您好,我一直在阅读有关 Thin 的文档,而且我对 eventmachine 相当陌生,但我知道 Deferrable 的工作原理。我的目标是了解当正文被延迟并逐部分流式传输时 Thin 是如何工作的。
以下是我正在处理并试图理解的示例。
class DeferrableBody
include EventMachine::Deferrable
def call(body)
body.each do |chunk|
@body_callback.call(chunk)
end
# @body_callback.call()
end
def each &blk
@body_callback = blk
end
end
class AsyncApp
# This is a template async response. N.B. Can't use string for body on 1.9
AsyncResponse = [-1, {}, []].freeze
puts "Aysnc testing #{AsyncResponse.inspect}"
def call(env)
body = DeferrableBody.new
# Get the headers out there asap, let the client know we're alive...
EventMachine::next_tick do
puts "Next tick running....."
env['async.callback'].call [200, {'Content-Type' => 'text/plain'}, body]
end
# Semi-emulate a long db request, instead of a timer, in reality we'd be
# waiting for the response data. Whilst this happens, other connections
# can be serviced.
# This could be any callback based thing though, a deferrable waiting on
# IO data, a db request, an http request, an smtp send, whatever.
EventMachine::add_timer(2) do
puts "Timer started.."
body.call ["Woah, async!\n"]
EventMachine::add_timer(5) {
# This could actually happen any time, you could spawn off to new
# threads, pause as a good looking lady walks by, whatever.
# Just shows off how we can defer chunks of data in the body, you can
# even call this many times.
body.call ["Cheers then!"]
puts "Succeed Called."
body.succeed
}
end
# throw :async # Still works for supporting non-async frameworks...
puts "Async REsponse sent."
AsyncResponse # May end up in Rack :-)
end
end
# The additions to env for async.connection and async.callback absolutely
# destroy the speed of the request if Lint is doing it's checks on env.
# It is also important to note that an async response will not pass through
# any further middleware, as the async response notification has been passed
# right up to the webserver, and the callback goes directly there too.
# Middleware could possibly catch :async, and also provide a different
# async.connection and async.callback.
# use Rack::Lint
run AsyncApp.new
我不太清楚的部分是 DeferrableBody 类中的 call
和 each
方法中发生的情况。
我知道,一旦计时器作为存储在 @body_callback 中的 block 触发,每个都会收到数据 block ,并且当在主体上调用成功时,它会发送主体,但何时是 yield
或 call
调用这些 block ,发送时它如何变成单个消息。
我觉得我对闭包的理解还不足以理解正在发生的事情。如果有任何帮助,我们将不胜感激。
谢谢。
最佳答案
好吧,我想我已经弄清楚每个 block 是如何工作的了。
瘦于post_init
似乎正在生成 @request
和@response
连接进入时的对象。响应对象需要响应 each
方法。这是我们重写的方法。
env['async.callback']
是一个闭包,分配给名为 post_process
的方法在 connection.rb
类方法,其中数据实际上发送到连接,如下所示
@response.each do |chunk|
trace { chunk }
puts "-- [THIN] sending data #{chunk} ---"
send_data chunk
end
如何定义每个响应对象
def each
yield head
if @body.is_a?(String)
yield @body
else
@body.each { |chunk| yield chunk }
end
end
所以我们的 env['async.callback'] 基本上是一个名为 post_process
的方法在通过method(:post_process)
访问的connection.rb类中定义允许我们的方法像闭包一样处理,其中包含对 @response 对象的访问。当 react 器启动时,它首先发送 next_tick
中的 header 数据。它产生头部,但此时 body 是空的,所以没有产生任何东西。
此后我们的each
方法覆盖 @response
拥有的旧实现反对所以当 add_timers
开火post_process
被触发的发送我们使用 body.call(["Wooah..."])
提供的数据到浏览器(或任何地方)
完全敬畏 macournoyer 和致力于瘦身的团队。如果您觉得这不是它的工作原理,请纠正我的理解。
关于ruby - 瘦异步应用程序示例如何缓冲对主体的响应?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11245872/