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dataserver.py
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dataserver.py
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import sys, SimpleXMLRPCServer, getopt, pickle, time, threading, xmlrpclib, unittest
from datetime import datetime, timedelta
from xmlrpclib import Binary
import shelve,binascii,socket
import numpy as np
REDUNDANCY = 2
class simpleHT:
def __init__(self,*argv):
# python dataserver.py 0 3333 4444 5555 6666
#The first argument tells which one is the current server. e.g., 0 means port 3333 is the port
#of current server.
#In this project, there are 5 arguments, the first one is index and the following four are ports of the
#data servers.
current_server = argv[0]
N = len(argv)-1
Ports_dataServ = argv[1:]
port = str(Ports_dataServ[current_server])
print 'dataserver',port,'is online...'
# Retrieve history data
# self.data is a dict of dicts that has REDUNDANCY ports:data pairs
# Actually, each server has its own data and the copy of last server's own data
# {}, the filename is dataserver_port
self.data = shelve.open('dataserver_'+port, writeback=True)
# connect to the nextServer for recovery
nextPort = str(Ports_dataServ[(current_server+1)%N])
self.nextServer = xmlrpclib.ServerProxy('http://localhost:' + nextPort)
self.ports = {}
self.servers = {}
for i in range(REDUNDANCY):
self.ports[i] = str(Ports_dataServ[(current_server-i)%N]) # ports[0] is the port of current dataserver
if i!= 0:
self.servers[self.ports[i]] = xmlrpclib.ServerProxy('http://localhost:' + self.ports[i])
#connect to the all the other dataservers
#check whether the data dic is empty. If it is empty, initialize them. get the replica from nextserver.
#Otherwise, get the replica from other servers.
if self.data!={}:
print("Loaded previous data from server backup file")
else:
for i in range(REDUNDANCY):
self.data[self.ports[i]] = {}
for i in self.ports:
p = self.ports[i]
if p == port:
try:
replica = self.nextServer.getReplica(Binary(port))
self.data[p] = pickle.loads(replica.data)
print 'Successfully loaded previous data from dataserver:', nextPort
except socket.error:
print 'Recovering previous data is passed'
pass
else:
try:
replica = self.servers[p].getReplica(Binary(p))
self.data[p] = pickle.loads(replica.data)
print "Successfully loaded previous copy from dataserver:", p
except socket.error:
print "Recovering previous copy is passed"
pass
def get(self,argv):
rv = False
datagram = pickle.loads(argv.data)
port = datagram['port']
path = datagram['path']
ID = datagram['blks']
version = datagram['version']
#check whether there is the specified block in the specified path on the specified server. Also,
#need to make sure it has the version.
if port in self.data and path in self.data[port] and \
ID in self.data[port][path] and \
version in self.data[port][path][ID]:
rv = Binary(self.data[port][path][ID][version])
return rv
# Put a new version of block
# return the length of received data
def put(self,argv):
datagram = pickle.loads(argv.data)
port = datagram['port']
path = datagram['path']
ID = datagram['blks']
version = datagram['version']
value = datagram['data']
length = str(len(value))
if path not in self.data[port]: # initialize a dict for a new file
self.data[port][path] = {}
if ID not in self.data[port][path]:
self.data[port][path][ID] = {} # initialize a dict for a new block
self.data[port][path][ID][version] = value + self.checksum(value)
return Binary(length)
def pop(self,argv):
rv = False
datagram = pickle.loads(argv.data)
port = datagram['port']
path = datagram['path']
ID = datagram['blks']
# version is the blocks of data from different time line. Each time it is modified, the version increases by one.
if port in self.data and path in self.data[port] and ID in self.data[port][path]:
if 'version' in datagram and datagram['version'] in self.data[port][path][ID]:
data = self.data[port][path][ID].pop(datagram['version'])
rv = Binary(data)
else:
data = self.data[port][path].pop(ID)
rv = Binary(data)
return rv
def keyRename(self,argv):
rv = False
datagram = pickle.loads(argv.data)
port = datagram['port']
old = datagram['old']
new = datagram['new']
ID = datagram['blks']
if port in self.data and old in self.data[port] and ID in self.data[port][old]:
if new not in self.data[port]:
self.data[port][new] = {}
self.data[port][new][ID] = self.data[port][old].pop(ID)
if self.data[port][old] == {}:
self.data[port].pop(old)
def getReplica(self,port):
port = str(port.data)
replica = self.data[port]
replica = pickle.dumps(replica,2)
return Binary(replica)
def corrupt(self,path):
rv = False
p = []
for i in self.ports:
if path in self.data[self.ports[i]]:
p.append(i)
if len(p)>0:
s = np.random.randint(0,len(p))
s = p[s]
# randomly pick up a block
IDlist = self.data[self.ports[s]][path].keys()
ID = np.random.randint(0,len(IDlist))
ID = IDlist[ID]
# randomly pick up a byte
version = len(self.data[self.ports[s]][path][ID])-1
mes = self.data[self.ports[s]][path][ID][version]
byte = np.random.randint(0,len(mes)-1)
i = 1
while(mes[byte]==str(i)):
i = i+1
mes = mes[:byte] + str(i) + mes[byte+1:]
self.data[self.ports[s]][path][ID][version] = mes
rv = True
print('Information:')
print 'Corrupted file:', path
print 'Corrupted blks: ', ID
else:
print("Path is unfound.")
return rv
#CRC32 for checksum
def checksum(self,data):
crc = binascii.crc32(data) & 0xffffffff
return "{0:x}".format(crc).rjust(8,'0') # take it as a 8-byte string
def main():
if len(sys.argv) < 4:
print('usage: %s <indexed server number> <ports for all dataservers sperated by spaces>' % sys.argv[0])
exit(1)
sys.argv[1:] = map(int, sys.argv[1:]) # convert the arguments into integers
serve(*sys.argv)
def serve(*argv):
index = argv[1] # The first argument is the index of this dataserver.
port = argv[index+2] # The first port start from the index 2.
argv = argv[1:] # from index to all the data servers.
file_server = SimpleXMLRPCServer.SimpleXMLRPCServer(('localhost', port),allow_none=True)
file_server.register_introspection_functions()
sht = simpleHT(*argv)
file_server.register_function(sht.get)
file_server.register_function(sht.put)
file_server.register_function(sht.pop)
file_server.register_function(sht.getReplica)
file_server.register_function(sht.corrupt)
file_server.register_function(sht.keyRename)
try:
file_server.serve_forever()
except KeyboardInterrupt:
print 'server crashed manually..'
if __name__ == "__main__":
main()