The R13B03 release.OTP_R13B03

1 files changed, 1218 insertions, 0 deletions

diff --git a/lib/mnesia/src/mnesia_dumper.erl b/lib/mnesia/src/mnesia_dumper.erl
new file mode 100644
index 0000000000..f669d009c6
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+++ b/lib/mnesia/src/mnesia_dumper.erl
@@ -0,0 +1,1218 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 1996-2009. All Rights Reserved.
+%% 
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+%%
+-module(mnesia_dumper).
+
+%% The InitBy arg may be one of the following:
+%% scan_decisions     Initial scan for decisions
+%% startup	      Initial dump during startup
+%% schema_prepare     Dump initiated during schema transaction preparation
+%% schema_update      Dump initiated during schema transaction commit
+%% fast_schema_update A schema_update, but ignores the log file
+%% user		      Dump initiated by user
+%% write_threshold    Automatic dump caused by too many log writes
+%% time_threshold     Automatic dump caused by timeout
+
+%% Public interface
+-export([
+	 get_log_writes/0,
+	 incr_log_writes/0,
+	 raw_dump_table/2,
+	 raw_named_dump_table/2,
+	 start_regulator/0,
+	 opt_dump_log/1,
+	 update/3
+	]).
+
+ %% Internal stuff
+-export([regulator_init/1]).
+	
+-include("mnesia.hrl").
+-include_lib("kernel/include/file.hrl").
+
+-import(mnesia_lib, [fatal/2, dbg_out/2]).
+
+-define(REGULATOR_NAME, mnesia_dumper_load_regulator).
+-define(DumpToEtsMultiplier, 4).
+
+get_log_writes() ->
+    Max = mnesia_monitor:get_env(dump_log_write_threshold),
+    Prev = mnesia_lib:read_counter(trans_log_writes),
+    Left = mnesia_lib:read_counter(trans_log_writes_left),
+    Diff = Max - Left,
+    Prev + Diff.
+
+incr_log_writes() ->
+    Left = mnesia_lib:incr_counter(trans_log_writes_left, -1),
+    if
+	Left > 0 ->
+	    ignore;
+	true ->
+	    adjust_log_writes(true)
+    end.
+
+adjust_log_writes(DoCast) ->
+    Token = {mnesia_adjust_log_writes, self()},
+    case global:set_lock(Token, [node()], 1) of 
+	false ->
+	    ignore; %% Somebody else is sending a dump request
+	true -> 
+	    case DoCast of 
+		false ->
+		    ignore;
+		true -> 
+		    mnesia_controller:async_dump_log(write_threshold)
+	    end,
+	    Max = mnesia_monitor:get_env(dump_log_write_threshold),
+	    Left = mnesia_lib:read_counter(trans_log_writes_left),
+	    %% Don't care if we lost a few writes
+	    mnesia_lib:set_counter(trans_log_writes_left, Max),
+	    Diff = Max - Left,
+	    mnesia_lib:incr_counter(trans_log_writes, Diff),
+	    global:del_lock(Token, [node()])
+    end.
+
+%% Returns 'ok' or exits
+opt_dump_log(InitBy) ->
+    Reg = case whereis(?REGULATOR_NAME) of
+	      undefined ->
+		  nopid; 
+	      Pid when is_pid(Pid) ->
+		  Pid 
+	  end,
+    perform_dump(InitBy, Reg).
+
+%% Scan for decisions
+perform_dump(InitBy, Regulator) when InitBy == scan_decisions ->
+    ?eval_debug_fun({?MODULE, perform_dump}, [InitBy]),
+    
+    dbg_out("Transaction log dump initiated by ~w~n", [InitBy]),
+    scan_decisions(mnesia_log:previous_log_file(), InitBy, Regulator),
+    scan_decisions(mnesia_log:latest_log_file(), InitBy, Regulator);
+
+%% Propagate the log into the DAT-files
+perform_dump(InitBy, Regulator) ->
+    ?eval_debug_fun({?MODULE, perform_dump}, [InitBy]),
+    LogState = mnesia_log:prepare_log_dump(InitBy),
+    dbg_out("Transaction log dump initiated by ~w: ~w~n",
+	    [InitBy, LogState]), 
+    adjust_log_writes(false),    
+    case LogState of
+	already_dumped ->
+	    mnesia_recover:allow_garb(),
+	    dumped;
+	{needs_dump, Diff} ->
+	    U = mnesia_monitor:get_env(dump_log_update_in_place),
+	    Cont = mnesia_log:init_log_dump(),
+	    mnesia_recover:sync(),
+	    case catch do_perform_dump(Cont, U, InitBy, Regulator, undefined) of
+		ok ->
+		    ?eval_debug_fun({?MODULE, post_dump}, [InitBy]),
+		    case mnesia_monitor:use_dir() of
+			true ->
+			    mnesia_recover:dump_decision_tab();
+			false ->
+			    mnesia_log:purge_some_logs()
+		    end,
+		    mnesia_recover:allow_garb(),
+		    %% And now to the crucial point...
+		    mnesia_log:confirm_log_dump(Diff);
+		{error, Reason} ->
+		    {error, Reason};
+ 		{'EXIT', {Desc, Reason}} ->
+		    case mnesia_monitor:get_env(auto_repair) of
+			true ->
+			    mnesia_lib:important(Desc, Reason),
+			    %% Ignore rest of the log
+			    mnesia_log:confirm_log_dump(Diff);
+			false -> 
+			    fatal(Desc, Reason)
+		    end
+	    end;
+	{error, Reason} ->
+	    {error, {"Cannot prepare log dump", Reason}}
+    end.
