From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from localhost (localhost [127.0.0.1]) by olra.theworths.org (Postfix) with ESMTP id 9402D431FDA for ; Sun, 12 Oct 2014 23:20:39 -0700 (PDT) X-Virus-Scanned: Debian amavisd-new at olra.theworths.org X-Spam-Flag: NO X-Spam-Score: -2.3 X-Spam-Level: X-Spam-Status: No, score=-2.3 tagged_above=-999 required=5 tests=[RCVD_IN_DNSWL_MED=-2.3] autolearn=disabled Received: from olra.theworths.org ([127.0.0.1]) by localhost (olra.theworths.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id vJiu2E2zbxAs for ; Sun, 12 Oct 2014 23:20:33 -0700 (PDT) Received: from dmz-mailsec-scanner-1.mit.edu (dmz-mailsec-scanner-1.mit.edu [18.9.25.12]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by olra.theworths.org (Postfix) with ESMTPS id 1ADED431FBF for ; Sun, 12 Oct 2014 23:20:20 -0700 (PDT) X-AuditID: 1209190c-f795e6d000006c66-f2-543b6f237023 Received: from mailhub-auth-4.mit.edu ( [18.7.62.39]) (using TLS with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by dmz-mailsec-scanner-1.mit.edu (Symantec Messaging Gateway) with SMTP id 56.75.27750.32F6B345; Mon, 13 Oct 2014 02:20:19 -0400 (EDT) Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) by mailhub-auth-4.mit.edu (8.13.8/8.9.2) with ESMTP id s9D6K8FI019182; Mon, 13 Oct 2014 02:20:08 -0400 Received: from drake.dyndns.org ([73.162.189.21]) (authenticated bits=0) (User authenticated as amdragon@ATHENA.MIT.EDU) by outgoing.mit.edu (8.13.8/8.12.4) with ESMTP id s9D6K5iL031977 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT); Mon, 13 Oct 2014 02:20:07 -0400 Received: from amthrax by drake.dyndns.org with local (Exim 4.84) (envelope-from ) id 1XdYzF-0000UC-9U; Mon, 13 Oct 2014 02:20:05 -0400 From: Austin Clements To: notmuch@notmuchmail.org Subject: [WIP PATCH 2/4] lib: Add per-message last modification tracking Date: Mon, 13 Oct 2014 02:20:01 -0400 Message-Id: <1413181203-1676-3-git-send-email-aclements@csail.mit.edu> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1413181203-1676-1-git-send-email-aclements@csail.mit.edu> References: <1413181203-1676-1-git-send-email-aclements@csail.mit.edu> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrIIsWRmVeSWpSXmKPExsUixG6nrqucbx1iMHOFuMX1mzOZHRg9nq26 xRzAGMVlk5Kak1mWWqRvl8CVcW9aRMHv0Ipf3/YxNzC+d+li5OSQEDCR6Js0mRXCFpO4cG89 WxcjF4eQwGwmiTvNX6CcjYwS3WeeMEM4y5kkPi2/wwzSIiSwhFFiwnpPEJtNQF9ixdpJYKNE BKQldt6dDWRzcDALqEn86VIBCQsLeEi8+7wVrJVFQFVi7/8WdhCbV8BN4te5X+wQV8hJbNj9 nxHE5hRwl7g48SzUKjeJY23XWCYw8i9gZFjFKJuSW6Wbm5iZU5yarFucnJiXl1qka6iXm1mi l5pSuokRFDKckjw7GN8cVDrEKMDBqMTDa/HHKkSINbGsuDL3EKMkB5OSKG9AmnWIEF9Sfkpl RmJxRnxRaU5q8SFGCQ5mJRHetzZAOd6UxMqq1KJ8mJQ0B4uSOO+mH3whQgLpiSWp2ampBalF MFkZDg4lCd53uUCNgkWp6akVaZk5JQhpJg5OkOE8QMNbckCGFxck5hZnpkPkTzEqSonzfgdp FgBJZJTmwfXCYvoVozjQK8K8hiBVPMB0ANf9CmgwE9Dgo13mIINLEhFSUg2MfF9C2Wt5M1rd T+6fNCV1mpKiInvAjHcdPLmbnndOcZZ0SvmTOcfS6lJZ/XWuuPvhLS1TJiox/PkZLidx7O0P X+Y/9o0uz6ZlHX1b4PJ4fvsdvaA5m747izaqfXnRyC9ilJl+YsH63dIPtIINVgZfs659+MtR 6NBW8clMv0IaHn59aP9qR1i7EktxRqKhFnNRcSIA1lCFZcQCAAA= X-BeenThere: notmuch@notmuchmail.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: "Use and development of the notmuch mail system." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Oct 2014 06:20:40 -0000 From: Austin Clements 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. --- lib/database-private.h | 15 ++++++++++++++- lib/database.cc | 49 +++++++++++++++++++++++++++++++++++++++++++++++-- lib/message.cc | 22 ++++++++++++++++++++++ lib/notmuch-private.h | 10 +++++++++- 4 files changed, 92 insertions(+), 4 deletions(-) diff --git a/lib/database-private.h b/lib/database-private.h index 15e03cc..465065d 100644 --- a/lib/database-private.h +++ b/lib/database-private.h @@ -92,6 +92,12 @@ enum _notmuch_features { * * Introduced: version 3. */ NOTMUCH_FEATURE_GHOSTS = 1 << 4, + + /* If set, messages