[snmp/agent] New behaviour module (snmpa_mib_data) and two impl mods

The old mib-server data module (snmpa_mib_data) has been changed into
a behaviour module. The old implementation is now instead in a new
module snmpa_mib_data_tree1. A new backend module has been added,
still only very preliminary, snmpa_mib_data_tree2.

1 files changed, 46 insertions, 1347 deletions

diff --git a/lib/snmp/src/agent/snmpa_mib_data.erl b/lib/snmp/src/agent/snmpa_mib_data.erl
index e20884c0a3..2872ee2127 100644
--- a/lib/snmp/src/agent/snmpa_mib_data.erl
+++ b/lib/snmp/src/agent/snmpa_mib_data.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1996-2009. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2013. 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
@@ -19,1371 +19,70 @@
 -module(snmpa_mib_data).
 
 %%%-----------------------------------------------------------------
-%%% This module implements the MIB internal data structures.
-%%% An MIB Data Structure consists of three items; an ets-table,
-%%% a tree and a list of registered subagents.
-%%% The subagent information is consequently duplicated. It resides
-%%% both in the tree and in the list.
-%%% The ets-table contains all data associated with each variable,
-%%% table, tableentry and tablecolumn in the MIB.
-%%% The tree contains information of the Oids in the MIB.
-%%%
-%%% When a mib is loaded, the tree is built from the plain list
-%%% in the binary file.
+%%% This is the behaviour for the MIB server backend internal 
+%%% data storage. 
 %%%-----------------------------------------------------------------
--include("snmp_types.hrl").
--include("snmp_debug.hrl").
 
--define(VMODULE,"MDATA").
--include("snmp_verbosity.hrl").
 
--define(MIB_DATA,snmpa_mib_data).
--define(MIB_NODE,snmpa_mib_node).
--define(MIB_TREE,snmpa_mib_tree).
--define(DUMMY_TREE_GENERATION,1).
--define(DEFAULT_TREE,{tree,{undefined_node},internal}).
-%%-define(DUMMY_TREE_DB,dummy_tree_db).
-%%-define(DUMMY_TREE_DB_INIT,{?DUMMY_TREE_DB,?DEFAULT_TREE}).
+-callback new(MibStorage :: mib_storage()) -> State :: term().
 
+-callback close(State :: term()) -> ok.
 
