Source Code for Module sick_ldmrs.xport

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 34   
 35  # Author: Brett Grandbois 
 36  #$Id$ 
 37   
 38  import socket 
 39  import errno 
 40   
 41  from exceptions import * 
 42   
 43 -class XPort(object): 
 44      '''Class representation of a socket transport thread. 
 45   
 46      Simplification wrapper around socket.socket and related objects. 
 47      The send and recv methods will wait for all requested data and/or 
 48      provide a filtered exception (something good, bad, or ugly happened). 
 49      ''' 
 50   
 51 -    def __init__ (self,  host,  port): 
 52          ''' XPort constructor, connect to requested peer. 
 53   
 54          Connect to requested network peer or raise reason why not. 
 55          @param host: hostname to connect to.  can be name or IPv4 dot notation. 
 56          @type host: str 
 57          @param port: network port to connect to 
 58          @type port: int 
 59          @raise FatalExcetpion: Host/port does not exist or is unreachable. 
 60          @raise TimeoutException: Network is reachable but timeout on connect. 
 61          Likely host is not yet ready. 
 62          @raise InfoRestartException: Non-fatal network problem, able to re-try. 
 63          @raise ErrorRestartException: More serious network problem, possibly can 
 64          re-try. 
 65          ''' 
 66          try: 
 67              self.__shutdown = False 
 68   
 69              self.__sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
 70              # don't want small messages lingering in the buffers 
 71              self.__sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) 
 72              # needed for just calling connect()?  doesn't hurt to set it... 
 73              self.__sock.setsockopt(socket.SOL_SOCKET,  socket.SO_REUSEADDR,  1) 
 74   
 75              # 5 second timeout should be more than sufficient 
 76              # in any case of this timeout happening we want the exception to 
 77              # force a restart 
 78              self.__sock.settimeout(5.0) 
 79   
 80              host_ip = socket.gethostbyname(host) 
 81   
 82              self.__sock.connect((host_ip, port)) 
 83   
 84          # addressing error is fatal, it means a supplied host does not exist 
 85          # or can not be found 
 86          except (socket.herror,  socket.gaierror),  e: 
 87             raise FatalException('address exception in XPort init:  %s' % e) 
 88   
 89          # in init a timeout means restart the system, most likely the LD-MRS 
 90          # isn't ready yet 
 91          except socket.timeout,  e: 
 92              raise TimeoutException('timeout exceeded in host connect: %s' % e) 
 93   
 94          except socket.error,  e: 
 95              fatals = [errno.ENETUNREACH, errno.EACCES, errno.EPERM, errno.EFAULT] 
 96              not_found = [errno.ECONNREFUSED, errno.EHOSTUNREACH, errno.EHOSTDOWN, 
 97                           errno.EALREADY] 
 98              if e.errno in fatals: 
 99                  raise FatalException('fatal error in socket init sequence: %s' 
100                                       % e) 
101              elif e.errno in not_found: 
102                  raise InfoRestartException('no host found at %s:%d...continuing to try' 
103                                             % (host,  port)) 
104              else: 
105                  raise ErrorRestartException('error in socket init sequence: %s' 
106                                              % e) 
107   
108 -    def recv(self,  length): 
109          ''' Wait for data from the network peer. 
110   
111          Wait until all requested data from the network peer has arrived. 
112          @param length: how much data is requested 
113          @type length: int 
114          @return: data from network peer 
115          @rtype: str 
116          @raise TimeoutException: no data has arrived in the timeout period 
117          @raise InfoRestartException: remote peer has closed the socket, the 
118          data request can not be fulfilled but able to reconnect to peer. 
119          @raise NextMsgException: signal interruption, current data request 
120          can not be fulfilled but new request can be issued 
121          @raise ErrorRestartException: network problem reported and data request 
122          can not be fulfilled.  should reconnect to peer. 
123          ''' 
124          data_recv = 0 
125          return_string = '' 
126          next_msg = [errno.EINTR,  ] 
127          info = [errno.ECONNRESET, errno.EPIPE] 
128          while data_recv < length: 
129              try: 
130                  data = self.__sock.recv(length - data_recv, socket.MSG_WAITALL) 
131              except socket.timeout: 
132                  raise TimeoutException('timeout on socket.recv') 
133              except socket.error,  e: 
134                  if e.errno in next_msg: 
135                      raise NextMsgException() 
136                  elif e.errno in info: 
137                      raise InfoRestartException('socket.recv restarting xport: %s' 
138                                                 % e) 
139                  else: 
140                      raise ErrorRestartException('error in socket recv: %s' % e) 
141   
142              if not data: 
143                  raise InfoRestartException('socket.recv zero-length, likely a shutdown signal') 
144              else: 
145                  return_string += data 
146                  data_recv += len(data) 
147   
148          return return_string 
149   
150   
151 -    def send(self,  cmd): 
152          '''Send a data message to the network peer. 
153   
154          Send all requested message data. 
155          @param cmd: data to send 
156          @type cmd: str 
157          @raise TimeoutException: data could not be sent during the timeout 
158          period, likely the peer has gone down 
159          @raise InfoRestartException: peer has closed connection or local shutdown 
160          signal caught.  either way current send can not be fulfilled. 
161          @raise ErrorRestartException: network problem reported and data send 
162          can not be fulfilled.  should reconnect to peer. 
163          ''' 
164   
165          info = [errno.EPIPE,  errno.ECONNRESET,  errno.EINTR] 
166          try: 
167              self.__sock.sendall(cmd) 
168          except socket.timeout: 
169              raise TimeoutException('timeout on socket.sendall') 
170          except socket.error,  e: 
171              if e.errno in info: 
172                  # EPIPE should be a shutdown signal 
173                  raise InfoRestartException('socket.sendall: %s' % e) 
174              else: 
175                  raise ErrorRestartExcetpion('error in socket.sendall: %s' % e) 
176   
177 -    def shutdown(self): 
178          ''' Call socket.shutdown to pop out of any blocking send/recv ''' 
179          # this can be called from external callbacks as well 
180          # as the main loop exit 
181          if not self.__shutdown: 
182              # call shutdown first to immediately terminate comms 
183              # close will linger trying to flush any pending data 
184              self.__shutdown = True 
185              try: 
186                  self.__sock.shutdown(socket.SHUT_RDWR) 
187              except socket.error: 
188                  # we're shutting down so don't care about socket level errors 
189                  pass 
190   
191 -    def close(self): 
192          '''close the xport socket''' 
193          try: 
194              self.__sock.close() 
195          except socket.error: 
196              # we're shutting down so don't care about socket-level errors 
197              pass 
198