We want to be able to query the properties directly, like:
notmuch count property:foo=bar
which should return a count of messages where the property with key
"foo" has value equal to "bar".
I believe the current one is misleading, because in my experiments
Xapian did not add : when prefix and term were both upper case. Indeed,
it's hard to see how it could, because prefixes are added at a layer
above Xapian in our code. See _notmuch_message_add_term for an example.
Also try to explain why this is a good idea. As far as I can ascertain,
this is more of an issue for a system trying to work with an unknown set
of prefixes. Since notmuch has a fixed set of prefixes, and we can
hopefully be trusted not to add XGOLD and XGOLDEN as prefixes, it is
harder for problems to arise.
_notmuch_database_log clears the log buffer each time. Rather than
introducing more complicated semantics about for this function, provide
a second function that does not clear the buffer. This is mainly a
convenience function for callers constructing complex or multi-line log
messages.
The changes to query.cc are to make sure that the common code path of
the new function is tested.
Xapian 1.3 has introduced the DB_RETRY_LOCK flag (Xapian bug
275). Detect it in configure and optionally use it. With this flag
commands that need the write lock will wait for their turn instead of
aborting when it's not immediately available.
Amended by db: allow disabling in configure
Many of the external links found in the notmuch source can be resolved
using https instead of http. This changeset addresses as many as i
could find, without touching the e-mail corpus or expected outputs
found in tests.
Cleaned the following whitespace in lib/* files:
lib/index.cc: 1 line: trailing whitespace
lib/database.cc 5 lines: 8 spaces at the beginning of line
lib/notmuch-private.h: 4 lines: 8 spaces at the beginning of line
lib/message.cc: 1 line: trailing whitespace
lib/sha1.c: 1 line: empty lines at the end of file
lib/query.cc: 2 lines: 8 spaces at the beginning of line
lib/gen-version-script.sh: 1 line: trailing whitespace
The code to skip multiple slashes in _notmuch_database_split_path()
skips back one character too much. This is compensated by a +1 in the
length parameter to the strndup() call. Mostly this works fine, but if
the path is to a file under a top level directory with one character
long name, the directory part is mistaken to be part of the file name
(slash == path in code). The returned directory name will be the empty
string and the basename will be the full path, breaking the indexing
logic in notmuch new.
Fix the multiple slash skipping to keep the slash variable pointing at
the last slash, and adjust strndup() accordingly.
The bug was introduced in
commit e890b0cf40
Author: Carl Worth <cworth@cworth.org>
Date: Sat Dec 19 13:20:26 2009 -0800
database: Store the parent ID for each directory document.
just a little over two months after the initial commit in the Notmuch
code history, making this the longest living bug in Notmuch to date.
We can't (but currently do) allow upgrades within transactions because
upgrades need their own transactions. We don't want to re-use the
current transaction because bailing out of an upgrade would mean loosing
all previous changes (because our "atomic" transactions don't commit
before hand). This gives us two options:
1. Fail at the beginning of upgrade (tell the user to end the
transaction, upgrade, and start over).
2. Don't allow the user to start the transaction.
I went with the latter because:
1. There is no reason to call `begin_atomic` unless you intend to to
write to the database and anyone intending to write to the database
should upgrade it first.
2. This means that nothing inside an atomic transaction can ever fail
with NOTMUCH_STATUS_UPGRADE_REQUIRED.
Although I think it's a pretty bad idea to continue using the old API,
this allows both a more gentle transition for clients of the library,
and allows us to break one monolithic change into a series
This exposes the committed database revision to library users along
with a UUID that can be used to detect when revision numbers are no
longer comparable (e.g., because the database has been replaced).
This adds a new document value that stores the revision of the last
modification to message metadata, where the revision number increases
monotonically with each database commit.
An alternative would be to store the wall-clock time of the last
modification of each message. In principle this is simpler and has
the advantage that any process can determine the current timestamp
without support from libnotmuch. However, even assuming a computer's
clock never goes backward and ignoring clock skew in networked
environments, this has a fatal flaw. Xapian uses (optimistic)
snapshot isolation, which means reads can be concurrent with writes.
Given this, consider the following time line with a write and two read
transactions:
write |-X-A--------------|
read 1 |---B---|
read 2 |---|
The write transaction modifies message X and records the wall-clock
time of the modification at A. The writer hangs around for a while
and later commits its change. Read 1 is concurrent with the write, so
it doesn't see the change to X. It does some query and records the
wall-clock time of its results at B. Transaction read 2 later starts
after the write commits and queries for changes since wall-clock time
B (say the reads are performing an incremental backup). Even though
read 1 could not see the change to X, read 2 is told (correctly) that
X has not changed since B, the time of the last read. In fact, X
changed before wall-clock time A, but the change was not visible until
*after* wall-clock time B, so read 2 misses the change to X.