+
+scan_decisions(Fname, InitBy, Regulator) ->
+    Exists = mnesia_lib:exists(Fname),
+    case Exists of
+	false ->
+	    ok;
+	true ->
+	    Header = mnesia_log:trans_log_header(),
+	    Name = previous_log,
+	    mnesia_log:open_log(Name, Header, Fname, Exists,
+				mnesia_monitor:get_env(auto_repair), read_only),
+	    Cont = start,
+	    Res = (catch do_perform_dump(Cont, false, InitBy, Regulator, undefined)),
+	    mnesia_log:close_log(Name),
+	    case Res of
+		ok -> ok;
+		{'EXIT', Reason} -> {error, Reason}
+	    end
+    end.
+
+do_perform_dump(Cont, InPlace, InitBy, Regulator, OldVersion) ->
+    case mnesia_log:chunk_log(Cont) of
+	{C2, Recs} ->
+	    case catch insert_recs(Recs, InPlace, InitBy, Regulator, OldVersion) of
+		{'EXIT', R} ->
+		    Reason = {"Transaction log dump error: ~p~n", [R]},
+		    close_files(InPlace, {error, Reason}, InitBy),
+		    exit(Reason);
+		Version ->
+		    do_perform_dump(C2, InPlace, InitBy, Regulator, Version)
+	    end;
+	eof ->
+	    close_files(InPlace, ok, InitBy),
+	    erase(mnesia_dumper_dets),
+	    ok
+    end.
+
+insert_recs([Rec | Recs], InPlace, InitBy, Regulator, LogV) ->
+    regulate(Regulator),
+    case insert_rec(Rec, InPlace, InitBy, LogV) of
+ 	LogH when is_record(LogH, log_header) ->	    
+	    insert_recs(Recs, InPlace, InitBy, Regulator, LogH#log_header.log_version);
+	_ -> 
+	    insert_recs(Recs, InPlace, InitBy, Regulator, LogV)
+    end;
+
+insert_recs([], _InPlace, _InitBy, _Regulator, Version) ->
+    Version.
+
+insert_rec(Rec, _InPlace, scan_decisions, _LogV) ->
+    if 
+	is_record(Rec, commit) ->
+	    ignore;
+	is_record(Rec, log_header) ->
+	    ignore;
+	true ->
+	    mnesia_recover:note_log_decision(Rec, scan_decisions)
+    end;
+insert_rec(Rec, InPlace, InitBy, LogV) when is_record(Rec, commit) ->
+    %% Determine the Outcome of the transaction and recover it
+    D = Rec#commit.decision,
+    case mnesia_recover:wait_for_decision(D, InitBy) of
+	{Tid, committed} ->
+	    do_insert_rec(Tid, Rec, InPlace, InitBy, LogV);
+	{Tid, aborted} ->
+	    mnesia_schema:undo_prepare_commit(Tid, Rec)
+    end;
+insert_rec(H, _InPlace, _InitBy, _LogV) when is_record(H, log_header) ->
+    CurrentVersion = mnesia_log:version(),
+    if
+        H#log_header.log_kind /= trans_log ->
+	    exit({"Bad kind of transaction log", H});
+	H#log_header.log_version == CurrentVersion ->
+	    ok; 
+	H#log_header.log_version == "4.2" ->
+	    ok;
+	H#log_header.log_version == "4.1" ->
+	    ok;
+	H#log_header.log_version == "4.0" ->
+	    ok;
+	true ->
+	    fatal("Bad version of transaction log: ~p~n", [H])
+    end,
+    H;
+
+insert_rec(_Rec, _InPlace, _InitBy, _LogV) ->
+    ok.
+
+do_insert_rec(Tid, Rec, InPlace, InitBy, LogV) ->
+    case Rec#commit.schema_ops of
+	[] ->
+	    ignore;
+	SchemaOps ->
+	    case val({schema, storage_type}) of 
+		ram_copies -> 
+		    insert_ops(Tid, schema_ops, SchemaOps, InPlace, InitBy, LogV);
+	        Storage ->
+		    true = open_files(schema, Storage, InPlace, InitBy),
+		    insert_ops(Tid, schema_ops, SchemaOps, InPlace, InitBy, LogV)
+	    end
+    end,
+    D = Rec#commit.disc_copies,
+    insert_ops(Tid, disc_copies, D, InPlace, InitBy, LogV),
+    case InitBy of
+	startup ->
+	    DO = Rec#commit.disc_only_copies,
+	    insert_ops(Tid, disc_only_copies, DO, InPlace, InitBy, LogV);
+	_ ->
+	    ignore
+    end.
+    
+
+update(_Tid, [], _DumperMode) ->
+    dumped;
+update(Tid, SchemaOps, DumperMode) ->
+    UseDir = mnesia_monitor:use_dir(),
+    Res = perform_update(Tid, SchemaOps, DumperMode, UseDir),    
+    mnesia_controller:release_schema_commit_lock(),
+    Res.
+
+perform_update(_Tid, _SchemaOps, mandatory, true) ->
+    %% Force a dump of the transaction log in order to let the
+    %% dumper perform needed updates
+
+    InitBy = schema_update,
+    ?eval_debug_fun({?MODULE, dump_schema_op}, [InitBy]),    
+    opt_dump_log(InitBy);
+perform_update(Tid, SchemaOps, _DumperMode, _UseDir) ->
+    %% No need for a full transaction log dump.
+    %% Ignore the log file and perform only perform
+    %% the corresponding updates.
+
+    InitBy = fast_schema_update, 
+    InPlace = mnesia_monitor:get_env(dump_log_update_in_place),
+    ?eval_debug_fun({?MODULE, dump_schema_op}, [InitBy]),
+    case catch insert_ops(Tid, schema_ops, SchemaOps, InPlace, InitBy, 
+			  mnesia_log:version()) of
+	{'EXIT', Reason} ->
+	    Error = {error, {"Schema update error", Reason}},
+	    close_files(InPlace, Error, InitBy),
+            fatal("Schema update error ~p ~p", [Reason, SchemaOps]);
+	_ ->		    
+	    ?eval_debug_fun({?MODULE, post_dump}, [InitBy]),
+	    close_files(InPlace, ok, InitBy),
+	    ok
+    end.
