The R13B03 release.OTP_R13B03

1 files changed, 1025 insertions, 0 deletions

diff --git a/lib/mnesia/src/mnesia_log.erl b/lib/mnesia/src/mnesia_log.erl
new file mode 100644
index 0000000000..00ec4740ee
--- /dev/null
+++ b/lib/mnesia/src/mnesia_log.erl
@@ -0,0 +1,1025 @@
+%%
+%% %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%
+%%
+
+%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%
+%% This module administers three kinds of log files:
+%%
+%% 1 The transaction log
+%%   mnesia_tm appends to the log (via mnesia_log) at the
+%%   end of each transaction (or dirty write) and
+%%   mnesia_dumper reads the log and performs the ops in
+%%   the dat files. The dump_log is done  at startup and
+%%   at intervals controlled by the user.
+%%
+%% 2 The mnesia_down log
+%%   mnesia_tm appends to the log (via mnesia_log) when it
+%%   realizes that mnesia goes up or down on another node.
+%%   mnesia_init reads the log (via mnesia_log) at startup.
+%%
+%% 3 The backup log
+%%   mnesia_schema produces one tiny log when the schema is
+%%   initially created. mnesia_schema also reads the log
+%%   when the user wants tables (possibly incl the schema)
+%%   to be restored. mnesia_log appends to the log when the
+%%   user wants to produce a real backup.
+%%
+%%   The actual access to the backup media is performed via the
+%%   mnesia_backup module for both read and write. mnesia_backup
+%%   uses the disk_log (*), BUT the user may write an own module
+%%   with the same interface as mnesia_backup and configure
+%%   Mnesia so the alternate module performs the actual accesses
+%%   to the backup media. This means that the user may put the
+%%   backup on medias that Mnesia does not know about possibly on
+%%   hosts where Erlang is not running.
+%%
+%% All these logs have to some extent a common structure.
+%% They are all using the disk_log module (*) for the basic
+%% file structure. The disk_log has a repair feature that
+%% can be used to skip erroneous log records if one comes to
+%% the conclusion that it is more important to reuse some
+%% of the log records than the risque of obtaining inconsistent
+%% data. If the data becomes inconsistent it is solely up to the
+%% application to make it consistent again. The automatic
+%% reparation of the disk_log is very powerful, but use it
+%% with extreme care.
+%%
+%% First in all Mnesia's log file is a mnesia log header.
+%% It contains a list with a log_header record as single
+%% element. The structure of the log_header may never be
+%% changed since it may be written to very old backup files.
+%% By holding this record definition stable we can be
+%% able to comprahend backups from timepoint 0. It also
+%% allows us to use the backup format as an interchange
+%% format between Mnesia releases.
+%%
+%% An op-list is a list of tuples with arity 3. Each tuple
+%% has this structure: {Oid, Recs, Op} where Oid is the tuple
+%% {Tab, Key}, Recs is a (possibly empty) list of records and
+%% Op is an atom.
+%%
+%% The log file structure for the transaction log is as follows.
+%%
+%%    After the mnesia log section follows an extended record section
+%%    containing op-lists. There are several values that Op may
+%%    have, such as write, delete, update_counter, delete_object,
+%%    and replace. There is no special end of section marker.
+%%
+%%    +-----------------+
+%%    | mnesia log head |
+%%    +-----------------+
+%%    | extended record |
+%%    | section         |
+%%    +-----------------+
+%%
+%% The log file structure for the mnesia_down log is as follows.
+%%
+%%    After the mnesia log section follows a mnesia_down section
+%%    containg lists with yoyo records as single element.
+%%
+%%    +-----------------+
+%%    | mnesia log head |
+%%    +-----------------+
+%%    | mnesia_down     |
+%%    | section         |
+%%    +-----------------+
+%%
+%% The log file structure for the backup log is as follows.
+%%
+%%    After the mnesia log section follows a schema section
+%%    containing record lists. A record list is a list of tuples
+%%    where {schema, Tab} is interpreted as a delete_table(Tab) and
+%%    {schema, Tab, CreateList} are interpreted as create_table.
+%%
+%%    The record section also contains record lists. In this section
+%%    {Tab, Key} is interpreted as delete({Tab, Key}) and other tuples
+%%    as write(Tuple). There is no special end of section marker.
+%%
+%%    +-----------------+
+%%    | mnesia log head |
+%%    +-----------------+
+%%    | schema section  |
+%%    +-----------------+
+%%    | record section  |
+%%    +-----------------+
+%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+-module(mnesia_log).