This is tricky to solve in full-blown snapshot isolation, but because
Xapian serializes writes, we can use a simple, monotonically
increasing database revision number. Furthermore, maintaining this
revision number requires no more IO than a wall-clock time solution
because Xapian already maintains statistics on the upper (and lower)
bound of each value stream.
There are many places in the notmuch code where the path is assumed to be absolute. If someone (TM) wants a project, one could remove these assumptions. In the mean time, prevent users from shooting themselves in the foot.
Update test suite mark tests for this error as no longer broken, and
also convert some tests that used relative paths for nonexistent
directories.
The difference with FILE_ERROR is that this is for things that are
wrong with the path before looking at the disk.
Add some 3 tests; two broken as a reminder to actually use this new
code.
You may wonder why _notmuch_message_file_open_ctx has two parameters.
This is because we need sometime to use a ctx which is a
notmuch_message_t. While we could get the database from this, there is
no easy way in C to tell type we are getting.
This is not supposed to change any functionality from an end user
point of view. Note that it will eliminate some output to stderr. The
query debugging output is left as is; it doesn't really fit with the
current primitive logging model. The remaining "bad" fprintf will need
an internal API change.
The compatibility wrapper ensures that clients calling
notmuch_database_open will receive consistent output for now.
The changes to notmuch-{new,search} and test/symbol-test are just to
make the test suite pass.
The use of IGNORE_RESULT is justified by two things. 1) I don't know
what else to do. 2) asprintf guarantees the output string is NULL if
an error occurs, so at least we are not passing garbage back.
This adds the indexing support for the "mimetype:" term and removes
the broken test flag. The indexing is probablistic in Xapian terms,
which gives a better experience to end users. Standard content-types
of the form "foo/bar" are automatically interpreted as phrases in
Xapian due to the embedded slash.
Assume, separate messages with application/pdf and application/x-pdf
are indexed, then:
- mimetype:application/x-pdf will find only the application/x-pdf
- mimetype:application/pdf will find only the application/pdf
- mimetype:pdf will find both of the messages
This feature will exist in all newly created databases, but there is
no upgrade provided for it. If this flag exists, it indicates that
the database was created after the indexed MIME-types feature was
added.
Previously, it was necessary to link new messages to children to work
around some (though not all) problems with the old metadata-based
approach to stored thread IDs. With ghost messages, this is no longer
necessary, so don't bother with child linking when ghost messages are
in use.
This updates the thread linking code to use ghost messages instead of
user metadata to link messages into threads.
In contrast with the old approach, this is actually correct.
Previously, thread merging updated only the thread IDs of message
documents, not thread IDs stored in user metadata. As originally
diagnosed by Mark Walters [1] and as demonstrated by the broken
T260-thread-order test, this can cause notmuch to fail to link
messages even though they're in the same thread. In principle the old
approach could have been fixed by updating the user metadata thread
IDs as well, but these are not indexed and hence this would have
required a full scan of all stored thread IDs. Ghost messages solve
this problem naturally by reusing the exact same thread ID and message
ID representation and indexing as regular messages.
Furthermore, thanks to this greater symmetry, ghost messages are also
algorithmically simpler. We continue to support the old user metadata
format, so this patch can't delete any code, but when we do remove
support for the old format, several functions can simply be deleted.
[1] id:8738h7kv2q.fsf@qmul.ac.uk
This moves the code to retrieve and clear the metadata thread ID out
of _notmuch_database_link_message into its own function. This will
simplify future changes.
Previously, this was performed by notmuch_database_add_message. This
happens to be the only caller currently (which is why this was safe),
but we're about to introduce more callers, and it makes more sense to
put responsibility for ID compression in the lower-level function
rather than requiring each caller to handle it.
In Xapian, closing a database implicitly aborts any outstanding
transaction and commits changes. For historical reasons,
notmuch_database_close had grown to almost, but not quite duplicate
this behavior. Before closing the database, it would explicitly (and
unnecessarily) commit it. However, if there was an outstanding
transaction (ie atomic section), commit would throw a Xapian
exception, which notmuch_database_close would unnecessarily print to
stderr, even though notmuch_database_close would ultimately abort the
transaction anyway when it called close.