+
+insert_ops(_Tid, _Storage, [], _InPlace, _InitBy, _) ->    ok;
+insert_ops(Tid, Storage, [Op], InPlace, InitBy, Ver)  when Ver >= "4.3"->
+    insert_op(Tid, Storage, Op, InPlace, InitBy),
+    ok;
+insert_ops(Tid, Storage, [Op | Ops], InPlace, InitBy, Ver)  when Ver >= "4.3"->
+    insert_op(Tid, Storage, Op, InPlace, InitBy),
+    insert_ops(Tid, Storage, Ops, InPlace, InitBy, Ver);
+insert_ops(Tid, Storage, [Op | Ops], InPlace, InitBy, Ver) when Ver < "4.3" ->
+    insert_ops(Tid, Storage, Ops, InPlace, InitBy, Ver),
+    insert_op(Tid, Storage, Op, InPlace, InitBy).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Normal ops
+
+disc_insert(_Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy) ->
+    case open_files(Tab, Storage, InPlace, InitBy) of
+	true ->
+	    case Storage of 
+		disc_copies when Tab /= schema ->
+		    mnesia_log:append({?MODULE,Tab}, {{Tab, Key}, Val, Op}),
+		    ok;
+		_ ->
+		    dets_insert(Op,Tab,Key,Val)
+	    end;
+	false ->
+	    ignore
+    end.
+
+%% To fix update_counter so that it behaves better.
+%% i.e. if nothing have changed in tab except update_counter
+%% trust that the value in the dets file is correct. 
+%% Otherwise we will get a double increment.
+%% This is perfect but update_counter is a dirty op.
+
+dets_insert(Op,Tab,Key,Val) ->
+    case Op of
+	write ->
+	    dets_updated(Tab,Key),
+	    ok = dets:insert(Tab, Val);
+	delete ->
+	    dets_updated(Tab,Key),
+	    ok = dets:delete(Tab, Key);
+	update_counter ->
+	    case dets_incr_counter(Tab,Key) of
+		true ->
+		    {RecName, Incr} = Val,
+		    case catch dets:update_counter(Tab, Key, Incr) of
+			CounterVal when is_integer(CounterVal) ->
+			    ok;
+			_ when Incr < 0 ->
+			    Zero = {RecName, Key, 0},
+			    ok = dets:insert(Tab, Zero);
+			_ -> 
+			    Init = {RecName, Key, Incr},
+			    ok = dets:insert(Tab, Init)
+		    end;
+		false ->  ok
+	    end;				    
+	delete_object ->
+	    dets_updated(Tab,Key),
+	    ok = dets:delete_object(Tab, Val);
+	clear_table ->
+	    dets_cleared(Tab),
+	    ok = dets:match_delete(Tab, '_')
+    end.
+	    
+dets_updated(Tab,Key) -> 
+    case get(mnesia_dumper_dets) of
+	undefined -> 
+	    Empty = gb_trees:empty(),
+	    Tree = gb_trees:insert(Tab, gb_sets:singleton(Key), Empty),
+	    put(mnesia_dumper_dets, Tree);
+	Tree ->
+	    case gb_trees:lookup(Tab,Tree) of
+		{value, cleared} -> ignore;
+		{value, Set} -> 
+		    T = gb_trees:update(Tab, gb_sets:add(Key, Set), Tree),
+		    put(mnesia_dumper_dets, T);
+		none ->
+		    T = gb_trees:insert(Tab, gb_sets:singleton(Key), Tree),
+		    put(mnesia_dumper_dets, T)
+	    end
+    end.
+
+dets_incr_counter(Tab,Key) ->
+    case get(mnesia_dumper_dets) of
+	undefined -> false;
+	Tree ->
+	    case gb_trees:lookup(Tab,Tree) of
+		{value, cleared} -> true;
+		{value, Set} -> gb_sets:is_member(Key, Set);
+		none -> false
+	    end
+    end.
+
+dets_cleared(Tab) ->
+    case get(mnesia_dumper_dets) of
+	undefined -> 
+	    Empty = gb_trees:empty(),
+	    Tree = gb_trees:insert(Tab, cleared, Empty),
+	    put(mnesia_dumper_dets, Tree);
+	Tree ->
+	    case gb_trees:lookup(Tab,Tree) of
+		{value, cleared} -> ignore;
+		_ -> 
+		    T = gb_trees:enter(Tab, cleared, Tree),
+		    put(mnesia_dumper_dets, T)
+	    end
+    end.
+
+insert(Tid, Storage, Tab, Key, [Val | Tail], Op, InPlace, InitBy) ->
+    insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy),
+    insert(Tid, Storage, Tab, Key, Tail, Op, InPlace, InitBy);
+
+insert(_Tid, _Storage, _Tab, _Key, [], _Op, _InPlace, _InitBy) ->
+    ok;
+    
+insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy) ->
+    Item = {{Tab, Key}, Val, Op},
+    case InitBy of
+	startup ->
+	    disc_insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy);
+
+	_ when Storage == ram_copies ->
+	    mnesia_tm:do_update_op(Tid, Storage, Item),
+	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
+	    mnesia_tm:do_snmp(Tid, Snmp);
+
+	_ when Storage == disc_copies ->
+	    disc_insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy),
+	    mnesia_tm:do_update_op(Tid, Storage, Item),
+	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
+	    mnesia_tm:do_snmp(Tid, Snmp);
+
+	_ when Storage == disc_only_copies ->
+	    mnesia_tm:do_update_op(Tid, Storage, Item),
+	    Snmp = mnesia_tm:prepare_snmp(Tab, Key, [Item]),
+	    mnesia_tm:do_snmp(Tid, Snmp);
+
+	_ when Storage == unknown ->
+	    ignore
+    end.
