這個怎麼運作
導演需要一個回撥模組（如 OTP 主管）。
在回撥模組中，你應該匯出函式 init/1。
init/1 應該返回什麼？等等，我會一步一步解釋。
-module(foo).
-export([init/1]).
init(_InitArg) ->
{ok, []}.
將以上程式碼儲存在 director 目錄的 foo.erl 中，然後轉到 Erlang shell。
如果你使用 rebar 編譯它，請使用 erl -pa ./ebin，如果你使用 rebar3，請使用 rebar3 shell。
Erlang/OTP 19 [erts-8.3] [source-d5c06c6] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V8.3 (abort with ^G)
1> c(foo).
{ok,foo}
2> Mod = foo.
foo
3> InitArg = undefined. %% i don't need it yet.
undefined
4> {ok, Pid} = director:start_link(Mod, InitArg).
{ok,<0.112.0>}
5>
現在我們有一個沒有孩子的主管。
好訊息是導演帶有完整的 OTP / supervisor API，它還具有高階功能和特定方法。
5> director:which_children(Pid). %% You can use supervisor:which_children(Pid) too :)
[]
6> director:count_children(Pid). %% You can use supervisor:count_children(Pid) too :)
[{specs,0},{active,0},{supervisors,0},{workers,0}]
7> director:get_pids(Pid). %% You can NOT use supervisor:get_pids(Pid) because it hasn't :D
[]
好的，我會簡單地把它變成我的導演。
-module(bar).
-behaviour(gen_server).
-export([start_link/0
,init/1
,terminate/2]). %% i am not going to use handle_call, handle_cast ,etc.
start_link() ->
gen_server:start_link(?MODULE, null, []).
init(_GenServerInitArg) ->
{ok, state}.
terminate(_Reason, _State) ->
ok.
將此程式碼儲存在 bar.erl 中並返回 Shell。
8> c(bar).
bar.erl:2: Warning: undefined callback function code_change/3 (behaviour 'gen_server')
bar.erl:2: Warning: undefined callback function handle_call/3 (behaviour 'gen_server')
bar.erl:2: Warning: undefined callback function handle_cast/2 (behaviour 'gen_server')
bar.erl:2: Warning: undefined callback function handle_info/2 (behaviour 'gen_server')
{ok,bar}
%% You should define unique id for your process.
9> Id = bar_id.
bar_id
%% You should tell diector about start module and function for your process.
%% Should be tuple {Module, Function, Args}.
%% If your start function doesn't need arguments (like our example)
%% just use {Module, function}.
10> start = {bar, start_link}.
{bar,start_link}
%% What is your plan for your process?
%% I asked you some questions at the first of this README file.
%% Plan should be an empty list or list with n elemenst.
%% Every element can be one of
%% 'restart'
%% 'delete'
%% 'stop'
%% {'stop', Reason::term()}
%% {'restart', Time::pos_integer()}
%% for example my plan is:
%% [restart, {restart, 5000}, delete]
%% In first crash director will restart my process,
%% after next crash director will restart it after 5000 mili-seconds
%% and after third crash director will not restart it and will delete it
11> Plan = [restart, {restart, 5000}, delete].
[restart,{restart,5000},delete]
%% What if i want to restart my process 500 times?
%% Do i need a list with 500 'restart's?
%% No, you just need a list with one element, I'll explain it later.
12> Childspec = #{id => Id
,start => Start
,plan => Plan}.
#{id => bar_id,
plan => [restart,{restart,5000},delete],
start => {bar,start_link}}
13> director:start_child(Pid, Childspec). %% You can use supervisor:start_child(Pid, ChildSpec) too :)
{ok,<0.160.0>}
14>
讓我們檢查一下
14> director:which_children(Pid).
[{bar_id,<0.160.0>,worker,[bar]}]
15> director:count_children(Pid).
[{specs,1},{active,1},{supervisors,0},{workers,1}]
%% What was get_pids/1?
%% It will returns all RUNNING ids with their pids.
16> director:get_pids(Pid).
