aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorJosé Valim <[email protected]>2015-02-19 11:46:14 +0100
committerJosé Valim <[email protected]>2015-02-19 11:46:14 +0100
commite8398cce2451f6323eb5d8cce4adf4d5b69bb098 (patch)
treeb8f632c638b93f7430adb09b05a286722a94ec8e
parentef8b1e3e8c908379cec8376ed515c920682224f9 (diff)
downloadotp-e8398cce2451f6323eb5d8cce4adf4d5b69bb098.tar.gz
otp-e8398cce2451f6323eb5d8cce4adf4d5b69bb098.tar.bz2
otp-e8398cce2451f6323eb5d8cce4adf4d5b69bb098.zip
Short-circuit common dict operations
Stop traversing all segments and buckets of empty dictionaries by adding a clause that checks the dictionary size. This improved compilation of an erlang project from 7.5s to 5.5s seconds when trying out a sample implementation of erl_lint that uses dicts.
-rw-r--r--lib/stdlib/src/dict.erl6
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/stdlib/src/dict.erl b/lib/stdlib/src/dict.erl
index cf8fb3114a..5a9f63c5e2 100644
--- a/lib/stdlib/src/dict.erl
+++ b/lib/stdlib/src/dict.erl
@@ -417,6 +417,8 @@ on_bucket(F, T, Slot) ->
%% could have implemented map and filter using fold but these are
%% faster. We hope!
+fold_dict(F, Acc, #dict{size=0}) when is_function(F, 3) ->
+ Acc;
fold_dict(F, Acc, D) ->
Segs = D#dict.segs,
fold_segs(F, Acc, Segs, tuple_size(Segs)).
@@ -434,6 +436,8 @@ fold_bucket(F, Acc, [?kv(Key,Val)|Bkt]) ->
fold_bucket(F, F(Key, Val, Acc), Bkt);
fold_bucket(F, Acc, []) when is_function(F, 3) -> Acc.
+map_dict(F, #dict{size=0} = Dict) when is_function(F, 2) ->
+ Dict;
map_dict(F, D) ->
Segs0 = tuple_to_list(D#dict.segs),
Segs1 = map_seg_list(F, Segs0),
@@ -453,6 +457,8 @@ map_bucket(F, [?kv(Key,Val)|Bkt]) ->
[?kv(Key,F(Key, Val))|map_bucket(F, Bkt)];
map_bucket(F, []) when is_function(F, 2) -> [].
+filter_dict(F, #dict{size=0} = Dict) when is_function(F, 2) ->
+ Dict;
filter_dict(F, D) ->
Segs0 = tuple_to_list(D#dict.segs),
{Segs1,Fc} = filter_seg_list(F, Segs0, [], 0),