/* Here's the current schema for our database (for NOTMUCH_DATABASE_VERSION):
*
- * We currently have two different types of documents: mail and directory.
+ * We currently have two different types of documents (mail and
+ * directory) and also some metadata.
*
* Mail document
* -------------
*
* The data portion of a directory document contains the path of the
* directory (relative to the database path).
+ *
+ * Database metadata
+ * -----------------
+ * Xapian allows us to store arbitrary name-value pairs as
+ * "metadata". We currently use the following metadata names with the
+ * given meanings:
+ *
+ * version The database schema version, (which is distinct
+ * from both the notmuch package version (see
+ * notmuch --version) and the libnotmuch library
+ * version. The version is stored as an base-10
+ * ASCII integer. The initial database version
+ * was 1, (though a schema existed before that
+ * were no "version" database value existed at
+ * all). Succesive versions are allocated as
+ * changes are made to the database (such as by
+ * indexing new fields).
+ *
+ * last_thread_id The last thread ID generated. This is stored
+ * as a 16-byte hexadecimal ASCII representation
+ * of a 64-bit unsigned integer. The first ID
+ * generated is 1 and the value will be
+ * incremented for each thread ID.
+ *
+ * thread_id_* A pre-allocated thread ID for a particular
+ * message. This is actually an arbitarily large
+ * family of metadata name. Any particular name
+ * is formed by concatenating "thread_id_" with a
+ * message ID. The value stored is a thread ID.
+ *
+ * These thread ID metadata values are stored
+ * whenever a message references a parent message
+ * that does not yet exist in the database. A
+ * thread ID will be allocated and stored, and if
+ * the message is later added, the stored thread
+ * ID will be used (and the metadata value will
+ * be cleared).
+ *
+ * Even before a message is added, it's
+ * pre-allocated thread ID is useful so that all
+ * descendant messages that reference this common
+ * parent can be recognized as belonging to the
+ * same thread.
*/
/* With these prefix values we follow the conventions published here:
const char *parent_thread_id;
parent_message_id = (char *) l->data;
+
+ _notmuch_message_add_term (message, "reference",
+ parent_message_id);
+
parent_thread_id = _resolve_message_id_to_thread_id (notmuch,
message,
parent_message_id);
- if (parent_thread_id == NULL) {
- _notmuch_message_add_term (message, "reference",
- parent_message_id);
- } else {
- if (*thread_id == NULL) {
- *thread_id = talloc_strdup (message, parent_thread_id);
- _notmuch_message_add_term (message, "thread", *thread_id);
- } else if (strcmp (*thread_id, parent_thread_id)) {
- ret = _merge_threads (notmuch, *thread_id, parent_thread_id);
- if (ret)
- goto DONE;
- }
+ if (*thread_id == NULL) {
+ *thread_id = talloc_strdup (message, parent_thread_id);
+ _notmuch_message_add_term (message, "thread", *thread_id);
+ } else if (strcmp (*thread_id, parent_thread_id)) {
+ ret = _merge_threads (notmuch, *thread_id, parent_thread_id);
+ if (ret)
+ goto DONE;
}
}
notmuch_message_file_t *message_file)
{
notmuch_status_t status;
- const char *thread_id = NULL;
- char *metadata_key = _get_metadata_thread_id_key (message,
- notmuch_message_get_message_id (message));
+ const char *message_id, *thread_id = NULL;
+ char *metadata_key;
+ string stored_id;
+
+ message_id = notmuch_message_get_message_id (message);
+ metadata_key = _get_metadata_thread_id_key (message, message_id);
+
/* Check if we have already seen related messages to this one.
* If we have then use the thread_id that we stored at that time.
*/
- string stored_id = notmuch->xapian_db->get_metadata (metadata_key);
- if (!stored_id.empty()) {
- Xapian::WritableDatabase *db = static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db);
+ stored_id = notmuch->xapian_db->get_metadata (metadata_key);
+ if (! stored_id.empty()) {
+ Xapian::WritableDatabase *db;
+
+ db = static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db);
+
+ /* Clear the metadata for this message ID. We don't need it
+ * anymore. */
db->set_metadata (metadata_key, "");
thread_id = stored_id.c_str();
+
_notmuch_message_add_term (message, "thread", thread_id);
}
talloc_free (metadata_key);