[WIP2 03/12] lib: API to retrieve database revision and UUID
David Bremner
david at tethera.net
Sun Apr 5 15:59:05 PDT 2015
From: Austin Clements <aclements at csail.mit.edu>
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).
---
lib/database-private.h | 1 +
lib/database.cc | 11 +++++++++++
lib/notmuch.h | 18 ++++++++++++++++++
test/T570-revision-tracking.sh | 37 +++++++++++++++++++++++++++++++++++++
4 files changed, 67 insertions(+)
create mode 100755 test/T570-revision-tracking.sh
diff --git a/lib/database-private.h b/lib/database-private.h
index 5c5a2bb..4e93257 100644
--- a/lib/database-private.h
+++ b/lib/database-private.h
@@ -170,6 +170,7 @@ struct _notmuch_database {
* under a higher revision number, which can be generated with
* notmuch_database_new_revision. */
unsigned long revision;
+ const char *uuid;
Xapian::QueryParser *query_parser;
Xapian::TermGenerator *term_gen;
diff --git a/lib/database.cc b/lib/database.cc
index 4378979..f88bdb3 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -978,6 +978,8 @@ notmuch_database_open_verbose (const char *path,
notmuch->revision = 0;
else
notmuch->revision = Xapian::sortable_unserialise (last_mod);
+ notmuch->uuid = talloc_strdup (
+ notmuch, notmuch->xapian_db->get_uuid ().c_str ());
notmuch->query_parser = new Xapian::QueryParser;
notmuch->term_gen = new Xapian::TermGenerator;
@@ -1651,6 +1653,15 @@ DONE:
return NOTMUCH_STATUS_SUCCESS;
}
+unsigned long
+notmuch_database_get_revision (notmuch_database_t *notmuch,
+ const char **uuid)
+{
+ if (uuid)
+ *uuid = notmuch->uuid;
+ return notmuch->revision;
+}
+
/* We allow the user to use arbitrarily long paths for directories. But
* we have a term-length limit. So if we exceed that, we'll use the
* SHA-1 of the path for the database term.
diff --git a/lib/notmuch.h b/lib/notmuch.h
index 20c4e01..b6be727 100644
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -461,6 +461,24 @@ notmuch_status_t
notmuch_database_end_atomic (notmuch_database_t *notmuch);
/**
+ * Return the committed database revision and UUID.
+ *
+ * The database revision number increases monotonically with each
+ * commit to the database. Hence, all messages and message changes
+ * committed to the database (that is, visible to readers) have a last
+ * modification revision <= the committed database revision. Any
+ * messages committed in the future will be assigned a modification
+ * revision > the committed database revision.
+ *
+ * The UUID is a NUL-terminated opaque string that uniquely identifies
+ * this database. Two revision numbers are only comparable if they
+ * have the same database UUID.
+ */
+unsigned long
+notmuch_database_get_revision (notmuch_database_t *notmuch,
+ const char **uuid);
+
+/**
* Retrieve a directory object from the database for 'path'.
*
* Here, 'path' should be a path relative to the path of 'database'
diff --git a/test/T570-revision-tracking.sh b/test/T570-revision-tracking.sh
new file mode 100755
index 0000000..8c12740
--- /dev/null
+++ b/test/T570-revision-tracking.sh
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+test_description="database revision tracking"
+
+. ./test-lib.sh
+
+add_email_corpus
+
+test_begin_subtest "notmuch_database_get_revision"
+test_C ${MAIL_DIR} <<'EOF'
+#include <stdio.h>
+#include <string.h>
+#include <notmuch.h>
+int main (int argc, char** argv)
+{
+ notmuch_database_t *db;
+ notmuch_status_t stat;
+ long revision;
+ const char *uuid;
+
+ unsigned long rev;
+
+ stat = notmuch_database_open (argv[1], NOTMUCH_DATABASE_MODE_READ_ONLY, &db);
+ if (stat)
+ fputs ("open failed\n", stderr);
+ revision = notmuch_database_get_revision (db, &uuid);
+ printf("revision=%d\nuuid_len=%d\n", revision, strlen (uuid));
+}
+EOF
+cat <<'EOF' >EXPECTED
+== stdout ==
+revision=53
+uuid_len=36
+== stderr ==
+EOF
+test_expect_equal_file OUTPUT EXPECTED
+
+test_done
--
2.1.4
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