[{bar_id,<0.160.0>}]
%% We can get Pid for specific RUNNING id too
17> {ok, BarPid1} = director:get_pid(Pid, bar_id).
{ok,<0.160.0>}
%% I want to kill that process
18> erlang:exit(BarPid1, kill).
true
%% Check all running pids again
19> director:get_pids(Pid).
[{bar_id,<0.174.0>}] %% changed (restarted)
%% I want to kill that process again
%% and i will check children before spending time
20> {ok, BarPid2} = director:get_pid(Pid, bar_id), erlang:exit(BarPid2, kill).
true
21> director:get_pids(Pid).
[]
22> director:which_children(Pid).
[{bar_id,restarting,worker,[bar]}] %% restarting
23> director:get_pid(Pid, bare_id).
{error,not_found}
%% after 5000 ms
24> director:get_pids(Pid).
[{bar_id,<0.181.0>}]
25> %% Yoooohoooooo
我提到了高階功能，它們是什麼？讓我們看看 Childspec 地圖的其他可接受的鍵。
-type childspec() :: #{'id' => id()
,'start' => start()
,'plan' => plan()
,'count' => count()
,'terminate_timeout' => terminate_timeout()
,'type' => type()
,'modules' => modules()
,'append' => append()}.
%% 'id' is mandatory and can be any Erlang term
-type id() :: term().
%% Sometimes 'start' is optional ! just wait and read carefully
-type start() :: {module(), function()} % default Args is []
| mfa().
%% I explained 'restart', 'delete' and {'restart', MiliSeconds}
%% 'stop': director will crash with reason {stop, [info about process crash]}.
%% {'stop', Reason}: director exactly will crash with reason Reason.
%% 'wait': director will not restart process,
%% but you can restart it using director:restart_child/2 and you can use supervisor:restart_child/2 too.
%% fun/2: director will execute fun with 2 arguments.
%% First argument is crash reason for process and second argument is restart count for process.
%% Fun should return terms like other plan elements.
%% Default plan is:
%% [fun
%% (normal, _RestartCount) ->
%% delete;
%% (shutdown, _RestartCount) ->
%% delete;
%% ({shutdown, _Reason}, _RestartCount) ->
%% delete;
%% (_Reason, _RestartCount) ->
%% restart
%% end]
-type plan() :: [plan_element()] | [].
-type plan_element() :: 'restart'
| {'restart', pos_integer()}
| 'wait'
| 'stop'
| {'stop', Reason::term()}
| fun((Reason::term()
,RestartCount::pos_integer()) ->
'restart'
| {'restart', pos_integer()}
| 'wait'
| 'stop'
| {'stop', Reason::term()}).
%% How much time you want to run plan?
%% Default value of 'count' is 1.
%% Again, What if i want to restart my process 500 times?
%% Do i need a list with 500 'restart's?
%% You just need plan ['restart'] and 'count' 500 :)
-type count() :: 'infinity' | non_neg_integer().
%% How much time director should wait for process termination?
%% 0 means brutal kill and director will kill your process using erlang:exit(YourProcess, kill).
%% For workers default value is 1000 mili-seconds and for supervisors default value is 'infinity'.
-type terminate_timeout() :: 'infinity' | non_neg_integer().
%% default is 'worker'
-type type() :: 'worker' | 'supervisor'.
%% Default is first element of 'start' (process start module)
-type modules() :: [module()] | 'dynamic'.
%% :)
%% Default value is 'false'
%% I'll explan it
-type append() :: boolean().
編輯 foo 模組：
-module(foo).
-export([start_link/0
,init/1]).
start_link() ->
director:start_link({local, foo_sup}, ?MODULE, null).
init(_InitArg) ->
Childspec = #{id => bar_id
,plan => [wait]
,start => {bar,start_link}
,count => 1
,terminate_timeout => 2000},
{ok, [Childspec]}.
再次轉到 Erlang shell：
1> c(foo).
{ok,foo}
2> foo:start_link().
{ok,<0.121.0>}
3> director:get_childspec(foo_sup, bar_id).