+
+-export([
+	 append/2,
+	 backup/1,
+	 backup/2,
+	 backup_checkpoint/2,
+	 backup_checkpoint/3,
+	 backup_log_header/0,
+	 backup_master/2,
+	 chunk_decision_log/1,
+	 chunk_decision_tab/1,
+	 chunk_log/1,
+	 chunk_log/2,
+	 close_decision_log/0,
+	 close_decision_tab/0,
+	 close_log/1,
+	 unsafe_close_log/1,
+	 confirm_log_dump/1,
+	 confirm_decision_log_dump/0,
+	 previous_log_file/0,
+	 previous_decision_log_file/0,
+	 latest_log_file/0,
+	 decision_log_version/0,
+	 decision_log_file/0,
+	 decision_tab_file/0,
+	 decision_tab_version/0,
+	 dcl_version/0,
+	 dcd_version/0,
+	 ets2dcd/1,
+	 ets2dcd/2,
+	 dcd2ets/1,
+	 dcd2ets/2,
+	 init/0,
+	 init_log_dump/0,
+	 log/1,
+	 slog/1,
+	 log_decision/1,
+	 log_files/0,
+	 open_decision_log/0,
+	 trans_log_header/0,
+	 open_decision_tab/0,
+	 dcl_log_header/0,
+	 dcd_log_header/0,
+	 open_log/4,
+	 open_log/6,
+	 prepare_decision_log_dump/0,
+	 prepare_log_dump/1,
+	 save_decision_tab/1,
+	 purge_all_logs/0,
+	 purge_some_logs/0,
+	 stop/0,
+	 tab_copier/3,
+	 version/0,
+	 view/0,
+	 view/1,
+	 write_trans_log_header/0
+	]).
+	
+	
+-include("mnesia.hrl").
+-import(mnesia_lib, [val/1, dir/1]).
+-import(mnesia_lib, [exists/1, fatal/2, error/2, dbg_out/2]).
+
+trans_log_header() -> log_header(trans_log, version()).
+backup_log_header() -> log_header(backup_log, "1.2").
+decision_log_header() -> log_header(decision_log, decision_log_version()).
+decision_tab_header() -> log_header(decision_tab, decision_tab_version()).
+dcl_log_header() -> log_header(dcl_log, dcl_version()).
+dcd_log_header() -> log_header(dcd_log, dcd_version()).
+
+log_header(Kind, Version) ->
+    #log_header{log_version=Version,
+		log_kind=Kind,
+		mnesia_version=mnesia:system_info(version),
+		node=node(),
+		now=now()}.
+
+version() -> "4.3".
+
+decision_log_version() -> "3.0".
+
+decision_tab_version() -> "1.0".
+
+dcl_version() -> "1.0".
+dcd_version() -> "1.0".
+     
+append(Log, Bin) when is_binary(Bin) ->
+    disk_log:balog(Log, Bin);
+append(Log, Term) ->
+    disk_log:alog(Log, Term).
+
+%% Synced append
+sappend(Log, Bin) when is_binary(Bin) ->
+    ok = disk_log:blog(Log, Bin);  
+sappend(Log, Term) ->
+    ok = disk_log:log(Log, Term).  
+
+%% Write commit records to the latest_log
+log(C) when  C#commit.disc_copies == [],
+             C#commit.disc_only_copies  == [],
+             C#commit.schema_ops == [] ->
+    ignore;
+log(C) ->
+    case mnesia_monitor:use_dir() of
+        true ->
+	    if
+		is_record(C, commit) ->
+		    C2 =  C#commit{ram_copies = [], snmp = []},
+		    append(latest_log, C2);
+		true ->
+		    %% Either a commit record as binary
+		    %% or some decision related info
+		    append(latest_log, C)
+	    end,
+	    mnesia_dumper:incr_log_writes();
+	false ->
+	    ignore
+    end.
+
+%% Synced
+
+slog(C) when  C#commit.disc_copies == [],
+             C#commit.disc_only_copies  == [],
+             C#commit.schema_ops == [] ->
+    ignore;
+slog(C) ->
+    case mnesia_monitor:use_dir() of
+        true ->
+	    if
+		is_record(C, commit) ->
+		    C2 =  C#commit{ram_copies = [], snmp = []},
+		    sappend(latest_log, C2);
+		true ->
+		    %% Either a commit record as binary
+		    %% or some decision related info
+		    sappend(latest_log, C)
+	    end,
+	    mnesia_dumper:incr_log_writes();
+	false ->
+	    ignore
+    end.
+
+
+%% Stuff related to the file LOG
+
+%% Returns a list of logfiles. The oldest is first.
+log_files() -> [previous_log_file(),
+		latest_log_file(),
+		decision_tab_file()
+	       ].
+
+latest_log_file() -> dir(latest_log_name()).
+
+previous_log_file() -> dir("PREVIOUS.LOG").
+
+decision_log_file() -> dir(decision_log_name()).
+
+decision_tab_file() -> dir(decision_tab_name()).
+    
+previous_decision_log_file() -> dir("PDECISION.LOG").
+
+latest_log_name() -> "LATEST.LOG".
+
+decision_log_name() -> "DECISION.LOG".
