mh,maildir: speed up scanning.

* include/mailutils/sys/amd.h (_amd_message_append, amd_sort): New protos.
* libmailutils/base/amd.c (amd_array_expand): Call memmove only if there is
actually something to move.
(_amd_message_append, amd_sort): New functions.
* libproto/maildir/mbox.c (maildir_scan_dir): Append new messages to the
end of the array, and sort it afterwards. This avoids unnecessary memory
moves, which improves performance considerably, especially on large
mailboxes.
* libproto/mh/mbox.c (mh_scan0): Likewise.

@@ -110,6 +110,8 @@ int _amd_message_lookup_or_insert (struct _amd_data *amd,
 				   struct _amd_message *key,
 				   size_t *pindex);
 int _amd_message_insert (struct _amd_data *mhd, struct _amd_message *msg);
+int _amd_message_append (struct _amd_data *amd, struct _amd_message *msg);
+void amd_sort (struct _amd_data *amd);
 int amd_message_stream_open (struct _amd_message *mhm);
 void amd_message_stream_close (struct _amd_message *mhm);
 void amd_cleanup (void *arg);

@@ -241,8 +241,9 @@ amd_array_expand (struct _amd_data *amd, size_t index)
 	}
       amd->msg_array = p;
     }
-  memmove (&amd->msg_array[index+1], &amd->msg_array[index],
-	   (amd->msg_count-index) * amd->msg_size);
+  if (amd->msg_count > index)
+    memmove (&amd->msg_array[index+1], &amd->msg_array[index],
+	     (amd->msg_count-index) * amd->msg_size);
   amd->msg_count++;
   return 0;
 }
@@ -1381,6 +1382,35 @@ _amd_message_insert (struct _amd_data *amd, struct _amd_message *msg)
   return 0;
 }
 
+/* Append message to the end of the array, expanding it if necessary */
+int
+_amd_message_append (struct _amd_data *amd, struct _amd_message *msg)
+{
+  size_t index = amd->msg_count;
+  int rc = amd_array_expand (amd, index);
+  if (rc)
+    return rc;
+  amd->msg_array[index] = msg;
+  msg->amd = amd;
+  return 0;
+}
+
+static int
+msg_array_comp (const void *a, const void *b)
+{
+  struct _amd_message **ma = (struct _amd_message **) a;
+  struct _amd_message **mb = (struct _amd_message **) b;
+  struct _amd_data *amd = (*ma)->amd;
+  return amd->msg_cmp (*ma, *mb);
+}
+
+void
+amd_sort (struct _amd_data *amd)
+{
+  qsort (amd->msg_array, amd->msg_count, sizeof (amd->msg_array[0]),
+	 msg_array_comp);
+}
+
 static void
 _amd_message_delete (struct _amd_data *amd, struct _amd_message *msg)
 {

@@ -584,7 +584,8 @@ maildir_scan_dir (struct _amd_data *amd, DIR *dir, char *dirname)
   char *p;
   size_t index;
   int rc = 0;
-
+  int need_sort = 0;
+  
   while ((entry = readdir (dir)))
     {
       switch (entry->d_name[0])
@@ -593,31 +594,23 @@ maildir_scan_dir (struct _amd_data *amd, DIR *dir, char *dirname)
 	  break;
 
 	default:
-	  key.file_name = entry->d_name;
-	  rc = _amd_message_lookup_or_insert (amd,
-					      (struct _amd_message *)&key,
-					      &index);
-	  if (rc == MU_ERR_NOENT)
-	    {
 	      /* Message not found. Index pointd to the array cell where it
 		 would be placed */
-	      msg = calloc (1, sizeof (*msg));
-	      if (!msg)
-		{
-		  rc = ENOMEM;
-		  break;
-		}
-	      amd->msg_array[index] = (struct _amd_message *)msg;
-	      msg->amd_message.amd = amd;
-	      rc = 0;
+	  msg = calloc (1, sizeof (*msg));
+	  if (!msg)
+	    {
+	      rc = ENOMEM;
+	      break;
 	    }
-	  else if (rc == 0)
+	  key.file_name = entry->d_name;
+	  if (!amd_msg_lookup (amd, (struct _amd_message *) &key, &index))
+	    continue;
+	  rc = _amd_message_append (amd, (struct _amd_message *) msg);
+	  if (rc)
 	    {
-	      msg = (struct _maildir_message *)amd->msg_array[index];
-	      free (msg->file_name);
+	      free (msg);
+	      break;
 	    }
-	  else
-	    break;
 	      