{ok,#{append => false,count => 1,id => bar_id,
modules => [bar],
plan => [wait],
start => {bar,start_link,[]},
terminate_timeout => 2000,type => worker}}
4> {ok, Pid} = director:get_pid(foo_sup, bar_id), erlang:exit(Pid, kill).
true
5> director:which_children(foo_sup).
[{bar_id,undefined,worker,[bar]}] %% undefined
6> director:count_children(foo_sup).
[{specs,1},{active,0},{supervisors,0},{workers,1}]
7> director:get_plan(foo_sup, bar_id).
{ok,[wait]}
%% I can change process plan
%% I killed process one time.
%% If i kill it again, entire supervisor will crash with reason {reached_max_restart_plan... because 'count' is 1
%% But after changing plan, its counter will restart from 0.
8> director:change_plan(foo_sup, bar_id, [restart]).
ok
9> director:get_childspec(foo_sup, bar_id).
{ok,#{append => false,count => 1,id => bar_id,
modules => [bar],
plan => [restart], %% here
start => {bar,start_link,[]},
terminate_timeout => 2000,type => worker}}
10> director:get_pids(foo_sup).
[]
11> director:restart_child(foo_sup, bar_id).
{ok,<0.111.0>}
12> {ok, Pid2} = director:get_pid(foo_sup, bar_id), erlang:exit(Pid2, kill).
true
13> director:get_pid(foo_sup, bar_id).
{ok,<0.113.0>}
14> %% Hold on
最後 append 的關鍵是什麼？
實際上我們總是有一個 DefaultChildspec。
14> director:get_default_childspec(foo_sup).
{ok,#{count => 0,modules => [],plan => [],terminate_timeout => 0}}
15>
DefaultChildspec 就像普通的 childspecs，除了它不能接受 id 和 append 鍵。
如果我在
Childspec 中將 append 值改為 true： 我的 terminate_timeout 將被新增到 DefaultChildspec 的 terminate_timeout 中。
我的 count 將被新增到 count 的 count 中。
我的 modules 將被新增到 modules 的 modules 中。
我的 plan 將被新增到 DefaultChildspec 的 plan 中。
如果我在 DefaultChildspec 中使用了 start 的 {ModX, FuncX, ArgsX} 和在 Childspec 中使用值 {ModY, FunY, ArgsY} 的 start 鍵，則最終值將為 {ModY, FuncY, ArgsX ++ ArgsY}。
最後如果我在 DefaultChildspec 中有 {Mod, Func, Args} 的 start 鍵，Childspec 中的 start 鍵對我來說是可選的。
你可以將自己的 DefaultChildspec 作為 init/1 中元組的第三個元素返回。
編輯 foo.erl：
-module(foo).
-behaviour(director). %% Yes, this is a behaviour
-export([start_link/0
,init/1]).
start_link() ->
director:start_link({local, foo_sup}, ?MODULE, null).
init(_InitArg) ->
Childspec = #{id => bar_id
,plan => [wait]
,start => {bar,start_link}
,count => 1
,terminate_timeout => 2000},
DefaultChildspec = #{start => {bar, start_link}
,terminate_timeout => 1000
,plan => [restart]
,count => 5},
{ok, [Childspec], DefaultChildspec}.
重啟 shell：
1> c(foo).
{ok,foo}
2> foo:start_link().
{ok,<0.111.0>}
3> director:get_pids(foo_sup).
[{bar_id,<0.112.0>}]
4> director:get_default_childspec(foo_sup).
{ok,#{count => 5,
plan => [restart],
start => {bar,start_link,[]},
terminate_timeout => 1000}}
5> Childspec1 = #{id => 1, append => true},
%% Default 'plan' is [Fun], so 'plan' will be [restart] ++ [Fun] or [restart, Fun].
%% Default 'count' is 1, so 'count' will be 1 + 5 or 6.
%% Args in above Childspec is [], so Args will be [] ++ [] or [].
%% Default 'terminate_timeout' is 1000, so 'terminate_timeout' will be 1000 + 1000 or 2000.
%% Default 'modules' is [bar], so 'modules' will be [bar] ++ [] or [bar].
5> director:start_child(foo_sup, Childspec1).
