int *size) {
> +    uint32_t decompressed_size = 0;
> +    char *decompressed = NULL;
> +
> +    switch(compressed_data_msg->type) {
> +#ifdef USE_LZ4
> +    case SPICE_DATA_COMPRESSION_TYPE_LZ4:
> +        decompressed = g_malloc(compressed_data_msg->uncompressed_size);
> +        decompressed_size = LZ4_decompress_safe ((char*)compressed_data_msg->compressed_data,
> +                                                 decompressed,
> +                                                 compressed_data_msg->compressed_size,
> +                                                 compressed_data_msg->uncompressed_size);
> +        break;
> +#endif
> +    default:
> +        spice_warning("Unknown Compression Type");
> +        return FALSE;
> +    }
> +    if (decompressed_size < 1 ||
> +        decompressed_size!= compressed_data_msg->uncompressed_size) {

I think you don't need to check for `decompressed_size < 1` as
`decompressed_size != compressed_data_msg->uncompressed_size` should
cover that too.

> +        spice_warning("Decompress Error decompressed_size=%d expected=%d",
> +                      decompressed_size, compressed_data_msg->uncompressed_size);
> +        g_free(decompressed);
> +        return FALSE;
> +    }
> +
> +    *size = decompressed_size;
> +    *buf = (uint8_t*)decompressed;
> +    return TRUE;
> +
> +}
> +
>  static void usbredir_handle_msg(SpiceChannel *c, SpiceMsgIn *in)
>  {
>      SpiceUsbredirChannel *channel = SPICE_USBREDIR_CHANNEL(c);
>      SpiceUsbredirChannelPrivate *priv = channel->priv;
> -    int r, size;
> +    int r = 0, size;
>      uint8_t *buf;
>
>      g_return_if_fail(priv->host != NULL);
> @@ -736,13 +843,23 @@ static void usbredir_handle_msg(SpiceChannel *c, SpiceMsgIn *in)
>      /* No recursion allowed! */
>      g_return_if_fail(priv->read_buf == NULL);
>
> -    buf = spice_msg_in_raw(in, &size);
> -    priv->read_buf = buf;
> -    priv->read_buf_size = size;
> +    if (spice_msg_in_type(in) == SPICE_MSG_SPICEVMC_COMPRESSED_DATA) {
> +        SpiceMsgCompressedData *compressed_data_msg = spice_msg_in_parsed(in);
> +        if(try_handle_compressed_msg(compressed_data_msg, &buf, &size)) {
> +            priv->read_buf_size = size;
> +            priv->read_buf = buf;
> +        } else {
> +            r = usbredirhost_read_parse_error;
> +        }
> +    } else { /*Regular SPICE_MSG_SPICEVMC_DATA msg*/
> +        buf = spice_msg_in_raw(in, &size);
> +        priv->read_buf_size = size;
> +        priv->read_buf = buf;
> +    }
>
>      spice_usbredir_channel_lock(channel);
> -
> -    r = usbredirhost_read_guest_data(priv->host);
> +    if (r == 0)
> +        r = usbredirhost_read_guest_data(priv->host);
>      if (r != 0) {
>          SpiceUsbDevice *spice_device = priv->spice_device;
>          device_error_data err_data;

Reviewed-by: Victor Toso <victortoso at redhat.com>

Cheers,
  toso

> --
> 2.5.5
>
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