diff options
Diffstat (limited to 'lib/mnesia')
| -rw-r--r-- | lib/mnesia/src/mnesia_locker.erl | 114 |
1 files changed, 75 insertions, 39 deletions
diff --git a/lib/mnesia/src/mnesia_locker.erl b/lib/mnesia/src/mnesia_locker.erl index 6e21332480..55df074c29 100644 --- a/lib/mnesia/src/mnesia_locker.erl +++ b/lib/mnesia/src/mnesia_locker.erl @@ -66,8 +66,8 @@ -record(queue, {oid, tid, op, pid, lucky}). -%% mnesia_held_locks: contain {{Oid,Tid}, Op} entries --define(match_oid_held_locks(Oid), {{Oid, '_'}, '_'}). +%% mnesia_held_locks: contain {Oid, MaxLock, [{Op, Tid}]} entries +-define(match_oid_held_locks(Oid), {Oid, '_', '_'}). %% mnesia_tid_locks: contain {Tid, Oid, Op} entries (bag) -define(match_oid_tid_locks(Tid), {Tid, '_', '_'}). %% mnesia_sticky_locks: contain {Oid, Node} entries and {Tab, Node} entries (set) @@ -237,7 +237,14 @@ loop(State) -> set_lock(Tid, Oid, Op) -> ?dbg("Granted ~p ~p ~p~n", [Tid,Oid,Op]), - ?ets_insert(mnesia_held_locks, {{Oid, Tid}, Op}), + case ?ets_lookup(mnesia_held_locks, Oid) of + [] -> + ?ets_insert(mnesia_held_locks, {Oid, Op, [{Op, Tid}]}); + [{Oid, Prev, Items}] when Op == read -> + ?ets_insert(mnesia_held_locks, {Oid, Prev, [{Op, Tid}|Items]}); + [{Oid, _, Items}] when Op == write -> + ?ets_insert(mnesia_held_locks, {Oid, Op, [{Op, Tid}|Items]}) + end, ?ets_insert(mnesia_tid_locks, {Tid, Oid, Op}). %%%%%%%%%%%%%%%%%%%%%%%%%%% @@ -321,19 +328,19 @@ grant_lock(Tid, write, Lock, Oid) -> can_lock(Tid, read, {Tab, Key}, AlreadyQ) when Key /= ?ALL -> %% The key is bound, no need for the other BIF Oid = {Tab, Key}, - ObjLocks = ?ets_match_object(mnesia_held_locks, {{Oid, '_'}, write}), - TabLocks = ?ets_match_object(mnesia_held_locks, {{{Tab, ?ALL}, '_'}, write}), + ObjLocks = filter_write(?ets_lookup(mnesia_held_locks, Oid)), + TabLocks = filter_write(?ets_lookup(mnesia_held_locks, {Tab, ?ALL})), check_lock(Tid, Oid, ObjLocks, TabLocks, yes, AlreadyQ, read); can_lock(Tid, read, Oid, AlreadyQ) -> % Whole tab Tab = element(1, Oid), - ObjLocks = ?ets_match_object(mnesia_held_locks, {{{Tab, '_'}, '_'}, write}), + ObjLocks = ?ets_match_object(mnesia_held_locks, {{Tab, '_'}, write, '_'}), check_lock(Tid, Oid, ObjLocks, [], yes, AlreadyQ, read); can_lock(Tid, write, {Tab, Key}, AlreadyQ) when Key /= ?ALL -> Oid = {Tab, Key}, - ObjLocks = ?ets_match_object(mnesia_held_locks, ?match_oid_held_locks(Oid)), - TabLocks = ?ets_match_object(mnesia_held_locks, ?match_oid_held_locks({Tab, ?ALL})), + ObjLocks = ?ets_lookup(mnesia_held_locks, Oid), + TabLocks = ?ets_lookup(mnesia_held_locks, {Tab, ?ALL}), check_lock(Tid, Oid, ObjLocks, TabLocks, yes, AlreadyQ, write); can_lock(Tid, write, Oid, AlreadyQ) -> % Whole tab @@ -341,29 +348,16 @@ can_lock(Tid, write, Oid, AlreadyQ) -> % Whole tab ObjLocks = ?ets_match_object(mnesia_held_locks, ?match_oid_held_locks({Tab, '_'})), check_lock(Tid, Oid, ObjLocks, [], yes, AlreadyQ, write). +filter_write([{_, read, _}]) -> []; +filter_write(Res) -> Res. + %% Check held locks for conflicting locks -check_lock(Tid, Oid, [{{_,Tid}, _} | Locks], TabLocks, X, AlreadyQ, Type) -> - check_lock(Tid, Oid, Locks, TabLocks, X, AlreadyQ, Type); -check_lock(Tid, Oid, [Lock = {{_,WaitForTid}, _} | Locks], TabLocks, _X, AlreadyQ, Type) -> - Queue = allowed_to_be_queued(WaitForTid,Tid), - if Queue == true -> - check_lock(Tid, Oid, Locks, TabLocks, {queue, WaitForTid}, AlreadyQ, Type); - Tid#tid.pid == WaitForTid#tid.pid -> - dbg_out("Spurious lock conflict ~w ~w: ~w -> ~w~n", - [Oid, Lock, Tid, WaitForTid]), - %% Test.. - {Tab, _Key} = Oid, - HaveQ = (ets:lookup(mnesia_lock_queue, Oid) /= []) - orelse (ets:lookup(mnesia_lock_queue,{Tab,?ALL}) /= []), - if - HaveQ -> - {no, WaitForTid}; - true -> - check_lock(Tid,Oid,Locks,TabLocks,{queue,WaitForTid},AlreadyQ,Type) - end; - %%{no, WaitForTid}; Safe solution - true -> - {no, WaitForTid} +check_lock(Tid, Oid, [{_, _, Lock} | Locks], TabLocks, _X, AlreadyQ, Type) -> + case can_queue(Lock, Tid, Oid, _X) of + {no, _} = Res -> + Res; + Res -> + check_lock(Tid, Oid, Locks, TabLocks, Res, AlreadyQ, Type) end; check_lock(_, _, [], [], X, {queue, bad_luck}, _) -> @@ -400,6 +394,26 @@ check_lock(Tid, Oid, [], [], X, AlreadyQ, Type) -> check_lock(Tid, Oid, [], TabLocks, X, AlreadyQ, Type) -> check_lock(Tid, Oid, TabLocks, [], X, AlreadyQ, Type). +can_queue([{_Op, Tid}|Locks], Tid, Oid, Res) -> + can_queue(Locks, Tid, Oid, Res); +can_queue([{Op, WaitForTid}|Locks], Tid, Oid = {Tab, _}, _) -> + case allowed_to_be_queued(WaitForTid,Tid) of + true when Tid#tid.pid == WaitForTid#tid.pid -> + dbg_out("Spurious lock conflict ~w ~w: ~w -> ~w~n", + [Oid, Op, Tid, WaitForTid]), + HaveQ = (ets:lookup(mnesia_lock_queue, Oid) /= []) + orelse (ets:lookup(mnesia_lock_queue,{Tab,?ALL}) /= []), + case HaveQ of + true -> {no, WaitForTid}; + false -> can_queue(Locks, Tid, Oid, {queue, WaitForTid}) + end; + true -> + can_queue(Locks, Tid, Oid, {queue, WaitForTid}); + false -> + {no, WaitForTid} + end; +can_queue([], _, _, Res) -> Res. + %% True if WaitForTid > Tid -> % Important order allowed_to_be_queued(WaitForTid, Tid) -> case get(pid_sort_order) of @@ -517,12 +531,23 @@ release_locks([]) -> release_lock({Tid, Oid, {queued, _}}) -> ?ets_match_delete(mnesia_lock_queue, #queue{oid=Oid, tid = Tid, op = '_', pid = '_', lucky = '_'}); -release_lock({Tid, Oid, Op}) -> - if - Op == write -> - ?ets_delete(mnesia_held_locks, {Oid, Tid}); - Op == read -> - ets:delete_object(mnesia_held_locks, {{Oid, Tid}, Op}) +release_lock({This, Oid, Op}) -> + case ?ets_lookup(mnesia_held_locks, Oid) of + [] -> ok; + [{Oid, Prev, Locks0}] -> + Locks = [{TOp, Tid} || {TOp, Tid} <- Locks0, Tid =/= This], + if Locks =:= [] -> + ?ets_delete(mnesia_held_locks, Oid); + Op =:= read -> + ?ets_insert(mnesia_held_locks, {Oid, Prev, Locks}); + true -> + case lists:any(fun({TOp, _}) -> TOp =:= write end, Locks) of + true -> + ?ets_insert(mnesia_held_locks, {Oid, write, Locks}); + false -> + ?ets_insert(mnesia_held_locks, {Oid, read, Locks}) + end + end end. rearrange_queue([{_Tid, {Tab, Key}, _} | Locks]) -> @@ -1113,12 +1138,23 @@ rec_requests([], _Oid, _Store) -> get_held_locks() -> ?MODULE ! {get_table, self(), mnesia_held_locks}, - Locks = receive {mnesia_held_locks, Ls} -> Ls end, - [{Oid, Op, Tid} || {{Oid, Tid}, Op} <- Locks]. + Locks = receive {mnesia_held_locks, Ls} -> Ls after 5000 -> [] end, + rewrite_locks(Locks, []). + +rewrite_locks([{Oid, _, Ls}|Locks], Acc0) -> + Acc = rewrite_locks(Ls, Oid, Acc0), + rewrite_locks(Locks, Acc); +rewrite_locks([], Acc) -> + lists:reverse(Acc). + +rewrite_locks([{Op, Tid}|Ls], Oid, Acc) -> + rewrite_locks(Ls, Oid, [{Oid, Op, Tid}|Acc]); +rewrite_locks([], _, Acc) -> + Acc. get_lock_queue() -> ?MODULE ! {get_table, self(), mnesia_lock_queue}, - Q = receive {mnesia_lock_queue, Locks} -> Locks end, + Q = receive {mnesia_lock_queue, Locks} -> Locks after 5000 -> [] end, [{Oid, Op, Pid, Tid, WFT} || {queue, Oid, Tid, Op, Pid, WFT} <- Q]. do_stop() -> |