This operation is relatively inexpensive, as the needed metadata is
already computed by our lazy metadata fetching. The goal is to support
better UI for messages with multipile files.
Commit d5523ead90 ("Mark some structures in the library interface
with visibility=default attribute.") fixed some mixed visibility
issues with structs. With the symbol default visibility reversed, this
is no longer a problem.
The index(3) function has been deprecated in POSIX since 2001 and
removed in 2008, and most code in notmuch already calls strchr(3).
This fixes a compilation error on Android whose libc does not have
index(3).
This function was deprecated in notmuch 0.21. We re-use the name for
a status returning version, and deprecate the _st name. One or two
remaining uses of the (removed) non-status returning version fixed at
the same time
The object where pointer to `data` was received was deleted before
it was used in _notmuch_string_list_append().
Relevant Coverity messages follow:
3: extract
Assigning: data = std::__cxx11::string(message->doc.()).c_str(),
which extracts wrapped state from temporary of type std::__cxx11::string.
4: dtor_free
The internal representation of temporary of type std::__cxx11::string
is freed by its destructor.
5: use after free:
Wrapper object use after free (WRAPPER_ESCAPE)
Using internal representation of destroyed object local data.
For reasons not completely understood at this time, gmime (as of
2.6.22) is returning a date before 1900 on bad date input. Since this
confuses some other software, we clamp such dates to 0,
i.e. 1970-01-01.
The retries are hardcoded to a small number, and error handling aborts
than propagating errors from notmuch_database_reopen. These are both
somewhat justified by the assumption that most things that can go
wrong in Xapian::Database::reopen are rare and fatal. Here's the brief
discussion with Xapian upstream:
24-02-2017 08:12:57 < bremner> any intuition about how likely
Xapian::Database::reopen is to fail? I'm catching a
DatabaseModifiedError somewhere where handling any further errors is
tricky, and wondering about treating a failed reopen as as "the
impossible happened, stopping"
24-02-2017 16:22:34 < olly> bremner: there should not be much scope for
failure - stuff like out of memory or disk errors, which are probably a
good enough excuse to stop
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
To fully complete the ghost-on-removal-when-shared-thread-exists
proposal, we need to clear all ghost messages when the last active
message is removed from a thread.
Amended by db: Remove the last test of T530, as it no longer makes sense
if we are garbage collecting ghost messages.
There is no need to add a ghost message upon deletion if there are no
other active messages in the thread.
Also, if the message being deleted was a ghost already, we can just go
ahead and delete it.
implement ghost-on-removal, the solution to T590-thread-breakage.sh
that just adds a ghost message after removing each message.
It leaks information about whether we've ever seen a given message id,
but it's a fairly simple implementation.
Note that _resolve_message_id_to_thread_id already introduces new
message_ids to the database, so i think just searching for a given
message ID may introduce the same metadata leakage.
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.
Previously, we updated the database copy of a message on every call to
_notmuch_message_sync, even if nothing had changed. In particular,
this always happens on a thaw, so a freeze/thaw pair with no
modifications between still caused a database update.
We only modify message documents in a handful of places, so keep track
of whether the document has been modified and only sync it when
necessary. This will be particularly important when we add message
revision tracking.
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.
Tamas Szakaly points out [1] that the bug fixed in 51b073c still
exists in at least one place. This change follows the suggestion of
[2] and creates a block scope temporary std::string to avoid the rules
of iterators temporaries.
[1]: id:20141226113755.GA64154@pamparam
[2]: id:20141226230655.GA41992@pamparam
This updates the message abstraction to support ghost messages: it
adds a message flag that distinguishes regular messages from ghost
messages, and an internal function for initializing a newly created
(blank) message as a ghost message.
In the interest of robustness, avoid undefined behavior of
sortable_unserialise if the date value is missing. This shouldn't
happen now, but ghost messages will have blank date values.
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.
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.
Commit 567bcbc2 introduced support for storing various headers in
document values. However, doing so in a backwards-compatible way
meant that genuinely empty header values could not be distinguished
from the old behavior of not storing the headers at all, so these
required parsing the original message.
Now that we have database features, new databases can declare that all
messages have header values, so if we have this feature flag, we can
use the stored header value even if it's the empty string.
