【select模块】select IO多路复用和select实现FTP

发布时间:2020-08-12 22:59:01 作者:等你的破船
来源:网络 阅读:1028

select是全平台通用的IO多路复用模块。最大连接数:1024。

poll和epoll没有最大连接数限制,但只能用在linux平台。

selectors是再封装模块,推荐使用。下篇会讨论。

select.select(rlist, wlist, xlist[, timeout])

方法、属性参数作用示例
select(rlist,wlist,rlist,[timout=1])



poll()
没人用了,已经升级为epoll


epoll(sizehint = -1,flags=0)

sizehint informs epoll about the expected number of events to be registered.  It must be positive, or-1to use the default. It is only used on older systems where epoll_create1() is not available; otherwise it has no effect (though its value is still checked).

flags is deprecated and completely ignored.  However, when supplied, its value must be 0 or select.EPOLL_CLOEXEC, otherwise OSError is raised.


(Only supported on Linux 2.5.44 and newer.) Return an edge polling object, which can be used as Edge or Level Triggered interface for I/O events.

devpoll()

 

(Only supported on Solaris and derivatives.)  Returns a /dev/poll polling object; see section /dev/poll Polling Objects below for the methods supported by devpoll objects.
kevent()

select.kevent(ident, filter=KQ_FILTER_READ, flags=KQ_EV_ADD, fflags=0, data=0, udata=0)
  • (Only supported on BSD.)  Returns a kernel event object; see section Kevent Objects below for the methods supported by kevent objects.


kqueue()
(Only supported on BSD.)  Returns a kernel queue object; see section Kqueue Objects below for the methods supported by kqueue objects.


import socket
import os
import select
import queue
import json


class SelectFTP(object):
    def __init__(self, ip, port):
        self.server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.server.setblocking(0)
        self.server.bind((ip, port))
        self.server.listen(20)
        

        self.inputs = [self.server]
        self.outputs = []
        self.file_attr = {}
        # file_attr format:file_attr[socket]:{func:'', filename:'', len:999, recv_len:0}      
        self.socket_queue = {}

    
    def upload(self, sock, write_data):
        # if os.path.isfile(self.file_attr[sock]['filename']):
        with open(self.file_attr[sock]['filename'], 'a+') as file:
            file.write(data)
            self.file_attr[sock][recv_len] += len(write_data)
            if self.file_attr[sock][recv_len] == self.file_attr[sock][len]:
                del self.file_attr[sock]
                file.close()
        
   
    def download(self, sock, *args):
        pass
        
    def run(self):
        while self.inputs:
            read_active, read_output, exception = select.select(self.inputs, self.outputs, self.inputs)
            
            for fd in read_active:
                if fd is server:
                    conn, addr = fd.accept(1024)
                    conn.setblocking(0)
                    self.inputs = self.inputs.append(conn)
                    self.socket_queue[fd] = queue.Queue()
                    
                else:
                    recv_data = fd.recv(1024)

                    if recv_data:
                        data = json.loads(recv_data.decode())
                        
                        if fd not in self.file_attr.keys:
                            self.file_attr[fd] = data
                        
                        else:
                            try:
                                self.socket_queue.put_nowait(data)
                                if fd not in self.outputs:
                                    self.outputs.append(fd)
                            except Exception as e:
                                print(e)
                            
                    else:
                        self.inputs.remove(fd)
                        if fd in self.outputs:
                            self.outputs.remove(fd)
                        del self.socket_queue[fd]
                        
                    send_data = 
                        
            for fd in read_output:
                try:
                    message = self.socket_queue.get_nowait()
                except queue.Empty:
                    self.outputs.remove(fd)
                    print('wait...')
                else:
                    getattr(self.file_attr[fd]['func'])(fd, message)

 

推荐阅读:
  1. IO_多路复用_select_epool模式
  2. I/O多路复用——select

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