diff options
Diffstat (limited to 'apps/couch/src/couch_lru.erl')
-rw-r--r-- | apps/couch/src/couch_lru.erl | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/apps/couch/src/couch_lru.erl b/apps/couch/src/couch_lru.erl new file mode 100644 index 00000000..ffddfdfc --- /dev/null +++ b/apps/couch/src/couch_lru.erl @@ -0,0 +1,49 @@ +-module(couch_lru). +-export([new/0, insert/2, update/2, close/1]). + +-include("couch_db.hrl"). + +new() -> + {gb_trees:empty(), dict:new()}. + +insert(DbName, {Tree0, Dict0}) -> + Lru = now(), + {gb_trees:insert(Lru, DbName, Tree0), dict:store(DbName, Lru, Dict0)}. + +update(DbName, {Tree0, Dict0}) -> + case dict:find(DbName, Dict0) of + {ok, Old} -> + New = now(), + Tree = gb_trees:insert(New, DbName, gb_trees:delete(Old, Tree0)), + Dict = dict:store(DbName, New, Dict0), + {Tree, Dict}; + error -> + % We closed this database before processing the update. Ignore + {Tree0, Dict0} + end. + +close({Tree, _} = Cache) -> + close_int(gb_trees:next(gb_trees:iterator(Tree)), Cache). + +%% internals + +close_int(none, _) -> + erlang:error(all_dbs_active); +close_int({Lru, DbName, Iter}, {Tree, Dict} = Cache) -> + case ets:update_element(couch_dbs, DbName, {#db.fd_monitor, locked}) of + true -> + [#db{main_pid = Pid} = Db] = ets:lookup(couch_dbs, DbName), + case couch_db:is_idle(Db) of true -> + true = ets:delete(couch_dbs, DbName), + exit(Pid, kill), + {gb_trees:delete(Lru, Tree), dict:erase(DbName, Dict)}; + false -> + true = ets:update_element(couch_dbs, DbName, {#db.fd_monitor, nil}), + twig:log(warn, "~p old active ~s", [?MODULE, Db#db.name]), + close_int(gb_trees:next(Iter), update(DbName, Cache)) + end; + false -> + NewTree = gb_trees:delete(Lru, Tree), + NewIter = gb_trees:iterator(NewTree), + close_int(gb_trees:next(NewIter), {NewTree, dict:erase(DbName, Dict)}) + end. |