From 793f8e3a3ad091b123925cefdb8c86b4b4186b79 Mon Sep 17 00:00:00 2001
From: Jesper Louis Andersen <jesper.louis.andersen@gmail.com>
Date: Sun, 8 Jan 2012 00:01:18 +0100
Subject: [PATCH] Optimize open dict check.

A dict is open and with keys if its size is greater than 0. Go through
the dicts one by one with lists:any/2 and use that to optimize the
check. Ought to run faster than traversing the full set.
---
 test/lsm_btree_tests.erl | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/test/lsm_btree_tests.erl b/test/lsm_btree_tests.erl
index 8877e39..2558274 100644
--- a/test/lsm_btree_tests.erl
+++ b/test/lsm_btree_tests.erl
@@ -265,14 +265,9 @@ cleanup_tree(Tree) ->
 %% Various Helper routines
 %% ----------------------------------------------------------------------
 
-%% @todo optimize this call. You can fast-exit as soon as you know
-%% there is a non-empty dict.
 open_dicts_with_keys(#state { open = Open}) ->
-    keysum_of_dicts(Open) > 0.
-
-keysum_of_dicts(DictOfDict) ->
-    Dicts = [ V || {_, V} <- dict:to_list(DictOfDict)],
-    lists:sum([dict:size(D) || D <- Dicts]).
+    lists:any(fun({_, D}) -> dict:size(D) > 0 end,
+              dict:to_list(Open)).
 
 open_dicts(#state { open = Open}) ->
     dict:size(Open) > 0.