Aside from increased code sharing, the benefit here is that now
thread_ids iterates over the terms of a message rather than the
thread_id value. So we'll now be able to drop that value.
The generic notmuch_terms_t iterator should provide support for
notmuch_thread_ids_t when we switch as well, (And it would be
interesting to see if we could reasonably make this support a
PostingIterator too. Time will tell.)
First, it's nice that for now we don't have any users yet, so we
can make incompatible changes to the database layout like this
without causing trouble. ;-)
There are a few reasons for this change. First, we now use value 0
uniformly as a timestamp for both mail and timestamp documents, (which
lets us cleanup an ugly and fragile bare 0 in the add_value and
get_value calls in the timestamp code).
Second, I want to drop the thread value entirely, so putting it at the
end of the list means we can drop it as compatible change in the
future. (I almost want to drop the message-ID value too, but it's nice
to be able to sort on it to get diff-able output from "notmuch dump".)
But the thread value we never use as a value, (we would never sort on
it, for example). And it's totally redundant with the thread terms we
store already. So expect it to disappear soon.
We're now dropping all pretense of keeping the database directly
compatible with sup's current xapian backend. (But perhaps someone
might write a new nothmuch backend for sup in the future.)
In coming up with the prefix values here, I tried to follow the
conventions of http://xapian.org/docs/omega/termprefixes.html as
closely as makes sense, (with some domain translation from "web"
to "email archive").
The idea here is that only some of the prefix names (such as "id" and
"tag") actually make sense in external user-supplied query
strings. Other things like "type" are internal implementation details
of how we store things in the database. So internal machinery will add
those terms to the database and we don't need to support them in the
string itself.
With this, we can now simply loop over the external prefix values to
let the quiery parser know about them. So as we add prefixes in the
future, we'll only need to add them to this list.
It's not much of a script, (we don't have that many commands after
all), but it's the kind of thing that's nice to have and gives the
tool a slightly more polished feel.
The key for this is call add_boolean_prefix on the QueryParser
object. That tells the query parser to take something like "tag:inbox"
and transform it into the "Linbox" term and do what it needs to do to
make this term a requirement of the search. We're starting to have a
real system here.
Also, I didn't want to expose the ugly name of "msgid" to the user, so
we add a prefix name of simply "id" instead.
I'm planning to change prefix values soon, which would break code
like this. So eliminate the fragility by going through our existing
_find_prefix function.
Here's the big bug that was preventing any searches from working at
all like desired. I did the work to carefully pick out exactly the
flags that I wanted, and then I threw it away by trying to combine
them with & instead of | (so just passing 0 for flags instead).
Much better now.
It's nice that Xapian provides a little function to print a textual
representation of the entire query tree. So now, if you compile
like so:
make CFLAGS=-DDEBUG_QUERY
then you get a nice output of the query string received by the query
module, and the final query actually being sent to Xapian.
This isn't behaving at all like it's documented yet, (for example,
it's returning message IDs not thread IDs[*]). In fact, the output
code is just a copy of the body of "notmuch dump", so all you
get for now is message ID and tags.
But this should at least be enough to start exercising the query
functionality, (which is currently very buggy).
[*] I'll want to convert the databse to store thread documents
before fixing that.
The current problem is that when this function fails the caller
doesn't get any information about what the particular failure
was, (something in the filesystem? or in Xapian?). We should fix
that.
With some recent testing, the timestamp was failing, (overflowing
the term limit), and reporting an error, but the top-level notmuch
command was still returning a success return value.
I think it's high time to add a test suite, (and the code base is
small enough that if we add it now it shouldn't be *too* hard to
shoot for a very high coverage percentage).
The previous code was only correct as long as the timestamp prefix
was only a single character. But with the recent change to a
multi-character prefix, this broke. So fix it now.
I've decided not to try for sup compatibility at the leve of the
xapian datbase. There's just too much about sup's usage of the
database that I don't like, (beyond the embedded ruby data structures
there is redundant storage of message IDs, thread IDs, and dates (in
both terms and values)).
I'm going to fix that up in the database of notmuch, with some other
changes as well. (I plan to drop "reference" terms once linkage to a
thread ID through the reference is established. I also plan to add
actual documents to represent threads.)
