| % Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| % use this file except in compliance with the License. You may obtain a copy of |
| % the License at |
| % |
| % http://www.apache.org/licenses/LICENSE-2.0 |
| % |
| % Unless required by applicable law or agreed to in writing, software |
| % distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| % WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| % License for the specific language governing permissions and limitations under |
| % the License. |
| |
| -module(couch_lru). |
| -export([new/0, insert/2, update/2, close/1]). |
| |
| -include_lib("couch/include/couch_db.hrl"). |
| |
| new() -> |
| Updates = ets:new(couch_lru_updates, [ordered_set]), |
| Dbs = ets:new(couch_lru_dbs, [set]), |
| {0, Updates, Dbs}. |
| |
| insert(DbName, {Count, Updates, Dbs}) -> |
| update(DbName, {Count, Updates, Dbs}). |
| |
| update(DbName, {Count, Updates, Dbs}) -> |
| case ets:lookup(Dbs, DbName) of |
| [] -> |
| true = ets:insert(Dbs, {DbName, Count}); |
| [{DbName, OldCount}] -> |
| true = ets:update_element(Dbs, DbName, {2, Count}), |
| true = ets:delete(Updates, {OldCount, DbName}) |
| end, |
| true = ets:insert(Updates, {{Count, DbName}}), |
| {Count + 1, Updates, Dbs}. |
| |
| |
| close({Count, Updates, Dbs}) -> |
| case close_int(ets:next(Updates, {-1, <<>>}), Updates, Dbs) of |
| true -> |
| {true, {Count, Updates, Dbs}}; |
| false -> |
| false |
| end. |
| |
| |
| %% internals |
| |
| close_int('$end_of_table', _Updates, _Dbs) -> |
| false; |
| close_int({_Count, DbName} = Key, Updates, Dbs) -> |
| 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), |
| true = ets:delete(couch_dbs_pid_to_name, Pid), |
| exit(Pid, kill), |
| true = ets:delete(Updates, Key), |
| true = ets:delete(Dbs, DbName), |
| true; |
| false -> |
| true = ets:update_element(couch_dbs, DbName, {#db.fd_monitor, nil}), |
| couch_stats:increment_counter([couchdb, couch_server, lru_skip]), |
| close_int(ets:next(Updates, Key), Updates, Dbs) |
| end; |
| false -> |
| true = ets:delete(Updates, Key), |
| true = ets:delete(Dbs, DbName), |
| close_int(ets:next(Updates, Key), Updates, Dbs) |
| end. |