-%%%-----------------------------------------------------------------
-%%% Table of contents
-%%% =================
-%%% 1. Interface
-%%% 2. Implementation of tree access
-%%% 3. Tree building functions
-%%% 4. Tree merging
-%%% 5. Tree deletion routines
-%%% 6. Functions for subagent handling
-%%% 7. Misc functions
-%%%-----------------------------------------------------------------
-
-
-%%----------------------------------------------------------------------
-%% data_db is an database containing loaded mibs as:
-%%    {MibName = atom(), Symbolic = ?, FullFileName = string()}
-%%    it is either ets or mnesia
-%% tree_db is a database containing _one_ record with the tree!
-%% (the reason for this is part to get replication and part out of convenience)
-%% ref_tree is the root node, without any subagent.
-%% tree is the root node (same as ref_tree but with the subagents added).
-%% subagents is a list of {SAPid, Oid}
-%%----------------------------------------------------------------------
--record(mib_data, {mib_db,  % table of #mib_info
-		   node_db, % table of #node_info
-		   tree_db, % table of #tree
-		   tree,    % The actual tree
-		   subagents = []}).
-
--record(mib_info,  {name, symbolic, file_name}).
--record(node_info, {oid, mib_name, me}).
-
-
-%% API
--export([new/0, new/1, sync/1, close/1, 
-	 load_mib/4, unload_mib/4, which_mibs/1, whereis_mib/2, 
-	 info/1, info/2,
-	 dump/1, dump/2, 
-	 backup/2, 
-	 lookup/2, next/3, which_mib/2, 
-	 register_subagent/3, unregister_subagent/2]).
-
-%% Internal exports
--export([code_change/2]).
-
-
-%%-----------------------------------------------------------------
-%% A tree is represented as a N-tuple, where each element is a
-%% node. A node is:
-%% 1) {tree, Tree, Info} where Info can be {table, Id}, {table_entry, Id}
-%%                                        or perhaps 'internal'
-%% 2) undefined_node  (memory optimization (instead of {node, undefined}))
-%% 3) {node, Info} where Info can be {subagent, Pid}, {variable, Id}, 
-%%                                   {table_column, Id}
-%% Id is {MibName, MibEntry}
-%% The over all root is represented as {tree, Tree, internal}.
-%%
-%% tree() = {tree, nodes(), tree_info()}
-%% nodes() = [tree() | node() | undefined_node]
-%% node() = {node, node_info()}
-%% tree_info() = {table, Id} | {table_entry, Id} | internal
-%% node_info() = {subagent, Pid} | {variable, Id} | {table_colum, Id}
-%%-----------------------------------------------------------------
-
--type tree_generation() :: non_neg_integer().
--type tree()            :: #tree{}.
--type tree_nodes()      :: [tree_node()].
--type tree_node()       :: tree() | 
-			   tree_node_elem() | 
-			   tree_node_empty().
--type tree_node_elem()  :: {node, tree_node_info()}.
--type tree_node_info()  :: {subagent,     Pid :: pid()} | 
-			   {variable,     Id  :: non_neg_integer()} | 
-			   {table_column, Id  :: non_neg_integer()}.
--type tree_node_empty() :: {undefined_node, N :: pos_integer()}.
--type tree_info()       :: {table,       Id :: non_neg_integer()} | 
-			   {table_entry, Id :: non_neg_integer()} | 
-			   internal.
-
-
-%% This record is what is stored in the database. The 'tree' part
-%% is described above...
--record(mtree, 
-	{
-	  generation = ?DUMMY_TREE_GENERATION :: tree_generation(), 
-	  root       = ?DEFAULT_TREE          :: tree()
-	}).
-
--record(tree, 
-	{
-	  %% The number of nodes is *not* actually the length of the
-	  %% nodes list. Since the undefined-node(s) can be collapsed
-	  %% into {undefined_node, N} we need to keep track of the 
-	  %% actual size some other way (so that we dont have the 
-	  %% traverse the nodes every time we want to check an index).
-	  num_nodes :: non_neg_integer(), 
-	  nodes     :: tree_nodes(), 
-	  tree_info :: tree_info()
-	}).
-
-
-
-
-%%%======================================================================
-%%% 1. Interface
-%%%======================================================================
-
-%%-----------------------------------------------------------------
-%% Func: new/0, new/1
-%% Returns: A representation of mib data.
-%%-----------------------------------------------------------------
-new() ->
-    new(ets).
-
-%% Where -> A list of nodes where the tables will be created
-new(Storage) ->
-    %% First we must check if there is already something to read
-    %% If a database already exists, then the tree structure has to be read
-    ?vtrace("open (mib) database",[]),
-    MibDb = snmpa_general_db:open(Storage, ?MIB_DATA,
-				  mib_info,
-				  record_info(fields, mib_info), set),
-    ?vtrace("open (mib) node database",[]),
-    NodeDb = snmpa_general_db:open(Storage, ?MIB_NODE,
-				   node_info,
-				   record_info(fields, node_info), set),
-    ?vtrace("open (mib) tree database",[]),
-    TreeDb = snmpa_general_db:open(Storage, ?MIB_TREE,
-				   tree,
-				   record_info(fields, mtree), set),
-    MTree = 
-	case snmpa_general_db:read(TreeDb, ?DUMMY_TREE_GENERATION) of
-	    false ->
-		T = #mtree{},
-		snmpa_general_db:write(TreeDb, T),
-		T;
-	    {value, T} ->
-		T
-	end,
-    install_mibs(MibDb, NodeDb),
-    #mib_data{mib_db   = MibDb, 
-	      node_db  = NodeDb,
-	      tree_db  = TreeDb, 
-	      mtree    = MTree}.
-
-
-%%----------------------------------------------------------------------
-%% Returns: new mib data | {error, Reason}
-%%----------------------------------------------------------------------
-load_mib(MibData,FileName,MeOverride,TeOverride) 
-  when is_record(MibData,mib_data) andalso is_list(FileName) -> 
-    ?vlog("load mib file: ~p",[FileName]),
-    ActualFileName = filename:rootname(FileName, ".bin") ++ ".bin",
-    MibName = list_to_atom(filename:basename(FileName, ".bin")),
-    (catch do_load_mib(MibData, ActualFileName, MibName, 
-                       MeOverride, TeOverride)).
-
-do_load_mib(MibData, ActualFileName, MibName, MeOverride, TeOverride) ->
-    ?vtrace("do_load_mib -> entry with"
-        "~n  ActualFileName: ~s"
-        "~n  MibName:        ~p",[ActualFileName, MibName]),
-    #mib_data{mib_db  = MibDb, 
-	      node_db = NodeDb, 
-	      %% tree_db = TreeDb,
-	      tree    = Tree} = MibData,
-    verify_not_loaded(MibDb, MibName),
-    ?vtrace("do_load_mib -> already loaded mibs:"
-	"~n   ~p",[loaded(MibDb)]),
-    Mib = do_read_mib(ActualFileName),
-    ?vtrace("do_load_mib -> read mib ~s",[Mib#mib.name]),
-    NonInternalMes = 
-        lists:filter(fun(ME) -> maybe_drop_me(ME) end, Mib#mib.mes),
-    OldRoot = Tree#tree.root,
-    T = build_tree(NonInternalMes, MibName),
-    ?d("load_mib -> "
-	"~n   OldRoot: ~p"
-	"~n   T:       ~p", [OldRoot, T]),
-    case (catch merge_nodes(T, OldRoot)) of
-	{error_merge_nodes, Node1, Node2} ->
-	    ?vlog("error merging nodes:"
-		"~n~p~nand~n~p", [Node1,Node2]),
-	    {error, oid_conflict};
-	NewRoot when is_tuple(NewRoot) andalso (element(1,NewRoot) =:= tree) ->
- 	    ?d("load_mib -> "
- 		"~n   NewRoot: ~p", [NewRoot]),
-	    Symbolic = not lists:member(no_symbolic_info, Mib#mib.misc),
-	    case (catch check_notif_and_mes(TeOverride, MeOverride, Symbolic, 
-					    Mib#mib.traps, NonInternalMes)) of
-		true ->
-		    install_mes(NodeDb, MibName, NonInternalMes),
-		    install_mib(MibDb, Symbolic, Mib, 
-				MibName, ActualFileName, NonInternalMes),
-		    ?vtrace("installed mib ~s", [Mib#mib.name]),
-		    Tree2 = Tree#tree{root = NewRoot},
-		    %% snmpa_general_db:write(TreeDb, Tree2), %% Store later?
-		    {ok, MibData#mib_data{tree = Tree2}};
-		Else -> 
-		    Else
-	    end
-    end.
-
-
-verify_not_loaded(Db, Name) ->
-    case snmpa_general_db:read(Db, Name) of
-        {value, #mib_info{name = Name}} -> 
-            throw({error, 'already loaded'});
-        false ->
-            ok
-    end.
-
-do_read_mib(ActualFileName) ->
-    case snmp_misc:read_mib(ActualFileName) of
-        {error, Reason} -> 
-            ?vlog("Failed reading mib file ~p with reason: ~p",
-                [ActualFileName,Reason]),
-            throw({error, Reason});
-        {ok, Mib} ->
-            Mib
-    end.
-
-%% The Tree DB is handled in a special way since it can be very large.
-sync(#mib_data{mib_db  = M, 
-	       node_db = N, 
-	       tree_db = T, tree = Tree, subagents = []}) ->
-    snmpa_general_db:sync(M),
-    snmpa_general_db:sync(N),
-    snmpa_general_db:write(T, Tree),
-    snmpa_general_db:sync(T);
-sync(#mib_data{mib_db  = M, 
-	       node_db = N, 
-	       tree_db = T, tree = Tree, subagents = SAs}) ->
-
-    snmpa_general_db:sync(M),
-    snmpa_general_db:sync(N),
-
-    %% Ouch. Since the subagent info is dynamic we do not 
-    %% want to store the tree containing subagent info. So, we 
-    %% have to create a tmp tree without those and store it.
-
-    case delete_subagents(Tree, SAs) of
-	{ok, TreeWithoutSAs} ->
-	    snmpa_general_db:write(T, TreeWithoutSAs),
-	    snmpa_general_db:sync(T);
-	Error ->
-	    Error
-    end.
-
-delete_subagents(Tree, []) ->
-    {ok, Tree};
-delete_subagents(Tree0, [{_, Oid}|SAs]) ->
-    case (catch delete_subagent(Tree0, Oid)) of
-	{tree, _Tree, _Info} = Tree1 ->
-	    delete_subagents(Tree1, SAs);
-	_Error ->
-	    {error, {'invalid oid', Oid}} 
-    end.
-
-%%----------------------------------------------------------------------
-%% (OTP-3601)
-%%----------------------------------------------------------------------
-check_notif_and_mes(TeOverride,MeOverride,Symbolic,Traps,MEs) ->
-    ?vtrace("check notifications and mib entries",[]),
-    check_notifications(TeOverride,Symbolic,Traps),
-    check_mes(MeOverride,MEs).
-
-check_notifications(true, _Symbolic, _Traps) ->
-    ?vtrace("trapentry override = true => skip check",[]),
-    true;
-check_notifications(_, Symbolic, Traps) -> 
-    check_notifications(Symbolic, Traps).
-
-check_notifications(true, Traps) ->
-    check_notifications(Traps);
-check_notifications(_, _) -> true.
-
-check_notifications([]) -> true;
-check_notifications([#trap{trapname = Key} = Trap | Traps]) ->
-    ?vtrace("check notification [trap] with Key: ~p",[Key]),
-    case snmpa_symbolic_store:get_notification(Key) of
-	{value, Trap} -> check_notifications(Traps);
-	{value,    _} -> throw({error, {'trap already defined', Key}});
-	undefined     -> check_notifications(Traps)
-    end;
-check_notifications([#notification{trapname = Key} = Notif | Traps]) ->
-    ?vtrace("check notification [notification] with Key: ~p",[Key]),
-    case snmpa_symbolic_store:get_notification(Key) of
-	{value, Notif} -> 
-	    check_notifications(Traps);
-	{value,     _} -> 
-	    throw({error, {'notification already defined', Key}});
-	undefined      -> 
-	    check_notifications(Traps)
-    end;
-check_notifications([Crap | Traps]) ->
-    ?vlog("skipped check of: ~n~p",[Crap]),
-    check_notifications(Traps).
-
-check_mes(true,_) ->
-    ?vtrace("mibentry override = true => skip check",[]),
-    true; 
-check_mes(_,MEs) ->
-    check_mes(MEs).
-
-check_mes([]) -> true;
-check_mes([#me{aliasname = Name, oid = Oid1} | MEs]) ->
-    ?vtrace("check mib entries with aliasname: ~p",[Name]),
-    case snmpa_symbolic_store:aliasname_to_oid(Name) of
-	{value, Oid1} -> 
-	    check_mes(MEs);
-	{value, Oid2} -> 
-	    ?vinfo("~n   expecting '~p'~n   but found '~p'",[Oid1, Oid2]),
-	    throw({error, {'mibentry already defined', Name}});
-	false -> 
-	    check_mes(MEs)
-    end;
-check_mes([Crap | MEs]) ->
-    ?vlog("skipped check of: ~n~p",[Crap]),
-    check_mes(MEs).
-    
-
-
-%%----------------------------------------------------------------------
-%% Returns: new mib data | {error, Reason}
-%%----------------------------------------------------------------------
-unload_mib(MibData, FileName, _, _) when is_list(FileName) -> 
-    MibName = list_to_atom(filename:basename(FileName, ".bin")),
-    (catch do_unload_mib(MibData, MibName)).
-
-do_unload_mib(MibData, MibName) ->
