[bitbake-devel] [PATCH] codeparser: Switch to sha256 from md5

[Jacob Kroon]

On Mon, Dec 17, 2018 at 3:40 PM Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
>
> We've reports of hash collision with codeparser. Looking at the way collision
> problems occur with md5 and the way our function templating works, I can believe
> we may run into issues.
>
> This patch therefore switches to sha256.
>
> Performance wise, parse time could appear to rise by 4s in 374s
>
> Before:
>
> 384329 in 2.966s (md5)
>
> After:
>
> 349743 in 2.340s (sha256)
> 34723 in 1.245s (md5)
>
> since we still have md5 used elsewhere in the code, something we should look at
> next (using sha256 everywhere is around 5.3s in total)
>
> Unfortunately this does nearly double the size of the codeparser cache file
> due to the hash size change.
>
> Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
> ---
>  lib/bb/codeparser.py | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lib/bb/codeparser.py b/lib/bb/codeparser.py
> index 3f8ac1d5f6..ac995a6a1d 100644
> --- a/lib/bb/codeparser.py
> +++ b/lib/bb/codeparser.py
> @@ -33,7 +33,7 @@ from bb.cache import MultiProcessCache
>  logger = logging.getLogger('BitBake.CodeParser')
>
>  def bbhash(s):
> -    return hashlib.md5(s.encode("utf-8")).hexdigest()
> +    return hashlib.sha256(s.encode("utf-8")).hexdigest()
>
>  def check_indent(codestr):
>      """If the code is indented, add a top level piece of code to 'remove' the indentation"""
> @@ -140,7 +140,7 @@ class CodeParserCache(MultiProcessCache):
>      # so that an existing cache gets invalidated. Additionally you'll need
>      # to increment __cache_version__ in cache.py in order to ensure that old
>      # recipe caches don't trigger "Taskhash mismatch" errors.
> -    CACHE_VERSION = 10
> +    CACHE_VERSION = 11

The comment above mentions a "__cache_version__" in cache.py. Should
that be bumped as well ?

>      def __init__(self):
>          MultiProcessCache.__init__(self)
> --
> 2.19.1
>
> --
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