[bitbake-devel] [PATCH 2/6] data_smart: Improve the calculation of config hash

[Xu, Dongxiao]

On Wed, 2012-04-11 at 00:00 +0100, Richard Purdie wrote:
> On Mon, 2012-04-09 at 16:41 +0800, Dongxiao Xu wrote:
> > The order of keys are not sensitive for config hash, so we need to
> > identify its order while calculating the md5 value.
> > 
> > While for certain values, order is also not sensitive (for example,
> > BBINCLUDED), we also need to identify its order while calculating md5
> > value.
> > 
> > This could fix the problem that Martin Jansa reported in the mailing
> > list:
> > 
> > http://lists.linuxtogo.org/pipermail/bitbake-devel/2012-March/002122.html
> > 
> > Signed-off-by: Dongxiao Xu <dongxiao.xu at intel.com>
> > ---
> >  lib/bb/data_smart.py |   10 +++++++---
> >  1 files changed, 7 insertions(+), 3 deletions(-)
> > 
> > diff --git a/lib/bb/data_smart.py b/lib/bb/data_smart.py
> > index 2c200db..cc61a03 100644
> > --- a/lib/bb/data_smart.py
> > +++ b/lib/bb/data_smart.py
> > @@ -462,13 +462,17 @@ class DataSmart(MutableMapping):
> >          self.delVar(var)
> >  
> >      def get_hash(self):
> > -        data = ""
> > +        data = {}
> >          config_whitelist = set((self.getVar("BB_HASHCONFIG_WHITELIST", True) or "").split())
> > +        config_sort = set((self.getVar("BB_HASHCONFIG_SORT", True) or "").split())
> >          keys = set(key for key in iter(self) if not key.startswith("__"))
> >          for key in keys:
> >              if key in config_whitelist:
> >                  continue
> >              value = self.getVar(key, False) or ""
> > -            data = data + key + ': ' + str(value) + '\n'
> > +            if key in config_sort:
> > +                value = " ".join(sorted(value.split()))
> > +            data.update({key:value})
> >  
> > -        return hashlib.md5(data).hexdigest()
> > +        data_str = str([(k, data[k]) for k in sorted(data.keys())])
> > +        return hashlib.md5(data_str).hexdigest()
> 
> 
> This and the corresponding change in bitbake.conf look rather worrying
> to me. The order in BBINCLUDED is significant and if it changes we
> should be reparsing.

Hi Richard,

Why do you say the order in BBINCLUDED is significant?

I saw the original code ignores the order when handling __depends and
__base_depends.

For example:

def mark_dependency(d, f):
    if f.startswith('./'):
        f = "%s/%s" % (os.getcwd(), f[2:]) 
    deps = d.getVar('__depends') or set() 
    deps.update([(f, cached_mtime(f))])
    d.setVar('__depends', deps)    

I think the get_file_depends(d) just follows the original logic.

Or do you mean the mark_dependency(d, f) is also buggy?

Thanks,
Dongxiao

> 
> Looking at the code, get_file_depends(d) is probably buggy due to the
> use of set() which could reorder the data. We need to keep the data in
> order there and this issue should then be resolved.
> 
> Lets fix the real bug.
> 
> Cheers,
> 
> Richard
> 
> 
>