#1. epoll並不代表一定比select好
# 在並發高的情況下，連接活躍度不是很高， epoll比select
# 並發性不高，同時連接很活躍， select比epoll好

#通過非阻塞io實現http請求
# select + 回調 + 事件循環
#  並發性高
# 使用單線程

import socket
from urllib.parse import urlparse
from selectors import DefaultSelector, EVENT_READ, EVENT_WRITE


selector = DefaultSelector()
#使用select完成http請求
 

urls = []
stop = False


class Fetcher:
    def connected(self, key):
        selector.unregister(key.fd)
        self.client.send("GET {} HTTP/1.1\r\nHost:{}\r\nConnection:close\r\n\r\n".format(self.path, self.host).encode("utf8"))
        selector.register(self.client.fileno(), EVENT_READ, self.readable)

    
 
def readable(self, key):
        d = self.client.recv(1024)
        if d:
            self.data += d
        else:
            selector.unregister(key.fd)
            data = self.data.decode("utf8")
            html_data = data.split("\r\n\r\n")[1]
            print(html_data)
            self.client.close()
            urls.remove(self.spider_url)
            
 
if not urls:
                global stop
                stop = True

    def get_url(self, url):
        self.spider_url = url
        url = urlparse(url)
        self.host = url.netloc
        self.path = url.path
        self.data = b""
        if self.path == "":
            self.path = "/"

        # 建立socket連接
        self.client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.client.setblocking(False)

        try:
            self.client.connect((self.host, 80))  # 阻塞不會消耗cpu
        except BlockingIOError as e:
            pass

        #註冊
        selector.register(self.client.fileno(), EVENT_WRITE, self.connected)


def loop():
    #事件循環，不停的請求socket的狀態並調用對應的回調函數
    #1. select本身是不支持register模式
    #2. socket狀態變化以後的回調是由程序員完成的
    while not stop:
        ready = selector.select()
        for key, mask in ready:
            call_back = key.data
            call_back(key)
    #回調+事件循環+select(poll\epoll)

if __name__ == "__main__":
    fetcher = Fetcher()
    import time
    start_time = time.time()
    for url in range(20):
        url = "http://shop.projectsedu.com/goods/{}/".format(url)
        urls.append(url)
        fetcher = Fetcher()
        fetcher.get_url(url)
    loop()
    print(time.time()-start_time)

# def get_url(url):
#     #通過socket請求html
#     url = urlparse(url)
#     host = url.netloc
#     path = url.path
#     if path == "":
#         path = "/"
# 
#     #建立socket連接
#     client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
#     client.setblocking(False)
#     try:
#         client.connect((host, 80)) #阻塞不會消耗cpu
#     except BlockingIOError as e:
#         pass
# 
#     #不停的詢問連接是否建立好， 需要while循環不停的去檢查狀態
#     #做計算任務或者再次發起其他的連接請求
# 
#     while True:
#         try:
#             client.send("GET {} HTTP/1.1\r\nHost:{}\r\nConnection:close\r\n\r\n".format(path, host).encode("utf8"))
#             break
#         except OSError as e:
#             pass
# 
# 
#     data = b""
#     while True:
#         try:
#             d = client.recv(1024)
#         except BlockingIOError as e:
#             continue
#         if d:
#             data += d
#         else:
#             break
# 
#     data = data.decode("utf8")
#     html_data = data.split("\r\n\r\n")[1]
#     print(html_data)
#     client.close()

select + 回調 + 事件循環