This patch simplifies notmuch_database_close to explicitly abort any
outstanding transaction and then just call Database::close. This
works for both read-only and read/write databases, takes care of
committing changes, unifies the exception handling path, and codifies
aborting outstanding transactions. This is currently the only way to
abort an atomic section (and may remain so, since it would be
difficult to roll back things we may have cached from rolled-back
modifications).
48db8c8 introduced a disagreement between when
notmuch_database_needs_upgrade returned TRUE and when
notmuch_database_upgrade actually performed an upgrade. As a result,
if a database had a version less than 3, but no new features were
required, notmuch new would call notmuch_database_upgrade to perform
an upgrade, but notmuch_database_upgrade would return immediately
without updating the database version. Hence, the next notmuch new
would do the same, and so on.
Fix this by ensuring that the upgrade-required logic is identical
between the two.
Previously, there was no protection against a caller invoking an
operation on an old database version that would effectively corrupt
the database by treating it like a newer version.
According to notmuch.h, any caller that opens the database in
read/write mode is supposed to check if the database needs upgrading
and perform an upgrade if it does. This would protect against this,
but nobody (even the CLI) actually does this.
However, with features, it's easy to protect against incompatible
operations on a fine-grained basis. This lightweight change allows
callers to safely operate on old database versions, while preventing
specific operations that would corrupt the database with an
informative error message.
Previously, some parts of upgrade didn't report progress and for
others it was possible for the progress meter to restart at 0 part way
through the upgrade because each stage was reported separately.
Fix this by computing the total amount of work that needs to be done
up-front and updating completed work monotonically.
Rather than potentially making multiple passes over the same type of
data in the database, reorganize upgrade around each type of data that
may be upgraded. This eliminates code duplication, will make
multi-version upgrades faster, and will let us improve progress
reporting.
Previously, we had database version information hard-coded in the
upgrade code. Slightly re-organize the upgrade process around the set
of new database features to be enabled by the upgrade.
Previously, the upgrade was organized as two passes -- an upgrade
pass, and a separate cleanup pass -- so the database was always in a
valid state. This change substantially simplifies this code by
performing the upgrade in a transaction and combining both passes in
to one. This 1) eliminates a lot of duplicate code between the
passes, 2) speeds up the upgrade process, 3) makes progress reporting
more accurate, 4) eliminates the potential for stale data if the
upgrade is interrupted during the cleanup pass, and 5) makes it easier
to reason about the safety of the upgrade code.
Previously, our database schema was versioned by a single number.
Each database schema change had to occur "atomically" in Notmuch's
development history: before some commit, Notmuch used version N, after
that commit, it used version N+1. Hence, each new schema version
could introduce only one change, the task of developing a schema
change fell on a single person, and it all had to happen and be
perfect in a single commit series. This made introducing a new schema
version hard. We've seen only two schema changes in the history of
Notmuch.
This commit introduces database schema version 3; hopefully the last
schema version we'll need for a while. With this version, we switch
from a single version number to "features": a set of named,
independent aspects of the database schema.
Features should make backwards compatibility easier. For many things,
it should be easy to support databases both with and without a
feature, which will allow us to make upgrades optional and will enable
"unstable" features that can be developed and tested over time.
Features also make forwards compatibility easier. The features
recorded in a database include "compatibility flags," which can
indicate to an older version of Notmuch when it must support a given
feature to open the database for read or for write. This lets us
replace the old vague "I don't recognize this version, so something
might go wrong, but I promise to try my best" warnings upon opening a
database with an unknown version with precise errors. If a database
is safe to open for read/write despite unknown features, an older
version will know that and issue no message at all. If the database
is not safe to open for read/write because of unknown features, an
older version will know that, too, and can tell the user exactly which
required features it lacks support for.
According to RFC2822 References and In-Reply-To headers are supposed
to contain one or more Message-IDs, however older RFC822 allowed
almost any content. When both References and In-Reply-To headers ends
with something else that a Message-ID (see e.g. [1]), the thread
structure presented by notmuch is incorrect. The reason is that
notmuch treats this case as if the email contained no "replyto"
information (see _notmuch_database_link_message_to_parents).
This patch changes the parse_references() function to return the last
valid Message-ID encountered rather than NULL resulting from the last
hunk of text not being the Message-ID.
