Packages
ra
2.0.4
3.1.9
3.1.8
3.1.7
3.1.6
3.1.5
3.1.4
3.1.3
3.1.2
3.1.1
3.1.0
3.0.2
3.0.1
3.0.0
3.0.0-beta.1
2.17.3
2.17.2
2.17.1
2.17.0
2.16.13
2.16.12
2.16.11
2.16.10
2.16.9
2.16.8
2.16.7
2.16.6
2.16.5
2.16.4
2.16.3
2.16.2
2.16.1
2.16.0
2.16.0-pre.12
2.16.0-pre.11
2.16.0-pre.10
2.16.0-pre.9
2.16.0-pre.8
2.16.0-pre.7
2.16.0-pre.6
2.16.0-pre.5
2.16.0-pre.4
2.16.0-pre.3
2.16.0-pre.2
2.16.0-pre.1
2.15.4
2.15.3
2.15.2
2.15.1
2.15.0
2.14.0
2.13.6
2.13.5
2.13.4
2.13.3
2.13.2
2.13.1
2.13.0
2.13.0-pre.1
2.12.0
2.11.0
2.11.0-pre.1
2.10.2-pre.2
2.10.2-pre.1
2.10.1
2.10.0
2.10.0-pre.3
2.10.0-pre.2
2.10.0-pre.1
2.9.10-pre.1
2.9.1
2.9.1-pre.2
2.9.1-pre.1
2.9.0
2.8.0
retired
2.7.3
2.7.2
2.7.1
2.7.0
2.7.0-pre.3
2.7.0-pre.2
2.7.0-pre.1
2.6.3
2.6.2
2.6.1
2.6.0-pre.1
2.5.1
2.5.1-pre.1
2.5.0
2.4.9
2.4.8
2.4.7
2.4.6
2.4.5
2.4.4
2.4.3
2.4.2
retired
2.4.1
2.4.0
2.3.0
2.2.0
2.1.0
2.0.13
2.0.12
2.0.11
2.0.10
2.0.9
2.0.8
2.0.7
2.0.6
2.0.5
2.0.4
2.0.3
2.0.2
2.0.1
2.0.0
1.1.9
1.1.8
1.1.7
1.1.6
1.1.5
1.1.4
1.1.3
1.1.2
1.1.1
1.1.0
1.0.8
1.0.7
1.0.6
1.0.5
1.0.4
1.0.3
1.0.2
1.0.1
1.0.0
0.9.6
0.9.5
0.9.4
0.9.2
0.3.3
retired
0.3.2
retired
0.3.1
retired
Raft library
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Files
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Files
src/ra_flru.erl
%% This Source Code Form is subject to the terms of the Mozilla Public
%% License, v. 2.0. If a copy of the MPL was not distributed with this
%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
%%
%% Copyright (c) 2017-2021 VMware, Inc. or its affiliates. All rights reserved.
%%
%% @hidden
-module(ra_flru).
%% small fixed size simple lru cache
%% inefficient on larger sizes
-export([
new/2,
fetch/2,
insert/3,
evict/2,
evict_all/1,
size/1
]).
-define(MAX_SIZE, 5).
-type kv_item() :: {Key :: term(), Value :: term()}.
-type handler_fun() :: fun((kv_item()) -> ok).
-record(?MODULE, {max_size = ?MAX_SIZE :: non_neg_integer(),
items = [] :: [term()],
handler = fun (_) -> ok end :: handler_fun()}).
-opaque state() :: #?MODULE{}.
-export_type([
state/0
]).
-spec new(non_neg_integer(), handler_fun()) ->
state().
new(MaxSize, Handler) ->
#?MODULE{handler = Handler,
max_size = MaxSize}.
-spec fetch(term(), state()) ->
{ok, term(), state()} | error.
fetch(Key, #?MODULE{items = [{Key, Value} | _]} = State) ->
%% head optimisation
{ok, Value, State};
fetch(Key, #?MODULE{items = Items0} = State0) ->
case lists:keytake(Key, 1, Items0) of
{value, {_, Value} = T, Items} ->
{ok, Value, State0#?MODULE{items = [T | Items]}};
false ->
error
end.
-spec insert(term(), term(), state()) -> state().
insert(Key, Value, #?MODULE{items = Items,
max_size = M,
handler = Handler} = State)
when length(Items) =:= M ->
%% cache is full, discard last item
[Old | Rem] = lists:reverse(Items),
%% call the handler
ok = Handler(Old),
State#?MODULE{items = [{Key, Value} | lists:reverse(Rem)]};
insert(Key, Value, #?MODULE{items = Items} = State) ->
%% else just append it
State#?MODULE{items = [{Key, Value} | Items]}.
-spec evict(Key :: term(), state()) ->
{Evicted :: kv_item(), state()} | error.
evict(Key, #?MODULE{items = Items0,
handler = Handler} = State) ->
case lists:keytake(Key, 1, Items0) of
{value, T, Items} ->
ok = Handler(T),
{T, State#?MODULE{items = Items}};
false ->
error
end.
-spec evict_all(state()) -> state().
evict_all(#?MODULE{items = Items,
handler = Handler}) ->
[Handler(T) || T <- Items],
#?MODULE{items = []}.
-spec size(state()) -> non_neg_integer().
size(#?MODULE{items = Items}) ->
length(Items).
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
evit_test() ->
C0 = new(3, fun(I) -> ?debugFmt("~w evicted", [I]) end),
C1 = insert(k1, v1, C0),
C2 = insert(k2, v2, C1),
{{k1, v1}, C3} = evict(k1, C2),
error = evict(k3, C3),
ok.
basics_test() ->
C0 = new(3, fun(I) -> ?debugFmt("~w evicted", [I]) end),
C1 = insert(k1, v1, C0),
C2 = insert(k2, v2, C1),
C3 = insert(k3, v3, C2),
C4 = insert(k4, v4, C3),
?assertEqual(error, fetch(k1, C4)),
{ok, v2, C5} = fetch(k2, C4),
C6 = insert(k5, v5, C5),
%% k2 should still be readable here
{ok, v2, C7} = fetch(k2, C6),
%% k3 should have been evicted
error = fetch(k3, C7),
ok.
-endif.