# API to communicate with a data transfer unit
__version__ = '0.0.1'
import zmq
import socket
import logging
import json
import errno
import os
import cPickle
import traceback
class loggingFunction:
def out (self, x, exc_info = None):
if exc_info:
print x, traceback.format_exc()
else:
print x
def __init__ (self):
self.debug = lambda x, exc_info=None: self.out(x, exc_info)
self.info = lambda x, exc_info=None: self.out(x, exc_info)
self.warning = lambda x, exc_info=None: self.out(x, exc_info)
self.error = lambda x, exc_info=None: self.out(x, exc_info)
self.critical = lambda x, exc_info=None: self.out(x, exc_info)
class dataTransfer():
def __init__ (self, connectionType, signalHost = None, useLog = False, context = None):
if useLog:
self.log = logging.getLogger("dataTransferAPI")
else:
self.log = loggingFunction()
# ZMQ applications always start by creating a context,
# and then using that for creating sockets
# (source: ZeroMQ, Messaging for Many Applications by Pieter Hintjens)
if context:
self.context = context
self.externalContext = True
else:
self.context = zmq.Context()
self.externalContext = False
self.signalHost = signalHost
self.signalPort = "50000"
self.requestPort = "50001"
self.dataHost = None
self.dataPort = None
self.signalSocket = None
self.dataSocket = None
self.requestSocket = None
self.targets = None
self.supportedConnections = ["stream", "streamMetadata", "queryNext", "queryMetadata"]
self.signalExchanged = None
self.streamStarted = None
self.queryNextStarted = None
self.socketResponseTimeout = 1000
if connectionType in self.supportedConnections:
self.connectionType = connectionType
else:
raise Exception("Chosen type of connection is not supported.")
# targets: [host, port, prio] or [[host, port, prio], ...]
def initiate (self, targets):
if type(targets) != list:
self.stop()
raise Excepition("Argument 'targets' must be list.")
signal = None
# Signal exchange
if self.connectionType == "stream":
signalPort = self.signalPort
signal = "START_STREAM"
elif self.connectionType == "streamMetadata":
signalPort = self.signalPort
signal = "START_STREAM_METADATA"
elif self.connectionType == "queryNext":
signalPort = self.signalPort
signal = "START_QUERY_NEXT"
elif self.connectionType == "queryMetadata":
signalPort = self.signalPort
signal = "START_QUERY_METADATA"
self.log.debug("Create socket for signal exchange...")
if self.signalHost:
self.__createSignalSocket(signalPort)
else:
self.stop()
raise Exception("No host to send signal to specified." )
self.targets = []
# [host, port, prio]
if len(targets) == 3 and type(targets[0]) != list and type(targets[1]) != list and type(targets[2]) != list:
host, port, prio = targets
self.targets = [[host + ":" + port, prio]]
# [[host, port, prio], ...]
else:
for t in targets:
if type(t) == list:
host, port, prio = t
self.targets.append([host + ":" + port, prio])
else:
self.stop()
self.log.debug("targets=" + str(targets))
raise Exception("Argument 'targets' is of wrong format.")
# if type(dataPort) == list:
# self.dataHost = str([socket.gethostname() for i in dataPort])
# else:
# self.dataHost = socket.gethostname()
message = self.__sendSignal(signal)
if message and message == "VERSION_CONFLICT":
self.stop()
raise Exception("Versions are conflicting.")
elif message and message == "NO_VALID_HOST":
self.stop()
raise Exception("Host is not allowed to connect.")
elif message and message == "CONNECTION_ALREADY_OPEN":
self.stop()
raise Exception("Connection is already open.")
elif message and message == "NO_VALID_SIGNAL":
self.stop()
raise Exception("Connection type is not supported for this kind of sender.")
# if there was no response or the response was of the wrong format, the receiver should be shut down
elif message and message.startswith(signal):
self.log.info("Received confirmation ...")
self.signalExchanged = signal
else:
raise Exception("Sending start signal ...failed.")
def __createSignalSocket (self, signalPort):
# To send a notification that a Displayer is up and running, a communication socket is needed
# create socket to exchange signals with Sender
self.signalSocket = self.context.socket(zmq.REQ)
# time to wait for the sender to give a confirmation of the signal
# self.signalSocket.RCVTIMEO = self.socketResponseTimeout
connectionStr = "tcp://" + str(self.signalHost) + ":" + str(signalPort)
try:
self.signalSocket.connect(connectionStr)
self.log.info("signalSocket started (connect) for '" + connectionStr + "'")
except Exception as e:
self.log.error("Failed to start signalSocket (connect): '" + connectionStr + "'", exc_info=True)
raise
# using a Poller to implement the signalSocket timeout (in older ZMQ version there is no option RCVTIMEO)
self.poller = zmq.Poller()
self.poller.register(self.signalSocket, zmq.POLLIN)
def __sendSignal (self, signal):
if not signal:
return
# Send the signal that the communication infrastructure should be established
self.log.info("Sending Signal")
sendMessage = ["0.0.1", signal]
trg = cPickle.dumps(self.targets)
sendMessage.append(trg)
# sendMessage = [__version__, signal, self.dataHost, self.dataPort]
self.log.debug("Signal: " + str(sendMessage))
try:
self.signalSocket.send_multipart(sendMessage)
except:
self.log.error("Could not send signal", exc_info=True)
raise
message = None
try:
socks = dict(self.poller.poll(self.socketResponseTimeout))
except:
self.log.error("Could not poll for new message", exc_info=True)
raise
# if there was a response
if self.signalSocket in socks and socks[self.signalSocket] == zmq.POLLIN:
try:
