我在玩 EventMachine 几天了,它有一个陡峭的学习曲线恕我直言;-) 我尝试通过触发回调中需要的 HttpHeaderCrawler.query() 来返回哈希值。但是在这种情况下我得到的不是哈希 {'http_status' => xxx, 'http_version' => xxx} 而是 EventMachine::HttpClient 对象本身。
我想保持 EM.run 块干净,并想在自己的类/模块中执行所有逻辑,那么如何将这样的值返回到主循环以通过回调访问它?提前谢谢了 ;-)
#!/usr/bin/env ruby
require 'eventmachine'
require 'em-http-request'
class HttpHeaderCrawler
include EM::Deferrable
def query(uri)
http = EM::HttpRequest.new(uri).get
http.callback do
http_header = {
"http_status" => http.response_header.http_status,
"http_version" => http.response_header.http_version
}
puts "Returns to EM main loop: #{http_header}"
succeed(http_header)
end
end
end
EM.run do
domains = ['http://www.google.com', 'http://www.facebook.com', 'http://www.twitter.com']
domains.each do |domain|
hdr = HttpHeaderCrawler.new.query(domain)
hdr.callback do |header|
puts "Received from HttpHeaderCrawler: #{header}"
end
end
end
此代码段产生以下输出:
Returns to EM main loop: {"http_status"=>302, "http_version"=>"1.1"}
Received from HttpHeaderCrawler: #<EventMachine::HttpClient:0x00000100d57388>
Returns to EM main loop: {"http_status"=>301, "http_version"=>"1.1"}
Received from HttpHeaderCrawler: #<EventMachine::HttpClient:0x00000100d551a0>
Returns to EM main loop: {"http_status"=>200, "http_version"=>"1.1"}
Received from HttpHeaderCrawler: #<EventMachine::HttpClient:0x00000100d56280>
最佳答案
我认为问题是 #query
返回 http.callback
,它返回 http 对象本身,而它应该返回 self
,即 HttpHeaderCrawler。看看这是否有效。
def query(uri)
http = EM::HttpRequest.new(uri).get
http.callback do
http_header = {
"http_status" => http.response_header.http_status,
"http_version" => http.response_header.http_version
}
puts "Returns to EM main loop: #{http_header}"
succeed(http_header)
end
self
end
关于Ruby EventMachine - 如何将值从 EM::Deferrable 返回到主 EM 循环?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/7910289/