+
+decision_tab_name() -> "DECISION_TAB.LOG".
+
+init() ->
+    case mnesia_monitor:use_dir() of
+	true ->
+	    Prev = previous_log_file(),
+	    verify_no_exists(Prev),
+	    
+	    Latest = latest_log_file(),
+	    verify_no_exists(Latest),
+	    
+	    Header = trans_log_header(),
+	    open_log(latest_log, Header, Latest);
+	false ->
+	    ok
+    end.
+
+verify_no_exists(Fname) ->
+    case exists(Fname) of
+	false ->
+	    ok;
+	true ->
+	    fatal("Log file exists: ~p~n", [Fname])
+    end.
+
+open_log(Name, Header, Fname) ->
+    Exists = exists(Fname),
+    open_log(Name, Header, Fname, Exists).
+
+open_log(Name, Header, Fname, Exists) ->
+    Repair = mnesia_monitor:get_env(auto_repair),
+    open_log(Name, Header, Fname, Exists, Repair).
+
+open_log(Name, Header, Fname, Exists, Repair) ->
+    case Name == previous_log of
+	true ->
+	    open_log(Name, Header, Fname, Exists, Repair, read_only);
+	false ->
+	    open_log(Name, Header, Fname, Exists, Repair, read_write)
+    end.
+
+open_log(Name, Header, Fname, Exists, Repair, Mode) ->
+    Args = [{file, Fname}, {name, Name}, {repair, Repair}, {mode, Mode}],
+%%    io:format("~p:open_log: ~p ~p~n", [?MODULE, Name, Fname]),
+    case mnesia_monitor:open_log(Args) of
+	{ok, Log} when Exists == true ->
+	    Log;
+	{ok, Log} ->
+	    write_header(Log, Header),
+	    Log;
+	{repaired, Log, _, {badbytes, 0}} when Exists == true ->
+	    Log;
+	{repaired, Log, _, {badbytes, 0}} ->
+	    write_header(Log, Header),
+	    Log;
+	{repaired, Log, _Recover, BadBytes} ->
+	    mnesia_lib:important("Data may be missing, log ~p repaired: Lost ~p bytes~n", 
+				 [Fname, BadBytes]),
+	    Log;
+	{error, Reason} when Repair == true ->
+	    file:delete(Fname),
+	    mnesia_lib:important("Data may be missing, Corrupt logfile deleted: ~p, ~p ~n", 
+				 [Fname, Reason]),
+	    %% Create a new 
+	    open_log(Name, Header, Fname, false, false, read_write);
+	{error, Reason} ->
+	    fatal("Cannot open log file ~p: ~p~n", [Fname, Reason])
+    end.
+
+write_header(Log, Header) -> 
+    append(Log, Header).
+
+write_trans_log_header() ->
+    write_header(latest_log, trans_log_header()).
+
+stop() ->
+    case mnesia_monitor:use_dir() of
+        true ->
+	    close_log(latest_log);
+	false ->
+	    ok
+    end.
+
+close_log(Log) ->
+%%    io:format("mnesia_log:close_log ~p~n", [Log]),
+%%    io:format("mnesia_log:close_log ~p~n", [Log]),
+    case disk_log:sync(Log) of 
+	ok -> ok;
+	{error, {read_only_mode, Log}} -> 
+	    ok;
+	{error, Reason} -> 
+	    mnesia_lib:important("Failed syncing ~p to_disk reason ~p ~n", 
+				 [Log, Reason])
+    end,
+    mnesia_monitor:close_log(Log).
+
+unsafe_close_log(Log) ->
+%%    io:format("mnesia_log:close_log ~p~n", [Log]),
+    mnesia_monitor:unsafe_close_log(Log).
+
+
+purge_some_logs() ->
+    mnesia_monitor:unsafe_close_log(latest_log), 
+    file:delete(latest_log_file()),
+    file:delete(decision_tab_file()).
+
+purge_all_logs() ->
+    file:delete(previous_log_file()),
+    file:delete(latest_log_file()),
+    file:delete(decision_tab_file()).
+
+%% Prepare dump by renaming the open logfile if possible
+%% Returns a tuple on the following format: {Res, OpenLog}
+%% where OpenLog is the file descriptor to log file, ready for append
+%% and Res is one of the following: already_dumped, needs_dump or {error, Reason}
+prepare_log_dump(InitBy) ->
+    Diff = mnesia_dumper:get_log_writes() -
+           mnesia_lib:read_counter(trans_log_writes_prev),
+    if
+	Diff == 0, InitBy /= startup ->
+	    already_dumped;
+	true ->
+	    case mnesia_monitor:use_dir() of
+		true ->
+		    Prev = previous_log_file(),
+		    prepare_prev(Diff, InitBy, Prev, exists(Prev));
+		false ->
+		    already_dumped
+	    end
+    end.