This requires slight cleanup to notmuch_message_get_header, since the
code previously couldn't distinguish between empty headers and headers
that are never stored in the database (previously this distinction
didn't matter).
Previously, we invalidated stored message metadata in
_notmuch_message_add_term and _notmuch_message_remove_term, but not in
_notmuch_message_gen_terms. This doesn't currently result in any bugs
because of our limited uses of _notmuch_message_gen_terms, but it may
could cause trouble in the future.
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>
This adds a 100 termpos gap between all phrases indexed by
_notmuch_message_gen_terms. This fixes a bug where terms from the end
of one header and the beginning of another header could match together
in a single phrase and a separate bug where term positions of
un-prefixed terms overlapped.
This fix only affects newly indexed messages. Messages that are
already indexed won't benefit from this fix without re-indexing, but
the fix won't make things any worse for existing messages.
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.
Currently if a Xapian exception happens in notmuch_message_get_header,
the exception is not caught leading to crash. In
notmuch_message_get_date the exception is caught, but an internal error
is raised, again leading to crash.
This patch fixes the error handling by making both functions catch the
Xapian exceptions, print an error and return NULL or 0.
The 'notmuch->exception_reported' is also set, as is done elsewhere,
even if I don't really get the idea of that field.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@iki.fi>
notmuch_message_tags_to_maildir_flags() unconditionally moves messages from
maildir directory "new/" to maildir directory "cur/", which makes messages lose
their "new" status in the MUA. However some users want to keep this "new"
status after, for instance, an auto-tagging of new messages.
However, as Austin mentioned and according to the maildir specification,
messages living in "new/" are not allowed to have flags, even if mutt allows it
to happen. For this reason, this patch prevents moving messages from "new/" to
"cur/", only if no flags have to be changed. It's hopefully enough to satisfy
mutt (and maybe other MUAs showing the "new" status) users checking the "new"
status.
Changelog:
* v2: Fix bool type as well as NULL returned despite having no errors (Austin
Clements)
* v4: Tag the related test (contributed by Michal Sojka) as working
Signed-off-by: Louis Rilling <l.rilling@av7.net>
[Condition for keeping messages in new/ was extended to satisfy all
tests from the previous patch. -Michal Sojka]
[Added by David Bremner, to keep the tests passing at each commit]
update insert tests for new maildir synchronization rules
As of id:1355952747-27350-4-git-send-email-sojkam1@fel.cvut.cz
we are more conservative about moving messages from ./new to ./cur.
This updates the insert tests to match
Xapian::TermIterator::operator* returns std::string which is destroyed
as soon as (*i).c_str() finishes. The remembered pointer 'term' then
references invalid memory.
Signed-off-by: Vladimir Marek <vlmarek@volny.cz>
Previously, thread.cc built up a list of all messages, then
proceeded to tear it apart to transform it into a list of
top-level messages. Now we simply build a new list of top-level
messages.
This simplifies the interface to _notmuch_message_add_reply,
eliminates the pointer acrobatics from
_resolve_thread_relationships, and will enable us to do things
with the list of all messages in the following patches.
Previously, notmuch new only synchronized maildir flags to tags for
files with a maildir "info" part. Since messages in new/ don't have
an info part, notmuch would ignore them for flag-to-tag
synchronization.
This patch makes notmuch consider messages in new/ to be legitimate
maildir messages that simply have no maildir flags set. The most
visible effect of this is that such messages now automatically get the
unread tag.
Previously, we synchronized flags to tags for any message that looked
like it had maildir flags in its file name, regardless of whether it
was in a maildir-like directory structure. This was asymmetric with
tag-to-flag synchronization, which only applied to messages in
directories named new/ and cur/ (introduced by 95dd5fe5).
This change makes our interpretation stricter and addresses this
asymmetry by only synchronizing flags to tags for messages in
directories named new/ or cur/. It also prepares us to treat messages
in new/ as maildir messages, even though they lack maildir flags.
This way notmuch_message_maildir_flags_to_tags can call it. It makes
more sense for this to be just above all of the maildir
synchronization code rather than mixed in the middle.
Previously, if passed a filename with a directory that did not exist
in the database, _notmuch_message_remove_filename would needlessly
create that directory document. Fix it so that doesn't happen.
