Python epoll网络编程二:客户端模型
第一篇简单介绍了一个使用epoll的服务器模型，本节介绍使用epoll的客户端模型，客户端连接多个服务器。
以下是发送hello请求的客户端，可以作为探测程序，探测服务器的工作状态，如果返回greeting，表示服务器正常工作。代码如下：
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def usage():
print 'python epoll_client.py ::...'
print '\texample: python epoll_client.py localhost:9999 localhost:9998'
sys.exit(1)
class HelloClient(EpollConnector):
''' extends EpolloServer, overload do_operation'''
def __init__(self, logger, srvs):
EpollConnector.__init__(self, logger, srvs)
def parse_response(self, fileno):
if self.responses[fileno] != epoll_util.greeting_response:
try:
print 'error in response %s'%str(self.connections[fileno].getpeername())
except:
print 'disconnect'
if __name__ == "__main__":
srvs = []
for arg in sys.argv[1:]:
try:
a, p = arg.split(':')
srvs.append((a, int(p)))
except :
usage()
if len(srvs) == 0:
usage()
srv = HelloClient(None, srvs)
srv.init_epoll()
srv.loop_epoll()
EpollConnector.init_epoll():
epoll_connector.py
21 def init_epoll(self):
22 # fileno set for connection
23 self.conns_index = {}
24 self.connections = {}
25 self.requests = {}
26 self.responses = {}
27 for i in range( len( self.srvs_addr ) ):
28 try:
29 s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
30 s.connect(self.srvs_addr[i])
31 s.setblocking(0)
32 fileno = s.fileno()
33 self.epoll.register(fileno, select.EPOLLOUT | select.EPOLLET)
34 except socket.error:
35 print 'ERROR in connect to %s'%str( self.srvs_addr[i] )
36 sys.exit(1)
37 else:
38 self.conns_index[fileno] = i
39 self.connections[fileno] = s
40 self.requests[fileno] = b''
41 self.responses[fileno] = b''
23－26行：初始化连接信息，key均为fileno； conns_index的value是客户连接编号； connections，requests，responses 的value分别是socket和请求与相应；
29-32行：初始化客户端连接，监听EPOLLOUT；与服务器模型相反，服务器模型初始化监听EPOLLIN；
34-36行：当连接失败时，退出；
38-41行：当连接成功，初始化连接的信息；
EpollConnector.loop_epoll():
epoll_connector.py
92 def loop_epoll(self):
93 try:
94 while self.status != epoll_util.close_status:
95 events = self.epoll.poll()
96 for fileno, event in events:
97 self.do_epoll(fileno, event)
98 finally:
99 self.close_epoll()
92-99行：与服务器模型相同，处理监听事件；
EpollConnector.do_epoll():
epoll_connector.py
72 def do_epoll(self, fileno, event):
73 try:
74 if event & select.EPOLLOUT:
75 self.do_request(fileno)
76 elif event & select.EPOLLIN:
77 self.do_response(fileno)
78 elif event & select.EPOLLHUP:
79 self.hup_epoll(fileno)
80 except:
81 raise
74-75行：EPOLLOUT 可读时，调用do_request读取相应；
77-78行：EPOLLIN可读时，调用do_response读取相应；
request和response是针对连接请求而言，因此客户端与服务器段的监听事件与监听动作正好相反；
EpollConnector.do_request(self, fileno):
epoll_connector.py
83 def set_request(self, fileno):
84 self.requests[fileno] = epoll_util.hello_request
85
86 def do_request(self, fileno):
87 self.set_request(fileno)
88 epoll_util.send_epoll(self.connections[fileno], self.requests[fileno])
89 self.epoll.modify(fileno, select.EPOLLIN | select.EPOLLET)
90 self.requests[fileno] = b''
87行：调用set_request(fileno)
设置请求，具体的客户端可overload此函数；
EpollConnector.do_response(self, fileno):
epoll_connector.py
43 #overload
44 def parse_response(self, response):
45 if self.responses[fileno] == epoll_util.fail_response:
46 pass
47
48 def do_response(self, fileno):
49 self.responses[fileno] = b''
50 s = self.connections[fileno]
51 self.responses[fileno] += epoll_util.recv_epoll(s)
52 self.parse_response(fileno)
53 self.epoll.modify(fileno, select.EPOLLOUT | select.EPOLLET)
52行：调用parse_response(response)
