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).
We're preparing for being able to deal with files with duplicate
message IDs here. The plan is to create a notmuch_message_t object in
add_message that may or may not reference a document that exists in
the database. So to do this, we have to find the message ID before we
do any manipulation of the doc.
The idea here is to allow internal users to see a non-synced message
object, (for example, while parsing a message file and incrementally
adding terms, etc.). We're willing to take the care to get the
improved performance.
But for the public interface, keeping everything synced will be much
less confusing, (reference lots of sup bugs that happen due to
message state being altered by the user but not synced to the database).
I still don't like the name message_file at all, but we're about
to start using a notmuch_message_t in this function so we need
to do something to keep the identifiers separate for now.
Eventually, it probably makes sense to push the message-parsing
code from database.cc to message.cc.
It's even enough to check if a "missing" header was accidentally
left off the list in the call to restrict_headers. (And it's
cheap since we only check in case no such header was found in the
message.)
We recently started discarding files as "not email" if they have none
of Subject, From, nor To. Apaprently, my mail collection contains a
number of messages that I sent, that are saved without Subject and
From, (perhaps these were drafts?).
Anyway, it's fortunate I had those since they alerted me to this bug,
where we were not parsing the "To" header in some cases.
This is important as we're using the message ID as the unique key
in our database. So previously, all messages with no message ID
would be treated as the same message---not good at all.
This way both the .c and .h files have the same name, and all of the
code imported from the "libsha1" implementation is in filenames
matching libsha1.*.
This also gives me room to make my own notmuch_sha1 wrapper functions
in sha1.c.
I'm glad that when I implemented "notmuch restore" I went through the
extra effort to take the code I had written in one sitting into over a
dozen commits. Sure enough, I hadn't tested well enough and had
totally broken "notmuch setup", (segfaults and bogus thread_id
values).
With the little commits I had made, git bisect saved the day, and I
went back to make the fixes right on top of the commits that
introduced the bugs. So now we octopus merge those in.
We deleted this in favor of our fancy new thread_ids iterator
from the message object. But one of the previous callers of
insert_thread_id isn't using notmuch_message_t yet. I made
the mistake of thinking I could just call g_hash_table_insert
directly, but the problem was that nobody was splitting
up the thread_id string at its commas.
So with this, we were inserting bogus comma-separated IDs
into the hash table, so thread_id values were ballooning
out of control. Should be much better now.
Here's more evidence that C++ is a nightmare to program---or that
I'm smart enough to realize that C++ is more clever than I will
ever be.
Most of my issues with C++ have to do with it hiding things from
me that I'd really like to and expect to be aware of as a C
programmer.
For example, the specific problem here is that there's a
short-lived std::string, from which I just want to copy
the C string. I try to do that on the next line, but before
I can, C++ has already called the destructor on the std::string.
Now, C++ isn't alone in doing garbage collecting like this.
But in a *real* garbage-collecting system, everything would
work that way. For example, here, I'm still holding a pointer
to the C string contents, so if the garbage collector were
aware of that reference, then it might clean up the std::string
container and leave the data I'm still using.
But that's not what we get with C++. Instead, some things are
reference counted and collected, (like the std::string), and
some things just aren't (like the C string it contains). The
end result is that it's very fragile. It forces me to be aware
of the timing of hidden functions. In a "real" system I wouldn't
have to be aware of that timing, and in C the function just
wouldn't be hidden.
Keith's name already shows up in the git log, so it would be
wrong to not mention him. And Martin and Jamey have been
helpful in discussions about what an ideal mail system
would look like.
This code comes courtesy of Brian Gladman and Mikhail Gusarov.
Both files are available under the GPL and were downloaded as
version 0.2 of libsha1 from git://github.com/dottedmag/libsha1.git
with the following commit:
commit d0f0e7e0dc5ce2d58972cb5a492183c0d4e58433
Author: Mikhail Gusarov <dottedmag@dottedmag.net>
Date: Mon Oct 20 22:38:47 2008 +0700
Version bump.
Signed-off-by: Mikhail Gusarov <dottedmag@dottedmag.net>
It's pretty easy to do with all the right infrastructure in place.
Now that I can get my tags from sup to notmuch, maybe I'll be able
to start reading mail again.
We actually need this before the include of xutil.h, but
it was previously stuck randomly among various system
includes. Instead, put it at the top, right after include
the notmuch.h header that defines it.
This is where we wanted to put the note to recommend the user
call notmuch_message_destroy if the lifetime of the message
is much shorter than the lifetime of the query. (Somehow this
had ended up in the documentation of notmuch_message_get_tags
before.)
Previously, this would allocate new memory with every call. That
was with talloc, of course, so there wasn't any leaking (eventually).
But since we're now calling this internally we want to be a little
less wasteful. It's easy enough to just stash the result into the
message on the first call, and then just return that on subsequent
calls.
With this function, and the recently added support for
notmuch_message_get_thread_ids, we now recode the find_thread_ids
function to work just the way we expect a user of the public
notmuch API to work. Not too bad really.
Along with all of the notmuch_thread_ids_t iterator functions.
Using a consistent idiom seems better here rather than returning
a comma-separated string and forcing the user to parse it.
The motivation here is that our top-level notmuch.c main program
wants to start using these, but we don't want it to see into
notmuch-private.h, (since our main program is a test vehicle
for the "public" notmuch interface in notmuch.h).
I'm too lazy to see what the RFC says, but I know that having
whitespace inside a message-ID is sure to confuse things. And
besides, this makes things more compatible with sup so that
I have some hope of importing sup labels.
To properly support sorting in notmuch_query we know use an
Enquire object. We also throw in a QueryParser too, so we're
really close to being able to support arbitrary full-text
searches.
I took a look at the supported QueryParser syntax and chose
a set of flags for everything I like, (such as supporting
Boolean operators in either case ("AND" or "and"), supporting
phrase searching, supporting + and - to include/preclude terms,
and supporting a trailing * on any term as a wildcard).
This is to help keep the report looking clean when a new report
is shorter than a previous reports, (say, when crossing the
boundary from over one minute remaining to less than one minute
remaining).
This used to be here, but I must have accidentally dropped it
when reformatting the progress report recently.
Using the address of a static char* was clever, but really
unnecessary. An empty string is much less magic, and even
easier to understand as the way to query everything from
the database.
Previously we were leaking[*] memory in that the memory footprint of
a "notmuch dump" run would continue to grow until the output was
complete, and then finally all the memory would be freed.
Now, the memory footprint is small and constant, O(1) rather than
O(n) in the number of messages.
[*] Not leaking in a valgrind sense---every byte was still carefully
being accounted for and freed eventually.
