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+%%
+%% %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_checkpoint).
+
+%% TM callback interface
+-export([
+ tm_add_copy/2,
+ tm_change_table_copy_type/3,
+ tm_del_copy/2,
+ tm_mnesia_down/1,
+ tm_prepare/1,
+ tm_retain/4,
+ tm_retain/5,
+ tm_enter_pending/1,
+ tm_enter_pending/3,
+ tm_exit_pending/1,
+ convert_cp_record/1
+ ]).
+
+%% Public interface
+-export([
+ activate/1,
+ checkpoints/0,
+ deactivate/1,
+ deactivate/2,
+ iterate/6,
+ most_local_node/2,
+ really_retain/2,
+ stop/0,
+ stop_iteration/1,
+ tables_and_cookie/1
+ ]).
+
+%% Internal
+-export([
+ call/2,
+ cast/2,
+ init/1,
+ remote_deactivate/1,
+ start/1
+ ]).
+
+%% sys callback interface
+-export([
+ system_code_change/4,
+ system_continue/3,
+ system_terminate/4
+ ]).
+
+-include("mnesia.hrl").
+-import(mnesia_lib, [add/2, del/2, set/2, unset/1]).
+-import(mnesia_lib, [dbg_out/2]).
+
+-record(checkpoint_args, {name = {now(), node()},
+ allow_remote = true,
+ ram_overrides_dump = false,
+ nodes = [],
+ node = node(),
+ now = now(),
+ cookie = ?unique_cookie,
+ min = [],
+ max = [],
+ pending_tab,
+ wait_for_old, % Initially undefined then List
+ is_activated = false,
+ ignore_new = [],
+ retainers = [],
+ iterators = [],
+ supervisor,
+ pid
+ }).
+
+%% Old record definition
+-record(checkpoint, {name,
+ allow_remote,
+ ram_overrides_dump,
+ nodes,
+ node,
+ now,
+ min,
+ max,
+ pending_tab,
+ wait_for_old,
+ is_activated,
+ ignore_new,
+ retainers,
+ iterators,
+ supervisor,
+ pid
+ }).
+
+-record(retainer, {cp_name, tab_name, store, writers = [], really_retain = true}).
+
+-record(iter, {tab_name, oid_tab, main_tab, retainer_tab, source, val, pid}).
+
+-record(pending, {tid, disc_nodes = [], ram_nodes = []}).
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% TM callback functions
+
+stop() ->
+ lists:foreach(fun(Name) -> call(Name, stop) end,
+ checkpoints()),
+ ok.
+
+tm_prepare(Cp) when is_record(Cp, checkpoint_args) ->
+ Name = Cp#checkpoint_args.name,
+ case lists:member(Name, checkpoints()) of
+ false ->
+ start_retainer(Cp);
+ true ->
+ {error, {already_exists, Name, node()}}
+ end;
+tm_prepare(Cp) when is_record(Cp, checkpoint) ->
+ %% Node with old protocol sent an old checkpoint record
+ %% and we have to convert it
+ case convert_cp_record(Cp) of
+ {ok, NewCp} ->
+ tm_prepare(NewCp);
+ {error, Reason} ->
+ {error, Reason}
+ end.
+
+tm_mnesia_down(Node) ->
+ lists:foreach(fun(Name) -> cast(Name, {mnesia_down, Node}) end,
+ checkpoints()).
+
+%% Returns pending
+tm_enter_pending(Tid, DiscNs, RamNs) ->
+ Pending = #pending{tid = Tid, disc_nodes = DiscNs, ram_nodes = RamNs},
+ tm_enter_pending(Pending).
+
+tm_enter_pending(Pending) ->
+ PendingTabs = val(pending_checkpoints),
+ tm_enter_pending(PendingTabs, Pending).
+
+tm_enter_pending([], Pending) ->
+ Pending;
+tm_enter_pending([Tab | Tabs], Pending) ->
+ catch ?ets_insert(Tab, Pending),
+ tm_enter_pending(Tabs, Pending).
+
+tm_exit_pending(Tid) ->
+ Pids = val(pending_checkpoint_pids),
+ tm_exit_pending(Pids, Tid).
+
+tm_exit_pending([], Tid) ->
+ Tid;
+tm_exit_pending([Pid | Pids], Tid) ->
+ Pid ! {self(), {exit_pending, Tid}},
+ tm_exit_pending(Pids, Tid).
+
+enter_still_pending([Tid | Tids], Tab) ->
+ ?ets_insert(Tab, #pending{tid = Tid}),
+ enter_still_pending(Tids, Tab);
+enter_still_pending([], _Tab) ->
+ ok.
+
+
+%% Looks up checkpoints for functions in mnesia_tm.
+tm_retain(Tid, Tab, Key, Op) ->
+ case val({Tab, commit_work}) of
+ [{checkpoints, Checkpoints} | _ ] ->
+ tm_retain(Tid, Tab, Key, Op, Checkpoints);
+ _ ->
+ undefined
+ end.
+
+tm_retain(Tid, Tab, Key, Op, Checkpoints) ->
+ case Op of
+ clear_table ->
+ OldRecs = mnesia_lib:db_match_object(Tab, '_'),
+ send_group_retain(OldRecs, Checkpoints, Tid, Tab, []),
+ OldRecs;
+ _ ->
+ OldRecs = mnesia_lib:db_get(Tab, Key),
+ send_retain(Checkpoints, {retain, Tid, Tab, Key, OldRecs}),
+ OldRecs
+ end.
+
+send_group_retain([Rec | Recs], Checkpoints, Tid, Tab, [PrevRec | PrevRecs])
+ when element(2, Rec) /= element(2, PrevRec) ->
+ Key = element(2, PrevRec),
+ OldRecs = lists:reverse([PrevRec | PrevRecs]),
+ send_retain(Checkpoints, {retain, Tid, Tab, Key, OldRecs}),
+ send_group_retain(Recs, Checkpoints, Tid, Tab, [Rec]);
+send_group_retain([Rec | Recs], Checkpoints, Tid, Tab, Acc) ->
+ send_group_retain(Recs, Checkpoints, Tid, Tab, [Rec | Acc]);
+send_group_retain([], Checkpoints, Tid, Tab, [PrevRec | PrevRecs]) ->
+ Key = element(2, PrevRec),
+ OldRecs = lists:reverse([PrevRec | PrevRecs]),
+ send_retain(Checkpoints, {retain, Tid, Tab, Key, OldRecs}),
+ ok;
+send_group_retain([], _Checkpoints, _Tid, _Tab, []) ->
+ ok.
+
+send_retain([Name | Names], Msg) ->
+ cast(Name, Msg),
+ send_retain(Names, Msg);
+send_retain([], _Msg) ->
+ ok.
