import selectors
import sys

sel = selectors.DefaultSelector()

file_obj = open('example.txt', 'r')
sel.register(file_obj, selectors.EVENT_READ)

while True:
    events = sel.select()
    for key, mask in events:
        if key.fileobj == sys.stdin and mask & selectors.EVENT_READ:
            # 从标准输入读取数据
            data = sys.stdin.readline()
            if data.strip() == 'quit':
                # 终止循环
                sel.close()
                sys.exit(0)
        elif key.fileobj == file_obj and mask & selectors.EVENT_READ:
            # 从文件描述符读取数据
            data = file_obj.read()
            if not data:
                # 文件读取完毕，终止循环
                sel.close()
                sys.exit(0)