On Sat, 23 Aug 2014, David Bremner <da...@tethera.net> wrote:
> Austin Clements <amdra...@mit.edu> writes:
>>
>> + /* Bit mask of features used by this database. Features are
>> + * named, independent aspects of the database schema. This is a
>> + * bitwise-OR of NOTMUCH_FEATURE_* values (below). */
>> + unsigned int features;
>
> Should we be using a fixed size integer (uint_32t or whatever) for
> features? iirc the metadata in the database is actually a string, so I
> guess arbitrary precision there.
Right; this doesn't matter for the on-disk format because these don't
appear on disk. But you're right that in principle we could overflow
this, leading to subtle bugs. I moved the enum above struct
_notmuch_database, gave it a name and bitwise operators for C++, and
used that enum name everywhere, so precision should never be a problem.
>> +/* Bit masks for _notmuch_database::features. */
>> +enum {
>> + /* If set, file names are stored in "file-direntry" terms. If
>> + * unset, file names are stored in document data.
>> + *
>> + * Introduced: version 1. Implementation support: both for read;
>> + * required for write. */
>> + NOTMUCH_FEATURE_FILE_TERMS = 1 << 0,
>
> I agree with Jani that the Implementation support: part is a bit
> mystifying without the commit message. Maybe part of the commit message
> could migrate here? Or maybe just add a pointer to the comment in database.cc.
I stripped these out because I don't think they're maintainable. See my
reply to Jani.
>> + if (! *incompat_out)
>
> Should we support passing NULL for incompat_out? or at least check for
> it?
Added a guard so it's safe to pass NULL.
>> @@ -1048,7 +1164,8 @@ notmuch_database_get_version (notmuch_database_t
>> *notmuch)
>> notmuch_bool_t
>> notmuch_database_needs_upgrade (notmuch_database_t *notmuch)
>> {
>> - return notmuch->needs_upgrade;
>> + return notmuch->mode == NOTMUCH_DATABASE_MODE_READ_WRITE &&
>> + (NOTMUCH_FEATURES_CURRENT & ~notmuch->features);
>> }
>
> Maybe I'm not thinking hard enough here, but how does this deal with a
> feature that is needed to open a database in read only mode? Maybe it
> needs a comment for people not as clever as Austin ;).
I'm not quite sure what you mean. notmuch_database_needs_upgrade
returns false for read-only databases because you can't upgrade a
read-only database. This was true before this patch, too, though it was
less obvious. (Maybe that's not what you're asking?)
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