+
+prepare_prev(Diff, _, _, true) ->
+    {needs_dump, Diff};
+prepare_prev(Diff, startup, Prev, false) ->
+    Latest = latest_log_file(),
+    case exists(Latest) of
+	true ->
+	    case file:rename(Latest, Prev) of
+		ok ->
+		    {needs_dump, Diff};
+		{error, Reason} ->
+		    {error, Reason}
+	    end;
+	false ->
+	    already_dumped
+    end;
+prepare_prev(Diff, _InitBy, Prev, false) ->
+    Head = trans_log_header(),
+    case mnesia_monitor:reopen_log(latest_log, Prev, Head) of
+	ok ->
+	    {needs_dump, Diff};
+	{error, Reason} ->
+	    Latest = latest_log_file(),
+	    {error, {"Cannot rename log file",
+		     [Latest, Prev, Reason]}}
+    end.
+
+%% Init dump and return PrevLogFileDesc or exit.
+init_log_dump() ->
+    Fname = previous_log_file(),
+    open_log(previous_log, trans_log_header(), Fname),
+    start.
+
+
+chunk_log(Cont) ->
+    chunk_log(previous_log, Cont).
+
+chunk_log(_Log, eof) ->
+    eof;
+chunk_log(Log, Cont) ->
+    case catch disk_log:chunk(Log, Cont) of
+	{error, Reason} ->
+	    fatal("Possibly truncated ~p file: ~p~n",
+		  [Log, Reason]);
+	{C2, Chunk, _BadBytes} ->
+	    %% Read_only case, should we warn about the bad log file?
+	    %% BUGBUG Should we crash if Repair == false ?? 
+	    %% We got to check this !!
+	    mnesia_lib:important("~p repaired, lost ~p bad bytes~n", [Log, _BadBytes]),
+	    {C2, Chunk}; 
+	Other ->
+	    Other
+    end.
+
+%% Confirms the dump by closing prev log and delete the file
+confirm_log_dump(Updates) ->
+    case mnesia_monitor:close_log(previous_log) of
+	ok ->
+	    file:delete(previous_log_file()),
+	    mnesia_lib:incr_counter(trans_log_writes_prev, Updates),
+	    dumped;
+	{error, Reason} ->
+	    {error, Reason}
+    end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Decision log
+
+open_decision_log() ->
+    Latest = decision_log_file(),
+    open_log(decision_log, decision_log_header(), Latest),
+    start.
+    
+prepare_decision_log_dump() ->
+    Prev = previous_decision_log_file(),
+    prepare_decision_log_dump(exists(Prev), Prev).
+
+prepare_decision_log_dump(false, Prev) ->
+    Head = decision_log_header(),
+    case mnesia_monitor:reopen_log(decision_log, Prev, Head) of
+	ok ->
+	    prepare_decision_log_dump(true, Prev);
+	{error, Reason} ->
+	    fatal("Cannot rename decision log file ~p -> ~p: ~p~n",
+		     [decision_log_file(), Prev, Reason])
+    end;
+prepare_decision_log_dump(true, Prev) ->
+    open_log(previous_decision_log, decision_log_header(), Prev),
+    start.
+
+chunk_decision_log(Cont) ->
+    %% dbg_out("chunk log ~p~n", [Cont]),
+    chunk_log(previous_decision_log, Cont).
+
+%% Confirms dump of the decision log
+confirm_decision_log_dump() ->
+    case mnesia_monitor:close_log(previous_decision_log) of
+	ok ->
+	    file:delete(previous_decision_log_file());
+	{error, Reason} ->
+	    fatal("Cannot confirm decision log dump: ~p~n",
+		  [Reason])
+    end.
+
+save_decision_tab(Decisions) ->
+    Log = decision_tab,
+    Tmp = mnesia_lib:dir("DECISION_TAB.TMP"),
+    file:delete(Tmp),
+    open_log(Log, decision_tab_header(), Tmp),
+    append(Log, Decisions),
+    close_log(Log),
+    TabFile = decision_tab_file(),
+    ok = file:rename(Tmp, TabFile).
+
+open_decision_tab() ->
+    TabFile = decision_tab_file(),
+    open_log(decision_tab, decision_tab_header(), TabFile),
+    start.
+
+close_decision_tab() ->
+    close_log(decision_tab).
+
+chunk_decision_tab(Cont) ->
+    %% dbg_out("chunk tab ~p~n", [Cont]),
+    chunk_log(decision_tab, Cont).
+
+close_decision_log() ->
+    close_log(decision_log).
+
+log_decision(Decision) ->
+    append(decision_log, Decision).
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Debug functions
+
+view() ->
+    lists:foreach(fun(F) -> view(F) end, log_files()).
