+ if (directory == NULL)
+ return NOTMUCH_STATUS_NULL_POINTER;
+ *directory = NULL;
+
+ try {
+ *directory = _notmuch_directory_create (notmuch, path,
+ NOTMUCH_FIND_LOOKUP, &status);
+ } catch (const Xapian::Error &error) {
+ fprintf (stderr, "A Xapian exception occurred getting directory: %s.\n",
+ error.get_msg().c_str());
+ notmuch->exception_reported = TRUE;
+ status = NOTMUCH_STATUS_XAPIAN_EXCEPTION;
+ }
+ return status;
+}
+
+/* Allocate a document ID that satisfies the following criteria:
+ *
+ * 1. The ID does not exist for any document in the Xapian database
+ *
+ * 2. The ID was not previously returned from this function
+ *
+ * 3. The ID is the smallest integer satisfying (1) and (2)
+ *
+ * This function will trigger an internal error if these constraints
+ * cannot all be satisfied, (that is, the pool of available document
+ * IDs has been exhausted).
+ */
+unsigned int
+_notmuch_database_generate_doc_id (notmuch_database_t *notmuch)
+{
+ assert (notmuch->last_doc_id >= notmuch->xapian_db->get_lastdocid ());
+
+ notmuch->last_doc_id++;
+
+ if (notmuch->last_doc_id == 0)
+ INTERNAL_ERROR ("Xapian document IDs are exhausted.\n");
+
+ return notmuch->last_doc_id;
+}
+
+static const char *
+_notmuch_database_generate_thread_id (notmuch_database_t *notmuch)
+{
+ /* 16 bytes (+ terminator) for hexadecimal representation of
+ * a 64-bit integer. */
+ static char thread_id[17];
+ Xapian::WritableDatabase *db;
+
+ db = static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db);
+
+ notmuch->last_thread_id++;
+
+ sprintf (thread_id, "%016" PRIx64, notmuch->last_thread_id);
+
+ db->set_metadata ("last_thread_id", thread_id);
+
+ return thread_id;
+}
+
+static char *
+_get_metadata_thread_id_key (void *ctx, const char *message_id)
+{
+ if (strlen (message_id) > NOTMUCH_MESSAGE_ID_MAX)
+ message_id = _message_id_compressed (ctx, message_id);
+
+ return talloc_asprintf (ctx, NOTMUCH_METADATA_THREAD_ID_PREFIX "%s",
+ message_id);