- -module(lzy_name_svc).
- -behaviour(gen_server).
- -export([init/0, init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
- -export([start/0, start/1, stop/0, save/2, load/1, load_all/0, remove/1, remove_all/0]).
- %% Interface functions.
- start() ->
- gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
- start(Args) ->
- gen_server:start_link({local, ?MODULE}, ?MODULE, Args, []).
- stop() ->
- gen_server:call(?MODULE, stop).
- %% @spec save(Key, Value) -> OldValue.
- save(Key, Value) ->
- gen_server:call(?MODULE, {save, Key, Value}).
- %% @spec load(Key) -> Value.
- load(Key) ->
- gen_server:call(?MODULE, {load, Key}).
- %% @spec load_all() -> [{Key, Value}].
- load_all() ->
- gen_server:call(?MODULE, {load_all}).
- %% @spec remove(Key) -> Value.
- remove(Key) ->
- gen_server:call(?MODULE, {remove, Key}).
- %% @spec remove_all() -> [{Key, Value}].
- remove_all() ->
- gen_server:call(?MODULE, {remove_all}).
- %% Callback functions.
- init([]) ->
- {ok, local};
- init([{isolation, NameServer}]) ->
- {ok, {isolation, NameServer}}.
- handle_call({save, Key, Value}, _From, NameServer) ->
- {reply, do_save(Key, Value, NameServer), NameServer};
- handle_call({load, Key}, _From, NameServer) ->
- {reply, do_load(Key, NameServer), NameServer};
- handle_call({load_all}, _From, NameServer) ->
- {reply, do_load_all(NameServer), NameServer};
- handle_call({remove, Key}, _From, NameServer) ->
- {reply, do_remove(Key, NameServer), NameServer};
- handle_call({remove_all}, _From, NameServer) ->
- {reply, do_remove_all(NameServer), NameServer};
- handle_call({stop}, _From, NameServer) ->
- {stop, normal, stopped, NameServer}.
- %% Default implement.
- handle_cast(_Msg, State) ->
- {noreply, State}.
- handle_info(_Info, State) ->
- {noreply, State}.
- terminate(_Reason, _State) ->
- ok.
- code_change(_OldVsn, State, _Extra) ->
- {ok, State}.
- %% Private functions.
- do_save(Key, Value, {isolation, NameServer}) ->
- NameServer ! {self(), save, Key, Value},
- receive
- Msg -> Msg
- end;
- do_save(Key, Value, _) ->
- erlang:put(Key, Value).
- do_load(Key, {isolation, NameServer}) ->
- NameServer ! {self(), load, Key},
- receive
- Msg -> Msg
- end;
- do_load(Key, _) ->
- erlang:get(Key).
- do_load_all({isolation, NameServer}) ->
- NameServer ! {self(), load_all},
- receive
- Msg -> Msg
- end;
- do_load_all(_) ->
- erlang:get().
- do_remove(Key, {isolation, NameServer}) ->
- NameServer ! {self(), remove, Key},
- receive
- Msg -> Msg
- end;
- do_remove(Key, _) ->
- erlang:erase(Key).
- do_remove_all({isolation, NameServer}) ->
- NameServer ! {self(), remove_all},
- receive
- Msg -> Msg
- end;
- do_remove_all(_) ->
- erlang:erase().
上面這段代碼就是 lzy_name_svc 名稱服務(wù)了,有些地方寫得有點(diǎn)冗余,呵呵。
為了能夠替換字典進(jìn)程來(lái)測(cè)試驗(yàn)證名稱服務(wù)功能,還寫了一個(gè)超簡(jiǎn)單的 foo_svc 服務(wù),用來(lái)和 lzy_name_svc 通信完成進(jìn)程字典存取。
- -module(foo_svc).
- -export([start/0, load_all/0, server_pid/0]).
- start() ->
- register(fs, spawn(fun() -> loop() end)).
- load_all() ->
- fs ! {self(), load_all},
- receive
- Msg -> Msg
- end.
- server_pid() ->
- fs ! { self(), server_pid},
- receive
- Msg -> Msg
- end.
- loop() ->
- receive
- {From, save, Key, Value} ->
- From ! erlang:put(Key, Value),
- loop();
- {From, load, Key} ->
- From ! erlang:get(Key),
- loop();
- {From, load_all} ->
- From ! erlang:get(),
- loop();
- {From, remove, Key} ->
- From ! erlang:erase(Key),
- loop();
- {From, remove_all} ->
- From ! erlang:erase(),
- loop();
- {From, server_pid} ->
- From ! self(),
- loop()
- end.
下面的代碼就是創(chuàng)建和調(diào)用服務(wù)的相關(guān)代碼了,一起貼上來(lái)。第一段是以缺省方式啟動(dòng)了 lzy_name_svc 服務(wù),并向存取 abc -> 123 名稱。
- C:\Program Files\erl5.6.4\usr>..\bin\erl -sname server
- Eshell V5.6.4 (abort with ^G)
- (server@lzy)1> c(lzy_name_svc).
- {ok,lzy_name_svc}
- (server@lzy)2> c(foo_svc.erl).
- {ok,foo_svc}
- (server@lzy)3> lzy_name_svc:start().