+
+view(File) ->
+    mnesia_lib:show("*****  ~p ***** ~n", [File]),
+    case exists(File) of
+	false ->
+	    nolog;
+	true ->
+	    N = view_only,
+	    Args = [{file, File}, {name, N}, {mode, read_only}],
+	    case disk_log:open(Args) of
+		{ok, N} ->
+		    view_file(start, N);
+		{repaired, _, _, _} ->
+		    view_file(start, N);
+		{error, Reason} ->
+		    error("Cannot open log ~p: ~p~n", [File, Reason])
+	    end
+    end.
+
+view_file(C, Log) ->
+    case disk_log:chunk(Log, C) of
+	{error, Reason} ->
+	    error("** Possibly truncated FILE ~p~n", [Reason]),
+	    error;
+	eof ->
+	    disk_log:close(Log),
+	    eof;
+	{C2, Terms, _BadBytes} ->
+	    dbg_out("Lost ~p bytes in ~p ~n", [_BadBytes, Log]),
+	    lists:foreach(fun(X) -> mnesia_lib:show("~p~n", [X]) end, 
+			  Terms),
+	    view_file(C2, Log);
+	{C2, Terms} ->
+	    lists:foreach(fun(X) -> mnesia_lib:show("~p~n", [X]) end, 
+			  Terms),
+	    view_file(C2, Log)
+    end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Backup
+
+-record(backup_args, {name, module, opaque, scope, prev_name, tables, cookie}).
+
+backup(Opaque) ->
+    backup(Opaque, []).
+
+backup(Opaque, Mod) when is_atom(Mod) ->
+    backup(Opaque, [{module, Mod}]);
+backup(Opaque, Args) when is_list(Args) ->
+    %% Backup all tables with max redundancy
+    CpArgs = [{ram_overrides_dump, false}, {max, val({schema, tables})}],
+    case mnesia_checkpoint:activate(CpArgs) of
+	{ok, Name, _Nodes} ->
+	    Res = backup_checkpoint(Name, Opaque, Args),
+	    mnesia_checkpoint:deactivate(Name),
+	    Res;
+	{error, Reason} ->
+	    {error, Reason}
+    end.
+
+backup_checkpoint(Name, Opaque) ->
+    backup_checkpoint(Name, Opaque, []).
+
+backup_checkpoint(Name, Opaque, Mod) when is_atom(Mod) ->
+    backup_checkpoint(Name, Opaque, [{module, Mod}]);
+backup_checkpoint(Name, Opaque, Args) when is_list(Args) ->
+    DefaultMod = mnesia_monitor:get_env(backup_module),
+    B = #backup_args{name = Name,
+		     module = DefaultMod,
+		     opaque = Opaque,
+		     scope = global,
+		     tables = all,
+		     prev_name = Name},
+    case check_backup_args(Args, B) of
+	{ok, B2} ->
+	    %% Decentralized backup
+	    %% Incremental
+
+	    Self = self(),
+	    Pid = spawn_link(?MODULE, backup_master, [Self, B2]),
+	    receive
+		{Pid, Self, Res} -> Res
+	    end;
+	{error, Reason} ->
+	    {error, Reason}
+    end.
+
+check_backup_args([Arg | Tail], B) ->
+    case catch check_backup_arg_type(Arg, B) of
+	{'EXIT', _Reason} ->
+	    {error, {badarg, Arg}};
+	B2 ->
+	    check_backup_args(Tail, B2)
+    end;
+
+check_backup_args([], B) ->
+    {ok, B}.
+
+check_backup_arg_type(Arg, B) ->    
+    case Arg of
+	{scope, global} ->
+	    B#backup_args{scope = global};
+	{scope, local} ->
+	    B#backup_args{scope = local};
+	{module, Mod} ->
+	    Mod2 = mnesia_monitor:do_check_type(backup_module, Mod),
+	    B#backup_args{module = Mod2};
+	{incremental, Name} ->
+	    B#backup_args{prev_name = Name};
+	{tables, Tabs} when is_list(Tabs) ->
+	    B#backup_args{tables = Tabs}
+    end.
+
+backup_master(ClientPid, B) ->
+    process_flag(trap_exit, true),
+    case catch do_backup_master(B) of
+	{'EXIT', Reason} ->
+	    ClientPid ! {self(), ClientPid, {error, {'EXIT', Reason}}};
+	Res ->
+	    ClientPid ! {self(), ClientPid, Res}
+    end,
+    unlink(ClientPid),
+    exit(normal).
+
+do_backup_master(B) ->
+    Name = B#backup_args.name,
+    B2 = safe_apply(B, open_write, [B#backup_args.opaque]),
+    B3 = safe_write(B2, [backup_log_header()]),
+    case mnesia_checkpoint:tables_and_cookie(Name) of
+	{ok, AllTabs, Cookie} ->
+	    Tabs = select_tables(AllTabs, B3),
+	    B4 = B3#backup_args{cookie = Cookie},
+	    %% Always put schema first in backup file
+	    B5 = backup_schema(B4, Tabs),
+	    B6 = lists:foldl(fun backup_tab/2, B5, Tabs -- [schema]),
+	    safe_apply(B6, commit_write, [B6#backup_args.opaque]),
+	    ok;
+	{error, Reason} ->
+	    abort_write(B3, {?MODULE, backup_master}, [B], {error, Reason})
+    end.
