[balsa/thread-date] mailbox: Optimize sorting for flat index

[Peter Bloomfield <peterb src gnome org>]

commit 2039c3f99d442e3c979b3613cbbb3696c0ff752f
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Sun Aug 5 12:01:22 2018 -0400

    mailbox: Optimize sorting for flat index
    
    Use the message-date for sorting when the index is flat (unthreaded),
    instead of traversing a one-node tree to find the same date.

 libbalsa/mailbox.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)
---
diff --git a/libbalsa/mailbox.c b/libbalsa/mailbox.c
index ee4c2b4d2..dbab60eb7 100644
--- a/libbalsa/mailbox.c
+++ b/libbalsa/mailbox.c
@@ -3333,6 +3333,13 @@ mbox_compare_subject(LibBalsaMailboxIndexEntry * message_a,
     return g_ascii_strcasecmp(message_a->subject, message_b->subject);
 }
 
+static gint
+mbox_compare_date(LibBalsaMailboxIndexEntry * message_a,
+                  LibBalsaMailboxIndexEntry * message_b)
+{
+    return message_a->msg_date - message_b->msg_date;
+}
+
 /* Thread date stuff */
 
 typedef struct {
@@ -3380,9 +3387,9 @@ mbox_get_thread_date(const SortTuple *tuple,
 }
 
 static gint
-mbox_compare_date(const SortTuple *a,
-                  const SortTuple *b,
-                  LibBalsaMailbox *mbox)
+mbox_compare_thread_date(const SortTuple *a,
+                         const SortTuple *b,
+                         LibBalsaMailbox *mbox)
 {
     return mbox_get_thread_date(a, mbox) - mbox_get_thread_date(b, mbox);
 }
@@ -3427,7 +3434,10 @@ mbox_compare_func(const SortTuple * a,
            retval = mbox_compare_subject(message_a, message_b);
            break;
        case LB_MAILBOX_SORT_DATE:
-           retval = mbox_compare_date(a, b, mbox);
+            retval =
+                mbox->view->threading_type == LB_MAILBOX_THREADING_FLAT
+                ? mbox_compare_date(message_a, message_b)
+                : mbox_compare_thread_date(a, b, mbox);
            break;
        case LB_MAILBOX_SORT_SIZE:
            retval = mbox_compare_size(message_a, message_b);
@@ -3447,7 +3457,10 @@ mbox_compare_func(const SortTuple * a,
                 retval = mbox_compare_subject(message_a, message_b);
                 break;
            case LB_MAILBOX_SORT_DATE:
-               retval = mbox_compare_date(a, b, mbox);
+               retval =
+                    mbox->view->threading_type == LB_MAILBOX_THREADING_FLAT
+                    ? mbox_compare_date(message_a, message_b)
+                    : mbox_compare_thread_date(a, b, mbox);
                break;
             case LB_MAILBOX_SORT_SIZE:
                 retval = mbox_compare_size(message_a, message_b);