Change database to store only a single thread ID per message.

Instead of supporting multiple thread IDs, we now merge together
thread IDs if one message is ever found to belong to more than one
thread. This allows for constructing complete threads when, for
example, a child message doesn't include a complete list of References
headers back to the beginning of the thread.

It also simplifies dealing with mapping a message ID to a thread ID
which is now a simple get_thread_id just like get_message_id, (and no
longer an iterator-based thing like get_tags).

1 files changed, 57 insertions, 58 deletions

diff --git a/message.cc b/message.cc
index 7a6c01d..75ec634 100644
--- a/message.cc
+++ b/message.cc
@@ -27,6 +27,7 @@ struct _notmuch_message {
     notmuch_database_t *notmuch;
     Xapian::docid doc_id;
     char *message_id;
+    char *thread_id;
     char *filename;
     Xapian::Document doc;
 };
@@ -41,10 +42,6 @@ struct _notmuch_tags {
     notmuch_terms_t terms;
 };
 
-struct _notmuch_thread_ids {
-    notmuch_terms_t terms;
-};
-
 /* "128 bits of thread-id ought to be enough for anybody" */
 #define NOTMUCH_THREAD_ID_BITS	 128
 #define NOTMUCH_THREAD_ID_DIGITS (NOTMUCH_THREAD_ID_BITS / 4)
@@ -80,13 +77,15 @@ _notmuch_message_destructor (notmuch_message_t *message)
  * caller *is* responsible for calling notmuch_message_destroy.
  *
  * If no document exists in the database with document ID of 'doc_id'
- * then this function returns NULL and sets *status to
+ * then this function returns NULL and optionally sets *status to
  * NOTMUCH_PRIVATE_STATUS_NO_DOCUMENT_FOUND.
  *
  * This function can also fail to due lack of available memory,
  * returning NULL and optionally setting *status to
- * NOTMUCH_PRIVATE_STATUS_OUT_OF_MEMORY. Caller can pass NULL
- * for status if uninterested in distinguishing these two cases.
+ * NOTMUCH_PRIVATE_STATUS_OUT_OF_MEMORY.
+ *
+ * The caller can pass NULL for status if uninterested in
+ * distinguishing these two cases.
  */
 notmuch_message_t *
 _notmuch_message_create (const void *talloc_owner,
@@ -109,6 +108,7 @@ _notmuch_message_create (const void *talloc_owner,
     message->notmuch = notmuch;
     message->doc_id = doc_id;
     message->message_id = NULL; /* lazily created */
+    message->thread_id = NULL; /* lazily created */
     message->filename = NULL; /* lazily created */
 
     /* This is C++'s creepy "placement new", which is really just an
@@ -195,12 +195,8 @@ _notmuch_message_create_for_message_id (const void *talloc_owner,
     message = _notmuch_message_create (talloc_owner, notmuch,
 				       doc_id, &private_status);
 
-    if (private_status >= (notmuch_private_status_t) NOTMUCH_STATUS_LAST_STATUS)
-    {
-	INTERNAL_ERROR ("Failed to find document immediately after adding it.\n");
-    }
-
-    *status = (notmuch_status_t) private_status;
+    *status = COERCE_STATUS (private_status,
+			     "Failed to find dcocument after inserting it.");
 
     return message;
 }
@@ -216,22 +212,63 @@ notmuch_message_get_message_id (notmuch_message_t *message)
     i = message->doc.termlist_begin ();
     i.skip_to (_find_prefix ("id"));
 
-    if (i == message->doc.termlist_end ()) {
+    if (i == message->doc.termlist_end ())
 	INTERNAL_ERROR ("Message with document ID of %d has no message ID.\n",
 			message->doc_id);
-    }
 
     message->message_id = talloc_strdup (message, (*i).c_str () + 1);
+
+#if DEBUG_DATABASE_SANITY
+    i++;
+
+    if (i != message->doc.termlist_end () &&
+	strncmp ((*i).c_str (), _find_prefix ("id"),
+		 strlen (_find_prefix ("id"))) == 0)
+    {
+	INTERNAL_ERROR ("Mail (doc_id: %d) has duplicate message IDs",
+			message->doc_id);
+    }
+#endif
+
     return message->message_id;
 }
 
+const char *
+notmuch_message_get_thread_id (notmuch_message_t *message)
+{
+    Xapian::TermIterator i;
+
+    if (message->thread_id)
+	return message->thread_id;
+
+    i = message->doc.termlist_begin ();
+    i.skip_to (_find_prefix ("thread"));
+
+    if (i == message->doc.termlist_end ())
+	INTERNAL_ERROR ("Message with document ID of %d has no thread ID.\n",
+			message->doc_id);
+
+    message->thread_id = talloc_strdup (message, (*i).c_str () + 1);
+
+#if DEBUG_DATABASE_SANITY
+    i++;
+
+    if (i != message->doc.termlist_end () &&
+	strncmp ((*i).c_str (), _find_prefix ("thread"),
+		 strlen (_find_prefix ("thread"))) == 0)
+    {
+	INTERNAL_ERROR ("Message with document ID of %d has duplicate thread IDs.\n",
+			message->doc_id);
+    }
+#endif
+
+    return message->thread_id;
+}
+
 /* Set the filename for 'message' to 'filename'.
  *
- * XXX: We should still figure out what we want to do for multiple
- * files with identical message IDs. We will probably want to store a
- * list of filenames here, (so that this will be "add_filename"
- * instead of "set_filename"). Which would make this very similar to
- * add_thread_ids.
+ * XXX: We should still figure out if we think it's important to store
+ * multiple filenames for email messages with identical message IDs.
  *
  * This change will not be reflected in the database until the next
  * call to _notmuch_message_set_sync. */
@@ -318,13 +355,6 @@ notmuch_message_get_tags (notmuch_message_t *message)
 				       notmuch_tags_t);
 }
 
-notmuch_thread_ids_t *
-notmuch_message_get_thread_ids (notmuch_message_t *message)
-{
-    return _notmuch_terms_create_type (message, message->doc, "thread",
-				       notmuch_thread_ids_t);
-}
-
 void
 _notmuch_message_set_date (notmuch_message_t *message,
 			   const char *date)
@@ -337,13 +367,6 @@ _notmuch_message_set_date (notmuch_message_t *message,
 			    Xapian::sortable_serialise (time_value));
 }
 
-void
-_notmuch_message_add_thread_id (notmuch_message_t *message,
-				const char *thread_id)
-{
-    _notmuch_message_add_term (message, "thread", thread_id);
-}
-
 static void
 thread_id_generate (thread_id_t *thread_id)
 {
@@ -559,27 +582,3 @@ notmuch_tags_destroy (notmuch_tags_t *tags)
 {
     return _notmuch_terms_destroy (&tags->terms);
 }
-
-notmuch_bool_t
-notmuch_thread_ids_has_more (notmuch_thread_ids_t *thread_ids)
-{
-    return _notmuch_terms_has_more (&thread_ids->terms);
-}
-
-const char *
-notmuch_thread_ids_get (notmuch_thread_ids_t *thread_ids)
-{
-    return _notmuch_terms_get (&thread_ids->terms);
-}
-
-void
-notmuch_thread_ids_advance (notmuch_thread_ids_t *thread_ids)
-{
-    return _notmuch_terms_advance (&thread_ids->terms);
-}
-
-void
-notmuch_thread_ids_destroy (notmuch_thread_ids_t *thread_ids)
-{
-    return _notmuch_terms_destroy (&thread_ids->terms);
-}