erlang gen_server bank_account

bank_account.erl

%%%-------------------------------------------------------------------
%%% @author Suncle
%%% @copyright (C) 2017, <COMPANY>
%%% @doc
%%% @end
%%% Created : 13. 十一月 2017 17:19
%%%-------------------------------------------------------------------
-module(bank_account).
-author("Suncle").
-behaviour(gen_server).

%% 回调接口
-export([init/1,
  handle_call/3,
  handle_cast/2,
  handle_info/2,
  code_change/3,
  terminate/2
]).

%% API
-export([start_link/3,
  withdraw/2,
  deposit/2,
  print/1,
  stop/1]).

-record(account,{
  id :: integer(),      %% ID
  name :: string(),     %% 帐号名
  money :: integer()    %% 帐号余额
}).

-define(PRINT(Msg),io:format(Msg ++ "\n")).
-define(PRINT(Format,Msg),io:format(Format ++ "\n",Msg)).


init([Id, Name, Money]) ->
  ?PRINT("bank account init,ID:~w,Name:~p,Money:~w",[Id,Name,Money]),
  State = #account{id = Id, name = Name, money = Money},
  {ok,State}.

%% asynchronous operation
%% handle_cast接收gen_server:cast消息
%% 打印帐号信息
handle_cast(print, State = #account{id = Id, name = Name, money = Money}) ->
  ?PRINT("account info, id: ~w, name: ~p, money: ~w", [Id, Name, Money]),
  {noreply, State};
%% 返回stop，进程将停止，调用terminate
handle_cast(stop, State) ->
  ?PRINT("handle cast stop"),
  {stop, normal, State}.

%% synchronous operation
%% handle_call接收gen_server:call消息
%% 取款
handle_call({withdraw, Num}, _From, State = #account{name = Name,money = Money}) when Num > 0, Num =< Money ->
  NewMoney = Money - Num,
  NewState = State#account{money = NewMoney},
  ?PRINT("~p withdraw:~w,NewMoney:~w",[Name, Num, NewMoney]),
  {reply, true, NewState};
%% 存款
handle_call({deposit, Num}, _From, State = #account{name = Name,money = Money}) ->
  NewMoney = Money + Num,
  NewState = State#account{money = NewMoney},
  ?PRINT("~p withdraw:~w,NewMoney:~w",[Name, Num, NewMoney]),
  {reply, true, NewState}.

%% handle_info，处理直接发给进程的消息
handle_info(Info, State) ->
  ?PRINT("handle_info receive msg:~p",[Info]),
  {noreply,State}.

code_change(_OldVsn, State, _Extra) ->
  {ok,State}.

%% 进程停止时，回调terminate
terminate(Reason, #account{id = ID,name = Name,money = Money}) ->
  ?PRINT("process stop,Reason:~p",[Reason]),
  ?PRINT("account Info,ID:~w,Name:~p,Money:~w",[ID,Name,Money]),
  ok.

%% 开启帐号进程，将回调init/1函数，返回{ok,Pid}
start_link(Id, Name, Money) ->
  gen_server:start_link({local, ?MODULE}, ?MODULE, [Id, Name, Money], []).

withdraw(Pid,Num) ->
  gen_server:call(Pid,{withdraw,Num}).

deposit(Pid,Num) ->
  gen_server:call(Pid,{deposit,Num}).

print(Pid) ->
  gen_server:cast(Pid,print).

stop(Pid) ->
  gen_server:cast(Pid,stop).