+
+select_tables(AllTabs, B) ->
+    Tabs =
+	case B#backup_args.tables of
+	    all -> AllTabs;
+	    SomeTabs when is_list(SomeTabs) -> SomeTabs
+	end,
+    case B#backup_args.scope of
+	global ->
+	    Tabs;
+	local ->
+	    Name = B#backup_args.name,
+	    [T || T <- Tabs, mnesia_checkpoint:most_local_node(Name, T) == {ok, node()}]
+    end.
+
+safe_write(B, []) ->
+    B;
+safe_write(B, Recs) ->	
+    safe_apply(B, write, [B#backup_args.opaque, Recs]).
+
+backup_schema(B, Tabs) ->
+    case lists:member(schema, Tabs) of
+	true ->
+	    backup_tab(schema, B);
+	false ->
+	    Defs = [{schema, T, mnesia_schema:get_create_list(T)} || T <- Tabs],
+	    safe_write(B, Defs)
+    end.
+
+safe_apply(B, write, [_, Items]) when Items == [] ->
+    B;
+safe_apply(B, What, Args) ->
+    Abort = fun(R) -> abort_write(B, What, Args, R) end,
+    receive
+	{'EXIT', Pid, R} -> Abort({'EXIT', Pid, R})
+    after 0 ->
+	    Mod = B#backup_args.module,
+	    case catch apply(Mod, What, Args) of
+		{ok, Opaque} -> B#backup_args{opaque=Opaque};
+		{error, R} -> Abort(R);
+		R -> Abort(R)
+	    end
+    end.
+
+abort_write(B, What, Args, Reason) ->
+    Mod = B#backup_args.module,
+    Opaque = B#backup_args.opaque,
+    dbg_out("Failed to perform backup. M=~p:F=~p:A=~p -> ~p~n",
+	    [Mod, What, Args, Reason]),
+    case catch apply(Mod, abort_write, [Opaque]) of
+	{ok, _Res} ->
+	    throw({error, Reason});
+	Other ->
+	    error("Failed to abort backup. ~p:~p~p -> ~p~n",
+		  [Mod, abort_write, [Opaque], Other]),
+	    throw({error, Reason})
+    end.
+	
+backup_tab(Tab, B) ->
+    Name = B#backup_args.name,
+    case mnesia_checkpoint:most_local_node(Name, Tab) of
+	{ok, Node} when Node == node() ->
+	    tab_copier(self(), B, Tab);
+	{ok, Node} ->
+	    RemoteB = B,
+	    Pid = spawn_link(Node, ?MODULE, tab_copier, [self(), RemoteB, Tab]),
+	    RecName = val({Tab, record_name}),
+	    tab_receiver(Pid, B, Tab, RecName, 0);
+	{error, Reason} ->
+	    abort_write(B, {?MODULE, backup_tab}, [Tab, B], {error, Reason})
+    end.
+    
+tab_copier(Pid, B, Tab) when is_record(B, backup_args) ->
+    %% Intentional crash at exit
+    Name = B#backup_args.name,
+    PrevName = B#backup_args.prev_name,
+    {FirstName, FirstSource} = select_source(Tab, Name, PrevName),
+
+    ?eval_debug_fun({?MODULE, tab_copier, pre}, [{name, Name}, {tab, Tab}]),
+    Res = handle_more(Pid, B, Tab, FirstName, FirstSource, Name),
+    ?eval_debug_fun({?MODULE, tab_copier, post}, [{name, Name}, {tab, Tab}]),
+
+    handle_last(Pid, Res).
+
+select_source(Tab, Name, PrevName) ->
+    if
+	Tab == schema ->
+	    %% Always full backup of schema
+	    {Name, table};
+	Name == PrevName ->
+	    %% Full backup
+	    {Name, table};
+	true ->
+	    %% Wants incremental backup
+	    case mnesia_checkpoint:most_local_node(PrevName, Tab) of
+		{ok, Node} when Node == node() ->
+		    %% Accept incremental backup
+		    {PrevName, retainer};
+		_ ->
+		    %% Do a full backup anyway
+		    dbg_out("Incremental backup escalated to full backup: ~p~n", [Tab]),
+		    {Name, table}
+	    end
+    end.
+
+handle_more(Pid, B, Tab, FirstName, FirstSource, Name) ->
+    Acc = {0, B},
+    case {mnesia_checkpoint:really_retain(Name, Tab),
+	  mnesia_checkpoint:really_retain(FirstName, Tab)} of
+	{true, true} ->
+	    Acc2 = iterate(B, FirstName, Tab, Pid, FirstSource, latest, first, Acc),
+	    iterate(B, Name, Tab, Pid, retainer, checkpoint, last, Acc2);
+	{false, false}->
+	    %% Put the dumped file in the backup
+	    %% instead of the ram table. Does
+	    %% only apply to ram_copies.