-    ?vtrace("do_unload_mib -> entry with"
-	"~n   MibName: ~p", [MibName]),
-    #mib_data{mib_db  = MibDb, 
-	      node_db = NodeDb, 
-	      %% tree_db = TreeDb, 
-	      tree    = Tree} = MibData,
-    #mib_info{symbolic = Symbolic} = verify_loaded(MibDb, MibName),
-    NewRoot = delete_mib_from_tree(MibName, Tree#tree.root),
-    MEs = uninstall_mes(NodeDb, MibName),
-    uninstall_mib(MibDb, Symbolic, MibName, MEs),
-    NewMibData = MibData#mib_data{tree = Tree#tree{root = NewRoot}},
-    {ok, NewMibData}.
-
-verify_loaded(Db, Name) ->
-    case snmpa_general_db:read(Db, Name) of
-        {value, MibInfo} ->
-            MibInfo;
-        false ->
-            throw({error, 'not loaded'})
-    end.
-    
-    
-close(#mib_data{mib_db = MibDb, node_db = NodeDb, tree_db = TreeDb}) ->
-    snmpa_general_db:close(MibDb),
-    snmpa_general_db:close(NodeDb),
-    snmpa_general_db:close(TreeDb),
-    ok.
-
-register_subagent(#mib_data{tree = T} = MibData, Oid, Pid) ->
-    case insert_subagent(Oid, T#tree.root) of
-	{error, Reason} -> 
-	    {error, Reason};
-	NewRootTree ->
-	    SAs = [{Pid, Oid} | MibData#mib_data.subagents],
-	    T2 = T#tree{root = NewRootTree},
-	    MibData#mib_data{tree = T2, subagents = SAs}
-    end.
-
-
-%%----------------------------------------------------------------------
-%% Purpose: Get a list of all loaded mibs
-%% Returns: [{Name, File}]
-%%----------------------------------------------------------------------
-
-which_mibs(#mib_data{mib_db = Db}) ->
-    Mibs = snmpa_general_db:tab2list(Db),
-    [{Name, File} || #mib_info{name = Name, file_name = File} <- Mibs].
-
-
-%%----------------------------------------------------------------------
-%% Purpose: Get a list of all loaded mibs
-%% Returns: [{Name, File}]
-%%----------------------------------------------------------------------
-
-whereis_mib(#mib_data{mib_db = Db}, Name) ->
-    case snmpa_general_db:read(Db, Name) of
-        {value, #mib_info{file_name = File}} ->
-	    {ok, File};
-	false ->
-	    {error, not_found}
-    end.
-
-
-%%----------------------------------------------------------------------
-%% Purpose: Deletes SA with Pid from all subtrees it handles.
-%% Returns: NewMibData.
-%%----------------------------------------------------------------------
-unregister_subagent(MibData, Pid) when is_pid(Pid) ->
-    SAs = MibData#mib_data.subagents,
-    case lists:keysearch(Pid, 1, SAs) of
-	false -> MibData;
-	{value, {Pid, Oid}} ->
-	    % we should never get an error since Oid is found in MibData.
-	    {ok, NewMibData, _DeletedSA} = unregister_subagent(MibData, Oid),
-	    % continue if the same Pid handles other mib subtrees.
-	    unregister_subagent(NewMibData, Pid)
-    end;
-
-%%----------------------------------------------------------------------
-%% Purpose: Deletes one unique subagent. 
-%% Returns: {error, Reason} | {ok, NewMibData, DeletedSubagentPid}
-%%----------------------------------------------------------------------
-unregister_subagent(#mib_data{tree = T} = MibData, Oid) when is_list(Oid) ->
-    case catch delete_subagent(T#tree.root, Oid) of
-	{tree, Tree, Info} ->
-	    OldSAs = MibData#mib_data.subagents,
-	    {value, {Pid, _Oid}} = lists:keysearch(Oid, 2, OldSAs),
-	    SAs = lists:keydelete(Oid, 2, OldSAs),
-	    T2 = T#tree{root = {tree, Tree, Info}},
-	    {ok, 
-	     MibData#mib_data{tree = T2, subagents = SAs},
-	     Pid};
-	_ ->
-	    {error, {'invalid oid', Oid}}
-    end.
-
-%%----------------------------------------------------------------------
-%% Purpose: To inpect memory usage, loaded mibs, registered subagents
-%%----------------------------------------------------------------------
-info(MibData) ->
-    ?vtrace("retrieve info",[]),
-    #mib_data{mib_db = MibDb, node_db = NodeDb, tree_db = TreeDb, 
-	      tree = Tree, subagents = SAs} = MibData,
-    LoadedMibs = old_format(snmpa_general_db:tab2list(MibDb)),
-    TreeSize = snmp_misc:mem_size(Tree),
-    {memory, ProcSize} = erlang:process_info(self(),memory),
-    MibDbSize  = snmpa_general_db:info(MibDb,  memory),
-    NodeDbSize = snmpa_general_db:info(NodeDb, memory),
-    TreeDbSize = snmpa_general_db:info(TreeDb, memory),
-    [{loaded_mibs, LoadedMibs}, {subagents, SAs}, {tree_size_bytes, TreeSize},
-     {process_memory, ProcSize}, 
-     {db_memory, [{mib,MibDbSize},{node,NodeDbSize},{tree,TreeDbSize}]}].
-
-info(#mib_data{mib_db = MibDb}, loaded_mibs) ->
-    Mibs = snmpa_general_db:tab2list(MibDb),
-    [filename:rootname(FN, ".bin") || #mib_info{file_name = FN} <- Mibs];
-info(#mib_data{tree = Tree}, tree_size_bytes) ->
-    snmp_misc:mem_size(Tree);
-info(_, process_memory) ->
-    {memory, ProcSize} = erlang:process_info(self(),memory),
-    ProcSize;
-info(#mib_data{mib_db = MibDb, node_db = NodeDb, tree_db = TreeDb}, 
-     db_memory) ->
-    MibDbSize  = snmpa_general_db:info(MibDb,  memory),
-    NodeDbSize = snmpa_general_db:info(NodeDb, memory),
-    TreeDbSize = snmpa_general_db:info(TreeDb, memory),
-    [{mib,MibDbSize},{node,NodeDbSize},{tree,TreeDbSize}];
-info(#mib_data{subagents = SAs}, subagents) ->
-    SAs.
-
-old_format(LoadedMibs) ->
-    ?vtrace("convert mib info to old format",[]),
-    [{N,S,F} || #mib_info{name=N,symbolic=S,file_name=F} <- LoadedMibs].
-
-    
-%%----------------------------------------------------------------------
-%% A total dump for debugging.
-%%----------------------------------------------------------------------
-dump(#mib_data{mib_db = MibDb, node_db = NodeDb, tree = Tree}) ->
-    (catch io:format("MIB-tables:~n~p~n~n", 
-		     [snmpa_general_db:tab2list(MibDb)])),
-    (catch io:format("MIB-entries:~n~p~n~n", 
-		     [snmpa_general_db:tab2list(NodeDb)])),
-    (catch io:format("Tree:~n~p~n", [Tree])), % good luck reading it!
-    ok.
-
-dump(#mib_data{mib_db = MibDb, node_db = NodeDb, tree = Tree}, File) ->
-    case file:open(File,[write]) of
-	{ok, Fd} ->
-	    io:format(Fd,"~s~n", 
-		      [snmp:date_and_time_to_string(snmp:date_and_time())]),
-	    (catch io:format(Fd,"MIB-tables:~n~p~n~n",
-			     [snmpa_general_db:tab2list(MibDb)])),
-	    (catch io:format(Fd, "MIB-entries:~n~p~n~n", 
-			     [snmpa_general_db:tab2list(NodeDb)])),
-	    io:format(Fd,"Tree:~n~p~n", [Tree]), % good luck reading it!
-	    file:close(Fd),
-	    ok;
-	{error,Reason} ->
-	    ?vinfo("~n   Failed opening file '~s' for reason ~p",
-		   [File,Reason]),
-	    {error,Reason}
-    end.
-
-
-backup(#mib_data{mib_db = M, node_db = N, tree_db = T}, BackupDir) ->
-    MRes = snmpa_general_db:backup(M, BackupDir),
-    NRes = snmpa_general_db:backup(N, BackupDir),
-    TRes = snmpa_general_db:backup(T, BackupDir),
-    handle_backup_res([{mib_db, MRes}, {node_db, NRes}, {tree_db, TRes}]).
-
-handle_backup_res(Res) ->
-    handle_backup_res(Res, []).
-
-handle_backup_res([], []) ->
-    ok;
-handle_backup_res([], Err) ->
-    {error, lists:reverse(Err)};
-handle_backup_res([{_, ok}|Res], Err) ->
-    handle_backup_res(Res, Err);
-handle_backup_res([{Tag, {error, Reason}}|Res], Err) ->
-    handle_backup_res(Res, [{Tag, Reason}|Err]);
-handle_backup_res([{Tag, Error}|Res], Err) ->
-    handle_backup_res(Res, [{Tag, Error}|Err]).
-
-
-%%%======================================================================
-%%% 2. Implementation of tree access
-%%%    lookup and next.
-%%%======================================================================
-
-
-which_mib(#mib_data{tree = T} = D, Oid) ->
-    ?vtrace("which_mib -> entry with"
-	    "~n   Oid: ~p",[Oid]),	    
-    case (catch find_node(D, T#tree.root, Oid, [])) of
-	{variable, _ME, Mib} ->
-	    ?vtrace("which_mib -> variable:"
-		"~n   Mib: ~p", [Mib]),	    
-	    {ok, Mib};
-	{table, _EntryME, _, Mib} ->
-	    ?vtrace("which_mib -> table:"
-		"~n   Mib: ~p", [Mib]),	    
-	    {ok, Mib};
-	{subagent, SubAgentPid, _SANextOid} ->
-	    ?vtrace("which_mib -> subagent:"
-		"~n   SubAgentPid: ~p", [SubAgentPid]),	    
-	    {error, {subagent, SubAgentPid}};
-	{false, ErrorCode} -> 
-	    ?vtrace("which_mib -> false:"
-		"~n   ErrorCode: ~p",[ErrorCode]),	    
-	    {error, ErrorCode};
-	false -> 
-	    ?vtrace("which_mib -> false",[]),	    
-	    {error, noSuchObject};
-	{'EXIT', R} -> 
-	    ?vtrace("which_mib -> exit:"
-		"~n   R:  ~p",[R]),	    
-	    {error, noSuchObject}
-    end.
-
-
-%%-----------------------------------------------------------------
-%% Func: lookup/2
-%% Purpose: Finds the mib entry corresponding to the Oid. If it is a
-%%          variable, the Oid must be <Oid for var>.0 and if it is
-%%          a table, Oid must be <table>.<entry>.<col>.<any>
-%% Returns: {variable, MibEntry} |
-%%          {table_column, MibEntry, TableEntryOid} |
-%%          {subagent, SubAgentPid, SAOid} |
-%%          {false, Reason}
-%%-----------------------------------------------------------------
-lookup(#mib_data{tree = T} = D, Oid) ->
-     ?vtrace("lookup -> entry with"
- 	"~n   Oid: ~p",[Oid]),	    
-    case (catch find_node(D, T#tree.root, Oid, [])) of
-	{variable, ME, _Mib} when is_record(ME, me) -> 
-	    ?vtrace("lookup -> variable:"
-		"~n   ME: ~p",[ME]),	    
-	    {variable, ME};
-	{table, EntryME, {ColME, TableEntryOid}, _Mib} ->
-	    ?vtrace("lookup -> table:"
-		"~n   EntryME:          ~p"
-		"~n   ColME:            ~p"
-		"~n   RevTableEntryOid: ~p",
-		[EntryME, ColME, TableEntryOid]),	    
-	    MFA = EntryME#me.mfa,
-	    RetME = ColME#me{mfa = MFA},
-	    {table_column, RetME, TableEntryOid};
-	{subagent, SubAgentPid, SANextOid} ->
-	    ?vtrace("lookup -> subagent:"
-		"~n   SubAgentPid: ~p"
-		"~n   SANextOid:   ~p", [SubAgentPid, SANextOid]),	    
-	    {subagent, SubAgentPid, SANextOid};
-	{false, ErrorCode} -> 
-	    ?vtrace("lookup -> false:"
-		"~n   ErrorCode: ~p",[ErrorCode]),	    
-	    {false, ErrorCode};
-	false -> 
-	    ?vtrace("lookup -> false",[]),	    
-	    {false, noSuchObject};
-	{'EXIT', R} -> 
-	    ?vtrace("lookup -> exit:"
-		"~n   R:  ~p",[R]),	    
-	    {false, noSuchObject}
-    end.
-
-
-find_node(D, {tree, Tree, {table, _}}, RestOfOid, RevOid) ->
-     ?vtrace("find_node(tree,table) -> entry with"
- 	"~n   RestOfOid: ~p"
- 	"~n   RevOid:    ~p",[RestOfOid, RevOid]),
-    find_node(D, {tree, Tree, internal}, RestOfOid, RevOid);
-find_node(D, {tree, Tree, {table_entry, _}}, RestOfOid, RevOid) ->
-     ?vtrace("find_node(tree,table_entry) -> entry with"
- 	"~n   RestOfOid: ~p"
- 	"~n   RevOid:    ~p",[RestOfOid, RevOid]),
-    #mib_data{node_db = Db} = D,
-    Oid = lists:reverse(RevOid),
-    case snmpa_general_db:read(Db, Oid) of
-	{value, #node_info{me = ME, mib_name = Mib}} ->
-	    case find_node(D, {tree, Tree, internal}, RestOfOid, RevOid) of
-		{false, ErrorCode} -> {false, ErrorCode};
-		Val -> {table, ME, Val, Mib}
-	    end;
-	false ->
-	    ?vinfo("find_node -> could not find table_entry ME with"
-		"~n   RevOid:    ~p"
-		"~n   when"
-		"~n   RestOfOid: ~p", 
-		[RevOid, RestOfOid]),
-	    false
-    end;
-find_node(D, {tree, Tree, _Internal}, [Int | RestOfOid], RevOid) ->
-    ?vtrace("find_node(tree) -> entry with"
-	"~n   Int:       ~p"
-	"~n   RestOfOid: ~p"
-	"~n   RevOid:    ~p",[Int, RestOfOid, RevOid]),
-    find_node(D, element(Int+1, Tree), RestOfOid, [Int | RevOid]);
-find_node(D, {node, {table_column, _}}, RestOfOid, [ColInt | RevOid]) ->
-     ?vtrace("find_node(tree,table_column) -> entry with"
- 	"~n   RestOfOid: ~p"
- 	"~n   ColInt:    ~p"
- 	"~n   RevOid:    ~p",[RestOfOid, ColInt, RevOid]),
-    #mib_data{node_db = Db} = D,
-    Oid = lists:reverse([ColInt | RevOid]),
-    case snmpa_general_db:read(Db, Oid) of
-	{value, #node_info{me = ME}} ->
-	    {ME, lists:reverse(RevOid)}; 
-	false ->
-	    X = snmpa_general_db:read(Db, lists:reverse([ColInt | RevOid])),
-	    ?vinfo("find_node -> could not find table_column ME with"
-		"~n   RevOid: ~p"
-		"~n   trying  [~p|~p]"
-		"~n   X:      ~p", 
