如何检测用户是否因断网离开凤凰频道?
How to detect if a user left a Phoenix channel due to a network disconnect?
我有一个 Elixir/Phoenix 服务器应用程序,客户端通过 websockets 通过内置通道系统进行连接。现在我想检测用户何时离开频道。
旁注:我在 Google Chrome 扩展中使用 javascript 客户端库。为此,我从 Phoenix 中提取了 ES6 代码,将其转换为 javascript,并对其进行了一些调整,使其独立运行。
现在,当我关闭弹出窗口时,服务器会立即使用 reason = {:shutdown, :closed}
触发 terminate/2
函数。分机端没有涉及任何关闭回调,这太棒了!
但是当客户端简单地断开网络连接时(我连接了第二台电脑,只是拔掉了网络插头)那么terminate/2
将不会触发。
为什么以及如何解决这个问题?
我尝试了 transport :websocket, Phoenix.Transports.WebSocket
的 timeout
选项,但没有成功。
更新:
有了新的很棒的 Phoenix 1.2 Presence
东西,应该不再需要它了。
执行此操作的正确方法是不要在您的频道中捕获退出,而是让另一个进程监视您。当你下来时,它可以调用回调。以下是帮助您入门的片段:
# 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
在 Elixir/Phoenix 的较新版本中,HashDict 已更名为 Map。
较新代码库的正确示例是:
# 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: Map.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 Map.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 Map.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: Map.delete(state.channels, pid)}
end
defp put_channel(state, pid, mfa) do
%{state | channels: Map.put(state.channels, pid, mfa)}
end
end
我有一个 Elixir/Phoenix 服务器应用程序,客户端通过 websockets 通过内置通道系统进行连接。现在我想检测用户何时离开频道。
旁注:我在 Google Chrome 扩展中使用 javascript 客户端库。为此,我从 Phoenix 中提取了 ES6 代码,将其转换为 javascript,并对其进行了一些调整,使其独立运行。
现在,当我关闭弹出窗口时,服务器会立即使用 reason = {:shutdown, :closed}
触发 terminate/2
函数。分机端没有涉及任何关闭回调,这太棒了!
但是当客户端简单地断开网络连接时(我连接了第二台电脑,只是拔掉了网络插头)那么terminate/2
将不会触发。
为什么以及如何解决这个问题?
我尝试了 transport :websocket, Phoenix.Transports.WebSocket
的 timeout
选项,但没有成功。
更新:
有了新的很棒的 Phoenix 1.2 Presence
东西,应该不再需要它了。
执行此操作的正确方法是不要在您的频道中捕获退出,而是让另一个进程监视您。当你下来时,它可以调用回调。以下是帮助您入门的片段:
# 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
在 Elixir/Phoenix 的较新版本中,HashDict 已更名为 Map。 较新代码库的正确示例是:
# 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: Map.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 Map.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 Map.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: Map.delete(state.channels, pid)}
end
defp put_channel(state, pid, mfa) do
%{state | channels: Map.put(state.channels, pid, mfa)}
end
end