+	    iterate(B, Name, Tab, Pid, retainer, checkpoint, last, Acc);
+	Bad ->
+	    Reason = {"Checkpoints for incremental backup must have same "
+		      "setting of ram_overrides_dump",
+		      Tab, Name, FirstName, Bad},
+	    abort_write(B, {?MODULE, backup_tab}, [Tab, B], {error, Reason})
+    end.
+
+handle_last(Pid, {_Count, B}) when Pid == self() ->
+    B;
+handle_last(Pid, _Acc) ->
+    unlink(Pid),
+    Pid ! {self(), {last, {ok, dummy}}},
+    exit(normal).
+
+iterate(B, Name, Tab, Pid, Source, Age, Pass, Acc) ->
+    Fun = 
+	if
+	    Pid == self() ->
+		RecName = val({Tab, record_name}),
+		fun(Recs, A) -> copy_records(RecName, Tab, Recs, A) end;
+	    true ->
+		fun(Recs, A) -> send_records(Pid, Tab, Recs, Pass, A) end
+	end,
+    case mnesia_checkpoint:iterate(Name, Tab, Fun, Acc, Source, Age) of
+	{ok, Acc2} ->
+	    Acc2;
+	{error, Reason} ->
+	    R = {error, {"Tab copier iteration failed", Reason}},
+	    abort_write(B, {?MODULE, iterate}, [self(), B, Tab], R)
+    end.
+
+copy_records(_RecName, _Tab, [], Acc) ->
+    Acc;
+copy_records(RecName, Tab, Recs, {Count, B}) ->
+    Recs2 = rec_filter(B, Tab, RecName, Recs),
+    B2 = safe_write(B, Recs2),
+    {Count + 1, B2}.
+
+send_records(Pid, Tab, Recs, Pass, {Count, B}) ->
+    receive
+	{Pid, more, Count} ->
+	    if
+		Pass == last, Recs == [] ->
+		    {Count, B};
+		true ->
+		    Next = Count + 1,
+		    Pid ! {self(), {more, Next, Recs}},
+		    {Next, B}
+	    end;
+	Msg ->
+	    exit({send_records_unexpected_msg, Tab, Msg})
+    end.
+
+tab_receiver(Pid, B, Tab, RecName, Slot) ->
+    Pid ! {self(), more, Slot},
+    receive
+	{Pid, {more, Next, Recs}} ->
+	    Recs2 = rec_filter(B, Tab, RecName, Recs),
+	    B2 = safe_write(B, Recs2),
+	    tab_receiver(Pid, B2, Tab, RecName, Next);
+	
+	{Pid, {last, {ok,_}}} ->
+	    B;
+
+	{'EXIT', Pid, {error, R}} ->
+	    Reason = {error, {"Tab copier crashed", R}},
+	    abort_write(B, {?MODULE, remote_tab_sender}, [self(), B, Tab], Reason);
+	{'EXIT', Pid, R} ->
+	    Reason = {error, {"Tab copier crashed", {'EXIT', R}}},
+	    abort_write(B, {?MODULE, remote_tab_sender}, [self(), B, Tab], Reason);
+	Msg ->
+	    R = {error, {"Tab receiver got unexpected msg", Msg}}, 
+	    abort_write(B, {?MODULE, remote_tab_sender}, [self(), B, Tab], R)
+    end.
+
+rec_filter(B, schema, _RecName, Recs) ->
+    case catch mnesia_bup:refresh_cookie(Recs, B#backup_args.cookie) of
+	Recs2 when is_list(Recs2) ->
+	    Recs2;
+	{error, _Reason} ->
+	    %% No schema table cookie
+	    Recs
+    end;
+rec_filter(_B, Tab, Tab, Recs) ->
+    Recs;
+rec_filter(_B, Tab, _RecName, Recs) ->
+    [setelement(1, Rec, Tab) || Rec <- Recs].
+
+ets2dcd(Tab) ->
+    ets2dcd(Tab, dcd).
+
+ets2dcd(Tab, Ftype) ->
+    Fname =
+	case Ftype of
+	    dcd -> mnesia_lib:tab2dcd(Tab);
+	    dmp -> mnesia_lib:tab2dmp(Tab)
+	end,    
+    TmpF = mnesia_lib:tab2tmp(Tab),
+    file:delete(TmpF),    
+    Log  = open_log({Tab, ets2dcd}, dcd_log_header(), TmpF, false),
+    mnesia_lib:db_fixtable(ram_copies, Tab, true),
+    ok   = ets2dcd(mnesia_lib:db_init_chunk(ram_copies, Tab, 1000), Tab, Log),
+    mnesia_lib:db_fixtable(ram_copies, Tab, false),
+    close_log(Log),
+    ok = file:rename(TmpF, Fname),
+    %% Remove old log data which is now in the new dcd.