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.
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.
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()
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.
Previously, this function would synchronize the folder list even if
removing the file name failed. Now it returns immediately if removing
the file name fails.
Add removal of all ZXFOLDER terms to removal of all XFOLDER terms for
each message filename removal.
The existing filename-list reindexing will put all the needed terms
back in. Test search-folder-coherence now passes.
Signed-off-by:Mark Anderson <ma.skies@gmail.com>
Various typo fixes in comments within the source code.
Signed-off-by: Pieter Praet <pieter@praet.org>
Edited-by: Carl Worth <cworth@cworth.org> Restricted to just
source-code comments, (and fixed fix of "descriptios" to "descriptors"
rather than "descriptions").
As of gcc 4.6, there are new warnings from -Wattributes along the lines of:
warning: ‘_notmuch_messages’ declared with greater visibility
than the type of its field ‘_notmuch_messages::iterator’
[-Wattributes]
To squelch these, we decorate all such containing structs with
__attribute__((visibility("default"))). We take care to let only the
C++ compiler see this, (since the C compiler would otherwise warn
about ignored visibility attributes on types).
gcc (at least as of version 4.6.0) is kind enough to point these out to us,
(when given -Wunused-but-set-variable explicitly or implicitly via -Wunused
or -Wall).
One of these cases was a legitimately unused variable. Two were simply
variables (named ignored) we were assigning only to squelch a warning about
unused function return values. I don't seem to be getting those warnings
even without setting the ignored variable. And the gcc docs. say that the
correct way to squelch that warning is with a cast to (void) anyway.
Now each caller of notmuch_message_get_tags only gets a new iterator,
instead of a whole new list. In principle this could cause problems
with iterating while modifying tags, but through the magic of talloc
references, we keep the old tag list alive even after the cache in the
message object is invalidated.
This reduces my index search from the 3.102 seconds before the unified
metadata pass to 1.811 seconds (1.7X faster). Combined with the
thread search optimization in b3caef1f06,
that makes this query 2.5X faster than when I started.
Even if the caller never uses the file names, there is little cost to
simply fetching the file name terms. However, retrieving the full
paths requires additional database work, so the expansion from terms
to full paths is performed lazily.
This also simplifies clearing the filename cache, since that's now
handled by the generic metadata cache code.
This further reduces my inbox search from 3.102 seconds before the
unified metadata pass to 2.206 seconds (1.4X faster).
Replace _notmuch_convert_tags with this and simplify
_create_filenames_for_terms_with_prefix. This will also come in handy
shortly to get the message file name list.
This replaces the guts of the filename list and tag list, making those
interfaces simple iterators over the generic string list. The
directory, message filename, and tags-related code now build generic
string lists and then wraps them in specific iterators. The real wins
come in later patches, when we use these for even more generic
functionality.
As a nice side-effect, this also eliminates the annoying dependency on
GList in the tag list.
This performs a single pass over a message's term list to fetch the
thread ID, message ID, and reply-to, rather than requiring a pass for
each. Xapian decompresses the term list anew for each iteration, so
this reduces the amount of time spent decompressing message metadata.
This reduces my inbox search from 3.102 seconds to 2.555 seconds (1.2X
faster).
A new "folder:" prefix in the query string can now be used to match
the directories in which mail files are stored.
The addition of this feature causes the recently added
search-by-folder tests to now pass.
This reduces thread search's 1+2t Xapian queries (where t is the
number of matched threads) to 1+t queries and constructs exactly one
notmuch_message_t for each message instead of 2 to 3.
notmuch_query_search_threads eagerly fetches the docids of all
messages matching the user query instead of lazily constructing
message objects and fetching thread ID's from term lists.
_notmuch_thread_create takes a seed docid and the set of all matched
docids and uses a single Xapian query to expand this docid to its
containing thread, using the matched docid set to determine which
messages in the thread match the user query instead of using a second
Xapian query.
This reduces the amount of time required to load my inbox from 4.523
seconds to 3.025 seconds (1.5X faster).
This is to prevent notmuch from destroying any information the user
has encoded as flags in the maildir filename. Tests are also added to
the test suite to verify the documented behavior.
Some people use notmuch with non-maildir files, (for example, email
messages in MH format, or else cool things like using sluk[*] to suck
down feeds into a format that notmuch can index).
