nickva commented on a change in pull request #3366:
URL: https://github.com/apache/couchdb/pull/3366#discussion_r574053457
##########
File path: src/couch/src/couch_server.erl
##########
@@ -860,19 +865,55 @@ get_engine_path(DbName, Engine) when is_binary(DbName),
is_atom(Engine) ->
end.
lock(DbName, Reason) when is_binary(DbName), is_binary(Reason) ->
- case ets:lookup(couch_dbs, DbName) of
+ case ets:lookup(couch_dbs(DbName), DbName) of
[] ->
- true = ets:insert(couch_dbs_locks, {DbName, Reason}),
+ true = ets:insert(couch_dbs_locks(DbName), {DbName, Reason}),
ok;
[#entry{}] ->
{error, already_opened}
end.
unlock(DbName) when is_binary(DbName) ->
- true = ets:delete(couch_dbs_locks, DbName),
+ true = ets:delete(couch_dbs_locks(DbName), DbName),
ok.
+db_updated(Db) ->
+ DbName = couch_db:name(Db),
+ gen_server:call(couch_server(DbName), {db_updated, Db}, infinity).
+
+
+couch_server(Arg) ->
+ name("couch_server", Arg).
+
+
+couch_dbs(Arg) ->
+ name("couch_dbs", Arg).
+
+
+couch_dbs_pid_to_name(Arg) ->
+ name("couch_dbs_pid_to_name", Arg).
+
+
+couch_dbs_locks(Arg) ->
+ name("couch_dbs_locks", Arg).
+
+
+name(BaseName, DbName) when is_binary(DbName) ->
+ N = 1 + (erlang:crc32(DbName) rem num_servers()),
Review comment:
May even be a tiny bit faster...
```
> DbName = crypto:strong_rand_bytes(100).
<<23,241,236,53,92,151,12,217,246,88,65,153,224,214,236,
240,126,243,188,248,53,187,206,165,235,96,24,5,38,...>>
> f(USec), {USec, ok} = timer:tc(fun() -> [erlang:crc32(DbName) rem 10 || I
<- lists:seq(1, 1000000)], ok end), USec/1.0e6.
1.499477
> f(USec), {USec, ok} = timer:tc(fun() -> [erlang:phash2(DbName, 10) || I <-
lists:seq(1, 1000000)], ok end), USec/1.0e6.
1.331179
```
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