-		[RevOid, [ColInt | RevOid], X]),
-	    false
-    end;
-find_node(D, {node, {variable, _MibName}}, [0], RevOid) ->
-     ?vtrace("find_node(tree,variable,[0]) -> entry with"
- 	"~n   RevOid:    ~p",[RevOid]),
-    #mib_data{node_db = Db} = D,
-    Oid = lists:reverse(RevOid),
-    %% {value, #node_info{me = ME}} = snmpa_general_db:read(Db, Oid),
-    case snmpa_general_db:read(Db, Oid) of
-	{value, #node_info{me = ME, mib_name = Mib}} ->
-	    {variable, ME, Mib};
-	false ->
-	    ?vinfo("find_node -> could not find variable ME with"
-		"~n   RevOid: ~p", [RevOid]),
-	    false
-    end;
-find_node(_D, {node, {variable, _MibName}}, [], _RevOid) ->
-    ?vtrace("find_node(tree,variable,[]) -> entry",[]),
-    {false, noSuchObject};
-find_node(_D, {node, {variable, _MibName}}, _, _RevOid) ->
-    ?vtrace("find_node(tree,variable) -> entry",[]),
-    {false, noSuchInstance};
-find_node(D, {node, subagent}, _RestOfOid, SARevOid) ->
-    ?vtrace("find_node(tree,subagent) -> entry with"
- 	"~n   SARevOid:    ~p",[SARevOid]),
-    #mib_data{subagents = SAs} = D,
-    SAOid = lists:reverse(SARevOid),
-    case lists:keysearch(SAOid, 2, SAs) of
-	{value, {SubAgentPid, SAOid}} ->
-	    {subagent, SubAgentPid, SAOid};
-	false ->
-	    ?vinfo("find_node -> could not find subagent with"
-		"~n   SAOid: ~p"
-		"~n   SAs:   ~p", [SAOid, SAs]),
-	    false
-    end;    
-find_node(_D, Node, _RestOfOid, _RevOid) ->
-    ?vtrace("find_node -> failed:~n~p",[Node]),
-    {false, noSuchObject}.
-
-
-%%-----------------------------------------------------------------
-%% Func: next/3
-%% Purpose: Finds the lexicographically next oid.
-%% Returns: endOfMibView |
-%%          {subagent, SubAgentPid, SAOid} |
-%%          {variable, MibEntry, VarOid} |
-%%          {table, TableOid, TableRestOid, MibEntry}
-%% If a variable is returnes, it is in the MibView.
-%% If a table or subagent is returned, it *may* be in the MibView.
-%%-----------------------------------------------------------------
-next(#mib_data{tree = T} = D, Oid, MibView) ->
-    case catch next_node(D, T#tree.root, Oid, [], MibView) of
-	false -> endOfMibView;
-	Else -> Else
-    end.
-
-%%-----------------------------------------------------------------
-%% This function is used as long as we have any Oid left. Take
-%% one integer at a time from the Oid, and traverse the tree
-%% accordingly. When the Oid is empty, call find_next.
-%% Returns: {subagent, SubAgentPid, SAOid} |
-%%          false |
-%%          {variable, MibEntry, VarOid} |
-%%          {table, TableOid, TableRestOid, MibEntry}
-%%-----------------------------------------------------------------
-next_node(_D, undefined_node, _Oid, _RevOidSoFar, _MibView) ->
-    ?vtrace("next_node(undefined_node) -> entry", []),
-    false;
-
-next_node(_D, {tree, Tree, {table_entry, _Id}}, [Int | _Oid], 
-	  _RevOidSoFar, _MibView)
-  when Int+1 > size(Tree) ->
-    ?vtrace("next_node(tree,table_entry) -> entry when not found whith"
-	"~n   Int:        ~p"
-	"~n   size(Tree): ~p", [Int, size(Tree)]),
-    false;
-next_node(D, {tree, Tree, {table_entry, _MibName}},
-	  Oid, RevOidSoFar, MibView) ->
-    ?vtrace("next_node(tree,table_entry) -> entry when"
-	"~n   size(Tree):  ~p"
-	"~n   Oid:         ~p"
-	"~n   RevOidSoFar: ~p"
-	"~n   MibView:     ~p", [size(Tree), Oid, RevOidSoFar, MibView]),
-    OidSoFar = lists:reverse(RevOidSoFar),
-    case snmpa_acm:is_definitely_not_in_mib_view(OidSoFar, MibView) of
-	true -> 
-	    ?vdebug("next_node(tree,table_entry) -> not in mib view",[]),
-	    false;
-	_ -> 
-	    #mib_data{node_db = Db} = D,
-	    case snmpa_general_db:read(Db, OidSoFar) of
-		false ->
-		    ?vinfo("next_node -> could not find table_entry with"
-			"~n   OidSoFar: ~p", [OidSoFar]),
-		    false;
-		{value, #node_info{me = ME}} ->
-		    ?vtrace("next_node(tree,table_entry) -> found: ~n   ~p",
-			[ME]),
-		    {table, OidSoFar, Oid, ME}
-	    end
-    end;
-
-next_node(D, {tree, Tree, _Info}, [Int | RestOfOid], RevOidSoFar, MibView) 
-  when (Int < size(Tree)) andalso (Int >= 0) ->
-    ?vtrace("next_node(tree) -> entry when"
-	"~n   size(Tree):  ~p"
-	"~n   Int:         ~p"
-	"~n   RestOfOid:   ~p"
-	"~n   RevOidSoFar: ~p"
-	"~n   MibView:     ~p", 
-	[size(Tree), Int, RestOfOid, RevOidSoFar, MibView]),
-    case next_node(D, element(Int+1,Tree), 
-		   RestOfOid, [Int|RevOidSoFar], MibView) of
-	false -> 
-	    find_next(D, {tree, Tree, _Info}, Int+1, RevOidSoFar, MibView);
-	Else -> 
-	    Else
-    end;
-%% no solution
-next_node(D, {tree, Tree, _Info}, [], RevOidSoFar, MibView) ->
-    ?vtrace("next_node(tree,[]) -> entry when"
-	"~n   size(Tree):  ~p"
-	"~n   RevOidSoFar: ~p"
-	"~n   MibView:     ~p", 
-	[size(Tree), RevOidSoFar, MibView]),
-    find_next(D, {tree, Tree, _Info}, 0, RevOidSoFar, MibView);
-next_node(_D, {tree, Tree, _Info}, _RestOfOid, _RevOidSoFar, _MibView) ->
-    ?vtrace("next_node(tree) -> entry when"
-	"~n   size(Tree):  ~p", [size(Tree)]),
-    false;
-
-next_node(D, {node, subagent}, Oid, RevOidSoFar, MibView) ->
-    ?vtrace("next_node(node,subagent) -> entry when"
-	"~n   Oid:         ~p"
-	"~n   RevOidSoFar: ~p"
-	"~n   MibView:     ~p", 
-	[Oid, RevOidSoFar, MibView]),
-    OidSoFar = lists:reverse(RevOidSoFar),
-    case snmpa_acm:is_definitely_not_in_mib_view(OidSoFar, MibView) of
-	true -> 
-	    false;
-	_ -> 
-	    #mib_data{subagents = SAs} = D,
-	    case lists:keysearch(OidSoFar, 2, SAs) of
-		{value, {SubAgentPid, OidSoFar}} ->
-		    {subagent, SubAgentPid, OidSoFar};
-		_ ->
-		    ?vinfo("next_node -> could not find subagent with"
-			"~n   OidSoFar: ~p"
-			"~n   SAs:      ~p", [OidSoFar, SAs]),
-		    false
-	    end
-    end;
-    
-next_node(D, {node, {variable, _MibName}}, [], RevOidSoFar, MibView) ->
-    ?vtrace("next_node(node,variable,[]) -> entry when"
-	"~n   RevOidSoFar: ~p"
-	"~n   MibView:     ~p", 
-	[RevOidSoFar, MibView]),
-    OidSoFar = lists:reverse([0 | RevOidSoFar]),
-    case snmpa_acm:validate_mib_view(OidSoFar, MibView) of
-	true ->
-	    #mib_data{node_db = Db} = D,
-	    case snmpa_general_db:read(Db, lists:reverse(RevOidSoFar)) of
-		false ->
-		    ?vinfo("next_node -> could not find variable with"
-			"~n   RevOidSoFar: ~p", [RevOidSoFar]),
-		    false;
-		{value, #node_info{me = ME}} ->
-		    {variable, ME, OidSoFar}
-	    end;
-	_ -> 
-	    false
-    end;
-
-next_node(_D, {node, {variable, _MibName}}, _Oid, _RevOidSoFar, _MibView) ->
-    ?vtrace("next_node(node,variable) -> entry", []),
-    false.
-
-%%-----------------------------------------------------------------
-%% This function is used to find the first leaf from where we
-%% are.
-%% Returns: {subagent, SubAgentPid, SAOid} |
-%%          false |
-%%          {variable, MibEntry, VarOid} |
-%%          {table, TableOid, TableRestOid, MibEntry}
-%% PRE: This function must always be called with a {internal, Tree}
-%%      node.
-%%-----------------------------------------------------------------
-find_next(D, {tree, Tree, internal}, Idx, RevOidSoFar, MibView) 
-  when Idx < size(Tree) ->
-    case find_next(D, element(Idx+1, Tree), 0, [Idx| RevOidSoFar], MibView) of
-	false -> 
-	    find_next(D, {tree, Tree, internal}, Idx+1, RevOidSoFar, MibView);
-	Other -> 
-	    Other
-    end;
-find_next(_D, {tree, _Tree, internal}, _Idx, _RevOidSoFar, _MibView) ->
-    false;
-find_next(_D, undefined_node, _Idx, _RevOidSoFar, _MibView) ->
-    false;
-find_next(D, {tree, Tree, {table, _MibName}}, Idx, RevOidSoFar, MibView) ->
-    find_next(D, {tree, Tree, internal}, Idx, RevOidSoFar, MibView);
-find_next(D, {tree, _Tree, {table_entry, _MibName}}, _Index,
-	  RevOidSoFar, MibView) ->
-    OidSoFar = lists:reverse(RevOidSoFar),
-    case snmpa_acm:is_definitely_not_in_mib_view(OidSoFar, MibView) of
-	true -> 
-	    false;
-	_ -> 
-	    #mib_data{node_db = Db} = D,
-	    case snmpa_general_db:read(Db, OidSoFar) of
-		false ->
-		    ?vinfo("find_next -> could not find table_entry ME with"
-			"~n   OidSoFar: ~p", [OidSoFar]),
-		    false;
-		{value, #node_info{me = ME}} ->
-		    {table, OidSoFar, [], ME}
-	    end
-    end;
-find_next(D, {node, {variable, _MibName}}, _Idx, RevOidSoFar, MibView) ->
-    OidSoFar = lists:reverse([0 | RevOidSoFar]),
-    case snmpa_acm:validate_mib_view(OidSoFar, MibView) of
-	true -> 
-	    #mib_data{node_db = Db} = D,
-	    case snmpa_general_db:read(Db, lists:reverse(RevOidSoFar)) of
-		false ->
-		    ?vinfo("find_next -> could not find variable with"
-			"~n   RevOidSoFar: ~p", [RevOidSoFar]),
-		    false;
-		{value, #node_info{me = ME}} ->
-		    {variable, ME, OidSoFar}
-	    end;
-	_ -> 
-	    false
-    end;
-find_next(D, {node, subagent}, _Idx, RevOidSoFar, MibView) ->
-    OidSoFar = lists:reverse(RevOidSoFar),
-    case snmpa_acm:is_definitely_not_in_mib_view(OidSoFar, MibView) of
-	true -> 
-	    false;
-	_ -> 
-	    #mib_data{subagents = SAs} = D,
-	    case lists:keysearch(OidSoFar, 2, SAs) of
-		{value, {SubAgentPid, OidSoFar}} ->
-		    {subagent, SubAgentPid, OidSoFar};
-		false ->
-		    ?vinfo("find_node -> could not find subagent with"
-			"~n   OidSoFar: ~p"
-			"~n   SAs:      ~p", [OidSoFar, SAs]),
-		    false
-	    end
-    end.
-
-%%%======================================================================
-%%% 3. Tree building functions
-%%%    Used when loading mibs.
-%%%======================================================================
-
-build_tree(Mes, MibName) ->
-    ?d("build_tree -> "
-	"~n   Mes: ~p", [Mes]),
-    {ListTree, []}  = build_subtree([], Mes, MibName),
-    {tree, convert_tree(ListTree), internal}.
-
-%%----------------------------------------------------------------------
-%% Purpose: Builds the tree where all oids have prefix equal to LevelPrefix.
-%% Returns: {Tree, RestMes}
-%% RestMes are Mes that should not be in this subtree.
-%% The Tree is a temporary and simplified data structure that is easy to
-%% convert to the final tuple tree used by the MIB process.
-%% A Node is represented as in the final tree.
-%% The tree is not represented as a N-tuple, but as an Index-list.
-%% Example: Temporary: [{1, Node1}, {3, Node3}]
-%%          Final:     {Node1, undefined_node, Node3}
-%% Pre: Mes are sorted on oid.
-%%----------------------------------------------------------------------
-build_subtree(LevelPrefix, [Me | Mes], MibName) ->
-    ?vtrace("build subtree -> ~n"
-	   "   oid:         ~p~n"
-	   "   LevelPrefix: ~p~n"
-	   "   MibName:     ~p", [Me#me.oid, LevelPrefix, MibName]),
-    EType = Me#me.entrytype,
-    ?vtrace("build subtree -> EType = ~p",[EType]),
-    case in_subtree(LevelPrefix, Me) of
-	above ->
-	    ?vtrace("build subtree -> above",[]),
-	    {[], [Me|Mes]};
-	{node, Index} ->
-	    ?vtrace("build subtree -> node at ~p",[Index]),
-	    {Tree, RestMes} = build_subtree(LevelPrefix, Mes, MibName),
-	    {[{Index, {node, {EType, MibName}}} | Tree], RestMes};
-	{subtree, Index, NewLevelPrefix} ->
-	    ?vtrace("build subtree -> subtree at"
-		    "~n   ~w with ~w",
-		   [Index, NewLevelPrefix]),
-	    {BelowTree, RestMes} = 
-		build_subtree(NewLevelPrefix, Mes, MibName),
-	    {CurTree, RestMes2} = 
-		build_subtree(LevelPrefix, RestMes, MibName),
-	    {[{Index, {tree, BelowTree, {EType,MibName}}}| CurTree], RestMes2};
-	{internal_subtree, Index, NewLevelPrefix} ->
-	    ?vtrace("build subtree -> internal_subtree at"
-		    "~n   ~w with ~w",
-		   [Index,NewLevelPrefix]),
-	    {BelowTree, RestMes} =
-		build_subtree(NewLevelPrefix, [Me | Mes], MibName),
-	    {CurTree, RestMes2} =
-		build_subtree(LevelPrefix, RestMes, MibName),
-	    {[{Index, {tree, BelowTree, internal}} | CurTree], RestMes2}
-    end;
-
-build_subtree(_LevelPrefix, [], _MibName) -> 
-    ?vtrace("build subtree -> done", []),
-    {[], []}.
-
-%%--------------------------------------------------
-%% Purpose: Determine how/if/where Me should be inserted in subtree