+
+disc_delete_table(Tab, Storage) ->
+    case mnesia_monitor:use_dir() of
+	true ->
+	    if 		
+		Storage == disc_only_copies; Tab == schema ->  
+		    mnesia_monitor:unsafe_close_dets(Tab),
+		    Dat = mnesia_lib:tab2dat(Tab),
+		    file:delete(Dat);		
+		true -> 
+		    DclFile = mnesia_lib:tab2dcl(Tab),
+		    case get({?MODULE,Tab}) of
+			{opened_dumper, dcl} ->
+			    del_opened_tab(Tab),
+			    mnesia_log:unsafe_close_log(Tab);
+			_ -> 
+			    ok
+		    end,
+		    file:delete(DclFile),
+		    DcdFile = mnesia_lib:tab2dcd(Tab),
+		    file:delete(DcdFile),
+		    ok
+	    end,
+	    erase({?MODULE, Tab});
+	false ->
+	    ignore
+    end.
+
+disc_delete_indecies(_Tab, _Cs, Storage) when Storage /= disc_only_copies ->
+    ignore;
+disc_delete_indecies(Tab, Cs, disc_only_copies) ->
+    Indecies = Cs#cstruct.index,
+    mnesia_index:del_transient(Tab, Indecies, disc_only_copies).
+
+insert_op(Tid, Storage, {{Tab, Key}, Val, Op}, InPlace, InitBy) ->
+    %% Propagate to disc only
+    disc_insert(Tid, Storage, Tab, Key, Val, Op, InPlace, InitBy);
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% NOTE that all operations below will only
+%% be performed if the dump is initiated by
+%% startup or fast_schema_update
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+insert_op(_Tid, schema_ops, _OP, _InPlace, Initby)
+  when Initby /= startup,
+       Initby /= fast_schema_update,
+       Initby /= schema_update -> 
+    ignore;
+
+insert_op(Tid, _, {op, rec, Storage, Item}, InPlace, InitBy) ->
+    {{Tab, Key}, ValList, Op} = Item,
+    insert(Tid, Storage, Tab, Key, ValList, Op, InPlace, InitBy);
+
+insert_op(Tid, _, {op, change_table_copy_type, N, FromS, ToS, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Val = mnesia_schema:insert_cstruct(Tid, Cs, true), % Update ram only
+    {schema, Tab, _} = Val,
+    case lists:member(N, val({current, db_nodes})) of
+	true when InitBy /= startup  ->
+	    mnesia_controller:add_active_replica(Tab, N, Cs);
+	_ ->
+	    ignore
+    end,
+    if  
+	N == node() ->
+	    Dmp  = mnesia_lib:tab2dmp(Tab),
+	    Dat  = mnesia_lib:tab2dat(Tab),
+	    Dcd  = mnesia_lib:tab2dcd(Tab),
+	    Dcl  = mnesia_lib:tab2dcl(Tab),
+	    case {FromS, ToS} of
+		{ram_copies, disc_copies} when Tab == schema ->
+		    ok = ensure_rename(Dmp, Dat);
+		{ram_copies, disc_copies} ->
+		    file:delete(Dcl),
+		    ok = ensure_rename(Dmp, Dcd);
+		{disc_copies, ram_copies} when Tab == schema ->
+		    mnesia_lib:set(use_dir, false),
+		    mnesia_monitor:unsafe_close_dets(Tab),
+		    file:delete(Dat);
+		{disc_copies, ram_copies} ->
+		    file:delete(Dcl),
+		    file:delete(Dcd);
+		{ram_copies, disc_only_copies} ->
+		    ok = ensure_rename(Dmp, Dat),
+		    true = open_files(Tab, disc_only_copies, InPlace, InitBy),
+		    %% ram_delete_table must be done before init_indecies,
+		    %% it uses info which is reset in init_indecies,
+		    %% it doesn't matter, because init_indecies don't use 
+		    %% the ram replica of the table when creating the disc 
+		    %% index; Could be improved :)
+		    mnesia_schema:ram_delete_table(Tab, FromS),
+		    PosList = Cs#cstruct.index,
+		    mnesia_index:init_indecies(Tab, disc_only_copies, PosList);
+		{disc_only_copies, ram_copies} ->
+		    mnesia_monitor:unsafe_close_dets(Tab),
+		    disc_delete_indecies(Tab, Cs, disc_only_copies),
+		    case InitBy of 
+			startup -> 
+			    ignore;
+			_ -> 
+			    mnesia_controller:get_disc_copy(Tab)
+		    end,
+		    disc_delete_table(Tab, disc_only_copies);
+		{disc_copies, disc_only_copies} ->
+		    ok = ensure_rename(Dmp, Dat),
+		    true = open_files(Tab, disc_only_copies, InPlace, InitBy),
+		    mnesia_schema:ram_delete_table(Tab, FromS), 
+		    PosList = Cs#cstruct.index,
+		    mnesia_index:init_indecies(Tab, disc_only_copies, PosList),
+		    file:delete(Dcl),
+		    file:delete(Dcd);
+		{disc_only_copies, disc_copies} ->
+		    mnesia_monitor:unsafe_close_dets(Tab),
+		    disc_delete_indecies(Tab, Cs, disc_only_copies),
+		    case InitBy of 
+			startup -> 
+			    ignore;
+			_ ->
+			    mnesia_log:ets2dcd(Tab),
+			    mnesia_controller:get_disc_copy(Tab),
+			    disc_delete_table(Tab, disc_only_copies)
+		    end
+	    end;
+	true ->
+	    ignore
+    end,
+    S = val({schema, storage_type}),
+    disc_insert(Tid, S, schema, Tab, Val, write, InPlace, InitBy);
+
+insert_op(Tid, _, {op, transform, _Fun, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    case mnesia_lib:cs_to_storage_type(node(), Cs) of
+	disc_copies -> 
+	    open_dcl(Cs#cstruct.name);
+	_ ->
+	    ignore
+    end,
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+%%%  Operations below this are handled without using the logg.
