我有一个花好月圆/凤凰服务器应用程序和客户端通过建立渠道体系然后通过WebSockets连接。现在我想,当一个用户离开通道来检测。
旁注:我使用的是谷歌Chrome扩展中的JavaScript客户端库。为此,我提取的ES6代码凤凰,它transpiled的JavaScript,和调整它一点,所以它单独运行。
现在,当我刚刚关闭弹出,服务器将立即触发与terminate/2
的reason = {:shutdown, :closed}
功能。有没有一种涉及的伸侧接近回调的,所以这是伟大的!
但是,当客户端只是失去网络连接(我连接第二台电脑,只是掏出网络插头),那么terminate/2
不会触发。
为什么?如何解决这个问题?
我打得四处timeout
的transport :websocket, Phoenix.Transports.WebSocket
option但没有成功。
更新:随着新真棒凤凰1.2 Presence
的东西,这不应该不再需要。
要做到这一点,正确的方法是在你的频道不陷阱退出,而是有另一个进程监视你。当你去,它可以调用回调。下面是一个片段,让你开始:
# lib/my_app.ex
children = [
...
worker(ChannelWatcher, [:rooms])
]
# web/channels/room_channel.ex
def join("rooms:", <> id, params, socket) do
uid = socket.assigns.user_id]
:ok = ChannelWatcher.monitor(:rooms, self(), {__MODULE__, :leave, [id, uid]})
{:ok, socket}
end
def leave(room_id, user_id) do
# handle user leaving
end
# lib/my_app/channel_watcher.ex
defmodule ChannelWatcher do
use GenServer
## Client API
def monitor(server_name, pid, mfa) do
GenServer.call(server_name, {:monitor, pid, mfa})
end
def demonitor(server_name, pid) do
GenServer.call(server_name, {:demonitor, pid})
end
## Server API
def start_link(name) do
GenServer.start_link(__MODULE__, [], name: name)
end
def init(_) do
Process.flag(:trap_exit, true)
{:ok, %{channels: HashDict.new()}}
end
def handle_call({:monitor, pid, mfa}, _from, state) do
Process.link(pid)
{:reply, :ok, put_channel(state, pid, mfa)}
end
def handle_call({:demonitor, pid}, _from, state) do
case HashDict.fetch(state.channels, pid) do
:error -> {:reply, :ok, state}
{:ok, _mfa} ->
Process.unlink(pid)
{:reply, :ok, drop_channel(state, pid)}
end
end
def handle_info({:EXIT, pid, _reason}, state) do
case HashDict.fetch(state.channels, pid) do
:error -> {:noreply, state}
{:ok, {mod, func, args}} ->
Task.start_link(fn -> apply(mod, func, args) end)
{:noreply, drop_channel(state, pid)}
end
end
defp drop_channel(state, pid) do
%{state | channels: HashDict.delete(state.channels, pid)}
end
defp put_channel(state, pid, mfa) do
%{state | channels: HashDict.put(state.channels, pid, mfa)}
end
end