lib: replace some uses of Query::MatchAll with a thread-safe alternative

2023-03-31T11:11:39Z

This replaces two instances of Xapian::Query::MatchAll with the equivalent but thread-safe alternative Xapian::Query(std::string()). Xapian::Query::MatchAll maintains an internal pointer to a refcounted Xapian::Internal::QueryTerm. None of this is thread-safe but that wouldn't be an issue if Xapian::Query::MatchAll wasn't static. Because it's static, the refcounting goes awry when Notmuch is called from multiple threads. This is actually documented by Xapian: https://github.com/xapian/xapian/blob/4715de3a9fcee741587439dc3cc1d2ff01ffeaf2/xapian-core/include/xapian/query.h#L65 While static, Xapian::Query::MatchNothing is safe because it doesn't maintain an internal object and as such, doesn't use references. Two best-effort tests making use of TSan were added to showcase the issue (I couldn't figure out a way to deterministically reproduce it without making an unmaintainable mess). First, when two databases are created in parallel, a query that uses Xapian::Query::MatchAll is made (lib/query.cc), resulting in the following backtrace on a segfault: #0 0x00007ffff76822af in Xapian::Query::get_terms_begin (this=0x7fffe80137f0) at api/query.cc:141 #1 0x00007ffff7f933f5 in _notmuch_query_cache_terms (query=0x7fffe80137c0) at lib/query.cc:176 #2 0x00007ffff7f93784 in _notmuch_query_ensure_parsed_xapian (query=0x7fffe80137c0) at lib/query.cc:225 #3 0x00007ffff7f9381a in _notmuch_query_ensure_parsed (query=0x7fffe80137c0) at lib/query.cc:260 #4 0x00007ffff7f93bfe in _notmuch_query_search_documents (query=0x7fffe80137c0, type=0x7ffff7fa9b1e "mail", out=0x7ffff666da18) at lib/query.cc:361 #5 0x00007ffff7f93ba4 in notmuch_query_search_messages (query=0x7fffe80137c0, out=0x7ffff666da18) at lib/query.cc:349 #6 0x00007ffff7f83d98 in notmuch_database_upgrade (notmuch=0x7fffe8000bd0, progress_notify=0x0, closure=0x0) at lib/database.cc:934 #7 0x00007ffff7fa110f in notmuch_database_create_with_config (database_path=0x7ffff666dcb0 "/tmp/notmuch.MZ2AGr", config_path=0x7ffff7faab3c "", profile=0x0, database=0x0, status_string=0x7ffff666dc90) at lib/open.cc:754 #8 0x00007ffff7fa0d6f in notmuch_database_create_verbose (path=0x7ffff666dcb0 "/tmp/notmuch.MZ2AGr", database=0x0, status_string=0x7ffff666dc90) at lib/open.cc:653 #9 0x00007ffff7fa0ceb in notmuch_database_create (path=0x7ffff666dcb0 "/tmp/notmuch.MZ2AGr", database=0x0) at lib/open.cc:637 ... Second, some queries would make use of Xapian::Query::MatchAll (lib/regexp-fields.cc), resulting in the following backtrace on a segfault: #0 0x00007f629828b690 in Xapian::Internal::QueryBranch::gather_terms (this=0x7f628800def0, void_terms=0x7f629726d5a0) at api/queryinternal.cc:1245 #1 0x00007f629828c260 in Xapian::Internal::QueryScaleWeight::gather_terms (this=0x7f628800df70, void_terms=0x7f629726d5a0) at api/queryinternal.cc:1434 #2 0x00007f629828b69f in Xapian::Internal::QueryBranch::gather_terms (this=0x7f628800dd90, void_terms=0x7f629726d5a0) at api/queryinternal.cc:1245 #3 0x00007f6298282571 in Xapian::Query::get_unique_terms_begin (this=0x7f628800dcd8) at api/query.cc:166 #4 0x00007f629841a59b in Xapian::Weight::Internal::accumulate_stats (this=0x7f628800dca0, subdb=..., rset=...) at weight/weightinternal.cc:86 #5 0x00007f62983c15ba in LocalSubMatch::prepare_match (this=0x7f628800df20, nowait=true, total_stats=...) at matcher/localsubmatch.cc:172 #6 0x00007f62983c8fcc in prepare_sub_matches (leaves=std::vector of length 1, capacity 1 = {...}, stats=...) at matcher/multimatch.cc:237 #7 0x00007f62983c98a3 in MultiMatch::MultiMatch (this=0x7f629726d9a0, db_=..., query_=..., qlen=3, omrset=0x0, collapse_max_=0, collapse_key_=4294967295, percent_cutoff_=0, weight_cutoff_=0, order_=Xapian::Enquire::ASCENDING, sort_key_=0, sort_by_=Xapian::Enquire::Internal::VAL, sort_value_forward_=true, time_limit_=0, stats=..., weight_=0x7f6288008d50, matchspies_=std::vector of length 0, capacity 0, have_sorter=false, have_mdecider=false) at matcher/multimatch.cc:353 #8 0x00007f629826fcba in Xapian::Enquire::Internal::get_mset (this=0x7f628800e0b0, first=0, maxitems=0, check_at_least=0, rset=0x0, mdecider=0x0) at api/omenquire.cc:569 #9 0x00007f629827181c in Xapian::Enquire::get_mset (this=0x7f629726db80, first=0, maxitems=0, check_at_least=0, rset=0x0, mdecider=0x0) at api/omenquire.cc:937 #10 0x00007f6298be529a in _notmuch_query_search_documents (query=0x7f6288009750, type=0x7f6298bfaafe "mail", out=0x7f629726dcc0) at lib/query.cc:447 #11 0x00007f6298be4ae8 in notmuch_query_search_messages (query=0x7f6288009750, out=0x7f629726dcc0) at lib/query.cc:349 ... Printing Xapian::Query::MatchAll->internal.px->_refs in these circumstances can help quickly identifying this scenario. This is motivated by some test frameworks (like Rust's Cargo) that runs unit tests in parallel and would easily encounter this issue, unless client code gates every call to Notmuch behind a lock. This is what can be expected from the tests when they fail: == stderr == +================== +WARNING: ThreadSanitizer: data race (pid=207931) + Read of size 1 at 0x7b10000001a0 by thread T2: + #0 memcpy (libtsan.so.2+0x62506) + #1 void std::__cxx11::basic_string, std::allocator >::_M_construct(char*, char*, std::forward_iterator_tag) [clone .isra.0] (libxapian.so.30+0x872b3) + + Previous write of size 8 at 0x7b10000001a0 by thread T1: + #0 operator new(unsigned long) (libtsan.so.2+0x8ba83) + #1 Xapian::Query::Query(std::__cxx11::basic_string, std::allocator > const&, unsigned int, unsigned int) (libxapian.so.30+0x855cd) ...