+
+tm_add_copy(Tab, Node) when Node /= node() ->
+ case val({Tab, commit_work}) of
+ [{checkpoints, Checkpoints} | _ ] ->
+ Fun = fun(Name) -> call(Name, {add_copy, Tab, Node}) end,
+ map_call(Fun, Checkpoints, ok);
+ _ ->
+ ok
+ end.
+
+tm_del_copy(Tab, Node) when Node == node() ->
+ mnesia_subscr:unsubscribe_table(Tab),
+ case val({Tab, commit_work}) of
+ [{checkpoints, Checkpoints} | _ ] ->
+ Fun = fun(Name) -> call(Name, {del_copy, Tab, Node}) end,
+ map_call(Fun, Checkpoints, ok);
+ _ ->
+ ok
+ end.
+
+tm_change_table_copy_type(Tab, From, To) ->
+ case val({Tab, commit_work}) of
+ [{checkpoints, Checkpoints} | _ ] ->
+ Fun = fun(Name) -> call(Name, {change_copy, Tab, From, To}) end,
+ map_call(Fun, Checkpoints, ok);
+ _ ->
+ ok
+ end.
+
+map_call(Fun, [Name | Names], Res) ->
+ case Fun(Name) of
+ ok ->
+ map_call(Fun, Names, Res);
+ {error, {no_exists, Name}} ->
+ map_call(Fun, Names, Res);
+ {error, Reason} ->
+ %% BUGBUG: We may end up with some checkpoint retainers
+ %% too much in the add_copy case. How do we remove them?
+ map_call(Fun, Names, {error, Reason})
+ end;
+map_call(_Fun, [], Res) ->
+ Res.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Public functions
+
+deactivate(Name) ->
+ case call(Name, get_checkpoint) of
+ {error, Reason} ->
+ {error, Reason};
+ Cp ->
+ deactivate(Cp#checkpoint_args.nodes, Name)
+ end.
+
+deactivate(Nodes, Name) ->
+ rpc:multicall(Nodes, ?MODULE, remote_deactivate, [Name]),
+ ok.
+
+remote_deactivate(Name) ->
+ call(Name, deactivate).
+
+checkpoints() -> val(checkpoints).
+
+tables_and_cookie(Name) ->
+ case call(Name, get_checkpoint) of
+ {error, Reason} ->
+ {error, Reason};
+ Cp ->
+ Tabs = Cp#checkpoint_args.min ++ Cp#checkpoint_args.max,
+ Cookie = Cp#checkpoint_args.cookie,
+ {ok, Tabs, Cookie}
+ end.
+
+most_local_node(Name, Tab) ->
+ case ?catch_val({Tab, {retainer, Name}}) of
+ {'EXIT', _} ->
+ {error, {"No retainer attached to table", [Tab, Name]}};
+ R ->
+ Writers = R#retainer.writers,
+ LocalWriter = lists:member(node(), Writers),
+ if
+ LocalWriter == true ->
+ {ok, node()};
+ Writers /= [] ->
+ {ok, hd(Writers)};
+ true ->
+ {error, {"No retainer attached to table", [Tab, Name]}}
+ end
+ end.
+
+really_retain(Name, Tab) ->
+ R = val({Tab, {retainer, Name}}),
+ R#retainer.really_retain.
+
+%% Activate a checkpoint.
+%%
+%% A checkpoint is a transaction consistent state that may be used to
+%% perform a distributed backup or to rollback the involved tables to
+%% their old state. Backups may also be used to restore tables to
+%% their old state. Args is a list of the following tuples:
+%%
+%% {name, Name}
+%% Name of checkpoint. Each checkpoint must have a name which
+%% is unique on the reachable nodes. The name may be reused when
+%% the checkpoint has been deactivated.
+%% By default a probably unique name is generated.
+%% Multiple checkpoints may be set on the same table.
+%%
+%% {allow_remote, Bool}
+%% false means that all retainers must be local. If the
+%% table does not reside locally, the checkpoint fails.
+%% true allows retainers on other nodes.
+%%
+%% {min, MinTabs}
+%% Minimize redundancy and only keep checkpoint info together with
+%% one replica, preferrably at the local node. If any node involved
+%% the checkpoint goes down, the checkpoint is deactivated.
+%%
+%% {max, MaxTabs}
+%% Maximize redundancy and keep checkpoint info together with all
+%% replicas. The checkpoint becomes more fault tolerant if the
+%% tables has several replicas. When new replicas are added, they
+%% will also get a retainer attached to them.
+%%
+%% {ram_overrides_dump, Bool}
+%% {ram_overrides_dump, Tabs}
+%% Only applicable for ram_copies. Bool controls which versions of
+%% the records that should be included in the checkpoint state.
+%% true means that the latest comitted records in ram (i.e. the
+%% records that the application accesses) should be included
+%% in the checkpoint. false means that the records dumped to
+%% dat-files (the records that will be loaded at startup) should
+%% be included in the checkpoint. Tabs is a list of tables.
+%% Default is false.
+%%
+%% {ignore_new, TidList}
+%% Normally we wait for all pending transactions to complete
+%% before we allow iteration over the checkpoint. But in order
+%% to cope with checkpoint activation inside a transaction that
+%% currently prepares commit (mnesia_init:get_net_work_copy) we
+%% need to have the ability to ignore the enclosing transaction.
+%% We do not wait for the transactions in TidList to end. The
+%% transactions in TidList are regarded as newer than the checkpoint.
+
+activate(Args) ->
+ case args2cp(Args) of
+ {ok, Cp} ->
+ do_activate(Cp);
+ {error, Reason} ->
+ {error, Reason}
+ end.
+
+args2cp(Args) when is_list(Args)->
+ case catch lists:foldl(fun check_arg/2, #checkpoint_args{}, Args) of
+ {'EXIT', Reason} ->
+ {error, Reason};
+ Cp ->
+ case check_tables(Cp) of
+ {error, Reason} ->
+ {error, Reason};
+ {ok, Overriders, AllTabs} ->
+ arrange_retainers(Cp, Overriders, AllTabs)
+ end
+ end;
+args2cp(Args) ->
+ {error, {badarg, Args}}.