+
+insert_op(Tid, _, {op, restore_recreate, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    Type = Cs#cstruct.type,
+    Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    %% Delete all possibly existing files and tables
+    disc_delete_table(Tab, Storage),
+    disc_delete_indecies(Tab, Cs, Storage),
+    case InitBy of
+	startup ->
+	    ignore;
+	_ ->
+	    case ?catch_val({Tab, cstruct}) of
+		{'EXIT', _} -> ignore;
+		_ ->
+		    mnesia_schema:ram_delete_table(Tab, Storage),
+		    mnesia_checkpoint:tm_del_copy(Tab, node())
+	    end
+    end,
+    %% And create new ones..
+    if
+	(InitBy == startup) or (Storage == unknown) ->
+	    ignore;
+	Storage == ram_copies ->
+	    Args = [{keypos, 2}, public, named_table, Type],
+	    mnesia_monitor:mktab(Tab, Args);
+	Storage == disc_copies ->
+	    Args = [{keypos, 2}, public, named_table, Type],
+	    mnesia_monitor:mktab(Tab, Args),
+	    File = mnesia_lib:tab2dcd(Tab),	    
+	    FArg = [{file, File}, {name, {mnesia,create}}, 
+		    {repair, false}, {mode, read_write}],
+	    {ok, Log} = mnesia_monitor:open_log(FArg),
+	    mnesia_monitor:unsafe_close_log(Log);
+	Storage == disc_only_copies ->
+	    File = mnesia_lib:tab2dat(Tab),
+	    file:delete(File),
+	    Args = [{file, mnesia_lib:tab2dat(Tab)},
+		    {type, mnesia_lib:disk_type(Tab, Type)},
+		    {keypos, 2},
+		    {repair, mnesia_monitor:get_env(auto_repair)}],
+	    mnesia_monitor:open_dets(Tab, Args)
+    end,
+    insert_op(Tid, ignore, {op, create_table, TabDef}, InPlace, InitBy);
+
+insert_op(Tid, _, {op, create_table, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    insert_cstruct(Tid, Cs, false, InPlace, InitBy),
+    Tab = Cs#cstruct.name,
+    Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    case InitBy of
+	startup ->
+	    case Storage of
+		unknown ->
+		    ignore;
+		ram_copies ->
+		    ignore;
+		disc_copies ->
+		    Dcd = mnesia_lib:tab2dcd(Tab),
+		    case mnesia_lib:exists(Dcd) of  
+			true -> ignore;
+			false ->
+			    mnesia_log:open_log(temp, 
+						mnesia_log:dcl_log_header(),
+						Dcd, 
+						false, 
+						false,
+						read_write),
+			    mnesia_log:unsafe_close_log(temp)
+		    end;
+		_ ->
+		    Args = [{file, mnesia_lib:tab2dat(Tab)},
+			    {type, mnesia_lib:disk_type(Tab, Cs#cstruct.type)},
+			    {keypos, 2},
+			    {repair, mnesia_monitor:get_env(auto_repair)}],
+		    case mnesia_monitor:open_dets(Tab, Args) of
+			{ok, _} ->
+			    mnesia_monitor:unsafe_close_dets(Tab);
+			{error, Error} ->
+			    exit({"Failed to create dets table", Error})
+		    end
+	    end;
+	_ ->
+	    Copies = mnesia_lib:copy_holders(Cs),
+	    Active = mnesia_lib:intersect(Copies, val({current, db_nodes})),
+	    [mnesia_controller:add_active_replica(Tab, N, Cs) || N <- Active],
+
+	    case Storage of
+		unknown ->
+		    mnesia_lib:unset({Tab, create_table}),
+		    case Cs#cstruct.local_content of
+			true ->
+			    ignore;
+			false ->
+			    mnesia_lib:set_remote_where_to_read(Tab)
+		    end;
+		_ ->
+		    case Cs#cstruct.local_content of
+			true ->
+			    mnesia_lib:set_local_content_whereabouts(Tab);
+			false ->
+			    mnesia_lib:set({Tab, where_to_read}, node())
+		    end,
+		    case Storage of
+			ram_copies ->
+			    ignore;
+			_ ->
+			    %% Indecies are still created by loader
+			    disc_delete_indecies(Tab, Cs, Storage)
+			    %% disc_delete_table(Tab, Storage)
+		    end, 
+		    
+		    %% Update whereabouts and create table
+		    mnesia_controller:create_table(Tab),
+		    mnesia_lib:unset({Tab, create_table})
+	    end
+    end;
+
+insert_op(_Tid, _, {op, dump_table, Size, TabDef}, _InPlace, _InitBy) ->
+    case Size of
+	unknown ->
+	    ignore;
+	_ ->
+	    Cs = mnesia_schema:list2cs(TabDef),
+	    Tab = Cs#cstruct.name,
+	    Dmp = mnesia_lib:tab2dmp(Tab),
+	    Dat = mnesia_lib:tab2dcd(Tab),
+	    case Size of
+		0 ->
+	    	    %% Assume that table files already are closed
+		    file:delete(Dmp),
+		    file:delete(Dat);
+		_ ->
+		    ok = ensure_rename(Dmp, Dat)
+	    end
+    end;
+
+insert_op(Tid, _, {op, delete_table, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    case mnesia_lib:cs_to_storage_type(node(), Cs) of
+	unknown ->
+	    ignore;
+	Storage ->
+	    disc_delete_table(Tab, Storage),
+	    disc_delete_indecies(Tab, Cs, Storage),
+	    case InitBy of
+		startup ->
+		    ignore;
+		_ ->
+		    mnesia_schema:ram_delete_table(Tab, Storage),
+		    mnesia_checkpoint:tm_del_copy(Tab, node())
+	    end
+    end,
+    delete_cstruct(Tid, Cs, InPlace, InitBy);
+
+insert_op(Tid, _, {op, clear_table, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    case mnesia_lib:cs_to_storage_type(node(), Cs) of
+	unknown ->
+	    ignore;
+	Storage ->
+	    Oid = '_', %%val({Tab, wild_pattern}),
+	    if Storage == disc_copies ->
+		    open_dcl(Cs#cstruct.name);
+	       true ->
+		    ignore
+	    end,
+	    %% Need to catch this, it crashes on ram_copies if 
+	    %% the op comes before table is loaded at startup.
