Erlang 了解Elixir badarg错误消息
当尝试从Erlang 了解Elixir badarg错误消息,erlang,elixir,Erlang,Elixir,当尝试从DynamicSupervisor启动我的流程时,我收到以下错误: {:error, {:EXIT, {:badarg, [ {:erlang, :apply, [ BfgEngine.MarketService, :start_link, {{BfgEngine.MarketService, :start_link, ["1111"]}, :permanent, 5000, :worke
DynamicSupervisor
启动我的流程时,我收到以下错误:
{:error,
{:EXIT,
{:badarg,
[
{:erlang, :apply,
[
BfgEngine.MarketService,
:start_link,
{{BfgEngine.MarketService, :start_link, ["1111"]}, :permanent, 5000,
:worker, [BfgEngine.MarketService]}
], []},
{:supervisor, :do_start_child_i, 3, [file: 'supervisor.erl', line: 379]},
{:supervisor, :handle_call, 3, [file: 'supervisor.erl', line: 404]},
{:gen_server, :try_handle_call, 4, [file: 'gen_server.erl', line: 661]},
{:gen_server, :handle_msg, 6, [file: 'gen_server.erl', line: 690]},
{:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 249]}
]}}}
我使用的代码是:
def start_market(market_id) do
spec = {MarketService, market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
然而,我不清楚出了什么问题。哪个函数的哪个参数不正确?如何分解并读取给定的错误消息
更新:
这是我的主管的初始方法:
@impl true
def init(initial_arg) do
DynamicSupervisor.init(
strategy: :one_for_one,
extra_arguments: [initial_arg]
)
end
更新2:
这是市场服务的启动链接:
def start_link(market_id) when is_bitstring(market_id) do
GenServer.start_link(__MODULE__, market_id, name: via_tuple(market_id))
end
Im使用默认的child\u spec
Im从GenServer
更新3:
改为:
def start_market(market_id) do
spec = {MarketService, market_id: market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
def start_market(market_id) do
spec = {MarketService, :market_id, market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
给出:
{:error,
{:undef,
[
{BfgEngine.MarketService, :start_link, [[], [market_id: "222"]], []},
{DynamicSupervisor, :start_child, 3,
[file: 'lib/dynamic_supervisor.ex', line: 654]},
{DynamicSupervisor, :handle_start_child, 2,
[file: 'lib/dynamic_supervisor.ex', line: 640]},
{:gen_server, :try_handle_call, 4, [file: 'gen_server.erl', line: 661]},
{:gen_server, :handle_msg, 6, [file: 'gen_server.erl', line: 690]},
{:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 249]}
]}}
** (ArgumentError) supervisors expect each child to be one of:
* a module
* a {module, arg} tuple
* a child specification as a map with at least the :id and :start fields
* or a tuple with 6 elements generated by Supervisor.Spec (deprecated)
Got: {BfgEngine.MarketService, :market_id, "222"}
(elixir) lib/supervisor.ex:657: Supervisor.init_child/1
(elixir) lib/supervisor.ex:744: Supervisor.child_spec/2
(elixir) lib/dynamic_supervisor.ex:304: DynamicSupervisor.start_child/2
改为:
def start_market(market_id) do
spec = {MarketService, market_id: market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
def start_market(market_id) do
spec = {MarketService, :market_id, market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
给出:
{:error,
{:undef,
[
{BfgEngine.MarketService, :start_link, [[], [market_id: "222"]], []},
{DynamicSupervisor, :start_child, 3,
[file: 'lib/dynamic_supervisor.ex', line: 654]},
{DynamicSupervisor, :handle_start_child, 2,
[file: 'lib/dynamic_supervisor.ex', line: 640]},
{:gen_server, :try_handle_call, 4, [file: 'gen_server.erl', line: 661]},
{:gen_server, :handle_msg, 6, [file: 'gen_server.erl', line: 690]},
{:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 249]}
]}}
** (ArgumentError) supervisors expect each child to be one of:
* a module
* a {module, arg} tuple