+
+check_arg({name, Name}, Cp) ->
+ case lists:member(Name, checkpoints()) of
+ true ->
+ exit({already_exists, Name});
+ false ->
+ case catch tab2retainer({foo, Name}) of
+ List when is_list(List) ->
+ Cp#checkpoint_args{name = Name};
+ _ ->
+ exit({badarg, Name})
+ end
+ end;
+check_arg({allow_remote, true}, Cp) ->
+ Cp#checkpoint_args{allow_remote = true};
+check_arg({allow_remote, false}, Cp) ->
+ Cp#checkpoint_args{allow_remote = false};
+check_arg({ram_overrides_dump, true}, Cp) ->
+ Cp#checkpoint_args{ram_overrides_dump = true};
+check_arg({ram_overrides_dump, false}, Cp) ->
+ Cp#checkpoint_args{ram_overrides_dump = false};
+check_arg({ram_overrides_dump, Tabs}, Cp) when is_list(Tabs) ->
+ Cp#checkpoint_args{ram_overrides_dump = Tabs};
+check_arg({min, Tabs}, Cp) when is_list(Tabs) ->
+ Cp#checkpoint_args{min = Tabs};
+check_arg({max, Tabs}, Cp) when is_list(Tabs) ->
+ Cp#checkpoint_args{max = Tabs};
+check_arg({ignore_new, Tids}, Cp) when is_list(Tids) ->
+ Cp#checkpoint_args{ignore_new = Tids};
+check_arg(Arg, _) ->
+ exit({badarg, Arg}).
+
+check_tables(Cp) ->
+ Min = Cp#checkpoint_args.min,
+ Max = Cp#checkpoint_args.max,
+ AllTabs = Min ++ Max,
+ DoubleTabs = [T || T <- Min, lists:member(T, Max)],
+ Overriders = Cp#checkpoint_args.ram_overrides_dump,
+ if
+ DoubleTabs /= [] ->
+ {error, {combine_error, Cp#checkpoint_args.name,
+ [{min, DoubleTabs}, {max, DoubleTabs}]}};
+ Min == [], Max == [] ->
+ {error, {combine_error, Cp#checkpoint_args.name,
+ [{min, Min}, {max, Max}]}};
+ Overriders == false ->
+ {ok, [], AllTabs};
+ Overriders == true ->
+ {ok, AllTabs, AllTabs};
+ is_list(Overriders) ->
+ case [T || T <- Overriders, not lists:member(T, Min)] of
+ [] ->
+ case [T || T <- Overriders, not lists:member(T, Max)] of
+ [] ->
+ {ok, Overriders, AllTabs};
+ Outsiders ->
+ {error, {combine_error, Cp#checkpoint_args.name,
+ [{ram_overrides_dump, Outsiders},
+ {max, Outsiders}]}}
+ end;
+ Outsiders ->
+ {error, {combine_error, Cp#checkpoint_args.name,
+ [{ram_overrides_dump, Outsiders},
+ {min, Outsiders}]}}
+ end
+ end.
+
+arrange_retainers(Cp, Overriders, AllTabs) ->
+ R = #retainer{cp_name = Cp#checkpoint_args.name},
+ case catch [R#retainer{tab_name = Tab,
+ writers = select_writers(Cp, Tab)}
+ || Tab <- AllTabs] of
+ {'EXIT', Reason} ->
+ {error, Reason};
+ Retainers ->
+ {ok, Cp#checkpoint_args{ram_overrides_dump = Overriders,
+ retainers = Retainers,
+ nodes = writers(Retainers)}}
+ end.
+
+select_writers(Cp, Tab) ->
+ case filter_remote(Cp, val({Tab, active_replicas})) of
+ [] ->
+ exit({"Cannot prepare checkpoint (replica not available)",
+ [Tab, Cp#checkpoint_args.name]});
+ Writers ->
+ This = node(),
+ case {lists:member(Tab, Cp#checkpoint_args.max),
+ lists:member(This, Writers)} of
+ {true, _} -> Writers; % Max
+ {false, true} -> [This];
+ {false, false} -> [hd(Writers)]
+ end
+ end.
+
+filter_remote(Cp, Writers) when Cp#checkpoint_args.allow_remote == true ->
+ Writers;
+filter_remote(_Cp, Writers) ->
+ This = node(),
+ case lists:member(This, Writers) of
+ true -> [This];
+ false -> []
+ end.
+
+writers(Retainers) ->
+ Fun = fun(R, Acc) -> R#retainer.writers ++ Acc end,
+ Writers = lists:foldl(Fun, [], Retainers),
+ mnesia_lib:uniq(Writers).
+
+do_activate(Cp) ->
+ Name = Cp#checkpoint_args.name,
+ Nodes = Cp#checkpoint_args.nodes,
+ case mnesia_tm:prepare_checkpoint(Nodes, Cp) of
+ {Replies, []} ->
+ check_prep(Replies, Name, Nodes, Cp#checkpoint_args.ignore_new);
+ {_, BadNodes} ->
+ {error, {"Cannot prepare checkpoint (bad nodes)",
+ [Name, BadNodes]}}
+ end.
+
+check_prep([{ok, Name, IgnoreNew, _Node} | Replies], Name, Nodes, IgnoreNew) ->
+ check_prep(Replies, Name, Nodes, IgnoreNew);
+check_prep([{error, Reason} | _Replies], Name, _Nodes, _IgnoreNew) ->
+ {error, {"Cannot prepare checkpoint (bad reply)",
+ [Name, Reason]}};
+check_prep([{badrpc, Reason} | _Replies], Name, _Nodes, _IgnoreNew) ->
+ {error, {"Cannot prepare checkpoint (badrpc)",
+ [Name, Reason]}};
+check_prep([], Name, Nodes, IgnoreNew) ->
+ collect_pending(Name, Nodes, IgnoreNew).
+
+collect_pending(Name, Nodes, IgnoreNew) ->
+ case rpc:multicall(Nodes, ?MODULE, call, [Name, collect_pending]) of
+ {Replies, []} ->
+ case catch ?ets_new_table(mnesia_union, [bag]) of
+ {'EXIT', Reason} -> %% system limit
+ Msg = "Cannot create an ets table pending union",
+ {error, {system_limit, Msg, Reason}};
+ UnionTab ->
+ compute_union(Replies, Nodes, Name, UnionTab, IgnoreNew)
+ end;
+ {_, BadNodes} ->
+ deactivate(Nodes, Name),
+ {error, {"Cannot collect from pending checkpoint", Name, BadNodes}}
+ end.
+
+compute_union([{ok, Pending} | Replies], Nodes, Name, UnionTab, IgnoreNew) ->
+ add_pending(Pending, UnionTab),
+ compute_union(Replies, Nodes, Name, UnionTab, IgnoreNew);
+compute_union([{error, Reason} | _Replies], Nodes, Name, UnionTab, _IgnoreNew) ->
+ deactivate(Nodes, Name),
+ ?ets_delete_table(UnionTab),
+ {error, Reason};
+compute_union([{badrpc, Reason} | _Replies], Nodes, Name, UnionTab, _IgnoreNew) ->
+ deactivate(Nodes, Name),
+ ?ets_delete_table(UnionTab),
+ {error, {badrpc, Reason}};
+compute_union([], Nodes, Name, UnionTab, IgnoreNew) ->
+ send_activate(Nodes, Nodes, Name, UnionTab, IgnoreNew).
