用redis管理nitrogen中的session

nitrogen使用中session问题

nitrogen中的session在集群情况下会找不到，经常会出现重新登录情况，试图修改成为mnesia管理session,在节点超过一定数量时mnesia同步机制会出现同步慢的问题，为此决定再次修改为redis来管理session。

 

修改为redis管理session

 

1 在nitrogen中调用wf:session/2设置session时调用了session_handler:set_value/2,回调behaviour (session_handler),wf_handler:call/3，这里实现了一个简单的session_handler，只要实现自己的session_handler行为，就可以了，在wf:context中会配置具体调用哪些handler,只要修改make_handler(session_handler, simple_session_handler), %simple_session_handler), 为自己的实现即可。

2 我实现的redis_session_handler

% Copyright (c) 2008-2010 Rusty Klophaus
% See MIT-LICENSE for licensing information.

% This is a "simple as possible" session handler. Unfortunately,
% due to time constraints, had to leave out some great code
% contributed by Dave Peticolas that fit Nitrogen sessions
% into a gen_server. My code below is far inferior. 
% Someone please make it better! - Rusty

-module (redis_session_handler).
-include_lib ("wf.hrl").
-behaviour (session_handler).
-export ([
    init/2, 
    finish/2,
    get_value/4, 
    set_value/4, 
    clear_all/2
]).
-record (state, {unique}).

init(_Config, _State) -> 
    Cookie = wf:cookie(get_cookie_name()),
    State = case wf:depickle(Cookie) of
        undefined -> new_state();
        Other -> Other
    end,
    {ok, State}.

finish(_Config, State) -> 
    % Drop the session cookie...
    Timeout = wf:config_default(session_timeout, 20),
    ok = wf:cookie(get_cookie_name(), wf:pickle(State), "/", Timeout),
    {ok, []}.

get_value(Key, DefaultValue, _Config, State) -> 
    %Host = wf:config_default(erldis_host, "127.0.0.1"),
    %Port = wf:config_default(erldis_port, 6379),
    %{ok, Client} = erldis:connect(Host, Port),
    %io:format("~p",[?LINE]),
    %io:format("get_value, Key = ~p~n",[Key]),
    Client = erldis_sup:client(),
    Value = case erldis:hget(Client, State#state.unique, Key) of
    nil ->
        DefaultValue;
    Any ->
        binary_to_term(Any)
    end,
    %io:format("get_value, Key = ~p, Value = ~p~n",[Key, Value]),
    Timeout = wf:config_default(session_timeout, 20),
    erldis:expire(Client, State#state.unique, Timeout*60),
    {ok, Value, State}.

set_value(Key, Value, _Config, State) -> 
    %io:format("set_value, Key = ~p, Value = ~p~n",[Key, Value]),
    Client = erldis_sup:client(),

    OldValue = case erldis:hget(Client, State#state.unique, Key) of
    nil ->
        undefined;
    Any ->
        binary_to_term(Any)
    end,
    %io:format("~p",[?LINE]),
    %io:format("OldValue = ~n~p~n",[OldValue]),
    erldis:hset(Client, State#state.unique, Key, term_to_binary(Value)),
    Timeout = wf:config_default(session_timeout, 20),
    erldis:expire(Client, State#state.unique, Timeout*60),
    {ok, OldValue, State}.

clear_all(_Config, State) -> 
    Client = erldis_sup:client(),
    case erldis:del(Client, State#state.unique) of
    nil ->
        undefined;
    Any ->
        %io:format("~p",[?LINE]),
        %io:format("~n~p~n",[Any]),
        Any
    end,
    {ok, State}.

%%% PRIVATE FUNCTIONS

get_cookie_name() ->
    wf:config_default(cookie_name, "lxbssn").

new_state() ->
    Unique = erlang:md5(term_to_binary({now(), erlang:make_ref()})),
    #state { unique=Unique }.

 

 3  在上面代码中我使用了erldis作为redis的erlang客户端，经测试未发现问题，很稳定。

 

4 问题： 以上代码实现中查阅过redis手册，想找到类似 setex直接设置过期时间的命令，但没有找到，用hash 实现是为了节省内存与方便管理，如有更好解决方案大家回复交流。

评论

1 楼 cz999 2013-05-20  

erldis_sup用这个干什么？是redis连接池吗？