store the revision number of the last + * modification in NOTMUCH_VALUE_LAST_MOD. + * + * Introduced: version 3. */ + NOTMUCH_FEATURE_LAST_MOD = 1 << 5, }; /* In C++, a named enum is its own type, so define bitwise operators @@ -137,6 +143,8 @@ struct _notmuch_database { notmuch_database_mode_t mode; int atomic_nesting; + /* TRUE if changes have been made in this atomic section */ + notmuch_bool_t atomic_dirty; Xapian::Database *xapian_db; /* Bit mask of features used by this database. This is a @@ -145,6 +153,10 @@ struct _notmuch_database { unsigned int last_doc_id; uint64_t last_thread_id; + /* Highest committed revision number. Modifications are recorded + * under a higher revision number, which can be generated with + * notmuch_database_new_revision. */ + unsigned long revision; Xapian::QueryParser *query_parser; Xapian::TermGenerator *term_gen; @@ -166,7 +178,8 @@ struct _notmuch_database { * databases will have it). */ #define NOTMUCH_FEATURES_CURRENT \ (NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_DIRECTORY_DOCS | \ - NOTMUCH_FEATURE_BOOL_FOLDER | NOTMUCH_FEATURE_GHOSTS) + NOTMUCH_FEATURE_BOOL_FOLDER | NOTMUCH_FEATURE_GHOSTS | \ + NOTMUCH_FEATURE_LAST_MOD) /* Return the list of terms from the given iterator matching a prefix. * The prefix will be stripped from the strings in the returned list. diff --git a/lib/database.cc b/lib/database.cc index 6e51a72..45d32ab 100644 --- a/lib/database.cc +++ b/lib/database.cc @@ -101,6 +101,9 @@ typedef struct { * * SUBJECT: The value of the "Subject" header * + * LAST_MOD: The revision number as of the last tag or + * filename change. + * * In addition, terms from the content of the message are added with * "from", "to", "attachment", and "subject" prefixes for use by the * user in searching. Similarly, terms from the path of the mail @@ -304,6 +307,8 @@ static const struct { "exact folder:/path: search", "rw" }, { NOTMUCH_FEATURE_GHOSTS, "mail documents for missing messages", "w"}, + { NOTMUCH_FEATURE_LAST_MOD, + "modification tracking", "w"}, }; const char * @@ -678,6 +683,23 @@ _notmuch_database_ensure_writable (notmuch_database_t *notmuch) return NOTMUCH_STATUS_SUCCESS; } +/* Allocate a revision number for the next change. */ +unsigned long +_notmuch_database_new_revision (notmuch_database_t *notmuch) +{ + unsigned long new_revision = notmuch->revision + 1; + + /* If we're in an atomic section, hold off on updating the + * committed revision number until we commit the atomic section. + */ + if (notmuch->atomic_nesting) + notmuch->atomic_dirty = TRUE; + else + notmuch->revision = new_revision; + + return new_revision; +} + /* Parse a database features string from the given database version. * Returns the feature bit set. * @@ -817,6 +839,7 @@ notmuch_database_open (const char *path, notmuch->atomic_nesting = 0; try { string last_thread_id; + string last_mod; if (mode == NOTMUCH_DATABASE_MODE_READ_WRITE) { notmuch->xapian_db = new Xapian::WritableDatabase (xapian_path, @@ -875,6 +898,14 @@ notmuch_database_open (const char *path, INTERNAL_ERROR ("Malformed database last_thread_id: %s", str); } + /* Get current highest revision number. */ + last_mod = notmuch->xapian_db->get_value_upper_bound ( + NOTMUCH_VALUE_LAST_MOD); + if (last_mod.empty ()) + notmuch->revision = 0; + else + notmuch->revision = Xapian::sortable_unserialise (last_mod); + notmuch->query_parser = new Xapian::QueryParser; notmuch->term_gen = new Xapian::TermGenerator; notmuch->term_gen->set_stemmer (Xapian::Stem ("english")); @@ -1266,7 +1297,8 @@ notmuch_database_upgrade (notmuch_database_t *notmuch, /* Figure out how much total work we need to do. */ if (new_features & - (NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_BOOL_FOLDER)) { + (NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_BOOL_FOLDER | + NOTMUCH_FEATURE_LAST_MOD)) { notmuch_query_t *query = notmuch_query_create (notmuch, ""); total += notmuch_query_count_messages (query); notmuch_query_destroy (query); @@ -1293,7 +1325,8 @@ notmuch_database_upgrade (notmuch_database_t *notmuch, /* Perform per-message upgrades. */ if (new_features & - (NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_BOOL_FOLDER)) { + (NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_BOOL_FOLDER | + NOTMUCH_FEATURE_LAST_MOD)) { notmuch_query_t *query = notmuch_query_create (notmuch, ""); notmuch_messages_t *messages; notmuch_message_t *message; @@ -1330,6 +1363,13 @@ notmuch_database_upgrade (notmuch_database_t *notmuch, if (new_features & NOTMUCH_FEATURE_BOOL_FOLDER) _notmuch_message_upgrade_folder (message); + /* Prior to NOTMUCH_FEATURE_LAST_MOD, messages did not + * track modification revisions. Give all messages a + * revision of 1. + */ + if (new_features & NOTMUCH_FEATURE_LAST_MOD) + _notmuch_message_upgrade_last_mod (message); + _notmuch_message_sync (message); notmuch_message_destroy (message); @@ -1512,6 +1552,11 @@ notmuch_database_end_atomic (notmuch_database_t *notmuch) return NOTMUCH_STATUS_XAPIAN_EXCEPTION; } + if (notmuch->atomic_dirty) { + ++notmuch->revision; + notmuch->atomic_dirty = FALSE; + } + DONE: notmuch->atomic_nesting--; return NOTMUCH_STATUS_SUCCESS; diff --git a/lib/message.cc b/lib/message.cc index cf2fd7c..767f0ab 100644 --- a/lib/message.cc +++ b/lib/message.cc @@ -996,6 +996,16 @@ _notmuch_message_set_header_values (notmuch_message_t *message, message->modified = TRUE; } +/* Upgrade a message to support NOTMUCH_FEATURE_LAST_MOD. The caller + * must call _notmuch_message_sync. */ +void +_notmuch_message_upgrade_last_mod (notmuch_message_t *message) +{ + /* _notmuch_message_sync will update the last modification + * revision; we just have to ask it to. */ + message->modified = TRUE; +} + /* Synchronize changes made to message->doc out into the database. */ void _notmuch_message_sync (notmuch_message_t *message) @@ -1008,6 +1018,18 @@ _notmuch_message_sync (notmuch_message_t *message) if (! message->modified) return; + /* Update the last modification of this message. */ + if (message->notmuch->features & NOTMUCH_FEATURE_LAST_MOD) + /* sortable_serialise gives a reasonably compact encoding, + * which directly translates to reduced IO when scanning the + * value stream. Since it's built for doubles, we only get 53 + * effective bits, but that's still enough for the database to + * last a few centuries at 1 million revisions per second. */ + message->doc.add_value (NOTMUCH_VALUE_LAST_MOD, + Xapian::sortable_serialise ( + _notmuch_database_new_revision ( + message->notmuch))); + db = static_cast (message->notmuch->xapian_db); db->replace_document (message->doc_id, message->doc); message->modified = FALSE; diff --git a/lib/notmuch-private.h b/lib/notmuch-private.h index 2f43c1d..cb85738 100644 --- a/lib/notmuch-private.h +++ b/lib/notmuch-private.h @@ -108,7 +108,8 @@ typedef enum { NOTMUCH_VALUE_TIMESTAMP = 0, NOTMUCH_VALUE_MESSAGE_ID, NOTMUCH_VALUE_FROM, - NOTMUCH_VALUE_SUBJECT + NOTMUCH_VALUE_SUBJECT, + NOTMUCH_VALUE_LAST_MOD, } notmuch_value_t; /* Xapian (with flint backend) complains if we provide a term longer @@ -191,6 +192,9 @@ _notmuch_message_id_compressed (void *ctx, const char *message_id); notmuch_status_t _notmuch_database_ensure_writable (notmuch_database_t *notmuch); +unsigned long +_notmuch_database_new_revision (notmuch_database_t *notmuch); + const char * _notmuch_database_relative_path (notmuch_database_t *notmuch, const char *path); @@ -302,6 +306,10 @@ _notmuch_message_set_header_values (notmuch_message_t *message, const char *date, const char *from, const char *subject); + +void +_notmuch_message_upgrade_last_mod (notmuch_message_t *message); + void _notmuch_message_sync (notmuch_message_t *message); -- 2.1.0