+
+add_pending([P | Pending], UnionTab) ->
+ add_pending_node(P#pending.disc_nodes, P#pending.tid, UnionTab),
+ add_pending_node(P#pending.ram_nodes, P#pending.tid, UnionTab),
+ add_pending(Pending, UnionTab);
+add_pending([], _UnionTab) ->
+ ok.
+
+add_pending_node([Node | Nodes], Tid, UnionTab) ->
+ ?ets_insert(UnionTab, {Node, Tid}),
+ add_pending_node(Nodes, Tid, UnionTab);
+add_pending_node([], _Tid, _UnionTab) ->
+ ok.
+
+send_activate([Node | Nodes], AllNodes, Name, UnionTab, IgnoreNew) ->
+ Pending = [Tid || {_, Tid} <- ?ets_lookup(UnionTab, Node),
+ not lists:member(Tid, IgnoreNew)],
+ case rpc:call(Node, ?MODULE, call, [Name, {activate, Pending}]) of
+ activated ->
+ send_activate(Nodes, AllNodes, Name, UnionTab, IgnoreNew);
+ {badrpc, Reason} ->
+ deactivate(Nodes, Name),
+ ?ets_delete_table(UnionTab),
+ {error, {"Activation failed (bad node)", Name, Node, Reason}};
+ {error, Reason} ->
+ deactivate(Nodes, Name),
+ ?ets_delete_table(UnionTab),
+ {error, {"Activation failed", Name, Node, Reason}}
+ end;
+send_activate([], AllNodes, Name, UnionTab, _IgnoreNew) ->
+ ?ets_delete_table(UnionTab),
+ {ok, Name, AllNodes}.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Checkpoint server
+
+cast(Name, Msg) ->
+ case ?catch_val({checkpoint, Name}) of
+ {'EXIT', _} ->
+ {error, {no_exists, Name}};
+
+ Pid when is_pid(Pid) ->
+ Pid ! {self(), Msg},
+ {ok, Pid}
+ end.
+
+call(Name, Msg) ->
+ case ?catch_val({checkpoint, Name}) of
+ {'EXIT', _} ->
+ {error, {no_exists, Name}};
+
+ Pid when is_pid(Pid) ->
+ Monitor = erlang:monitor(process, Pid), %catch link(Pid), % Always local
+ Pid ! {self(), Msg},
+ Self = self(),
+ receive
+ {'EXIT', Pid, Reason} ->
+ {error, {"Got exit", [Name, Reason]}};
+ {'DOWN', Monitor, _, Pid, Reason} ->
+ {error, {"Got exit", [Name, Reason]}};
+ {Name, Self, Reply} ->
+ erlang:demonitor(Monitor),
+ Reply
+ end;
+ Error ->
+ Error
+ end.
+
+abcast(Nodes, Name, Msg) ->
+ rpc:eval_everywhere(Nodes, ?MODULE, cast, [Name, Msg]).
+
+reply(nopid, _Name, _Reply) ->
+ ignore;
+reply(ReplyTo, Name, Reply) ->
+ ReplyTo ! {Name, ReplyTo, Reply}.
+
+%% Returns {ok, NewCp} or {error, Reason}
+start_retainer(Cp) ->
+ % Will never be restarted
+ Name = Cp#checkpoint_args.name,
+ case supervisor:start_child(mnesia_checkpoint_sup, [Cp]) of
+ {ok, _Pid} ->
+ {ok, Name, Cp#checkpoint_args.ignore_new, node()};
+ {error, Reason} ->
+ {error, {"Cannot create checkpoint retainer",
+ Name, node(), Reason}}
+ end.
+
+start(Cp) ->
+ Name = Cp#checkpoint_args.name,
+ Args = [Cp#checkpoint_args{supervisor = self()}],
+ mnesia_monitor:start_proc({?MODULE, Name}, ?MODULE, init, Args).
+
+init(Cp) ->
+ process_flag(trap_exit, true),
+ process_flag(priority, high), %% Needed dets files might starve the system
+ Name = Cp#checkpoint_args.name,
+ Props = [set, public, {keypos, 2}],
+ case catch ?ets_new_table(mnesia_pending_checkpoint, Props) of
+ {'EXIT', Reason} -> %% system limit
+ Msg = "Cannot create an ets table for pending transactions",
+ Error = {error, {system_limit, Name, Msg, Reason}},
+ proc_lib:init_ack(Cp#checkpoint_args.supervisor, Error);
+ PendingTab ->
+ Rs = [prepare_tab(Cp, R) || R <- Cp#checkpoint_args.retainers],
+ Cp2 = Cp#checkpoint_args{retainers = Rs,
+ pid = self(),
+ pending_tab = PendingTab},
+ add(pending_checkpoint_pids, self()),
+ add(pending_checkpoints, PendingTab),
+ set({checkpoint, Name}, self()),
+ add(checkpoints, Name),
+ dbg_out("Checkpoint ~p (~p) started~n", [Name, self()]),
+ proc_lib:init_ack(Cp2#checkpoint_args.supervisor, {ok, self()}),
+ retainer_loop(Cp2)
+ end.
+
+prepare_tab(Cp, R) ->
+ Tab = R#retainer.tab_name,
+ prepare_tab(Cp, R, val({Tab, storage_type})).
+
+prepare_tab(Cp, R, Storage) ->
+ Tab = R#retainer.tab_name,
+ Name = R#retainer.cp_name,
+ case lists:member(node(), R#retainer.writers) of
+ true ->
+ R2 = retainer_create(Cp, R, Tab, Name, Storage),
+ set({Tab, {retainer, Name}}, R2),
+ %% Keep checkpoint info for table_info & mnesia_session
+ add({Tab, checkpoints}, Name),
+ add_chkp_info(Tab, Name),
+ R2;
+ false ->
+ set({Tab, {retainer, Name}}, R#retainer{store = undefined}),
+ R
+ end.
+
+add_chkp_info(Tab, Name) ->
+ case val({Tab, commit_work}) of
+ [{checkpoints, OldList} | CommitList] ->
+ case lists:member(Name, OldList) of
+ true ->
+ ok;
+ false ->
+ NewC = [{checkpoints, [Name | OldList]} | CommitList],
+ mnesia_lib:set({Tab, commit_work}, NewC)
+ end;
+ CommitList ->
+ Chkp = {checkpoints, [Name]},
+ %% OBS checkpoints needs to be first in the list!
+ mnesia_lib:set({Tab, commit_work}, [Chkp | CommitList])
+ end.