{ok,<0.116.0>}
%% Test
6> director:get_childspec(foo_sup, 1).
{ok,#{append => true,
count => 6,
id => 1,
modules => [bar],
plan => [restart,#Fun<director.default_plan_element_fun.2>],
start => {bar,start_link,[]},
terminate_timeout => 2000,
type => worker}}
7> director:get_pids(foo_sup).
[{bar_id,<0.112.0>},{1,<0.116.0>}]
%% I want to have 9 more children like that
8> [director:start_child(foo_sup
,#{id => Count, append => true})
|| Count <- lists:seq(2, 10)].
[{ok,<0.126.0>},
{ok,<0.127.0>},
{ok,<0.128.0>},
{ok,<0.129.0>},
{ok,<0.130.0>},
{ok,<0.131.0>},
{ok,<0.132.0>},
{ok,<0.133.0>},
{ok,<0.134.0>}]
10> director:count_children(foo_sup).
[{specs,11},{active,11},{supervisors,0},{workers,11}]
11>
你可以使用 change_default_childspec/2 動態更改 defaultChildspec！
你也可以動態地改變孩子們，並將他們的 append 設定為 true！
但是通過在程式碼的不同部分更改它們，你將製作義大利麵條程式碼
我可以除錯導演嗎？
Yessssss， diorector 有自己的除錯並接受標準的 sys:dbg_opt/0。
導演也將有效日誌傳送到不同狀態的 sasl 和 error_logger。
1> Name = {local, dname},
Mod = foo,
InitArg = undefined,
DbgOpts = [trace],
Opts = [{debug, DbgOpts}].
[{debug,[trace]}]
2> director:start_link(Name, Mod, InitArg, Opts).
{ok,<0.106.0>}
3>
3> director:count_children(dname).
*DBG* director "dname" got request "count_children" from "<0.102.0>"
*DBG* director "dname" sent "[{specs,1},
{active,1},
{supervisors,0},
{workers,1}]" to "<0.102.0>"
[{specs,1},{active,1},{supervisors,0},{workers,1}]
4> director:change_plan(dname, bar_id, [{restart, 5000}]).
*DBG* director "dname" got request "{change_plan,bar_id,[{restart,5000}]}" from "<0.102.0>"
*DBG* director "dname" sent "ok" to "<0.102.0>"
ok
5> {ok, Pid} = director:get_pid(dname, bar_id).
*DBG* director "dname" got request "{get_pid,bar_id}" from "<0.102.0>"
*DBG* director "dname" sent "{ok,<0.107.0>}" to "<0.102.0>"
{ok,<0.107.0>}
%% Start SASL
6> application:start(sasl).
ok
... %% Log about starting SASL
7> erlang:exit(Pid, kill).
*DBG* director "dname" got exit signal for pid "<0.107.0>" with reason "killed"
true
=SUPERVISOR REPORT==== 4-May-2017::12:37:41 ===
Supervisor: dname
Context: child_terminated
Reason: killed
Offender: [{id,bar_id},
{pid,<0.107.0>},
{plan,[{restart,5000}]},
{count,1},
{count2,0},
{restart_count,0},
{mfargs,{bar,start_link,[]}},
{plan_element_index,1},
{plan_length,1},
{timer_reference,undefined},
{terminate_timeout,2000},
{extra,undefined},
{modules,[bar]},
{type,worker},
{append,false}]
8>
%% After 5000 mili-seconds
*DBG* director "dname" got timer event for child-id "bar_id" with timer reference "#Ref<0.0.1.176>"
=PROGRESS REPORT==== 4-May-2017::12:37:46 ===
supervisor: dname
started: [{id,bar_id},
{pid,<0.122.0>},
{plan,[{restart,5000}]},
{count,1},
{count2,1},
{restart_count,1},
{mfargs,{bar,start_link,[]}},
{plan_element_index,1},
{plan_length,1},
{timer_reference,#Ref<0.0.1.176>},
{terminate_timeout,2000},
{extra,undefined},
{modules,[bar]},
{type,worker},
{append,false}]
8>