+    %% No one else should be accessing this file!
+    file:delete(mnesia_lib:tab2dcl(Tab)),
+    ok.
+
+ets2dcd('$end_of_table', _Tab, _Log) ->
+    ok;
+ets2dcd({Recs, Cont}, Tab, Log) -> 
+    ok = disk_log:alog_terms(Log, Recs),     
+    ets2dcd(mnesia_lib:db_chunk(ram_copies, Cont), Tab, Log).
+
+dcd2ets(Tab) ->
+    dcd2ets(Tab, mnesia_monitor:get_env(auto_repair)).
+
+dcd2ets(Tab, Rep) ->
+    Dcd = mnesia_lib:tab2dcd(Tab),
+    case mnesia_lib:exists(Dcd) of
+	true ->
+	    Log = open_log({Tab, dcd2ets}, dcd_log_header(), Dcd, 
+			   true, Rep, read_only),
+	    Data = chunk_log(Log, start),
+	    ok = insert_dcdchunk(Data, Log, Tab),
+	    close_log(Log),
+	    load_dcl(Tab, Rep); 
+	false -> %% Handle old dets files, and conversion from disc_only to disc.
+	    Fname = mnesia_lib:tab2dat(Tab),
+	    Type = val({Tab, setorbag}),
+	    case mnesia_lib:dets_to_ets(Tab, Tab, Fname, Type, Rep, yes) of
+		loaded ->
+		    ets2dcd(Tab),
+		    file:delete(Fname),
+		    0;
+		{error, Error} ->
+		    erlang:error({"Failed to load table from disc", [Tab, Error]})
+	    end
+    end.
+
+insert_dcdchunk({Cont, [LogH | Rest]}, Log, Tab) 
+  when is_record(LogH, log_header),  
+       LogH#log_header.log_kind == dcd_log, 
+       LogH#log_header.log_version >= "1.0" ->    
+    insert_dcdchunk({Cont, Rest}, Log, Tab);   
+
+insert_dcdchunk({Cont, Recs}, Log, Tab) ->     
+    true = ets:insert(Tab, Recs),
+    insert_dcdchunk(chunk_log(Log, Cont), Log, Tab);
+insert_dcdchunk(eof, _Log, _Tab) ->
+    ok.
+
+load_dcl(Tab, Rep) ->
+    FName = mnesia_lib:tab2dcl(Tab),
+    case mnesia_lib:exists(FName) of
+	true -> 	    
+	    Name = {load_dcl,Tab},
+	    open_log(Name, 
+		     dcl_log_header(), 
+		     FName, 
+		     true,
+		     Rep, 
+		     read_only),
+	    FirstChunk = chunk_log(Name, start),
+            N = insert_logchunk(FirstChunk, Name, 0),
+	    close_log(Name),
+	    N;
+	false ->
+	    0
+    end.
+
+insert_logchunk({C2, Recs}, Tab, C) ->
+    N = add_recs(Recs, C),
+    insert_logchunk(chunk_log(Tab, C2), Tab, C+N);
+insert_logchunk(eof, _Tab, C) ->
+    C.
+
+add_recs([{{Tab, _Key}, Val, write} | Rest], N) ->
+    true = ets:insert(Tab, Val),
+    add_recs(Rest, N+1);
+add_recs([{{Tab, Key}, _Val, delete} | Rest], N) ->
+    true = ets:delete(Tab, Key),
+    add_recs(Rest, N+1);
+add_recs([{{Tab, _Key}, Val, delete_object} | Rest], N) ->
+    true = ets:match_delete(Tab, Val),
+    add_recs(Rest, N+1);
+add_recs([{{Tab, Key}, Val, update_counter} | Rest], N) ->
+    {RecName, Incr} = Val,
+    case catch ets:update_counter(Tab, Key, Incr) of
+	CounterVal when is_integer(CounterVal) ->
+	    ok;
+	_ when Incr < 0 ->
+	    Zero = {RecName, Key, 0},
+	    true = ets:insert(Tab, Zero);
+	_ ->
+	    Zero = {RecName, Key, Incr},
+	    true = ets:insert(Tab, Zero)
+    end,
+    add_recs(Rest, N+1);
+add_recs([LogH|Rest], N) 
+  when is_record(LogH, log_header),  
+       LogH#log_header.log_kind == dcl_log, 
+       LogH#log_header.log_version >= "1.0" ->    
+    add_recs(Rest, N);
+add_recs([{{Tab, _Key}, _Val, clear_table} | Rest], N) ->
+    true = ets:match_delete(Tab, '_'),
+    add_recs(Rest, N+ets:info(Tab, size));  
+add_recs([], N) ->
+    N.