* a child specification as a map with at least the :id and :start fields
* or a tuple with 6 elements generated by Supervisor.Spec (deprecated)
Got: {BfgEngine.MarketService, :market_id, "222"}
(elixir) lib/supervisor.ex:657: Supervisor.init_child/1
(elixir) lib/supervisor.ex:744: Supervisor.child_spec/2
(elixir) lib/dynamic_supervisor.ex:304: DynamicSupervisor.start_child/2
很难从发布的代码中分辨出来,但您能否尝试将
start\u market
更改为:
def start_market(market_id) do
spec = {MarketService, :market_id, market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
更新(以下是两个选项):
或
当有三个参数
BfgEngine.MarketService
,:start_link
和{{BfgEngine.MarketService,:start_link,[“1111”]},:permanent,5000,:worker,[bfgengingine.MarketService]}时,您得到了函数badarg
的异常
并且它发生在函数主管:do\u start\u child\u i/3
中
函数erlang:apply/3
的参数应该是MFA a a.k.a模块、函数、参数<代码>{BfgEngine.MarketService,:start_link,[“1111”]},:permanent,5000,:worker,[BfgEngine.MarketService]}不是参数,因为它显然不是参数列表。从您的代码中,我可以猜到错误是变量spec
的内容。你应该提供一些道具列表或地图。我不知道,您应该更仔细地阅读DynamicSupervisor
的文档。错误消息
在理解Elixir抛出的错误消息时,您可以参考。关于从中学习一些Erlang For Great Good的部分可以帮助您。@Hynek-Pichi Vychodil
的答案也是准确的
你的具体问题
正如@Milan Jaric
所述,您的错误可能来自:
def start_market(market_id) do
spec = {MarketService, market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
但不仅如此DynamicSupervisor.start\u child(\uu模块,spec)
正在调用MarketService.start\u link/1
!
您的问题在于DynamicSupervisor模块中的此函数与您在MarketService.start\u link/1中解析值的方式的组合:
def start_link(market_id) when is_bitstring(market_id) do
GenServer.start_link(__MODULE__, market_id, name: via_tuple(market_id))
end
事实上,如果您还正确实现了MarketService.init/1,那么这段代码应该可以工作。我无法重现这个错误。您确定market\u id
真的是位字符串吗
就我个人而言,我的代码基于:
如您所见,他们建议在此处使用关键字列表:
spec = {MyWorker, foo: foo, bar: bar, baz: baz}
仅当您已实现MyWorker时,它才起作用。按如下方式启动链接/1:
def start_link(args) do
foo = Keyword.fetch!(args, :foo)
bar = Keyword.fetch!(args, :bar)
baz = Keyword.fetch!(args, :baz)
Genserver.start_link(__MODULE__, {foo, bar, baz}, [])
def init({foo, bar, baz}) do
# do something...
state = {foo, bar, baz}
{:ok, state}
def init(market_id) do
# do something... Let's keep it simple for the example:
state = market_id
{:ok, state}
end
在您的情况下,如果您将start_market/1更改为:
def start_market(market_id) do
spec = {MarketService, market_id: market_id}
DynamicSupervisor.start_child(__MODULE__, spec)
end
它将不工作,因为此MarketService.start\u链接/1将失败:
def start_link(market_id) when is_bitstring(market_id) do
GenServer.start_link(__MODULE__, market_id, name: via_tuple(market_id))
end
这里的market\u id不是一个位字符串,而是一个关键字列表。因此,您必须将MarketService.start\u link/1函数修改为:
def start_link(args) when is_list(args) do
market_id = Keyword.fetch!(args, :market_id)
GenServer.start_link(__MODULE__, market_id, name: via_tuple(market_id))
end
并编写一个MarketService.init/1,如下所示:
def start_link(args) do
foo = Keyword.fetch!(args, :foo)
bar = Keyword.fetch!(args, :bar)
baz = Keyword.fetch!(args, :baz)
Genserver.start_link(__MODULE__, {foo, bar, baz}, [])
def init({foo, bar, baz}) do
# do something...
state = {foo, bar, baz}
{:ok, state}
def init(market_id) do
# do something... Let's keep it simple for the example:
state = market_id
{:ok, state}
end
有用的资源
- 一本关于长生不老药的GenServer和Supervisors的好书
- …和
您是否也可以分享主管的init
功能的定义?问题出在MarketService的start\u链接中。这里要看的是你的开始链接函数和你的孩子规范。你能把它们添加到你的帖子中吗?我已经更新了一些例子,现在我发现了一个不同的错误。你不能使用我的代码。它应该只是元组{MarketService,:market\u id,market\u id}
而不是{MarketService,market\u id:market\u id}
,这是两种不同的数据结构。请注意:market\u id atom后面的逗号!我知道这是旧的,但是,我更新了答案。这应该是正确的