处理请求相应，具体的客户端可overload此函数；
源代码如下：
1import socket
2import select
3import sys
4import epoll_util
5
6class EpollConnector:
7'''generic epoll connectors which connect to down stream server'''
8def __init__(self, logger, srvs):
9self.logger = logger
10self.srvs_addr = srvs
11#status
12self.status = epoll_util.begin_status
13
14# initial epoll fileno
15self.epoll = select.epoll()
16
17def set_epoll(self, poll):
18self.epoll.close()
19self.epoll = poll
20
21def init_epoll(self):
22# fileno set for connection
23self.conns_index = {}
24self.connections = {}
25self.requests = {}
26self.responses = {}
27for i in range( len( self.srvs_addr ) ):
28try:
29s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
30s.connect(self.srvs_addr[i])
31s.setblocking(0)
32fileno = s.fileno()
33self.epoll.register(fileno, select.EPOLLOUT | select.EPOLLET)
34except socket.error:
35print 'ERROR in connect to %s'%str( self.srvs_addr[i] )
36sys.exit(1)
37else:
38self.conns_index[fileno] = i
39self.connections[fileno] = s
40self.requests[fileno] = b''
41self.responses[fileno] = b''
42
43#overload
44def parse_response(self, response):
45if self.responses[fileno] == epoll_util.fail_response:
46pass
47
48def do_response(self, fileno):
49self.responses[fileno] = b''
50s = self.connections[fileno]
51self.responses[fileno] += epoll_util.recv_epoll(s)
52self.parse_response(fileno)
53self.epoll.modify(fileno, select.EPOLLOUT | select.EPOLLET)
54
55#overload
56def recover(self, fileno):
57print 'hup_epoll', fileno
58
59def hup_epoll(self, fileno):
60self.recover(fileno)
61self.epoll.unregister(fileno)
62self.connections[fileno].close()
63del self.connections[fileno]
64del self.requests[fileno]
65del self.responses[fileno]
66del self.conns_index[fileno]
67
68
69def close_epoll(self):
70self.epoll.close()
71
72def do_epoll(self, fileno, event):
73try:
74if event & select.EPOLLOUT:
75self.do_request(fileno)
76elif event & select.EPOLLIN:
77self.do_response(fileno)
78elif event & select.EPOLLHUP:
79self.hup_epoll(fileno)
80except:
81raise
82
83def set_request(self, fileno):
84self.requests[fileno] = epoll_util.hello_request
85
86def do_request(self, fileno):
87self.set_request(fileno)
88epoll_util.send_epoll(self.connections[fileno], self.requests[fileno])
89self.epoll.modify(fileno, select.EPOLLIN | select.EPOLLET)
90self.requests[fileno] = b''
91
92def loop_epoll(self):
93try:
94while self.status != epoll_util.close_status:
95events = self.epoll.poll()
96for fileno, event in events:
97self.do_epoll(fileno, event)
98finally:
99self.close_epoll()
100
101
102def usage():
103print 'python epoll_client.py ::...'
104print '\texample: python epoll_client.py 218.241.108.68:9999 218.241.108.68:9998'
105sys.exit(2)
106
107
108class HelloClient(EpollConnector):
109''' extends EpolloServer, overload do_operation'''
110def __init__(self, logger, srvs):
111EpollConnector.__init__(self, logger, srvs)
112
113def parse_response(self, fileno):
114if self.responses[fileno] != epoll_util.greeting_response:
115try:
116print 'error in response %s'%str(self.connections[fileno].getpeername())
117except:
118print 'disconnect'
119
120
121if __name__ == "__main__":
122srvs = []
123for arg in sys.argv[1:]:
124try:
125a, p = arg.split(':')
126srvs.append((a, int(p)))
127except :
128usage()
129if len(srvs) == 0:
130usage()
131srv = HelloClient(None, srvs)
132srv.init_epoll()
133srv.loop_epoll()