1%%
2%% Licensed to the Apache Software Foundation (ASF) under one
3%% or more contributor license agreements. See the NOTICE file
4%% distributed with this work for additional information
5%% regarding copyright ownership. The ASF licenses this file
6%% to you under the Apache License, Version 2.0 (the
7%% "License"); you may not use this file except in compliance
8%% with the License. You may obtain a copy of the License at
9%%
10%%   http://www.apache.org/licenses/LICENSE-2.0
11%%
12%% Unless required by applicable law or agreed to in writing,
13%% software distributed under the License is distributed on an
14%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15%% KIND, either express or implied. See the License for the
16%% specific language governing permissions and limitations
17%% under the License.
18%%
19
20-module(thrift_transport_state_test).
21
22-behaviour(gen_server).
23-behaviour(thrift_transport).
24
25%% API
26-export([new/1]).
27
28%% gen_server callbacks
29-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
30         terminate/2, code_change/3]).
31
32%% thrift_transport callbacks
33-export([write/2, read/2, flush/1, close/1]).
34
35-record(trans, {wrapped, % #thrift_transport{}
36                version :: integer(),
37                counter :: pid()
38               }).
39-type state() :: #trans{}.
40-include("thrift_transport_behaviour.hrl").
41
42-record(state, {cversion :: integer()}).
43
44
45new(WrappedTransport) ->
46    case gen_server:start_link(?MODULE, [], []) of
47        {ok, Pid} ->
48            Trans = #trans{wrapped = WrappedTransport,
49                           version = 0,
50                           counter = Pid},
51            thrift_transport:new(?MODULE, Trans);
52        Else ->
53            Else
54    end.
55
56%%====================================================================
57%% thrift_transport callbacks
58%%====================================================================
59
60write(Transport0 = #trans{wrapped = Wrapped0}, Data) ->
61    Transport1 = check_version(Transport0),
62    {Wrapped1, Result} = thrift_transport:write(Wrapped0, Data),
63    Transport2 = Transport1#trans{wrapped = Wrapped1},
64    {Transport2, Result}.
65
66flush(Transport0 = #trans{wrapped = Wrapped0}) ->
67    Transport1 = check_version(Transport0),
68    {Wrapped1, Result} = thrift_transport:flush(Wrapped0),
69    Transport2 = Transport1#trans{wrapped = Wrapped1},
70    {Transport2, Result}.
71
72close(Transport0 = #trans{wrapped = Wrapped0}) ->
73    Transport1 = check_version(Transport0),
74    shutdown_counter(Transport1),
75    {Wrapped1, Result} = thrift_transport:close(Wrapped0),
76    Transport2 = Transport1#trans{wrapped = Wrapped1},
77    {Transport2, Result}.
78
79read(Transport0 = #trans{wrapped = Wrapped0}, Len) ->
80    Transport1 = check_version(Transport0),
81    {Wrapped1, Result} = thrift_transport:read(Wrapped0, Len),
82    Transport2 = Transport1#trans{wrapped = Wrapped1},
83    {Transport2, Result}.
84
85
86%%====================================================================
87%% gen_server callbacks
88%%====================================================================
89
90init([]) ->
91    {ok, #state{cversion = 0}}.
92
93handle_call(check_version, _From, State = #state{cversion = Version}) ->
94    {reply, Version, State#state{cversion = Version+1}}.
95
96handle_cast(shutdown, State) ->
97    {stop, normal, State}.
98
99handle_info(_Info, State) -> {noreply, State}.
100code_change(_OldVsn, State, _Extra) -> {ok, State}.
101terminate(_Reason, _State) -> ok.
102
103%%--------------------------------------------------------------------
104%% Internal functions
105%%--------------------------------------------------------------------
106
107check_version(Transport = #trans{version = Version, counter = Counter}) ->
108    case gen_server:call(Counter, check_version) of
109        Version ->
110            Transport#trans{version = Version+1};
111        _Else ->
112            % State wasn't propagated properly.  Die.
113            erlang:error(state_not_propagated)
114    end.
115
116shutdown_counter(#trans{counter = Counter}) ->
117    gen_server:cast(Counter, shutdown).
118