+	    catch insert(Tid, Storage, Tab, '_', Oid, clear_table, InPlace, InitBy)
+    end;
+
+insert_op(Tid, _, {op, merge_schema, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    case Cs#cstruct.name of
+	schema ->
+	    %% If we bootstrap an empty (diskless) mnesia from another node
+	    %% we might have changed the storage_type of schema.
+	    %% I think this is a good place to do it.
+	    Update = fun(NS = {Node,Storage}) -> 
+			     case mnesia_lib:cs_to_storage_type(Node, Cs) of
+				 Storage -> NS;
+				 disc_copies when Node == node() -> 
+				     Dir = mnesia_lib:dir(),    
+				     ok = mnesia_schema:opt_create_dir(true, Dir),
+				     mnesia_schema:purge_dir(Dir, []),
+				     mnesia_log:purge_all_logs(),
+
+				     mnesia_lib:set(use_dir, true),	     
+				     mnesia_log:init(),
+				     Ns = val({current, db_nodes}),
+				     F = fun(U) -> mnesia_recover:log_mnesia_up(U) end,
+				     lists:foreach(F, Ns),
+				     raw_named_dump_table(schema, dat),
+				     temp_set_master_nodes(),
+				     {Node,disc_copies};
+				 CSstorage -> 
+				     {Node,CSstorage}
+			     end
+		     end,
+	    
+	    W2C0 = val({schema, where_to_commit}),
+	    W2C = case W2C0 of
+		      {blocked, List} ->
+			  {blocked,lists:map(Update,List)};
+		      List ->
+			  lists:map(Update,List)
+		  end,
+	    if W2C == W2C0 -> ignore;
+	       true -> mnesia_lib:set({schema, where_to_commit}, W2C)
+	    end;
+	_ ->
+	    ignore
+    end,
+    insert_cstruct(Tid, Cs, false, InPlace, InitBy);
+
+insert_op(Tid, _, {op, del_table_copy, Storage, Node, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    if
+	Tab == schema, Storage == ram_copies ->
+	    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+        Tab /= schema ->
+	    mnesia_controller:del_active_replica(Tab, Node),
+	    mnesia_lib:del({Tab, Storage}, Node),
+	    if
+		Node == node() ->
+		    case Cs#cstruct.local_content of
+			true -> mnesia_lib:set({Tab, where_to_read}, nowhere);
+			false -> mnesia_lib:set_remote_where_to_read(Tab)
+		    end,
+		    mnesia_lib:del({schema, local_tables}, Tab),
+		    mnesia_lib:set({Tab, storage_type}, unknown),
+		    insert_cstruct(Tid, Cs, true, InPlace, InitBy),
+		    disc_delete_table(Tab, Storage),
+		    disc_delete_indecies(Tab, Cs, Storage),
+		    mnesia_schema:ram_delete_table(Tab, Storage),
+		    mnesia_checkpoint:tm_del_copy(Tab, Node);
+		true ->
+		    case val({Tab, where_to_read}) of
+			Node ->
+			    mnesia_lib:set_remote_where_to_read(Tab);
+			_  ->
+			    ignore
+		    end,
+		    insert_cstruct(Tid, Cs, true, InPlace, InitBy)
+	    end
+    end;
+
+insert_op(Tid, _, {op, add_table_copy, _Storage, _Node, TabDef}, InPlace, InitBy) ->
+    %% During prepare commit, the files was created
+    %% and the replica was announced
+    Cs = mnesia_schema:list2cs(TabDef),
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, add_snmp, _Us, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, del_snmp, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    if
+	InitBy /= startup,
+	Storage /= unknown ->
+	    case ?catch_val({Tab, {index, snmp}}) of
+		{'EXIT', _} -> 
+		    ignore;
+		Stab -> 
+		    mnesia_snmp_hook:delete_table(Tab, Stab),
+		    mnesia_lib:unset({Tab, {index, snmp}})
+	    end;
+	true ->
+	    ignore
+    end,
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, add_index, Pos, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = insert_cstruct(Tid, Cs, true, InPlace, InitBy),
+    Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    case InitBy of
+	startup when Storage == disc_only_copies ->
+	    true = open_files(Tab, Storage, InPlace, InitBy),
+	    mnesia_index:init_indecies(Tab, Storage, [Pos]);
+	startup ->
+	    ignore; 
+	_  ->
+	    mnesia_index:init_indecies(Tab, Storage, [Pos])
+    end;
+
+insert_op(Tid, _, {op, del_index, Pos, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    Storage = mnesia_lib:cs_to_storage_type(node(), Cs),
+    case InitBy of
+	startup when Storage == disc_only_copies ->
+	    mnesia_index:del_index_table(Tab, Storage, Pos);
+	startup -> 
+	    ignore;
+	_ ->
+	    mnesia_index:del_index_table(Tab, Storage, Pos)
+    end,
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, change_table_access_mode,TabDef, _OldAccess, _Access}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    case InitBy of
+	startup -> ignore;
+	_ -> mnesia_controller:change_table_access_mode(Cs)
+    end,
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, change_table_load_order, TabDef, _OldLevel, _Level}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, delete_property, TabDef, PropKey}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    Tab = Cs#cstruct.name,
+    mnesia_lib:unset({Tab, user_property, PropKey}),
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, write_property, TabDef, _Prop}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy);
+
+insert_op(Tid, _, {op, change_table_frag, _Change, TabDef}, InPlace, InitBy) ->
+    Cs = mnesia_schema:list2cs(TabDef),
+    insert_cstruct(Tid, Cs, true, InPlace, InitBy).