-%%          with LevelPrefix. This function does not build any tree, only 
-%%          determinses what should be done (by build subtree).
-%% Returns:
-%% above - Indicating that this ME should _not_ be in this subtree.
-%% {node, Index} - yes, construct a node with index Index on this level
-%% {internal_subtree, Index, NewLevelPrefix} - yes, there should be an
-%%   internal subtree at this index.
-%% {subtree, Index, NewLevelPrefix} - yes, construct a subtree with 
-%%   NewLevelPrefix and insert this on current level in position Index.
-%%--------------------------------------------------
-in_subtree(LevelPrefix, Me) ->
-    case lists:prefix(LevelPrefix, Me#me.oid) of
-	true when length(Me#me.oid) > length(LevelPrefix) ->
-	    classify_how_in_subtree(LevelPrefix, Me);
-	_ ->
-	    above
-    end.
-
-%%--------------------------------------------------
-%% See comment about in_subtree/2.  This function takes care of all cases
-%% where the ME really should be in _this_ subtree (not above).
-%%--------------------------------------------------
-classify_how_in_subtree(LevelPrefix, Me) 
-  when (length(Me#me.oid) =:= (length(LevelPrefix) + 1)) ->
-    Oid = Me#me.oid,
-    case node_or_subtree(Me#me.entrytype) of
-	subtree ->
-	    {subtree, lists:last(Oid), Oid};
-	node ->
-	    {node, lists:last(Oid)}
-    end;
-
-classify_how_in_subtree(LevelPrefix, Me) 
-  when (length(Me#me.oid) > (length(LevelPrefix) + 1)) ->
-    L1 = length(LevelPrefix) + 1,
-    Oid = Me#me.oid,
-    {internal_subtree, lists:nth(L1, Oid), lists:sublist(Oid, 1, L1)}.
-
-%%--------------------------------------------------
-%% Determines how to treat different kinds om MEs in the tree building process.
-%% Pre: all internal nodes have been removed.
-%%--------------------------------------------------
-node_or_subtree(table) -> subtree;
-node_or_subtree(table_entry) -> subtree;
-node_or_subtree(variable) -> node;
-node_or_subtree(table_column) -> node.
-
-%%--------------------------------------------------
-%% Purpose: (Recursively) Converts a temporary tree (see above) to a final tree.
-%% If input is a ListTree, output is a TupleTree.
-%% If input is a Node, output is the same Node.
-%% Pre: All Indexes are >= 0.
-%%--------------------------------------------------
-convert_tree({Index, {tree, Tree, Info}}) when Index >= 0 ->
-    L = lists:map(fun convert_tree/1, Tree),
-    {Index, {tree, dict_list_to_tuple(L), Info}};
-convert_tree({Index, {node, Info}}) when Index >= 0 ->
-    {Index, {node, Info}};
-convert_tree(Tree) when is_list(Tree) ->
-    L = lists:map(fun convert_tree/1, Tree),
-    dict_list_to_tuple(L).
-
-%%----------------------------------------------------------------------
-%% Purpose: Converts a single level (that is non-recursively) from
-%%          the temporary indexlist to the N-tuple.
-%% Input: A list of {Index, Data}.
-%% Output: A tuple where element Index is Data.
-%%----------------------------------------------------------------------
-dict_list_to_tuple(L) ->
-    L2 = lists:keysort(1, L),
-    list_to_tuple(integrate_indexes(0, L2)).
-
-%%----------------------------------------------------------------------
-%% Purpose: Helper function for dict_list_to_tuple/1.
-%%          Converts an indexlist to a N-list.
-%% Input: A list of {Index, Data}.
-%% Output: A (usually longer, never shorter) list where element Index is Data.
-%% Example: [{1,hej}, {3, sven}] will give output 
-%% [undefined_node, hej, undefined_node, sven].
-%% Initially CurIndex should be 0.
-%%----------------------------------------------------------------------
-integrate_indexes(CurIndex, [{CurIndex, Data} | T]) ->
-    [Data | integrate_indexes(CurIndex + 1, T)];
-integrate_indexes(_Index, []) ->
-    [];
-integrate_indexes(CurIndex, L) ->
-    [undefined_node | integrate_indexes(CurIndex + 1, L)].
-
-%%%======================================================================
-%%% 4. Tree merging
-%%%    Used by: load mib, insert subagent.
-%%%======================================================================
-
-%%----------------------------------------------------------------------
-%% Arg: Two root nodes (that is to be merged).
-%% Returns: A new root node where the nodes have been merger to one.
-%%----------------------------------------------------------------------
-merge_nodes(Same, Same) -> 
-    Same;
-merge_nodes(Node, undefined_node) -> 
-    Node;
-merge_nodes(undefined_node, Node) -> 
-    Node;
-merge_nodes({tree, Tree1, internal}, {tree, Tree2, internal}) ->
-    {tree, merge_levels(tuple_to_list(Tree1),tuple_to_list(Tree2)), internal};
-merge_nodes(Node1, Node2) ->
-    throw({error_merge_nodes, Node1, Node2}).
-
-%%----------------------------------------------------------------------
-%% Arg: Two levels to be merged.
-%%      Here, a level is represented as a list of nodes. A list is easier
-%%      to extend than a tuple.
-%% Returns: The resulting, merged level tuple.
-%%----------------------------------------------------------------------
-merge_levels(Level1, Level2) when length(Level1) =:= length(Level2) ->
-    MergeNodes = fun(N1, N2) -> merge_nodes(N1, N2) end,
-    list_to_tuple(snmp_misc:multi_map(MergeNodes, [Level1, Level2]));
-merge_levels(Level1, Level2) when length(Level1) > length(Level2) ->
-    merge_levels(Level1, Level2 ++ 
-		 undefined_nodes_list(length(Level1) - length(Level2)));
-merge_levels(Level1, Level2) when length(Level1) < length(Level2) ->
-    merge_levels(Level2, Level1).
-
-undefined_nodes_list(N) -> lists:duplicate(N, undefined_node).
-
-
-%%%======================================================================
-%%% 5. Tree deletion routines
-%%%    (for unload mib)
-%%%======================================================================
-
-%%----------------------------------------------------------------------
-%% Purpose:  Actually kicks of the tree reconstruction.
-%% Returns: {list of removed MEs, NewTree}
-%%----------------------------------------------------------------------
-delete_mib_from_tree(MibName, {tree, Tree, internal}) ->
-    case delete_tree(Tree, MibName) of
-	[] -> 
-	    {tree, {undefined_node}, internal}; % reduce
-	LevelList -> 
-	    {tree, list_to_tuple(LevelList), internal}
-    end.
-
-%%----------------------------------------------------------------------
-%% Purpose: Deletes all nodes associated to MibName from this level and
-%%          all levels below.
-%%          If the new level does not contain information (that is, no 
-%%          other mibs use it) anymore the empty list is returned.
-%% Returns: {MEs, The new level represented as a list}
-%%----------------------------------------------------------------------
-delete_tree(Tree, MibName) when is_tuple(Tree) ->
-    NewLevel = delete_nodes(tuple_to_list(Tree), MibName, []),
-    case lists:filter(fun drop_undefined_nodes/1,NewLevel) of
-	[] -> [];
-	_A_perhaps_shorted_list ->
-	    NewLevel  % some other mib needs this level
-    end.
-    
-%%----------------------------------------------------------------------
-%% Purpose: Nodes belonging to MibName are removed from the tree.
-%%          Recursively deletes sub trees to this node.
-%% Returns: {MEs, NewNodesList}
-%%----------------------------------------------------------------------
-delete_nodes([], _MibName, AccNodes) ->
-    lists:reverse(AccNodes);
-
-delete_nodes([{node, {variable, MibName}}|T], MibName, AccNodes) ->
-    delete_nodes(T, MibName, [undefined_node | AccNodes]);
-
-delete_nodes([{node, {table_column, MibName}}|T], MibName, AccNodes) ->
-    delete_nodes(T, MibName, [undefined_node | AccNodes]);
-
-delete_nodes([{tree, _Tree, {table, MibName}}|T], MibName, AccNodes) ->
-    delete_nodes(T, MibName, [undefined_node | AccNodes]);
-
-delete_nodes([{tree, _Tree, {table_entry, MibName}}|T], MibName, AccNodes) ->
-    delete_nodes(T, MibName, [undefined_node | AccNodes]);
-
-delete_nodes([{tree, Tree, Info}|T], MibName, AccNodes) ->
-    case delete_tree(Tree, MibName) of
-	[] -> % tree completely deleted
-	    delete_nodes(T, MibName, [undefined_node | AccNodes]);
-	LevelList ->
-	    delete_nodes(T, MibName, 
-			 [{tree, list_to_tuple(LevelList), Info} | AccNodes])
-    end;
-
-delete_nodes([NodeToKeep|T], MibName, AccNodes) ->
-    delete_nodes(T, MibName, [NodeToKeep | AccNodes]).
-
-drop_undefined_nodes(undefined_node) -> false;
-drop_undefined_nodes(_) -> true.
-
-
-%%%======================================================================
-%%% 6. Functions for subagent handling
-%%%======================================================================
-
-%%----------------------------------------------------------------------
-%% Returns: A new Root|{error, reason}
-%%----------------------------------------------------------------------
-insert_subagent(Oid, OldRoot) ->
-    ListTree = build_tree_for_subagent(Oid),
-    case catch convert_tree(ListTree) of
-	{'EXIT', _Reason} ->
-	    {error, 'cannot construct tree from oid'};
-	Level when is_tuple(Level) ->
-	    T = {tree, Level, internal},
-	    case catch merge_nodes(T, OldRoot) of
-		{error_merge_nodes, _Node1, _Node2} ->
-		    {error, oid_conflict};
-		NewRoot when is_tuple(NewRoot) andalso 
-			     (element(1, NewRoot) =:= tree) ->
-		    NewRoot
-	    end
-    end.
-
-build_tree_for_subagent([Index]) ->
-    [{Index, {node, subagent}}];
-
-build_tree_for_subagent([Index | T]) ->
-    [{Index, {tree, build_tree_for_subagent(T), internal}}].
-
-%%----------------------------------------------------------------------
-%% Returns: A new tree where the subagent at Oid (2nd arg) has been deleted.
-%%----------------------------------------------------------------------
-delete_subagent({tree, Tree, Info}, [Index]) ->
-    {node, subagent} = element(Index+1, Tree),
-    {tree, setelement(Index+1, Tree, undefined_node), Info};
-delete_subagent({tree, Tree, Info}, [Index | TI]) ->
-    {tree, setelement(Index+1, Tree,
-		      delete_subagent(element(Index+1, Tree), TI)), Info}.
-
-%%%======================================================================
-%%% 7. Misc functions
-%%%======================================================================
-
-%%----------------------------------------------------------------------
-%% Installs the mibs found in the database when starting the agent.
-%% Basically calls the instrumentation functions for all non-internal
-%% mib-entries
-%%----------------------------------------------------------------------
-install_mibs(MibDb, NodeDb) ->
-    MibNames = loaded(MibDb),
-    ?vtrace("install_mibs -> found following mibs in database: ~n"
-	"~p", [MibNames]),
-    install_mibs2(NodeDb, MibNames).
-
-install_mibs2(_, []) ->
-    ok;
-install_mibs2(NodeDb, [MibName|MibNames]) ->
-    Pattern = #node_info{oid = '_', mib_name = MibName, me = '_'},
-    Nodes = snmpa_general_db:match_object(NodeDb, Pattern),
-    MEs = [ME || #node_info{me = ME} <- Nodes],
-    ?vtrace("install_mibs2 -> installing ~p MEs for mib ~p", 
-	[length(MEs),MibName]),
-    NewF = fun(ME) -> call_instrumentation(ME, new) end,
-    lists:foreach(NewF, MEs),
-    install_mibs2(NodeDb, MibNames).
-    
-    
-%%----------------------------------------------------------------------
-%% Does all side effect stuff during load_mib.
-%%----------------------------------------------------------------------
-install_mib(Db, Symbolic, Mib, MibName, FileName, NonInternalMes) ->
-    ?vdebug("install_mib -> entry with"
-	    "~n   Symbolic: ~p"
-	    "~n   MibName:  ~p"
-	    "~n   FileName: ~p", [Symbolic, MibName, FileName]),
-    Rec = #mib_info{name = MibName, symbolic = Symbolic, file_name = FileName},
-    snmpa_general_db:write(Db, Rec),
-    install_mib2(Symbolic, MibName, Mib),
-    NewF = fun(ME) -> call_instrumentation(ME, new) end,
-    lists:foreach(NewF, NonInternalMes).
+-callback sync(State :: term()) -> ok.
 