# Get the reply.
message = self.signalSocket.recv()
self.log.info("Received answer to signal: " + str(message) )
except KeyboardInterrupt:
self.log.error("KeyboardInterrupt: No message received")
self.stop()
raise
except:
self.log.error("Could not receive answer to signal", exc_info=True)
self.stop()
raise
return message
def start (self, dataSocket = False, requestHost = None):
# if not self.connectionType:
# raise Exception("No connection specified. Please initiate a connection first.")
alreadyConnected = self.streamStarted or self.queryNextStarted
if alreadyConnected:
raise Exception("Connection already started.")
ip = "0.0.0.0" #TODO use IP of hostname?
host = ""
port = ""
if dataSocket:
if type(dataSocket) == list:
socketIdToConnect = dataSocket[0] + ":" + dataSocket[1]
ip = dataSocket[0]
host = dataSocket[0]
port = dataSocket[1]
else:
self.log.debug("dataSocket=" + str(dataSocket))
port = str(dataSocket)
host = socket.gethostname()
socketId = host + ":" + port
ipFromHost = socket.gethostbyaddr(host)[2]
if len(ipFromHost) == 1:
ip = ipFromHost[0]
elif len(self.targets) == 1:
host, port = self.targets[0][0].split(":")
ipFromHost = socket.gethostbyaddr(host)[2]
if len(ipFromHost) == 1:
ip = ipFromHost[0]
else:
raise Exception("Multipe possible ports. Please choose which one to use.")
socketId = host + ":" + port
socketIdToConnect = ip + ":" + port
self.dataSocket = self.context.socket(zmq.PULL)
# An additional socket is needed to establish the data retriving mechanism
connectionStr = "tcp://" + socketIdToConnect
try:
self.dataSocket.bind(connectionStr)
self.log.info("Socket of type " + self.connectionType + " started (bind) for '" + connectionStr + "'")
except:
self.log.error("Failed to start Socket of type " + self.connectionType + " (bind): '" + connectionStr + "'", exc_info=True)
if self.connectionType in ["queryNext", "queryMetadata"]:
self.requestSocket = self.context.socket(zmq.PUSH)
# An additional socket is needed to establish the data retriving mechanism
connectionStr = "tcp://" + self.signalHost + ":" + self.requestPort
try:
self.requestSocket.connect(connectionStr)
self.log.info("Socket started (connect) for '" + connectionStr + "'")
except:
self.log.error("Failed to start Socket of type " + self.connectionType + " (connect): '" + connectionStr + "'", exc_info=True)
self.queryNextStarted = socketId
else:
self.streamStarted = socketId
##
#
# Receives or queries for new files depending on the connection initialized
#
# returns either
# the next file
# (if connection type "stream" was choosen)
# the newest file
# (if connection type "queryNext" was choosen)
# the path of the newest file
# (if connection type "queryMetadata" was choosen)
#
##
def get (self):
if not self.streamStarted and not self.queryNextStarted:
self.log.info("Could not communicate, no connection was initialized.")
return None, None
if self.queryNextStarted :
sendMessage = ["NEXT", self.queryNextStarted]
# self.log.debug("Asking for next file with message " + str(sendMessage))
try:
self.requestSocket.send_multipart(sendMessage)
except Exception as e:
self.log.error("Could not send request to requestSocket", exc_info=True)
return None, None
try:
return self.__getMultipartMessage()
except KeyboardInterrupt:
self.log.debug("Keyboard interrupt detected. Stopping to receive.")
raise
except:
self.log.error("Unknown error while receiving files. Need to abort.", exc_info=True)
return None, None
def __getMultipartMessage (self):
#save all chunks to file
multipartMessage = self.dataSocket.recv_multipart()
if len(multipartMessage) < 2:
self.log.error("Received mutipart-message is too short. Either config or file content is missing.")
self.log.debug("multipartMessage=" + str(mutipartMessage))
#extract multipart message
try:
metadata = cPickle.loads(multipartMessage[0])
except:
self.log.error("Could not extract metadata from the multipart-message.", exc_info=True)
metadata = None
#TODO validate multipartMessage (like correct dict-values for metadata)
try:
payload = multipartMessage[1:]
except:
self.log.warning("An empty file was received within the multipart-message", exc_info=True)
payload = None
return [metadata, payload]
def store (self, targetBasePath, dataObject):
if type(dataObject) is not list and len(dataObject) != 2:
raise Exception("Wrong input type for 'store'")
payloadMetadata = dataObject[0]
payload = dataObject[1]
if type(payloadMetadata) is not dict or type(payload) is not list:
raise Exception("payload: Wrong input format in 'store'")
#save all chunks to file
while True:
if payloadMetadata and payload:
#append to file
try:
self.log.debug("append to file based on multipart-message...")