+
+open_files(Tab, Storage, UpdateInPlace, InitBy)
+  when Storage /= unknown, Storage /= ram_copies ->
+    case get({?MODULE, Tab}) of
+	undefined ->
+	    case ?catch_val({Tab, setorbag}) of
+		{'EXIT', _} ->
+		    false;
+		Type ->
+		    case Storage of 
+			disc_copies when Tab /= schema ->
+			    Bool = open_disc_copies(Tab, InitBy),
+			    Bool;
+			_ ->
+			    Fname = prepare_open(Tab, UpdateInPlace),
+			    Args = [{file, Fname},
+				    {keypos, 2},
+				    {repair, mnesia_monitor:get_env(auto_repair)},
+				    {type, mnesia_lib:disk_type(Tab, Type)}],
+			    {ok, _} = mnesia_monitor:open_dets(Tab, Args),
+			    put({?MODULE, Tab}, {opened_dumper, dat}),
+			    true
+		    end
+	    end;
+	already_dumped ->
+	    false;
+	{opened_dumper, _} ->
+	    true
+    end;
+open_files(_Tab, _Storage, _UpdateInPlace, _InitBy) ->
+    false.
+
+open_disc_copies(Tab, InitBy) ->
+    DclF = mnesia_lib:tab2dcl(Tab),
+    DumpEts = 
+	case file:read_file_info(DclF) of
+	    {error, enoent} ->
+		false;
+	    {ok, DclInfo} ->
+		DcdF =  mnesia_lib:tab2dcd(Tab),
+		case file:read_file_info(DcdF) of
+		    {error, Reason} ->
+			mnesia_lib:dbg_out("File ~p info_error ~p ~n",
+					   [DcdF, Reason]),
+			true;
+		    {ok, DcdInfo} -> 
+			Mul = case ?catch_val(dc_dump_limit) of
+				  {'EXIT', _} -> ?DumpToEtsMultiplier;
+				  Val -> Val
+			      end,
+			DcdInfo#file_info.size =< (DclInfo#file_info.size * Mul)
+		end
+	end,
+    if 
+	DumpEts == false; InitBy == startup ->	    
+	    mnesia_log:open_log({?MODULE,Tab}, 
+				mnesia_log:dcl_log_header(), 
+				DclF, 
+				mnesia_lib:exists(DclF), 
+				mnesia_monitor:get_env(auto_repair),
+				read_write),
+	    put({?MODULE, Tab}, {opened_dumper, dcl}),
+	    true;
+	true ->
+	    mnesia_log:ets2dcd(Tab),
+	    put({?MODULE, Tab}, already_dumped),
+	    false
+    end. 
+
+%% Always opens the dcl file for writing overriding already_dumped 
+%% mechanismen, used for schema transactions.
+open_dcl(Tab) ->
+    case get({?MODULE, Tab}) of
+    	{opened_dumper, _} ->
+	    true;
+	_ -> %% undefined or already_dumped
+	    DclF = mnesia_lib:tab2dcl(Tab),
+	    mnesia_log:open_log({?MODULE,Tab}, 
+				mnesia_log:dcl_log_header(), 
+				DclF, 
+				mnesia_lib:exists(DclF), 
+				mnesia_monitor:get_env(auto_repair),
+				read_write),
+	    put({?MODULE, Tab}, {opened_dumper, dcl}),
+	    true
+    end.
+
+prepare_open(Tab, UpdateInPlace) ->
+    Dat =  mnesia_lib:tab2dat(Tab),
+    case UpdateInPlace of
+	true ->
+	    Dat;
+	false ->
+	    Tmp = mnesia_lib:tab2tmp(Tab),
+	    case catch mnesia_lib:copy_file(Dat, Tmp) of
+		ok ->
+		    Tmp;
+		Error ->
+		    fatal("Cannot copy dets file ~p to ~p: ~p~n",
+			  [Dat, Tmp, Error])
+	    end
+	end.
+
+del_opened_tab(Tab) ->
+    erase({?MODULE, Tab}).
+
+close_files(UpdateInPlace, Outcome, InitBy) -> % Update in place
+    close_files(UpdateInPlace, Outcome, InitBy, get()).
+
+close_files(InPlace, Outcome, InitBy, [{{?MODULE, Tab}, already_dumped} | Tail]) ->
+    erase({?MODULE, Tab}),
+    close_files(InPlace, Outcome, InitBy, Tail);
+close_files(InPlace, Outcome, InitBy, [{{?MODULE, Tab}, {opened_dumper, Type}} | Tail]) ->
+    erase({?MODULE, Tab}),
+    case val({Tab, storage_type}) of
+	disc_only_copies when InitBy /= startup ->
+	    ignore;
+	disc_copies when Tab /= schema -> 
+	    mnesia_log:close_log({?MODULE,Tab});
+	Storage ->
+	    do_close(InPlace, Outcome, Tab, Type, Storage)
+    end,
+    close_files(InPlace, Outcome, InitBy, Tail);
+
+close_files(InPlace, Outcome, InitBy, [_ | Tail]) ->
+    close_files(InPlace, Outcome, InitBy, Tail);
+close_files(_, _, _InitBy, []) ->
+    ok.
+
+%% If storage is unknown during close clean up files, this can happen if timing
+%% is right and dirty_write conflicts with schema operations.
+do_close(_, _, Tab, dcl, unknown) ->
+    mnesia_log:close_log({?MODULE,Tab}),
+    file:delete(mnesia_lib:tab2dcl(Tab));
+do_close(_, _, Tab, dcl, _) ->  %% To be safe, can it happen?
+    mnesia_log:close_log({?MODULE,Tab});
+
+do_close(InPlace, Outcome, Tab, dat, Storage) ->
+    mnesia_monitor:close_dets(Tab),
+    if
+	Storage == unknown, InPlace == true  ->
+	    file:delete(mnesia_lib:tab2dat(Tab));
+	InPlace == true ->
+	    %% Update in place
+	    ok;
+	Outcome == ok, Storage /= unknown ->
+	    %% Success: swap tmp files with dat files
+	    TabDat = mnesia_lib:tab2dat(Tab),
+	    ok = file:rename(mnesia_lib:tab2tmp(Tab), TabDat);
+	true ->
+	    file:delete(mnesia_lib:tab2tmp(Tab))
+    end.