To better support uses like that, don't do any renaming for files that
are not in a directory named either "new" or "cur".
[*] https://github.com/krl/sluk/
It is totally legitimate for a non-maildir directory to be named "new"
(and not have a directory next to it named "cur"). To support this
case at least, be silent about any rename failure.
If a filename has no maildir info at all, (that is, it does not
contain the sequence ":2,"), we consider this distinct from a filename
with an empty maildir info, (the ":2," separator is present, but no
flags characters follow).
Specifically, we regard a missing info field as providing no
information, so tags will remain unchanged. On the other hand, an info
field that is present but has no flags set will cause various tags to
be cleared, (or in the case of "unread", added).
This fixes the "remove info" case of the maildir-sync tests in the
test suite.
We have tests to ensure that when the notmuch library renames a file
that that rename takes place immediately in the database, (without
requiring something like "notmuch new" to notice the change).
This was working when the code was first added, but recently broke in
the reworking of the maildir-synchronization interface since the
tags_to_maildir_flags function can no longer assume that it is being
called as part of _notmuch_message_sync.
Fortunately, the fix is as simple as adding an explicit call to
_notmuch_message_sync.
As documented, this function now iterates over all filenames for the
message, computing a logical OR of the flags set on the filenames,
then uses the final result to set tags on the message.
This change fixes 3 of the 10 maildir-sync tests that have been
failing since being added.
This augments the existing notmuch_message_get_filename by allowing
the caller access to all filenames in the case of multiple files for a
single message.
To support this, we split the iterator (notmuch_filenames_t) away from
the list storage (notmuch_filename_list_t) where previously these were
a single object (notmuch_filenames_t). Then, whenever the user asks
for a file or filename, the message object lazily creates a complete
notmuch_filename_list_t and then:
For notmuch_message_get_filename, returns the first filename
in the list.
For notmuch_message_get_filenames, creates and returns a new
iterator for the filename list.
This rather ugly hack was recently obviated by the removal of the
notmuch_database_set_maildir_sync function. Now, clients must make
explicit calls to do any syncrhonization between maildir flags and
tags. So the library no longer needs to worry about doing inconsistent
synchronization while a message is only partially added.
Instead of having an API for setting a library-wide flag for
synchronization (notmuch_database_set_maildir_sync) we instead
implement maildir synchronization with two new library functions:
notmuch_message_maildir_flags_to_tags
and notmuch_message_tags_to_maildir_flags
These functions are nicely documented here, (though the implementation
does not quite match the documentation yet---as plainly evidenced by
the current results of the test suite).
Tags in a notmuch database affect all messages with the identical
message-ID. But maildir tags affect individual files. And since
multiple files can contain the identical message-ID, there is not a
one-to-one correspondence between messages affected by tags and flags.
This is particularly dangerous with the 'T' (== "trashed") maildir
flag and the corresponding "deleted" tag in the notmuch
database. Since these flags/tags are often used to trigger
irreversible deletion operations, the lack of one-to-one
correspondence can be potentially dangerous.
For example, consider the following sequence:
1. A third-party application is used to identify duplicate messages
in the mail store, and mark all-but-one of each duplicate with
the 'T' flag for subsequent deletion.
2. A "notmuch new" operation reads that 'T' flag, adding the
"deleted" flag to the corresponding messages within the notmuch
database.
3. A subsequent notmuch operation, (such as a "notmuch dump; notmuch
restore" cycle) synchronized the "deleted" tag back to the mail
store, applying the 'T' flag to all(!) filenames with duplicate
message IDs.
4. A third-party application reads the 'T' flags and irreversibly
deletes all mail messages which had any duplicates(!).
In order to avoid this scenario, we simply refuse to synchronize the
'T' flag with the "deleted" tag. Instead, applications can set 'T' and
act on it to delete files, or can set "deleted" and act on it to
delete files. But in either case the semantics are clear and there is
never dangerous propagation through the one-to-many mapping of notmuch
message objects to files.
This adds group [maildir] and key 'synchronize_flags' to the
configuration file. Its value enables (true) or diables (false) the
synchronization between notmuch tags and maildir flags. By default,
the synchronization is disabled.