-install_mib2(true, MibName, Mib) ->
-    #mib{table_infos    = TabInfos,
-	 variable_infos = VarInfos,
-	 mes            = MEs,
-	 asn1_types     = ASN1Types,
-	 traps          = Traps} = Mib,
-    snmpa_symbolic_store:add_table_infos(MibName, TabInfos),
-    snmpa_symbolic_store:add_variable_infos(MibName, VarInfos),
-    snmpa_symbolic_store:add_aliasnames(MibName, MEs),
-    snmpa_symbolic_store:add_types(MibName, ASN1Types),
-    SetF = fun(Trap) -> 
-		   snmpa_symbolic_store:set_notification(Trap, MibName)
-	   end,
-    lists:foreach(SetF, Traps);
-install_mib2(_, _, _) ->
-    ok.
+-callback load_mib(State :: term(), FileName :: string(), 
+		   MeOverride :: boolean(), 
+		   TeOverride :: boolean()) -> 
+    {ok, NewState :: term()} | {error, already_loaded | Reason :: term()}.
 
-install_mes(_Db, _MibName, []) ->
-    ok;
-install_mes(Db, MibName, [ME|MEs]) ->
-    Node = #node_info{oid = ME#me.oid, mib_name = MibName, me = ME},
-    snmpa_general_db:write(Db, Node),
-    install_mes(Db, MibName, MEs).
+-callback unload_mib(State :: term(), FileName :: string(), 
+		   MeOverride :: boolean(), 
+		   TeOverride :: boolean()) -> 
+    {ok, NewState :: term()} | {error, not_loaded | Reason :: term()}.
 