- {ok,<0.47.0>}
- (server@lzy)4> lzy_name_svc:save(abc, 123).
- undefined
- (server@lzy)5> lzy_name_svc:load(abc).
- 123
- (server@lzy)6> lzy_name_svc:load(efg).
- undefined
- (server@lzy)7> lzy_name_svc:load_all().
- [{abc,123},
- {'$ancestors',[<0.35.0>]},
- {'$initial_call',{gen,init_it,
- [gen_server,<0.35.0>,<0.35.0>,
- {local,lzy_name_svc},
- lzy_name_svc,[],[]]}}]
- (server@lzy)8> lzy_name_svc:remove(abc).
- 123
- (server@lzy)9> lzy_name_svc:load(abc).
- undefined
下面這段是啟動(dòng) foo_svc 服務(wù),用它創(chuàng)建的進(jìn)程來(lái)專門存儲(chǔ)名稱數(shù)據(jù),是通過(guò) lzy_name_svc:start/1 傳入的 PID。
- C:\Program Files\erl5.6.4\usr>..\bin\erl -sname server
- Eshell V5.6.4 (abort with ^G)
- (server@lzy)1> foo_svc:start().
- true
- (server@lzy)2> NameSvcPid = foo_svc:server_pid().
- <0.37.0>
- (server@lzy)3> lzy_name_svc:start([{isolation, NameSvcPid}]).
- {ok,<0.40.0>}
- (server@lzy)4> lzy_name_svc:save(abc, 123).
- undefined
- (server@lzy)5> lzy_name_svc:load(abc).
- 123
- (server@lzy)6> foo_svc:load_all().
- [{abc,123}]
- (server@lzy)7> lzy_name_svc:remove_all().
- [{abc,123}]
- (server@lzy)8> foo_svc:load_all().
- []
上邊的兩段都是在同一機(jī)器上的同一 erlang 節(jié)點(diǎn)上完成服務(wù)調(diào)用的,下面這段代碼是 lzy_name_svc 服務(wù)基于上邊狀態(tài)時(shí),在同一機(jī)器的另外了個(gè) erlang 節(jié)點(diǎn)上通過(guò) rpc 庫(kù)完成服務(wù)調(diào)用的。
- C:\Program Files\erl5.6.4\usr>..\bin\erl -sname client1
- Eshell V5.6.4 (abort with ^G)
- (client1@lzy)1> rpc:call(server@lzy, lzy_name_svc, save, [abc, 123]).
- undefined
- (client1@lzy)2> rpc:call(server@lzy, foo_svc, load_all, []).
- [{abc,123}]
呵呵,挺入門的,就當(dāng)做為學(xué)習(xí)過(guò)程的記錄吧。看好 erlang。
在學(xué)習(xí)的過(guò)程中,有一個(gè)事情比較不解,就是對(duì)于 字典進(jìn)程的 “熱替換” 。 我想本應(yīng)該是可以通過(guò) gen_server behaviour 用于“熱代碼替換”的 code_change 方法完成的,但試了幾次都達(dá)不到目的,服務(wù)倒是跑的正常,可是字典進(jìn)程就是不能熱替換,code_change 正常返回,可是名稱數(shù)據(jù)卻還是原有字典進(jìn)程的。測(cè)試驗(yàn)證代碼如下:
- C:\Program Files\erl5.6.4\usr>..\bin\erl -sname server
- Eshell V5.6.4 (abort with ^G)
- (server@lzy)1> lzy_name_svc:start().
- {ok,<0.37.0>}
- (server@lzy)2> lzy_name_svc:save(abc, 123).
- undefined
- (server@lzy)3> lzy_name_svc:load_all().
- [{abc,123},
- {'$ancestors',[<0.35.0>]},
- {'$initial_call',{gen,init_it,
- [gen_server,<0.35.0>,<0.35.0>,
- {local,lzy_name_svc},
- lzy_name_svc,[],[]]}}]
- (server@lzy)4> foo_svc:start().
- true
- (server@lzy)5> NameSvcPid = foo_svc:server_pid().
- <0.41.0>
- (server@lzy)6> foo_svc:load_all().
- []
- (server@lzy)7> lzy_name_svc:code_change(foo, NameSvcPid, foo).
- {ok,<0.41.0>}
- (server@lzy)8> lzy_name_svc:load_all().
- [{abc,123},
- {'$ancestors',[<0.35.0>]},
- {'$initial_call',{gen,init_it,
- [gen_server,<0.35.0>,<0.35.0>,
- {local,lzy_name_svc},
- lzy_name_svc,[],[]]}}]
還請(qǐng)哪位 erlang guru 指點(diǎn)~
// 2009.02.07 22:52 添加 ////
這里提供了該名稱服務(wù)的新迭代版本。
gen_server tasting 之超簡(jiǎn)單名稱服務(wù)(續(xù))
添加了如下功能:
- 使用 otp 監(jiān)控樹保證服務(wù)可靠性。
- 添加日志功能,記錄警告事件。
- 將名稱服務(wù)打包為 application。
- 開放 socket 服務(wù),使用 vsns://verb /param 自定義協(xié)議對(duì)外提供訪問(wèn)支持。
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