This patch allows bi-directional synchronization between maildir
flags and certain tags. The flag-to-tag mapping is defined by flag2tag
array.
The synchronization works this way:
1) Whenever notmuch new is executed, the following happens:
o New messages are tagged with configured new_tags.
o For new or renamed messages with maildir info present in the file
name, the tags defined in flag2tag are either added or removed
depending on the flags from the file name.
2) Whenever notmuch tag (or notmuch restore) is executed, a new set of
flags based on the tags is constructed for every message and a new
file name is prepared based on the old file name but with the new
flags. If the flags differs and the old message was in 'new'
directory then this is replaced with 'cur' in the new file name. If
the new and old file names differ, the file is renamed and notmuch
database is updated accordingly.
The rename happens before the database is updated. In case of crash
between rename and database update, the next run of notmuch new
brings the database in sync with the mail store again.
Previously we were using Xapian's add_document to allocate document ID
values for notmuch_message_t objects. This had the drawback of adding
a partially constructed mail document to the database. If notmuch was
subsequently interrupted before fully populating this document, then
later runs would be quite confused when seeing the partial documents.
There are reports from the wild of people hitting internal errors of
the form "Message ... has no thread ID" for example, (which is
currently an unrecoverable error).
We fix this by manually allocating document IDs without adding
documents. With this change, we never call Xapian's add_document
method, but only replace_document with either the current document ID
of a message or a new one that we have allocated.
message->authors contains the author's name (as we want to print it)
get / set methods are declared in notmuch-private.h
Signed-off-by: Dirk Hohndel <hohndel@infradead.org>
We rename 'has_more' to 'valid' so that it can function whether
iterating in a forward or reverse direction. We also rename
'advance' to 'move_to_next' to setup parallel naming with
the proposed functions 'move_to_first', 'move_to_last', and
'move_to_previous'.
The sequential identifiers have the advantage of being guaranteed to
be unique (until we overflow a 64-bit unsigned integer), and also take
up half as much space in the "notmuch search" output (16 columns
rather than 32).
This change also has the side effect of fixing a bug where notmuch
could block on /dev/random at startup (waiting for some entropy to
appear). This bug was hit hard by the test suite, (which could easily
exhaust the available entropy on common systems---resulting in large
delays of the test suite).
The WDF is the "within-document frequency" value for a particular
term. It's intended to provide an indication of how frequent a term is
within a document, (for use in computing relevance). Xapian's term
generator already computes WDF values when we use that, (which we do
for indexing all mail content).
We don't use the term generator when adding single terms for things
that don't actually appear in the mail document, (such as tags, the
filename, etc.). In this case, the WDF value for these terms doesn't
matter much.
But Xapian's flint backend can be more efficient with changes to terms
that don't affect the document "length". So there's a performance
advantage for manipulating tags (with the flint backend) if the WDF of
these terms is 0.
The first phase copies data from the old format to the new format
without deleting anything. This allows an old notmuch to still use the
database if the upgrade process gets interrupted. The second phase
performs the deletion (after updating the database version number). If
the second phase is interrupted, there will be some unused data in the
database, but it shouldn't cause any actual harm.
The recent support for renames in the database is our first time
(since notmuch has had more than a single user) that we have a
database format change. To support smooth upgrades we now encode a
database format version number in the Xapian metadata.
Going forward notmuch will emit a warning if used to read from a
database with a newer version than it natively supports, and will
refuse to write to a database with a newer version.
The library also provides functions to query the database format
version:
notmuch_database_get_version
to ask if notmuch wants a newer version than that:
notmuch_database_needs_upgrade
and a function to actually perform that upgrade:
notmuch_database_upgrade
Previously, many checks were deep in the library just before a cast
operation. These have now been replaced with internal errors and new
checks have instead been added at the beginning of all top-levelentry
points requiring a read-write database.
The new checks now also use a single function for checking and
printing the error message. This will give us a convenient location to
extend the check, (such as based on database version as well).
When a notmuch database is upgraded to the new database format, (to
support file rename and deletion), any message documents corresponding
to deleted files will not currently be upgraded. This means that a
search matching these documents will find no filenames in the expected
place.
Go ahead and return the filename as originally stored, (rather than
aborting with an internal error), in this case.