+
+tab2retainer({Tab, Name}) ->
+ FlatName = lists:flatten(io_lib:write(Name)),
+ mnesia_lib:dir(lists:concat([?MODULE, "_", Tab, "_", FlatName, ".RET"])).
+
+retainer_create(_Cp, R, Tab, Name, disc_only_copies) ->
+ Fname = tab2retainer({Tab, Name}),
+ file:delete(Fname),
+ Args = [{file, Fname}, {type, set}, {keypos, 2}, {repair, false}],
+ {ok, _} = mnesia_lib:dets_sync_open({Tab, Name}, Args),
+ dbg_out("Checkpoint retainer created ~p ~p~n", [Name, Tab]),
+ R#retainer{store = {dets, {Tab, Name}}, really_retain = true};
+retainer_create(Cp, R, Tab, Name, Storage) ->
+ T = ?ets_new_table(mnesia_retainer, [set, public, {keypos, 2}]),
+ Overriders = Cp#checkpoint_args.ram_overrides_dump,
+ ReallyR = R#retainer.really_retain,
+ ReallyCp = lists:member(Tab, Overriders),
+ ReallyR2 = prepare_ram_tab(Tab, T, Storage, ReallyR, ReallyCp),
+ dbg_out("Checkpoint retainer created ~p ~p~n", [Name, Tab]),
+ R#retainer{store = {ets, T}, really_retain = ReallyR2}.
+
+%% Copy the dumped table into retainer if needed
+%% If the really_retain flag already has been set to false,
+%% it should remain false even if we change storage type
+%% while the checkpoint is activated.
+prepare_ram_tab(Tab, T, ram_copies, true, false) ->
+ Fname = mnesia_lib:tab2dcd(Tab),
+ case mnesia_lib:exists(Fname) of
+ true ->
+ Log = mnesia_log:open_log(prepare_ram_tab,
+ mnesia_log:dcd_log_header(),
+ Fname, true,
+ mnesia_monitor:get_env(auto_repair),
+ read_only),
+ Add = fun(Rec) ->
+ Key = element(2, Rec),
+ Recs =
+ case ?ets_lookup(T, Key) of
+ [] -> [];
+ [{_, _, Old}] -> Old
+ end,
+ ?ets_insert(T, {Tab, Key, [Rec | Recs]}),
+ continue
+ end,
+ traverse_dcd(mnesia_log:chunk_log(Log, start), Log, Add),
+ mnesia_log:close_log(Log);
+ false ->
+ ok
+ end,
+ false;
+prepare_ram_tab(_, _, _, ReallyRetain, _) ->
+ ReallyRetain.
+
+traverse_dcd({Cont, [LogH | Rest]}, Log, Fun)
+ when is_record(LogH, log_header),
+ LogH#log_header.log_kind == dcd_log,
+ LogH#log_header.log_version >= "1.0" ->
+ traverse_dcd({Cont, Rest}, Log, Fun); %% BUGBUG Error handling repaired files
+traverse_dcd({Cont, Recs}, Log, Fun) -> %% trashed data??
+ lists:foreach(Fun, Recs),
+ traverse_dcd(mnesia_log:chunk_log(Log, Cont), Log, Fun);
+traverse_dcd(eof, _Log, _Fun) ->
+ ok.
+
+retainer_get({ets, Store}, Key) -> ?ets_lookup(Store, Key);
+retainer_get({dets, Store}, Key) -> dets:lookup(Store, Key).
+
+retainer_put({ets, Store}, Val) -> ?ets_insert(Store, Val);
+retainer_put({dets, Store}, Val) -> dets:insert(Store, Val).
+
+retainer_first({ets, Store}) -> ?ets_first(Store);
+retainer_first({dets, Store}) -> dets:first(Store).
+
+retainer_next({ets, Store}, Key) -> ?ets_next(Store, Key);
+retainer_next({dets, Store}, Key) -> dets:next(Store, Key).
+
+%% retainer_next_slot(Tab, Pos) ->
+%% case retainer_slot(Tab, Pos) of
+%% '$end_of_table' ->
+%% '$end_of_table';
+%% [] ->
+%% retainer_next_slot(Tab, Pos + 1);
+%% Recs when is_list(Recs) ->
+%% {Pos, Recs}
+%% end.
+%%
+%% retainer_slot({ets, Store}, Pos) -> ?ets_next(Store, Pos);
+%% retainer_slot({dets, Store}, Pos) -> dets:slot(Store, Pos).
+
+retainer_fixtable(Tab, Bool) when is_atom(Tab) ->
+ mnesia_lib:db_fixtable(val({Tab, storage_type}), Tab, Bool);
+retainer_fixtable({ets, Tab}, Bool) ->
+ mnesia_lib:db_fixtable(ram_copies, Tab, Bool);
+retainer_fixtable({dets, Tab}, Bool) ->
+ mnesia_lib:db_fixtable(disc_only_copies, Tab, Bool).
+
+retainer_delete({ets, Store}) ->
+ ?ets_delete_table(Store);
+retainer_delete({dets, Store}) ->
+ mnesia_lib:dets_sync_close(Store),
+ Fname = tab2retainer(Store),
+ file:delete(Fname).