[1] https://lkml.org/lkml/headers/2014/5/19/864
As noted in devel/STYLE, every private library function should start
with _notmuch. This patch corrects function naming that did not adhere
to this style in lib/notmuch-private.h. In particular, the old function
names that now begin with _notmuch are
notmuch_sha1_of_file
notmuch_sha1_of_string
notmuch_message_file_close
notmuch_message_file_get_header
notmuch_message_file_open
notmuch_message_get_author
notmuch_message_set_author
Signed-off-by: Charles Celerier <cceleri@cs.stanford.edu>
notmuch_database_close may fail in Xapian ->flush() or ->close(), so
report the status. Similarly for notmuch_database_destroy which calls
close.
This is required for notmuch insert to report error status if message
indexing failed.
The notmuch library includes a full blown message header parser. Yet
the same message headers are parsed by gmime during indexing. Switch
to gmime parsing completely.
These are the main changes:
* Gmime stops header parsing at the first invalid header, and presumes
the message body starts from there. The current parser is quite
liberal in accepting broken headers. The change means we will be
much pickier about accepting invalid messages.
* The current parser converts tabs used in header folding to
spaces. Gmime preserve the tabs. Due to a broken python library used
in mailman, there are plenty of mailing lists that produce headers
with tabs in header folding, and we'll see plenty of tabs. (This
change has been mitigated in preparatory patches.)
* For pure header parsing, the current parser is likely faster than
gmime, which parses the whole message rather than just the
headers. Since we parse the message and its headers using gmime for
indexing anyway, this avoids and extra header parsing round when
adding new messages. In case of duplicate messages, we'll end up
parsing the full message although just headers would be
sufficient. All in all this should still speed up 'notmuch new'.
* Calls to notmuch_message_get_header() may be slightly slower than
previously for headers that are not indexed in the database, due to
parsing of the whole message. Within the notmuch code base, notmuch
reply is the only such user.
In xapian terms, convert folder: prefix from probabilistic to boolean
prefix, matching the paths, relative from the maildir root, of the
message files, ignoring the maildir new and cur leaf directories.
folder:foo matches all message files in foo, foo/new, and foo/cur.
folder:foo/new does *not* match message files in foo/new.
folder:"" matches all message files in the top level maildir and its
new and cur subdirectories.
This change constitutes a database change: bump the database version
and add database upgrade support for folder: terms. The upgrade also
adds path: terms.
Finally, fix the folder search test for literal folder: search, as
some of the folder: matching capabilities are lost in the
probabilistic to boolean prefix change.
The path: prefix is a literal boolean prefix matching the paths,
relative from the maildir root, of the message files.
path:foo matches all message files in foo (but not in foo/new or
foo/cur).
path:foo/new matches all message files in foo/new.
path:"" matches all message files in the top level maildir.
path:foo/** matches all message files in foo and recursively in all
subdirectories of foo.
path:** matches all message files recursively, i.e. all messages.
In case previous notmuch compact has been interrupted there is old
work-in-progress database compact directory partially filled. Remove
it just before starting to fill the directory with new files.
It is less error prone and window of failure opportunity is smaller
if the old (backup) database is always renamed (instead of sometimes
rmtree'd) before new (compacted) database is put into its place.
Finally rmtree() old database in case old database backup is not kept.
catch Xapian::Error in compact code in lib/database.cc to be consistent
with other code in addition to not making software crash on uncaught
other Xapian error.
The extra path component added by the lib is a magic value that the
caller just has to know. This is demonstrated by the current code,
which indeed has "xapian.old" both sides of the interface. Use the
backup path provided by the lib caller verbatim, without adding
anything to it.
This function uses Xapian's Compactor machinery to compact the notmuch
database. The compacted database is built in a temporary directory and
later moved into place while the original uncompacted database is
preserved.
Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
As explained by Jeffrey Stedfast, the author of GMime, quoted in [1]:
> Passing the GMIME_ENABLE_RFC2047_WORKAROUNDS flag to g_mime_init()
> *should* solve the decoding problem mentioned in the thread. This
> flag should be safe to pass into g_mime_init() without any bad side
> effects and my unit tests do test that code-path.
The thread being referred to is [2].
[1] id:87bo56viyo.fsf@nikula.org
[2] id:08cb1dcd-c5db-4e33-8b09-7730cb3d59a2@gmail.com
Presently, the code which finds the parent of a message as it is being
added to the database assumes that the first Message-ID-like substring
of the In-Reply-To header is the parent Message ID. Some mail clients,
however, put stuff other than the Message-ID of the parent in the
In-Reply-To header, such as the email address of the sender of the
parent. This can fool notmuch.