#TODO: save message to file using a thread (avoids blocking)
#TODO: instead of open/close file for each chunk recyle the file-descriptor for all chunks opened
self.__appendChunksToFile(targetBasePath, payloadMetadata, payload)
self.log.debug("append to file based on multipart-message...success.")
except KeyboardInterrupt:
self.log.info("KeyboardInterrupt detected. Unable to append multipart-content to file.")
break
except Exception, e:
self.log.error("Unable to append multipart-content to file.", exc_info=True)
self.log.debug("Append to file based on multipart-message...failed.")
if len(payload) < payloadMetadata["chunkSize"] :
#indicated end of file. Leave loop
filename = self.generateTargetFilepath(targetBasePath, payloadMetadata)
fileModTime = payloadMetadata["fileModTime"]
self.log.info("New file with modification time " + str(fileModTime) + " received and saved: " + str(filename))
break
try:
[payloadMetadata, payload] = self.get()
except:
self.log.error("Getting data failed.", exc_info=True)
break
def __appendChunksToFile (self, targetBasePath, configDict, payload):
chunkCount = len(payload)
#generate target filepath
targetFilepath = self.generateTargetFilepath(targetBasePath, configDict)
self.log.debug("new file is going to be created at: " + targetFilepath)
#append payload to file
try:
newFile = open(targetFilepath, "a")
except IOError, e:
# errno.ENOENT == "No such file or directory"
if e.errno == errno.ENOENT:
#TODO create subdirectory first, then try to open the file again
try:
targetPath = self.__generateTargetPath(targetBasePath, configDict)
os.makedirs(targetPath)
newFile = open(targetFilepath, "w")
self.log.info("New target directory created: " + str(targetPath))
except:
self.log.error("Unable to save payload to file: '" + targetFilepath + "'", exc_info=True)
self.log.debug("targetPath:" + str(targetPath))
raise
else:
self.log.error("Failed to append payload to file: '" + targetFilepath + "'", exc_info=True)
except:
self.log.error("Failed to append payload to file: '" + targetFilepath + "'", exc_info=True)
self.log.debug("e.errno = " + str(e.errno) + " errno.EEXIST==" + str(errno.EEXIST))
#only write data if a payload exist
try:
if payload != None:
for chunk in payload:
newFile.write(chunk)
newFile.close()
except:
self.log.error("Unable to append data to file.", exc_info=True)
raise
def generateTargetFilepath (self, basePath, configDict):
"""
generates full path where target file will saved to.
"""
filename = configDict["filename"]
#TODO This is due to Windows path names, check if there has do be done anything additionally to work
# e.g. check sourcePath if it's a windows path
relativePath = configDict["relativePath"].replace('\\', os.sep)
if relativePath is '' or relativePath is None:
targetPath = basePath
else:
targetPath = os.path.normpath(basePath + os.sep + relativePath)
filepath = os.path.join(targetPath, filename)
return filepath
def __generateTargetPath (self, basePath, configDict):
"""
generates path where target file will saved to.
"""
#TODO This is due to Windows path names, check if there has do be done anything additionally to work
# e.g. check sourcePath if it's a windows path
relativePath = configDict["relativePath"].replace('\\', os.sep)
# if the relative path starts with a slash path.join will consider it as absolute path
if relativePath.startswith("/"):
relativePath = relativePath[1:]
targetPath = os.path.join(basePath, relativePath)
return targetPath
##
#
# Send signal that the displayer is quitting, close ZMQ connections, destoying context
#
##
def stop (self):
if self.signalSocket and self.signalExchanged:
self.log.info("Sending close signal")
signal = None
if self.streamStarted or ( "STREAM" in self.signalExchanged):
signal = "STOP_STREAM"
elif self.queryNextStarted or ( "QUERY" in self.signalExchanged):
signal = "STOP_QUERY_NEXT"
self.log.debug("signal=" + str(signal))
message = self.__sendSignal(signal)
#TODO need to check correctness of signal?
try:
if self.signalSocket:
self.log.info("closing signalSocket...")
self.signalSocket.close(linger=0)
self.signalSocket = None
if self.dataSocket:
self.log.info("closing dataSocket...")
self.dataSocket.close(linger=0)
self.dataSocket = None
except:
self.log.error("closing ZMQ Sockets...failed.", exc_info=True)
# if the context was created inside this class,
# it has to be destroyed also within the class
if not self.externalContext and self.context:
try:
self.log.info("Closing ZMQ context...")
self.context.destroy(0)
self.context = None
self.log.info("Closing ZMQ context...done.")
except:
self.log.error("Closing ZMQ context...failed.", exc_info=True)
def __exit__ (self):
self.stop()
def __del__ (self):
self.stop()