+-callback lookup(State :: term(), Oid :: oid()) -> 
+    {false, Reason :: term()} | 
+    {variable, MibEntry :: me()} |
+    {table_column, MibEntry :: me(), TableEntryOid :: oid()} |
+    {subagent, SubAgentPid :: pid(), SAOid :: oid()}.
 
-%%----------------------------------------------------------------------
-%% Does all side effect stuff during unload_mib.
-%%----------------------------------------------------------------------
-uninstall_mib(Db, Symbolic, MibName, MEs) ->
-    ?vtrace("uninstall_mib -> entry with"
-	"~n   Db:       ~p"
-	"~n   Symbolic: ~p"
-	"~n   MibName:  ~p", [Db, Symbolic, MibName]),
-    Res = snmpa_general_db:delete(Db, MibName),
-    ?vtrace("uninstall_mib -> (mib) db delete result: ~p", [Res]),
-    uninstall_mib2(Symbolic, MibName),
-    DelF = fun(ME) -> call_instrumentation(ME, delete) end,
-    lists:foreach(DelF, MEs).
+-callback next(State :: term(), Oid :: oid(), MibView :: mib_view()) -> 
+    endOfView | false | 
+    {subagent, SubAgentPid :: pid(), SAOid :: oid()} |
+    {variable, MibEntry :: me(), VarOid :: oid()} |
+    {table, TableOid :: oid(), TableRestOid :: oid(), MibEntry :: me()}
 