So with all that incompatibility, I might as well make my own prefix
values. And while doing that, I should try to be as compatible as
possible with the conventions described here:
http://xapian.org/docs/omega/termprefixes.html
With this, "notmuch new" is now plenty fast even with large archives
spanning many sub-directories. Document this both in "notmuch help"
and also in the output of notmuch setup.
Finally, I can get new messages into my notmuch database without
having to run a complete "notmuch setup" again. This takes
advantage of the recent timestamp capabilities in the database
to avoid looking into directories that haven't changed since the
last time "notmuch new" was run.
Get rid of a useless leading 0 on the seconds value, and make a
distinction between "files" and "messages", (we process many
files, but not all of them are recongized as messages). Finally,
add a summary line at the end saying how many unique messages
were added to the database. Since this comes right after the
total number of files, it gives the user at least a hint as
to how many messages were encountered with duplicate message IDs.
The notmuch_database_get_default_path function is unique in not
accepting a notmuch_database_t* (nor creating one). So list it
outside the other notmuch_database functions.
Some people might argue for more initializers to be "safer",
but I actually prefer to leave things this way. It saves
typing, but the real benefit is that the things that do
require initialization stand out so we know to watch them
carefully. And with valgrind, we actually get to catch
errors earlier if we *don't* initialize them. So that can
be "safer" ironically enough.
And document that notmuch_database_add_message can return this
value. This pushes the hard decision of what to do with duplicate
messages out to the user, but that's OK. (We weren't really doing
anything with these ourselves, and this way the user is at least
informed of the issue, rather than it just getting papered over
internally.)
This were just unclean, (an invisble sort of uncleanliness, but still
there are liable to make for ugly diffs). Oh, wait, like this one!
But at least it's not sprinkled among code changes.
Again preferring notmuch_database_t* over Xapian::Database*.
Also, we're standardizing on "doc_id" rather than "docid" locally, (as
an analoge to "message_id"), in spite of the "Xapian::docid" name,
(which, fortunately, we can ignore and just us "unsigned int" instead).
This name is a more accurate description of what it does, and
the more general naming will make sense as we start storing
non-message documents in the database (such as directory
timestamps).
Also, don't pass around a Xapian::Database where it's more our
style to pass a notmuch_database_t*.
We'll be using this for storing really long terms in the database
and when we just need to look them up, (and never read back the
original data directly from the database). For example, storing
arbitrarily long directory paths in the database along with
mtime timestamps.
Note that if we did want to store arbitrarily long terms and also
be able to read them back, the Xapian folks recommending splitting
the term off with multiple prefixes. See the note near the end
of this page:
http://trac.xapian.org/wiki/FAQ/UniqueIds
This helps the user gauge the severity of the error.
For example, when restoring my sup tags I see a bunch of tags missing
for message IDs of the form "sup-faked-...". That's not surprising
since I know that sup generates these with the md5sum of the message
header while notmuch uses the sha-1 of the entire message. But how
much will this hurt?
Well, now that I can see that most of the missing tags are just
"attachment", then I'm not concerned, (I'll be automatically creating
that tag in the future based on the message contents). But if a
missing tag is "inbox" then that's more concerning because that's data
that I can't easily regenerate outside of sup.
With the recent improvements to the handling of message IDs we
"know" that a NULL message ID is impossible, (so we simply
abort if the impossible happens).
Here's the second big fix to message-ID handling, (the first was to
generate message IDs when an email contained none). Now, with no
document missing a message ID, and no two documents having the same
message ID, we have a nice consistent database where the message ID
can be used as a unique key.
This is the last piece needed for add_message to be able to properly
support a message with a duplicate message ID. This function creates
a new notmuch_message_t object but one that may reference an existing
document in the database.
This function is only supposed to be called with a doc_id that
was queried from the database already. So there's an internal
error if no document with that doc_id can be found in the database.
In that case, return NULL.
This will support the add_message function in incrementally creating
state in a new notmuch_message_t. The new functions are
_notmuch_message_set_filename
_notmuch_message_add_thread_id
_notmuch_message_ensure_thread_id
_notmuch_message_set_date
_notmuch_message_sync
This is a new public function to find the filename of the original
email message for a message-object that was found in the database.
We may change this function in the future to support returning a
list of filenames, (for messages with duplicate message IDs).
