%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1997-2016. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(snmp_index).
-export([new/1, new/2,
insert/3,
delete/1, delete/2,
get/2, get_next/2,
get_last/1,
key_to_oid/2]).
-define(VMODULE,"IDX").
-include("snmp_verbosity.hrl").
-record(tab, {id, keys}).
-define(badarg(F, A), exit({badarg, {?MODULE, F, A}})).
-define(bad_new(A), ?badarg(new, A)).
-define(bad_get(A), ?badarg(get, A)).
%%%-----------------------------------------------------------------
%%% This module implements an SNMP index structure as an ADT.
%%% It is supposed to be used as a separate structure which implements
%%% the SNMP ordering of the keys in the SNMP table. The advantage
%%% with this is that the get-next operation is automatically
%%% taken care of.
%%%-----------------------------------------------------------------
%%-----------------------------------------------------------------
%% Args: KeyTypes = key() | {key(), ...}
%% key() = integer | string | fix_string
%% Returns: handle()
%%-----------------------------------------------------------------
new(KeyTypes) ->
?vlog("new -> entry with"
"~n KeyTypes: ~p", [KeyTypes]),
do_new(KeyTypes, ?MODULE, [public, ordered_set]).
new(KeyTypes, Name) when is_atom(Name) ->
?vlog("new -> entry with"
"~n KeyTypes: ~p"
"~n Name: ~p", [KeyTypes, Name]),
do_new(KeyTypes, Name, [public, ordered_set, named_table]);
new(KeyTypes, Name) ->
?vinfo("new -> bad data"
"~n KeyTypes: ~p"
"~n Name: ~p", [KeyTypes, Name]),
?bad_new([KeyTypes, Name]).
do_new(KeyTypes, EtsName, EtsOpts) ->
?vdebug("do_new -> entry with"
"~n KeyTypes: ~p"
"~n EtsName: ~p"
"~n EtsOpts: ~p", [KeyTypes, EtsName, EtsOpts]),
case is_snmp_type(to_list(KeyTypes)) of
true ->
Tab = #tab{id = ets:new(EtsName, EtsOpts), keys = KeyTypes},
?vtrace("do_new -> "
"~n Tab: ~p", [Tab]),
Tab;
false ->
?bad_new([KeyTypes, EtsName])
end.
get(#tab{id = OrdSet}, KeyOid) ->
?vlog("get -> entry with"
"~n OrdSet: ~p"
"~n KeyOid: ~p", [OrdSet, KeyOid]),
case ets:lookup(OrdSet, KeyOid) of
[X] ->
{ok, X};
_ ->
undefined
end.
get_next(#tab{id = OrdSet} = Tab, KeyOid) ->
?vlog("get_next -> entry with"
"~n Tab: ~p"
"~n KeyOid: ~p", [Tab, KeyOid]),
case ets:next(OrdSet, KeyOid) of
'$end_of_table' ->
undefined;
Key ->
get(Tab, Key)
end.
get_last(#tab{id = OrdSet} = Tab) ->
?vlog("get_last -> entry with"
"~n Tab: ~p", [Tab]),
case ets:last(OrdSet) of
'$end_of_table' ->
undefined;
Key ->
get(Tab, Key)
end.
insert(#tab{id = OrdSet, keys = KeyTypes} = Tab, Key, Val) ->
ets:insert(OrdSet, {key_to_oid_i(Key, KeyTypes), Val}),
Tab.
delete(#tab{id = OrdSet, keys = KeyTypes} = Tab, Key) ->
ets:delete(OrdSet, key_to_oid_i(Key, KeyTypes)),
Tab.
delete(#tab{id = OrdSet}) ->
ets:delete(OrdSet).
key_to_oid(#tab{keys = KeyTypes}, Key) ->
key_to_oid_i(Key, KeyTypes).
to_list(Tuple) when is_tuple(Tuple) -> tuple_to_list(Tuple);
to_list(X) -> [X].
is_snmp_type([integer | T]) -> is_snmp_type(T);
is_snmp_type([string | T]) -> is_snmp_type(T);
is_snmp_type([fix_string | T]) -> is_snmp_type(T);
is_snmp_type([]) -> true;
is_snmp_type(_) -> false.
%%-----------------------------------------------------------------
%% Args: Key = key()
%% key() = int() | string() | {int() | string(), ...}
%% Type = {fix_string | term()}
%% Make an OBJECT IDENTIFIER out of it.
%% Variable length objects are prepended by their length.
%% Ex. Key = {"pelle", 42} AND Type = {string, integer} =>
%% OID [5, $p, $e, $l, $l, $e, 42]
%% Key = {"pelle", 42} AND Type = {fix_string, integer} =>
%% OID [$p, $e, $l, $l, $e, 42]
%%-----------------------------------------------------------------
key_to_oid_i(Key, _Type) when is_integer(Key) -> [Key];
key_to_oid_i(Key, fix_string) -> Key;
key_to_oid_i(Key, _Type) when is_list(Key) -> [length(Key) | Key];
key_to_oid_i(Key, Types) -> keys_to_oid(size(Key), Key, [], Types).
keys_to_oid(0, _Key, Oid, _Types) -> Oid;
keys_to_oid(N, Key, Oid, Types) ->
Oid2 = lists:append(key_to_oid_i(element(N, Key), element(N, Types)), Oid),
keys_to_oid(N-1, Key, Oid2, Types).