+
+retainer_loop(Cp) ->
+ Name = Cp#checkpoint_args.name,
+ receive
+ {_From, {retain, Tid, Tab, Key, OldRecs}}
+ when Cp#checkpoint_args.wait_for_old == [] ->
+ R = val({Tab, {retainer, Name}}),
+ PendingTab = Cp#checkpoint_args.pending_tab,
+ case R#retainer.really_retain of
+ true when PendingTab =:= undefined ->
+ Store = R#retainer.store,
+ case retainer_get(Store, Key) of
+ [] -> retainer_put(Store, {Tab, Key, OldRecs});
+ _ -> already_retained
+ end;
+ true ->
+ case ets:member(PendingTab, Tid) of
+ true -> ignore;
+ false ->
+ Store = R#retainer.store,
+ case retainer_get(Store, Key) of
+ [] -> retainer_put(Store, {Tab, Key, OldRecs});
+ _ -> already_retained
+ end
+ end;
+ false ->
+ ignore
+ end,
+ retainer_loop(Cp);
+
+ %% Adm
+ {From, deactivate} ->
+ do_stop(Cp),
+ reply(From, Name, deactivated),
+ unlink(From),
+ exit(shutdown);
+
+ {'EXIT', Parent, _} when Parent == Cp#checkpoint_args.supervisor ->
+ %% do_stop(Cp),
+ %% assume that entire Mnesia is terminating
+ exit(shutdown);
+
+ {_From, {mnesia_down, Node}} ->
+ Cp2 = do_del_retainers(Cp, Node),
+ retainer_loop(Cp2);
+ {From, get_checkpoint} ->
+ reply(From, Name, Cp),
+ retainer_loop(Cp);
+ {From, {add_copy, Tab, Node}} when Cp#checkpoint_args.wait_for_old == [] ->
+ {Res, Cp2} = do_add_copy(Cp, Tab, Node),
+ reply(From, Name, Res),
+ retainer_loop(Cp2);
+ {From, {del_copy, Tab, Node}} when Cp#checkpoint_args.wait_for_old == [] ->
+ Cp2 = do_del_copy(Cp, Tab, Node),
+ reply(From, Name, ok),
+ retainer_loop(Cp2);
+ {From, {change_copy, Tab, From, To}} when Cp#checkpoint_args.wait_for_old == [] ->
+ Cp2 = do_change_copy(Cp, Tab, From, To),
+ reply(From, Name, ok),
+ retainer_loop(Cp2);
+ {_From, {add_retainer, R, Node}} ->
+ Cp2 = do_add_retainer(Cp, R, Node),
+ retainer_loop(Cp2);
+ {_From, {del_retainer, R, Node}} when Cp#checkpoint_args.wait_for_old == [] ->
+ Cp2 = do_del_retainer(Cp, R, Node),
+ retainer_loop(Cp2);
+
+ %% Iteration
+ {From, {iter_begin, Iter}} when Cp#checkpoint_args.wait_for_old == [] ->
+ Cp2 = iter_begin(Cp, From, Iter),
+ retainer_loop(Cp2);
+
+ {From, {iter_end, Iter}} when Cp#checkpoint_args.wait_for_old == [] ->
+ retainer_fixtable(Iter#iter.oid_tab, false),
+ Iters = Cp#checkpoint_args.iterators -- [Iter],
+ reply(From, Name, ok),
+ retainer_loop(Cp#checkpoint_args{iterators = Iters});
+
+ {_From, {exit_pending, Tid}}
+ when is_list(Cp#checkpoint_args.wait_for_old) ->
+ StillPending = lists:delete(Tid, Cp#checkpoint_args.wait_for_old),
+ Cp2 = Cp#checkpoint_args{wait_for_old = StillPending},
+ Cp3 = maybe_activate(Cp2),
+ retainer_loop(Cp3);
+
+ {From, collect_pending} ->
+ PendingTab = Cp#checkpoint_args.pending_tab,
+ del(pending_checkpoints, PendingTab),
+ Pending = ?ets_match_object(PendingTab, '_'),
+ reply(From, Name, {ok, Pending}),
+ retainer_loop(Cp);
+
+ {From, {activate, Pending}} ->
+ StillPending = mnesia_recover:still_pending(Pending),
+ enter_still_pending(StillPending, Cp#checkpoint_args.pending_tab),
+ Cp2 = maybe_activate(Cp#checkpoint_args{wait_for_old = StillPending}),
+ reply(From, Name, activated),
+ retainer_loop(Cp2);
+
+ {'EXIT', From, _Reason} ->
+ Iters = [Iter || Iter <- Cp#checkpoint_args.iterators,
+ check_iter(From, Iter)],
+ retainer_loop(Cp#checkpoint_args{iterators = Iters});
+
+ {system, From, Msg} ->
+ dbg_out("~p got {system, ~p, ~p}~n", [?MODULE, From, Msg]),
+ sys:handle_system_msg(Msg, From, no_parent, ?MODULE, [], Cp)
+ end.
+
+maybe_activate(Cp)
+ when Cp#checkpoint_args.wait_for_old == [],
+ Cp#checkpoint_args.is_activated == false ->
+ Cp#checkpoint_args{pending_tab = undefined, is_activated = true};
+maybe_activate(Cp) ->
+ Cp.
+
+iter_begin(Cp, From, Iter) ->
+ Name = Cp#checkpoint_args.name,
+ R = val({Iter#iter.tab_name, {retainer, Name}}),
+ Iter2 = init_tabs(R, Iter),
+ Iter3 = Iter2#iter{pid = From},
+ retainer_fixtable(Iter3#iter.oid_tab, true),
+ Iters = [Iter3 | Cp#checkpoint_args.iterators],
+ reply(From, Name, {ok, Iter3, self()}),
+ Cp#checkpoint_args{iterators = Iters}.
+
+do_stop(Cp) ->
+ Name = Cp#checkpoint_args.name,
+ del(pending_checkpoints, Cp#checkpoint_args.pending_tab),
+ del(pending_checkpoint_pids, self()),
+ del(checkpoints, Name),
+ unset({checkpoint, Name}),
+ lists:foreach(fun deactivate_tab/1, Cp#checkpoint_args.retainers),
+ Iters = Cp#checkpoint_args.iterators,
+ lists:foreach(fun(I) -> retainer_fixtable(I#iter.oid_tab, false) end, Iters).
+
+deactivate_tab(R) ->
+ Name = R#retainer.cp_name,
+ Tab = R#retainer.tab_name,
+ try
+ Active = lists:member(node(), R#retainer.writers),
+ case R#retainer.store of
+ undefined ->
+ ignore;
+ Store when Active == true ->
+ retainer_delete(Store);
+ _ ->
+ ignore
+ end,
+ unset({Tab, {retainer, Name}}),
+ del({Tab, checkpoints}, Name), %% Keep checkpoint info for table_info & mnesia_session
+ del_chkp_info(Tab, Name)
+ catch _:_ -> ignore
+ end.
+
+del_chkp_info(Tab, Name) ->
+ case val({Tab, commit_work}) of
+ [{checkpoints, ChkList} | Rest] ->
+ case lists:delete(Name, ChkList) of
+ [] ->
+ %% The only checkpoint was deleted
+ mnesia_lib:set({Tab, commit_work}, Rest);
+ NewList ->
+ mnesia_lib:set({Tab, commit_work},
+ [{checkpoints, NewList} | Rest])
+ end;
+ _ -> ignore
+ end.
+
+do_del_retainers(Cp, Node) ->
+ Rs = [do_del_retainer2(Cp, R, Node) || R <- Cp#checkpoint_args.retainers],
+ Cp#checkpoint_args{retainers = Rs, nodes = writers(Rs)}.
+
+do_del_retainer2(Cp, R, Node) ->
+ Writers = R#retainer.writers -- [Node],
+ R2 = R#retainer{writers = Writers},
+ set({R2#retainer.tab_name, {retainer, R2#retainer.cp_name}}, R2),
+ if
+ Writers == [] ->
+ Event = {mnesia_checkpoint_deactivated, Cp#checkpoint_args.name},
+ mnesia_lib:report_system_event(Event),
+ do_stop(Cp),
+ exit(shutdown);
+ Node == node() ->
+ deactivate_tab(R), % Avoids unnecessary tm_retain accesses
+ set({R2#retainer.tab_name, {retainer, R2#retainer.cp_name}}, R2),
+ R2;
+ true ->
+ R2
+ end.
