[Http-crcsync] crccache ready for some testing I think

[Toby Collett]

I have pulled these changes into the git repo.

Thanks,
Toby

2009/3/30 Rusty Russell <rusty at rustcorp.com.au>

> On Monday 30 March 2009 07:31:38 Alex Wulms wrote:
> > I have also investigated why the cache-server stops finding block matches
> > after the first difference. I think it is because at this moment, the
> cache
> > server does not read ahead enough in the data-stream. Basically, the
> > crc_read_block function of Rusty must be fed with as much data as
> possible,
>
> Bug fixed.  Grab latest from ccan, or just apply this patch.
>
> Thanks for this: I added tests for feeding 1 byte at a time, and it showed
> the
> issue immediately.
>
> Cheers,
> Rusty.
>
> === modified file 'ccan/crcsync/crcsync.c'
> --- ccan/crcsync/crcsync.c      2009-02-17 09:16:33 +0000
> +++ ccan/crcsync/crcsync.c      2009-03-30 00:07:04 +0000
> @@ -138,6 +138,7 @@
>                goto have_match;
>        }
>
> +       /* old is the trailing edge of the checksum window. */
>        if (buffer_size(ctx) >= ctx->block_size)
>                old = ctx->buffer + ctx->buffer_start;
>        else
> @@ -153,6 +154,7 @@
>                                                    *old, *p,
>                                                    ctx->uncrc_tab);
>                        old++;
> +                       /* End of stored buffer?  Start on data they gave
> us. */
>                        if (old == ctx->buffer + ctx->buffer_end)
>                                old = buf;
>                } else {
> @@ -167,11 +169,6 @@
>                p++;
>        }
>
> -       /* Make sure we have a copy of the last block_size bytes.
> -        * First, copy down the old data.  */
> -       if (buffer_size(ctx)) {
> -       }
> -
>        if (crcmatch >= 0) {
>                /* We have a match! */
>                if (ctx->literal_bytes > ctx->block_size) {
> @@ -187,12 +184,15 @@
>                        assert(ctx->literal_bytes == 0);
>                        ctx->have_match = -1;
>                        ctx->running_crc = 0;
> +                       /* Nothing more in the buffer. */
> +                       ctx->buffer_start = ctx->buffer_end = 0;
>                }
>        } else {
>                /* Output literal if it's more than 1 block ago. */
>                if (ctx->literal_bytes > ctx->block_size) {
>                        *result = ctx->literal_bytes - ctx->block_size;
> -                       ctx->literal_bytes = ctx->block_size;
> +                       ctx->literal_bytes -= *result;
> +                       ctx->buffer_start += *result;
>                } else
>                        *result = 0;
>
> @@ -243,29 +243,34 @@
>  long crc_read_flush(struct crc_context *ctx)
>  {
>        long ret;
> +       size_t final;
>
> -       /* In case we ended on a whole block match. */
> -       if (ctx->have_match == -1) {
> -               size_t final;
> -
> -               final = final_block_match(ctx);
> -               if (!final) {
> -                       /* This is how many bytes we're about to consume.
> */
> -                       ret = buffer_size(ctx);
> -                       ctx->buffer_start += ret;
> -                       ctx->literal_bytes -= ret;
> -
> -                       return ret;
> -               }
> -               ctx->buffer_start += final;
> -               ctx->literal_bytes -= final;
> -               ctx->have_match = ctx->num_crcs-1;
> -       }
> -
> -       /* It might be a partial block match, so no assert */
> -       ctx->literal_bytes = 0;
> -       ret = -ctx->have_match-1;
> -       ctx->have_match = -1;
> +       /* We might have ended right on a matched block. */
> +       if (ctx->have_match != -1) {
> +               ctx->literal_bytes -= ctx->block_size;
> +               assert(ctx->literal_bytes == 0);
> +               ret = -ctx->have_match-1;
> +               ctx->have_match = -1;
> +               ctx->running_crc = 0;
> +               /* Nothing more in the buffer. */
> +               ctx->buffer_start = ctx->buffer_end;
> +               return ret;
> +       }
> +
> +       /* Look for truncated final block. */
> +       final = final_block_match(ctx);
> +       if (!final) {
> +               /* Nope?  Just a literal. */
> +               ret = buffer_size(ctx);
> +               ctx->buffer_start += ret;
> +               ctx->literal_bytes -= ret;
> +               return ret;
> +       }
> +
> +       /* We matched (some of) what's left. */
> +       ret = -(ctx->num_crcs-1)-1;
> +       ctx->buffer_start += final;
> +       ctx->literal_bytes -= final;
>        return ret;
>  }
>
>
>
>
>


-- 
This email is intended for the addressee only and may contain privileged
and/or confidential information
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.laptop.org/pipermail/http-crcsync/attachments/20090330/f8b75533/attachment-0001.htm