lib: Add support for nested atomic sections.

[notmuch] / lib / notmuch.h

diff --git a/lib/notmuch.h b/lib/notmuch.h
index 413b57095dd1bf78ef3dfc89cc41c4855d3a94c7..bfa2ced88a3f3893bc43b63ec495ce68fb41cd29 100644 (file)
--- a/lib/notmuch.h
+++ b/lib/notmuch.h
@@ -81,6 +81,9 @@ typedef int notmuch_bool_t;
  * NOTMUCH_STATUS_UNBALANCED_FREEZE_THAW: The notmuch_message_thaw
  *     function has been called more times than notmuch_message_freeze.
  *
+ * NOTMUCH_STATUS_UNBALANCED_ATOMIC: notmuch_database_end_atomic has
+ *     been called more times than notmuch_database_begin_atomic.
+ *
  * And finally:
  *
  * NOTMUCH_STATUS_LAST_STATUS: Not an actual status value. Just a way
@@ -97,13 +100,14 @@ typedef enum _notmuch_status {
     NOTMUCH_STATUS_NULL_POINTER,
     NOTMUCH_STATUS_TAG_TOO_LONG,
     NOTMUCH_STATUS_UNBALANCED_FREEZE_THAW,
+    NOTMUCH_STATUS_UNBALANCED_ATOMIC,
 
     NOTMUCH_STATUS_LAST_STATUS
 } notmuch_status_t;
 
 /* Get a string representation of a notmuch_status_t value.
  *
- * The result is readonly.
+ * The result is read-only.
  */
 const char *
 notmuch_status_to_string (notmuch_status_t status);
@@ -214,6 +218,42 @@ notmuch_database_upgrade (notmuch_database_t *database,
                                                   double progress),
                          void *closure);
 
+/* Begin an atomic database operation.
+ *
+ * Any modifications performed between a successful begin and a
+ * notmuch_database_end_atomic will be applied to the database
+ * atomically.  Note that, unlike a typical database transaction, this
+ * only ensures atomicity, not durability; neither begin nor end
+ * necessarily flush modifications to disk.
+ *
+ * Atomic sections may be nested.  begin_atomic and end_atomic must
+ * always be called in pairs.
+ *
+ * Return value:
+ *
+ * NOTMUCH_STATUS_SUCCESS: Successfully entered atomic section.
+ *
+ * NOTMUCH_STATUS_XAPIAN_EXCEPTION: A Xapian exception occurred;
+ *     atomic section not entered.
+ */
+notmuch_status_t
+notmuch_database_begin_atomic (notmuch_database_t *notmuch);
+
+/* Indicate the end of an atomic database operation.
+ *
+ * Return value:
+ *
+ * NOTMUCH_STATUS_SUCCESS: Successfully completed atomic section.
+ *
+ * NOTMUCH_STATUS_XAPIAN_EXCEPTION: A Xapian exception occurred;
+ *     atomic section not ended.
+ *
+ * NOTMUCH_STATUS_UNBALANCED_ATOMIC: The database is not currently in
+ *     an atomic section.
+ */
+notmuch_status_t
+notmuch_database_end_atomic (notmuch_database_t *notmuch);
+
 /* Retrieve a directory object from the database for 'path'.
  *
  * Here, 'path' should be a path relative to the path of 'database'
@@ -510,7 +550,7 @@ notmuch_threads_move_to_next (notmuch_threads_t *threads);
  *
  * It's not strictly necessary to call this function. All memory from
  * the notmuch_threads_t object will be reclaimed when the
- * containg query object is destroyed.
+ * containing query object is destroyed.
  */
 void
 notmuch_threads_destroy (notmuch_threads_t *threads);
@@ -915,19 +955,19 @@ notmuch_message_remove_all_tags (notmuch_message_t *message);
  * flags, and adds or removes tags on 'message' as follows when these
  * flags are present:
  *
- *     Flag    Action
- *     ----    ------
+ *     Flag    Action if present
+ *     ----    -----------------
  *     'D'     Adds the "draft" tag to the message
  *     'F'     Adds the "flagged" tag to the message
  *     'P'     Adds the "passed" tag to the message
  *     'R'     Adds the "replied" tag to the message
  *     'S'     Removes the "unread" tag from the message
  *
- * The only filenames examined for flags are filenames which appear to
- * be within a maildir directory, (the file must be in a directory
- * named "new" or "cur" and there must be a neighboring directory
- * named respectively "cur" or "new"). The flags are identified as
- * trailing components of the filename after a sequence of ":2,".
+ * For each flag that is not present, the opposite action (add/remove)
+ * is performed for the corresponding tags.
+ *
+ * Flags are identified as trailing components of the filename after a
+ * sequence of ":2,".
  *
  * If there are multiple filenames associated with this message, the
  * flag is considered present if it appears in one or more
@@ -947,23 +987,24 @@ notmuch_message_maildir_flags_to_tags (notmuch_message_t *message);
  *
  * Specifically, for each filename corresponding to this message:
  *
- * If the filename is not in a maildir directory, do nothing.
- * (A maildir directory is determined as a directory named "new" or
- * "cur" with a neighboring directory named respectively "cur" or
- * "new".)
+ * If the filename is not in a maildir directory, do nothing.  (A
+ * maildir directory is determined as a directory named "new" or
+ * "cur".) Similarly, if the filename has invalid maildir info,
+ * (repeated or outof-ASCII-order flag characters after ":2,"), then
+ * do nothing.
  *
  * If the filename is in a maildir directory, rename the file so that
  * its filename ends with the sequence ":2," followed by zero or more
  * of the following single-character flags (in ASCII order):
  *
- *   'D' if the message has the "draft" tag
- *   'F' if the message has the "flagged" tag
- *   'P' if the message has the "passed" tag
- *   'R' if the message has the "replied" tag
- *   'S' if the message does not have the "unread" tag
+ *   'D' iff the message has the "draft" tag
+ *   'F' iff the message has the "flagged" tag
+ *   'P' iff the message has the "passed" tag
+ *   'R' iff the message has the "replied" tag
+ *   'S' iff the message does not have the "unread" tag
  *
- * Any existing flags unmentioned in the list above are left
- * unaffected by the rename.
+ * Any existing flags unmentioned in the list above will be preserved
+ * in the renaming.
  *
  * Also, if this filename is in a directory named "new", rename it to
  * be within the neighboring directory named "cur".