The updated algorithm prefers the last Message ID in the References
header. The References header lists messages oldest-first, so the last
Message ID is the parent (RFC2822, p. 24). The References header is
also less likely to be in a non-standard
syntax (http://cr.yp.to/immhf/thread.html,
http://www.jwz.org/doc/threading.html). In case the References header
is not to be found, fall back to the old behavior.
V2 of this patch, incorporating feedback from Jani and (indirectly)
Austin.
Previously, we would treat multi-message mboxes as one giant email,
which, besides the obvious incorrect indexing, often led to
out-of-memory errors for archival mboxes. Now we explicitly reject
multi-message mboxes. For historical reasons, we retain support for
single-message mboxes, but official deprecate this behavior.
Add a custom value range processor to enable date and time searches of
the form date:since..until, where "since" and "until" are expressions
understood by the previously added date/time parser, to restrict the
results to messages within a particular time range (based on the Date:
header).
If "since" or "until" describes date/time at an accuracy of days or
less, the values are rounded according to the accuracy, towards past
for "since" and towards future for "until". For example,
date:november..yesterday would match from the beginning of November
until the end of yesterday. Expressions such as date:today..today
means since the beginning of today until the end of today.
Open-ended ranges are supported (since Xapian 1.2.1), i.e. you can
specify date:..until or date:since.. to not limit the start or end
date, respectively.
CAVEATS:
Xapian does not support spaces in range expressions. You can replace
the spaces with '_', or (in most cases) '-', or (in some cases) leave
the spaces out altogether.
Entering date:expr without ".." (for example date:yesterday) will not
work as you might expect. You can achieve the expected result by
duplicating the expr both sides of ".." (for example
date:yesterday..yesterday).
Open-ended ranges won't work with pre-1.2.1 Xapian, but they don't
produce an error either.
Signed-off-by: Jani Nikula <jani@nikula.org>
Previously, _notmuch_database_filename_to_direntry would abort with an
internal error when called on a read-only database. Now that creating
the directory document is optional,
notmuch_database_find_message_by_filename can disable directory
document creation (as it should) and, as a result, not abort on
read-only databases.
Using the new support from _notmuch_directory_create, this makes
notmuch_database_get_directory a read-only operation that simply
returns the directory object if it exists or NULL otherwise. This
also means that notmuch_database_get_directory can work on read-only
databases.
This change breaks the directory mtime workaround in notmuch-new.c by
fixing the exact issue it was working around. This permits mtime
update races to prevent scans of changed directories, which
non-deterministically breaks a few tests. The next patch fixes this.
Now _notmuch_database_filename_to_direntry takes a flags argument and
can indicate if the necessary directory documents do not exist.
Again, callers have been updated, but retain their original behavior.
Now _notmuch_database_find_directory_id takes a flags argument, which
it passes through to _notmuch_directory_create and can indicate if the
directory does not exist. Again, callers have been updated, but
retain their original behavior.
Previously this function would create directory documents if they
didn't exist. As a result, it could only be used on writable
databases. This adds an argument to make creation optional and to
make this function work on read-only databases. We use a flag
argument to avoid a bare boolean and to permit future expansion.
Both callers have been updated, but currently retain the old behavior.
We'll take advantage of the new argument in the following patches.
Previously, notmuch_database_get_directory had no way to indicate how
it had failed. This changes its prototype to return a status code and
set an out-argument to the retrieved directory, like similar functions
in the library API. This does *not* change its currently broken
behavior of creating directory objects when they don't exist, but it
does document it and paves the way for fixing this. Also, it can now
check for a read-only database and return
NOTMUCH_STATUS_READ_ONLY_DATABASE instead of crashing.
In the interest of atomicity, this also updates calls from the CLI so
that notmuch still compiles.
This is the notmuch_database_create equivalent of the previous change.
In this case, there were places where errors were not being propagated
correctly in notmuch_database_create or in calls to it. These have
been fixed, using the new status value.
It has been a long-standing issue that notmuch_database_open doesn't
return any indication of why it failed. This patch changes its
prototype to return a notmuch_status_t and set an out-argument to the
database itself, like other functions that return both a status and an
object.
In the interest of atomicity, this also updates every use in the CLI
so that notmuch still compiles. Since this patch does not update the
bindings, the Python bindings test fails.
Formerly notmuch_database_close closed the xapian database and
destroyed the talloc structure associated with the notmuch database
object. Split notmuch_database_close into notmuch_database_close and
notmuch_database_destroy.
This makes it possible for long running programs to close the xapian
database and thus release the lock associated with it without
destroying the data structures obtained from it.