 	  msg->dir = dirname;
 	  msg->file_name = strdup (entry->d_name);
@@ -628,9 +621,12 @@ maildir_scan_dir (struct _amd_data *amd, DIR *dir, char *dirname)
 	  else
 	    msg->amd_message.attr_flags = 0;
 	  msg->amd_message.orig_flags = msg->amd_message.attr_flags;
+	  need_sort = 1;
 	}
     }
 
+  if (rc == 0 && need_sort)
+    amd_sort (amd);
   return rc;
 }
 

@@ -181,6 +181,7 @@ mh_scan0 (mu_mailbox_t mailbox, size_t msgno MU_ARG_UNUSED, size_t *pcount,
   struct dirent *entry;
   int status = 0;
   struct stat st;
+  int need_sort = 0;
 
   if (amd == NULL)
     return EINVAL;
@@ -235,12 +236,18 @@ mh_scan0 (mu_mailbox_t mailbox, size_t msgno MU_ARG_UNUSED, size_t *pcount,
       if (!msg)
 	{
 	  msg = calloc (1, sizeof(*msg));
+	  status = _amd_message_append (amd, (struct _amd_message *) msg);
+	  if (status)
+	    {
+	      free (msg);
+	      break;
+	    }
 
 	  msg->seq_number = num;
 	  msg->amd_message.attr_flags = attr_flags;
 	  msg->amd_message.orig_flags = msg->amd_message.attr_flags;
 
-	  _amd_message_insert (amd, (struct _amd_message*) msg);
+	  need_sort = 1;
 	}
       else
 	{
@@ -251,38 +258,43 @@ mh_scan0 (mu_mailbox_t mailbox, size_t msgno MU_ARG_UNUSED, size_t *pcount,
 
   closedir (dir);
 
-  if (do_notify)
-    {
-      size_t i;
+  if (need_sort)
+    amd_sort (amd);
 
-      for (i = 0; i < amd->msg_count; i++)
+  if (status == 0)
+    {
+      if (do_notify)
 	{
-	  DISPATCH_ADD_MSG (mailbox, amd, i);
+	  size_t i;
+
+	  for (i = 0; i < amd->msg_count; i++)
+	    {
+	      DISPATCH_ADD_MSG (mailbox, amd, i);
+	    }
 	}
-    }
   
-  if (stat (amd->name, &st) == 0)
-    amd->mtime = st.st_mtime;
+      if (stat (amd->name, &st) == 0)
+	amd->mtime = st.st_mtime;
 
-  if (pcount)
-    *pcount = amd->msg_count;
+      if (pcount)
+	*pcount = amd->msg_count;
 
-  /* Reset the uidvalidity.  */
-  if (amd->msg_count > 0)
-    {
-      if (amd->uidvalidity == 0)
+      /* Reset the uidvalidity.  */
+      if (amd->msg_count > 0)
 	{
-	  amd->uidvalidity = (unsigned long)time (NULL);
-	  /* Tell that we have been modified for expunging.  */
-	  if (amd->msg_count)
+	  if (amd->uidvalidity == 0)
 	    {
-	      amd_message_stream_open (amd->msg_array[0]);
-	      amd_message_stream_close (amd->msg_array[0]);
-	      amd->msg_array[0]->attr_flags |= MU_ATTRIBUTE_MODIFIED;
+	      amd->uidvalidity = (unsigned long)time (NULL);
+	      /* Tell that we have been modified for expunging.  */
+	      if (amd->msg_count)
+		{
+		  amd_message_stream_open (amd->msg_array[0]);
+		  amd_message_stream_close (amd->msg_array[0]);
+		  amd->msg_array[0]->attr_flags |= MU_ATTRIBUTE_MODIFIED;
+		}
 	    }
 	}
     }
-
   /* Clean up the things */
 
   amd_cleanup (mailbox);