+
+do_del_retainer(Cp, R0, Node) ->
+ {R, Rest} = find_retainer(R0, Cp#checkpoint_args.retainers, []),
+ R2 = do_del_retainer2(Cp, R, Node),
+ Rs = [R2|Rest],
+ Cp#checkpoint_args{retainers = Rs, nodes = writers(Rs)}.
+
+do_del_copy(Cp, Tab, ThisNode) when ThisNode == node() ->
+ Name = Cp#checkpoint_args.name,
+ Others = Cp#checkpoint_args.nodes -- [ThisNode],
+ R = val({Tab, {retainer, Name}}),
+ abcast(Others, Name, {del_retainer, R, ThisNode}),
+ do_del_retainer(Cp, R, ThisNode).
+
+do_add_copy(Cp, Tab, Node) when Node /= node()->
+ case lists:member(Tab, Cp#checkpoint_args.max) of
+ false ->
+ {ok, Cp};
+ true ->
+ Name = Cp#checkpoint_args.name,
+ R0 = val({Tab, {retainer, Name}}),
+ W = R0#retainer.writers,
+ R = R0#retainer{writers = W ++ [Node]},
+
+ case lists:member(Node, Cp#checkpoint_args.nodes) of
+ true ->
+ send_retainer(Cp, R, Node);
+ false ->
+ case tm_remote_prepare(Node, Cp) of
+ {ok, Name, _IgnoreNew, Node} ->
+ case lists:member(schema, Cp#checkpoint_args.max) of
+ true ->
+ %% We need to send schema retainer somewhere
+ RS0 = val({schema, {retainer, Name}}),
+ WS = RS0#retainer.writers,
+ RS1 = RS0#retainer{writers = WS ++ [Node]},
+ {ok, Cp1} = send_retainer(Cp, RS1, Node),
+ send_retainer(Cp1, R, Node);
+ false ->
+ send_retainer(Cp, R, Node)
+ end;
+ {badrpc, Reason} ->
+ {{error, {badrpc, Reason}}, Cp};
+ {error, Reason} ->
+ {{error, Reason}, Cp}
+ end
+ end
+ end.
+
+tm_remote_prepare(Node, Cp) ->
+ rpc:call(Node, ?MODULE, tm_prepare, [Cp]).
+
+do_add_retainer(Cp, R0, Node) ->
+ Writers = R0#retainer.writers,
+ {R, Rest} = find_retainer(R0, Cp#checkpoint_args.retainers, []),
+ NewRet =
+ if
+ Node == node() ->
+ prepare_tab(Cp, R#retainer{writers = Writers});
+ true ->
+ R#retainer{writers = Writers}
+ end,
+ Rs = [NewRet | Rest],
+ set({NewRet#retainer.tab_name, {retainer, NewRet#retainer.cp_name}}, NewRet),
+ Cp#checkpoint_args{retainers = Rs, nodes = writers(Rs)}.
+
+find_retainer(#retainer{cp_name = CP, tab_name = Tab},
+ [Ret = #retainer{cp_name = CP, tab_name = Tab} | R], Acc) ->
+ {Ret, R ++ Acc};
+find_retainer(Ret, [H|R], Acc) ->
+ find_retainer(Ret, R, [H|Acc]).
+
+send_retainer(Cp, R, Node) ->
+ Name = Cp#checkpoint_args.name,
+ Nodes0 = Cp#checkpoint_args.nodes -- [Node],
+ Nodes = Nodes0 -- [node()],
+ Msg = {add_retainer, R, Node},
+ abcast(Nodes, Name, Msg),
+ {ok, _} = rpc:call(Node, ?MODULE, cast, [Name, Msg]),
+ Store = R#retainer.store,
+ send_retainer2(Node, Name, Store, retainer_first(Store)),
+ Cp2 = do_add_retainer(Cp, R, Node),
+ {ok, Cp2}.
+
+send_retainer2(_, _, _, '$end_of_table') ->
+ ok;
+%%send_retainer2(Node, Name, Store, {Slot, Records}) ->
+send_retainer2(Node, Name, Store, Key) ->
+ [{Tab, _, Records}] = retainer_get(Store, Key),
+ abcast([Node], Name, {retain, {dirty, send_retainer}, Tab, Key, Records}),
+ send_retainer2(Node, Name, Store, retainer_next(Store, Key)).
+
+do_change_copy(Cp, Tab, FromType, ToType) ->
+ Name = Cp#checkpoint_args.name,
+ R = val({Tab, {retainer, Name}}),
+ R2 = prepare_tab(Cp, R, ToType),
+ {_, Old} = R#retainer.store,
+ {_, New} = R2#retainer.store,
+
+ Fname = tab2retainer({Tab, Name}),
+ if
+ FromType == disc_only_copies ->
+ mnesia_lib:dets_sync_close(Old),
+ loaded = mnesia_lib:dets_to_ets(Old, New, Fname, set, no, yes),
+ ok = file:delete(Fname);
+ ToType == disc_only_copies ->
+ TabSize = ?ets_info(Old, size),
+ Props = [{file, Fname},
+ {type, set},
+ {keypos, 2},
+%% {ram_file, true},
+ {estimated_no_objects, TabSize + 256},
+ {repair, false}],
+ {ok, _} = mnesia_lib:dets_sync_open(New, Props),
+ ok = mnesia_dumper:raw_dump_table(New, Old),
+ ?ets_delete_table(Old);
+ true ->
+ ignore
+ end,
+ Pos = #retainer.tab_name,
+ Rs = lists:keyreplace(Tab, Pos, Cp#checkpoint_args.retainers, R2),
+ Cp#checkpoint_args{retainers = Rs, nodes = writers(Rs)}.
+
+check_iter(From, Iter) when Iter#iter.pid == From ->
+ retainer_fixtable(Iter#iter.oid_tab, false),
+ false;
+check_iter(_From, _Iter) ->
+ true.
+
+init_tabs(R, Iter) ->
+ {Kind, _} = Store = R#retainer.store,
+ Main = {Kind, Iter#iter.tab_name},
+ Ret = Store,
+ Iter2 = Iter#iter{main_tab = Main, retainer_tab = Ret},
+ case Iter#iter.source of
+ table -> Iter2#iter{oid_tab = Main};
+ retainer -> Iter2#iter{oid_tab = Ret}
+ end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Iteration
+%%
+%% Iterates over a table and applies Fun(ListOfRecords)
+%% with a suitable amount of records, e.g. 1000 or so.
+%% ListOfRecords is [] when the iteration is over.
+%%
+%% OidKind affects which internal table to be iterated over and
+%% ValKind affects which table to pick the actual records from. Legal
+%% values for OidKind and ValKind is the atom table or the atom
+%% retainer.