This also makes the api more consistent since every other data
structure has a destructor function.
The comments in notmuch.h are a courtesy of Austin Clements.
Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>
Formerly it was possible for *message_ret to be left
uninitialized. The documentation however clearly states that "[o]n any
failure or when the message is not found, this function initializes
'*message' to NULL".
Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>
Formerly the xapian database object was deleted and closed in its
destructor once the object was garbage collected. Explicitly call
close() so that the database and the associated lock is released
immediately.
The comment is a courtesy of Austin Clements.
Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>
Previously opening a notmuch database in read write mode that has been
locked resulted in the notmuch_database_open function executing
notmuch_database_close as a cleanup function. notmuch_database_close
failed to check whether the xapian database has in fact been created.
Add a check whether the xapian database object has actually been
created before trying to call its flush method.
Signed-off-by: Justus Winter <4winter@informatik.uni-hamburg.de>
Previously, we manually "free"d various pointers in
notmuch_database_open. Use a local talloc context instead to simplify
cleanup and eliminate various NULL pointer initializations and
conditionals.
In the error-handling paths of notmuch_database_open, we call
notmuch_database_close, which "delete"s several objects referenced by
the notmuch_database_t object. However, some of these pointers may be
uninitialized, resulting in undefined behavior. Hence, allocate the
notmuch_database_t with talloc_zero to make sure these pointers are
NULL so that "delete"ing them is harmless.
As reported in
id:"CAEbOPGyuHnz4BPtDutnTPUHcP3eYcRCRkXhYoJR43RUMw671+g@mail.gmail.com"
sometimes gmime tries to access a NULL pointer, e.g. g_mime_iconv_open()
tries to access iconv_cache that is NULL if g_mime_init() is not called.
This causes notmuch to segfault when calling gmime functions.
Calling g_mime_init() initializes iconv_cache and others variables needed
by gmime, making sure they are initialized when notmuch calls gmime
functions.
Test marked fix by db.
Commit 567bcbc2 introduced two new values for each message (content of the
"From" and "Subject" headers), but the comments about the database schema had
not been updated accordingly.
This is a rebase and cleanup of Istvan Marko's patch from
id:m3pqnj2j7a.fsf@zsu.kismala.com
Search retrieves these headers for every message in the search
results. Previously, this required opening and parsing every message
file. Storing them directly in the database significantly reduces IO
and computation, speeding up search by between 50% and 10X.
Taking full advantage of this requires a database rebuild, but it will
fall back to the old behavior for messages that do not have headers
stored in the database.
Apparently the method was renamed in Xapian 1.1.0 but the old method
name will stay around for a while. It seems better to stick with the
old name to make notmuch compile with older versions of Xapian, at
least for now.
We keep the lib/xutil.c version. As a consequence, also factor out
_internal_error and associated macros. It might be overkill to make a
new file error_util.c for this, but _internal_error does not really
belong in database.cc.
Previously, the functions notmuch_database_find_message() and
notmuch_database_find_message_by_filename() functions did not properly
report error condition to the library user.
For more information, read the thread on the notmuch mailing list
starting with my mail "id:871uv2unfd.fsf@gmail.com"
Make these functions accept a pointer to 'notmuch_message_t' as argument
and return notmuch_status_t which may be used to check for any error
condition.
restore: Modify for the new notmuch_database_find_message()
new: Modify for the new notmuch_database_find_message_by_filename()
Adding a message may involve changes to multiple database documents,
and thus needs to be done in a transaction. This makes add_message
(and, I think, the whole library) atomicity-safe: library callers only
needs to use atomic sections if they needs atomicity across multiple
library calls.
notmuch_database_find_message_by_filename is mostly stolen from
notmuch_database_remove_message, so this patch also vastly simplfies
the latter using the former.
This API is also useful in its own right and will be used in a later
patch for eager maildir flag synchronization.
Previously, notmuch_database_remove_message would remove the message
file name, sync the change to the message document, re-find the
message document, and then delete it if there were no more file names.
An interruption after sync'ing would result in a file-name-less,
permanently un-removable zombie message that would produce errors and
odd results in searches. We could wrap this in an atomic section, but
it's much simpler to eliminate the round-about approach and just
delete the message document instead of sync'ing it if we removed the
last filename.
notmuch_database_t now keeps a nesting count and we only start a
transaction or commit for the outermost atomic section.
Introduces a new error, NOTMUCH_STATUS_UNBALANCED_ATOMIC.
