diff options
Diffstat (limited to 'lib/mnesia/src/mnesia_tm.erl')
| -rw-r--r-- | lib/mnesia/src/mnesia_tm.erl | 76 |
1 files changed, 66 insertions, 10 deletions
diff --git a/lib/mnesia/src/mnesia_tm.erl b/lib/mnesia/src/mnesia_tm.erl index bb8e788b40..c7a0c28589 100644 --- a/lib/mnesia/src/mnesia_tm.erl +++ b/lib/mnesia/src/mnesia_tm.erl @@ -64,7 +64,8 @@ prev_tab = [], % initiate to a non valid table name prev_types, prev_snmp, - types + types, + majority = [] }). -record(participant, {tid, pid, commit, disc_nodes = [], @@ -1100,9 +1101,12 @@ t_commit(Type) -> case arrange(Tid, Store, Type) of {N, Prep} when N > 0 -> multi_commit(Prep#prep.protocol, + majority_attr(Prep), Tid, Prep#prep.records, Store); {0, Prep} -> - multi_commit(read_only, Tid, Prep#prep.records, Store) + multi_commit(read_only, + majority_attr(Prep), + Tid, Prep#prep.records, Store) end; true -> %% nested commit @@ -1117,6 +1121,12 @@ t_commit(Type) -> do_commit_nested end. +majority_attr(#prep{majority = M}) -> + M; +majority_attr(_) -> + []. + + %% This function arranges for all objects we shall write in S to be %% in a list of {Node, CommitRecord} %% Important function for the performance of mnesia. @@ -1222,11 +1232,13 @@ prepare_items(Tid, Tab, Key, Items, Prep) -> {blocked, _} -> unblocked = req({unblock_me, Tab}), prepare_items(Tid, Tab, Key, Items, Prep); - _ -> + _ -> + Majority = needs_majority(Tab, Prep), Snmp = val({Tab, snmp}), Recs2 = do_prepare_items(Tid, Tab, Key, Types, Snmp, Items, Prep#prep.records), Prep2 = Prep#prep{records = Recs2, prev_tab = Tab, + majority = Majority, prev_types = Types, prev_snmp = Snmp}, check_prep(Prep2, Types) end. @@ -1235,6 +1247,41 @@ do_prepare_items(Tid, Tab, Key, Types, Snmp, Items, Recs) -> Recs2 = prepare_snmp(Tid, Tab, Key, Types, Snmp, Items, Recs), % May exit prepare_nodes(Tid, Types, Items, Recs2, normal). + +needs_majority(Tab, #prep{majority = M}) -> + case lists:keymember(Tab, 1, M) of + true -> + M; + false -> + case ?catch_val({Tab, majority}) of + {'EXIT', _} -> + M; + false -> + [{Tab, []} | M]; + true -> + CopyHolders = all_copy_holders(Tab), + [{Tab, CopyHolders} | M] + end + end. + +all_copy_holders(Tab) -> + DC = val({Tab, disc_copies}), + DO = val({Tab, disc_only_copies}), + RC = val({Tab, ram_copies}), + DC ++ DO ++ RC. + +have_majority([], _) -> + ok; +have_majority([{Tab, AllNodes} | Rest], Nodes) -> + Missing = AllNodes -- Nodes, + Present = AllNodes -- Missing, + case length(Present) > length(Missing) of + true -> + have_majority(Rest, Nodes); + false -> + {error, Tab} + end. + prepare_snmp(Tab, Key, Items) -> case val({Tab, snmp}) of [] -> @@ -1261,10 +1308,15 @@ prepare_snmp(Tid, Tab, Key, Types, Us, Items, Recs) -> prepare_nodes(Tid, Types, [{clear_table, Tab}], Recs, snmp) end. -check_prep(Prep, Types) when Prep#prep.types == Types -> +check_prep(#prep{majority = [], types = Types} = Prep, Types) -> Prep; -check_prep(Prep, Types) when Prep#prep.types == undefined -> - Prep#prep{types = Types}; +check_prep(#prep{majority = M, types = undefined} = Prep, Types) -> + Protocol = if M == [] -> + Prep#prep.protocol; + true -> + asym_trans + end, + Prep#prep{protocol = Protocol, types = Types}; check_prep(Prep, _Types) -> Prep#prep{protocol = asym_trans}. @@ -1311,7 +1363,7 @@ prepare_node(_Node, _Storage, [], Rec, _Kind) -> %% multi_commit((Protocol, Tid, CommitRecords, Store) %% Local work is always performed in users process -multi_commit(read_only, Tid, CR, _Store) -> +multi_commit(read_only, _Maj = [], Tid, CR, _Store) -> %% This featherweight commit protocol is used when no %% updates has been performed in the transaction. @@ -1324,7 +1376,7 @@ multi_commit(read_only, Tid, CR, _Store) -> ?MODULE ! {delete_transaction, Tid}, do_commit; -multi_commit(sym_trans, Tid, CR, Store) -> +multi_commit(sym_trans, _Maj = [], Tid, CR, Store) -> %% This lightweight commit protocol is used when all %% the involved tables are replicated symetrically. %% Their storage types must match on each node. @@ -1376,7 +1428,7 @@ multi_commit(sym_trans, Tid, CR, Store) -> [{tid, Tid}, {outcome, Outcome}]), Outcome; -multi_commit(sync_sym_trans, Tid, CR, Store) -> +multi_commit(sync_sym_trans, _Maj = [], Tid, CR, Store) -> %% This protocol is the same as sym_trans except that it %% uses syncronized calls to disk_log and syncronized commits %% when several nodes are involved. @@ -1408,7 +1460,7 @@ multi_commit(sync_sym_trans, Tid, CR, Store) -> [{tid, Tid}, {outcome, Outcome}]), Outcome; -multi_commit(asym_trans, Tid, CR, Store) -> +multi_commit(asym_trans, Majority, Tid, CR, Store) -> %% This more expensive commit protocol is used when %% table definitions are changed (schema transactions). %% It is also used when the involved tables are @@ -1469,6 +1521,10 @@ multi_commit(asym_trans, Tid, CR, Store) -> {D2, CR2} = commit_decision(D, CR, [], []), DiscNs = D2#decision.disc_nodes, RamNs = D2#decision.ram_nodes, + case have_majority(Majority, DiscNs ++ RamNs) of + ok -> ok; + {error, Tab} -> mnesia:abort({no_majority, Tab}) + end, Pending = mnesia_checkpoint:tm_enter_pending(Tid, DiscNs, RamNs), ?ets_insert(Store, Pending), {WaitFor, Local} = ask_commit(asym_trans, Tid, CR2, DiscNs, RamNs), |