-uninstall_mib2(true, MibName) ->
-    snmpa_symbolic_store:delete_table_infos(MibName),
-    snmpa_symbolic_store:delete_variable_infos(MibName),
-    snmpa_symbolic_store:delete_aliasnames(MibName),
-    snmpa_symbolic_store:delete_types(MibName),
-    snmpa_symbolic_store:delete_notifications(MibName);
-uninstall_mib2(_, _) ->
-    ok.
+-callback register_subagent(State :: term(), Oid :: oid(), Pid :: pid()) -> 
+    {error, Reason :: term()} | NewState :: term().
 
-uninstall_mes(Db, MibName) ->
-    Pattern = #node_info{oid = '_', mib_name = MibName, me = '_'},
-    snmpa_general_db:match_delete(Db, Pattern).
+-callback unregister_subagent(State :: term(), 
+			      Pid :: pid() | Oid :: oid()) -> 
+    {ok, NewState :: term()}               | % When second arg wa a pid()
+    {ok, NewState :: term(), Pid :: pid()} | % When second arg was a oid()
+    {error, Reason :: term()}.
 
+-callback dump(State :: term(), Filename :: string()) -> 
+    ok | {error, Reason :: term()}.
 
-%%----------------------------------------------------------------------
-%% Create a list of the names of all the loaded mibs
-%%----------------------------------------------------------------------
-loaded(Db) ->
-    [N || #mib_info{name = N} <- snmpa_general_db:tab2list(Db)].
-    
+-callback print(State :: term()) -> ok.
 
-%%----------------------------------------------------------------------
-%% Calls MFA-instrumentation with 'new' or 'delete' operation.
-%%----------------------------------------------------------------------
-call_instrumentation(#me{entrytype = variable, mfa={M,F,A}}, Operation) ->
-    ?vtrace("call instrumentation with"
-	    "~n   entrytype: variable"
-	    "~n   MFA:       {~p,~p,~p}"
-	    "~n   Operation: ~p",
-	    [M,F,A,Operation]),
-    catch apply(M, F, [Operation | A]);
-call_instrumentation(#me{entrytype = table_entry, mfa={M,F,A}}, Operation) ->
-    ?vtrace("call instrumentation with"
-	    "~n   entrytype: table_entry"
-	    "~n   MFA:       {~p,~p,~p}"
-	    "~n   Operation: ~p",
-	    [M,F,A,Operation]),
-    catch apply(M, F, [Operation | A]);
-call_instrumentation(_ShitME, _Operation) ->
-    done.
+-callback which_mib(State :: term(), Oid :: oid()) -> 
+    {ok, Mib :: string()} | {error, Reason :: term()}.
 
+-callback which_mibs(State :: term()) -> 
+    [{MibName :: atom(), Filename :: string()}].
 
-maybe_drop_me(#me{entrytype = internal}) -> false;
-maybe_drop_me(#me{entrytype = group}) -> false;
-maybe_drop_me(#me{imported = true}) -> false;
-maybe_drop_me(_) -> true.
+-callback whereis_mib(State :: term(), MibName :: atom()) -> 
+    {ok, Filename :: string()} | {error, Reason :: term()}.
 
+-callback info(State :: term()) -> list().
+-callback info(State :: term(), Item :: atom()) -> term().
 
-%%----------------------------------------------------------------------
-%% Code change functions
-%%----------------------------------------------------------------------
+-callback backup(State :: term(), BackupDir :: string()) -> 
+    ok |  {error, Reason :: term()}.
 
-code_change(down, State) ->
-    ?d("code_change(down) -> entry",[]),
-    State;
+-callback code_change(Direction :: up | down, State :: term()) -> 
+    NewState :: term().
 
-code_change(up, State) ->
-    ?d("code_change(up)",[]),
-    State;
 
-code_change(_Vsn, State) ->
-    State.