lib: do not phrase parse prefixed bracketed subexpressions

2022-03-19T10:27:29Z

Since Xapian does not preserve quotes when passing the subquery to a field processor, we have to make a guess as to what the user intended. Here the added assumption is that a string surrounded by parens is not intended to be a phrase.

lib: drop trailing slash for path and folder searches (infix)

2022-01-27T11:48:27Z

This resolves an old bug reported by David Edmondson in 2014. The fix is only needed for the "boolean" case, as probabilistic / phrase searching already ignores punctuation. This fix is only for the infix (xapian provided) query parser. [1]: id:cunoasuolcv.fsf@gargravarr.hh.sledj.net

lib: factor out query construction from regexp

2021-09-05T00:07:19Z

This will allow re-use of this code outside of the Xapian query parser.

build: drop support for xapian versions less than 1.4

2020-04-24T00:28:45Z

Xapian 1.4 is over 3 years old now (1.4.0 released 2016-06-24), and 1.2 has been deprecated in Notmuch version 0.27 (2018-06-13). Xapian 1.4 supports compaction, field processors and retry locking; conditionals checking compaction and field processors were removed but user may want to disable retry locking at configure time so it is kept.

lib: run uncrustify

2019-06-14T10:41:27Z

This is the result of running $ uncrustify --replace --config ../devel/uncrustify.cfg *.c *.h *.cc in the lib directory

lib: use phrase search for anything not ending in '*'

2019-03-28T17:34:37Z

Anything that does not look like a wildcard should be safe to quote. This should fix the problem searching for xapian keywords.

Prepend regerror() messages with "regexp error: "

2019-03-12T01:24:55Z

The exact error messages returned by regerror() aren't standardized; relying on them isn't portable. Thus, add a a prefix to make clear that the subsequent message is a regexp parsing error, and only look for this prefix in the test suite, ignoring the rest of the message.

lib: Add regexp expansion for for tags and paths

2017-05-09T10:44:29Z

From a UI perspective this looks similar to what was already provided for from, subject, and mid, but the implementation is quite different. It uses the database's list of terms to construct a term based query equivalent to the passed regular expression.

lib: Add regexp searching for mid: prefix

2017-05-09T10:44:15Z

The bulk of the change is passing in the field options to the regexp field processor, so that we can properly handle the fallback (non-regexp case).

notmuch/lib/regexp-fields.cc, branch master