+    
+
+ensure_rename(From, To) ->
+    case mnesia_lib:exists(From) of
+	true ->
+	    file:rename(From, To);
+	false ->
+	    case mnesia_lib:exists(To) of
+		true ->
+		    ok;
+		false ->
+		    {error, {rename_failed, From, To}}
+	    end
+    end.
+    
+insert_cstruct(Tid, Cs, KeepWhereabouts, InPlace, InitBy) ->
+    Val = mnesia_schema:insert_cstruct(Tid, Cs, KeepWhereabouts),
+    {schema, Tab, _} = Val,
+    S = val({schema, storage_type}),
+    disc_insert(Tid, S, schema, Tab, Val, write, InPlace, InitBy),
+    Tab.
+
+delete_cstruct(Tid, Cs, InPlace, InitBy) ->
+    Val = mnesia_schema:delete_cstruct(Tid, Cs),
+    {schema, Tab, _} = Val,
+    S = val({schema, storage_type}),
+    disc_insert(Tid, S, schema, Tab, Val, delete, InPlace, InitBy),
+    Tab.
+
+
+temp_set_master_nodes() ->
+    Tabs = val({schema, local_tables}),
+    Masters = [{Tab, (val({Tab, disc_copies}) ++ 
+		      val({Tab, ram_copies}) ++ 
+		      val({Tab, disc_only_copies})) -- [node()]} 
+	       || Tab <- Tabs],
+    %% UseDir = false since we don't want to remember these
+    %% masternodes and we are running (really soon anyway) since we want this
+    %% to be known during table loading.
+    mnesia_recover:log_master_nodes(Masters, false, yes),
+    ok.    
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Raw dump of table. Dumper must have unique access to the ets table.
+
+raw_named_dump_table(Tab, Ftype) ->
+    case mnesia_monitor:use_dir() of
+	true ->
+	    mnesia_lib:lock_table(Tab),
+	    TmpFname = mnesia_lib:tab2tmp(Tab),
+	    Fname =
+		case Ftype of
+		    dat -> mnesia_lib:tab2dat(Tab);
+		    dmp -> mnesia_lib:tab2dmp(Tab)
+		end,
+	    file:delete(TmpFname),
+	    file:delete(Fname),
+	    TabSize = ?ets_info(Tab, size),
+	    TabRef = Tab,
+	    DiskType = mnesia_lib:disk_type(Tab),
+	    Args = [{file, TmpFname},
+		    {keypos, 2},
+		    %%		    {ram_file, true},
+		    {estimated_no_objects, TabSize + 256},
+		    {repair, mnesia_monitor:get_env(auto_repair)},
+		    {type, DiskType}],
+	    case mnesia_lib:dets_sync_open(TabRef, Args) of
+		{ok, TabRef} ->
+		    Storage = ram_copies,
+		    mnesia_lib:db_fixtable(Storage, Tab, true),
+		    
+		    case catch raw_dump_table(TabRef, Tab) of
+			{'EXIT', Reason} ->
+			    mnesia_lib:db_fixtable(Storage, Tab, false),
+			    mnesia_lib:dets_sync_close(Tab),
+			    file:delete(TmpFname),
+			    mnesia_lib:unlock_table(Tab),
+			    exit({"Dump of table to disc failed", Reason});
+			ok ->
+			    mnesia_lib:db_fixtable(Storage, Tab, false),
+			    mnesia_lib:dets_sync_close(Tab),
+			    mnesia_lib:unlock_table(Tab),
+			    ok = file:rename(TmpFname, Fname)
+		    end;
+		{error, Reason} ->
+		    mnesia_lib:unlock_table(Tab),
+		    exit({"Open of file before dump to disc failed", Reason})
+	    end;
+	false ->
+	    exit({has_no_disc, node()})
+    end.
+
+raw_dump_table(DetsRef, EtsRef) ->
+    dets:from_ets(DetsRef, EtsRef).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Load regulator
+%% 
+%% This is a poor mans substitute for a fair scheduler algorithm 
+%% in the Erlang emulator. The mnesia_dumper process performs many 
+%% costly BIF invokations and must pay for this. But since the 
+%% Emulator does not handle this properly we must compensate for 
+%% this with some form of load regulation of ourselves in order to
+%% not steal all computation power in the Erlang Emulator ans make
+%% other processes starve. Hopefully this is a temporary solution.
+
+start_regulator() ->
+    case mnesia_monitor:get_env(dump_log_load_regulation) of
+	false ->
+	    nopid;
+	true ->
+	    N = ?REGULATOR_NAME,
+	    case mnesia_monitor:start_proc(N, ?MODULE, regulator_init, [self()]) of
+		{ok, Pid} ->
+		    Pid;
+		{error, Reason} ->
+		    fatal("Failed to start ~n: ~p~n", [N, Reason])
+	    end
+    end.
+
+regulator_init(Parent) ->
+    %% No need for trapping exits.
+    %% Using low priority causes the regulation
+    process_flag(priority, low),
+    register(?REGULATOR_NAME, self()),
+    proc_lib:init_ack(Parent, {ok, self()}),
+    regulator_loop().
+
+regulator_loop() ->
+    receive
+	{regulate, From} ->
+	    From ! {regulated, self()},
+	    regulator_loop();
+	{stop, From} ->
+	    From ! {stopped, self()},
+	    exit(normal)
+    end.
+
+regulate(nopid) ->
+    ok;
+regulate(RegulatorPid) ->
+    RegulatorPid ! {regulate, self()},
+    receive
+	{regulated, RegulatorPid} -> ok
+    end.
+
+val(Var) ->
+    case ?catch_val(Var) of
+	{'EXIT', Reason} -> mnesia_lib:other_val(Var, Reason); 
+	Value -> Value 
+    end.