+%%
+%% The iteration may either be performed over the main table (which
+%% contains the latest values of the records, i.e. the values that
+%% are visible to the applications) or over the checkpoint retainer
+%% (which contains the values as the looked like the timepoint when
+%% the checkpoint was activated).
+%%
+%% It is possible to iterate over the main table and pick values
+%% from the retainer and vice versa.
+
+iterate(Name, Tab, Fun, Acc, Source, Val) ->
+ Iter0 = #iter{tab_name = Tab, source = Source, val = Val},
+ case call(Name, {iter_begin, Iter0}) of
+ {error, Reason} ->
+ {error, Reason};
+ {ok, Iter, Pid} ->
+ link(Pid), % We don't want any pending fixtable's
+ Res = (catch iter(Fun, Acc, Iter)),
+ unlink(Pid),
+ call(Name, {iter_end, Iter}),
+ case Res of
+ {'EXIT', Reason} -> {error, Reason};
+ {error, Reason} -> {error, Reason};
+ Acc2 -> {ok, Acc2}
+ end
+ end.
+
+iter(Fun, Acc, Iter)->
+ iter(Fun, Acc, Iter, retainer_first(Iter#iter.oid_tab)).
+
+iter(Fun, Acc, Iter, Key) ->
+ case get_records(Iter, Key) of
+ {'$end_of_table', []} ->
+ Fun([], Acc);
+ {'$end_of_table', Records} ->
+ Acc2 = Fun(Records, Acc),
+ Fun([], Acc2);
+ {Next, Records} ->
+ Acc2 = Fun(Records, Acc),
+ iter(Fun, Acc2, Iter, Next)
+ end.
+
+stop_iteration(Reason) ->
+ throw({error, {stopped, Reason}}).
+
+get_records(Iter, Key) ->
+ get_records(Iter, Key, 500, []). % 500 keys
+
+get_records(_Iter, Key, 0, Acc) ->
+ {Key, lists:append(lists:reverse(Acc))};
+get_records(_Iter, '$end_of_table', _I, Acc) ->
+ {'$end_of_table', lists:append(lists:reverse(Acc))};
+get_records(Iter, Key, I, Acc) ->
+ Recs = get_val(Iter, Key),
+ Next = retainer_next(Iter#iter.oid_tab, Key),
+ get_records(Iter, Next, I-1, [Recs | Acc]).
+
+get_val(Iter, Key) when Iter#iter.val == latest ->
+ get_latest_val(Iter, Key);
+get_val(Iter, Key) when Iter#iter.val == checkpoint ->
+ get_checkpoint_val(Iter, Key).
+
+get_latest_val(Iter, Key) when Iter#iter.source == table ->
+ retainer_get(Iter#iter.main_tab, Key);
+get_latest_val(Iter, Key) when Iter#iter.source == retainer ->
+ DeleteOid = {Iter#iter.tab_name, Key},
+ [DeleteOid | retainer_get(Iter#iter.main_tab, Key)].
+
+get_checkpoint_val(Iter, Key) when Iter#iter.source == table ->
+ retainer_get(Iter#iter.main_tab, Key);
+get_checkpoint_val(Iter, Key) when Iter#iter.source == retainer ->
+ DeleteOid = {Iter#iter.tab_name, Key},
+ case retainer_get(Iter#iter.retainer_tab, Key) of
+ [{_, _, []}] -> [DeleteOid];
+ [{_, _, Records}] -> [DeleteOid | Records]
+ end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% System upgrade
+
+system_continue(_Parent, _Debug, Cp) ->
+ retainer_loop(Cp).
+
+system_terminate(_Reason, _Parent,_Debug, Cp) ->
+ do_stop(Cp).
+
+system_code_change(Cp, _Module, _OldVsn, _Extra) ->
+ {ok, Cp}.
+
+convert_cp_record(Cp) when is_record(Cp, checkpoint) ->
+ ROD =
+ case Cp#checkpoint.ram_overrides_dump of
+ true -> Cp#checkpoint.min ++ Cp#checkpoint.max;
+ false -> []
+ end,
+
+ {ok, #checkpoint_args{name = Cp#checkpoint.name,
+ allow_remote = Cp#checkpoint.name,
+ ram_overrides_dump = ROD,
+ nodes = Cp#checkpoint.nodes,
+ node = Cp#checkpoint.node,
+ now = Cp#checkpoint.now,
+ cookie = ?unique_cookie,
+ min = Cp#checkpoint.min,
+ max = Cp#checkpoint.max,
+ pending_tab = Cp#checkpoint.pending_tab,
+ wait_for_old = Cp#checkpoint.wait_for_old,
+ is_activated = Cp#checkpoint.is_activated,
+ ignore_new = Cp#checkpoint.ignore_new,
+ retainers = Cp#checkpoint.retainers,
+ iterators = Cp#checkpoint.iterators,
+ supervisor = Cp#checkpoint.supervisor,
+ pid = Cp#checkpoint.pid
+ }};
+convert_cp_record(Cp) when is_record(Cp, checkpoint_args) ->
+ AllTabs = Cp#checkpoint_args.min ++ Cp#checkpoint_args.max,
+ ROD = case Cp#checkpoint_args.ram_overrides_dump of
+ [] ->
+ false;
+ AllTabs ->
+ true;
+ _ ->
+ error
+ end,
+ if
+ ROD == error ->
+ {error, {"Old node cannot handle new checkpoint protocol",
+ ram_overrides_dump}};
+ true ->
+ {ok, #checkpoint{name = Cp#checkpoint_args.name,
+ allow_remote = Cp#checkpoint_args.name,
+ ram_overrides_dump = ROD,
+ nodes = Cp#checkpoint_args.nodes,
+ node = Cp#checkpoint_args.node,
+ now = Cp#checkpoint_args.now,
+ min = Cp#checkpoint_args.min,
+ max = Cp#checkpoint_args.max,
+ pending_tab = Cp#checkpoint_args.pending_tab,
+ wait_for_old = Cp#checkpoint_args.wait_for_old,
+ is_activated = Cp#checkpoint_args.is_activated,
+ ignore_new = Cp#checkpoint_args.ignore_new,
+ retainers = Cp#checkpoint_args.retainers,
+ iterators = Cp#checkpoint_args.iterators,
+ supervisor = Cp#checkpoint_args.supervisor,
+ pid = Cp#checkpoint_args.pid
+ }}
+ end.
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+val(Var) ->
+ case ?catch_val(Var) of
+ {'EXIT', _ReASoN_} -> mnesia_lib:other_val(Var, _ReASoN_);
+ _VaLuE_ -> _VaLuE_
+ end.
+