class LockServer:
def _lock_handler(self, conn, host, port, f):
status = self._lock_list.check_file(f)
if status is None:
self._lock_list.add(f, host, port)
conn.send(Response.OK)
elif status[0] == host and status[1] == port:
conn.send(Response.OK)
else:
conn.send(Response.LOCK_TAKEN)
def _unlock_handler(self, conn, host, port, f):
status = self._lock_list.check_file(f)
if status is None:
conn.send(Response.LOCK_FREE)
elif status[0] == host and status[1] == port:
self._lock_list.remove(f, host, port)
conn.send(Response.OK)
else:
conn.send(Response.LOCK_TAKEN)
def _request_handler(self, conn):
try:
# no initial request can be longer than 8096 bytes
data = conn.recv(8096)
input = data.split(" ")
# invoke respective handlers for the input command
if input[0] == "LOCK":
self._lock_handler(conn, input[1], input[2], input[3])
print "Received LOCK from "+input[1]+":"+input[2]+" for: "+input[3]
elif input[0] == "UNLOCK":
self._unlock_handler(conn, input[1], input[2], input[3])
else:
conn.send("INVALID_COMMAND")
conn.close()
except Exception as e:
exc_type, exc_obj, exc_tb = sys.exc_info()
fname = os.path.split(exc_tb.tb_frame.f_code.co_filename)[1]
print exc_type.__name__ + " " + fname + ":" + str(exc_tb.tb_lineno) + " " + str(e)
conn.send(Response.ERROR)
conn.close()
def __init__(self, port):
self._port = port
self._server = TCPServer(self._port, 10, self._request_handler)
self._lock_list = LockList()
self._server.start()
class ReplicationManager:
def _advertise_handler(self, conn, host, port):
location = Location(host, port)
self._replication_controller.add(location)
conn.send(Response.OK)
def _lookup_handler(self, conn, host, port):
location = Location(host, port)
set = self._replication_controller.lookup(location)
for i in range(0, len(set)):
if set[i].compare(location):
del set[i] # don't include the requesting node in the response, it already knows it's in the set
break
str_set = "" # a string representation of the response set
for item in set:
# convert each item in the response set to the string representation (easier to parse for the client)
str_set += item.get_string() + " "
conn.send(Response.OK + " " + str_set.rstrip(" "))
def _request_handler(self, conn):
try:
# no initial request can be longer than 8096 bytes
data = conn.recv(8096)
input = data.split(" ")
# invoke respective handlers for the input command
if input[0] == "ADVERTISE":
self._advertise_handler(conn, input[1], input[2])
print "Received ADVERTISE from "+input[1]+":"+input[2]
elif input[0] == "LOOKUP":
self._lookup_handler(conn, input[1], input[2])
else:
conn.send("INVALID_COMMAND")
conn.close()
except Exception as e:
print str(e)
conn.send(Response.ERROR)
conn.close()
def __init__(self, port):
self._port = port
self._server = TCPServer(self._port, 10, self._request_handler)
self._server.start()
self._replication_controller = ReplicationController()
class Node(object):
# convert a fully qualified path to a relative path
def _relative_path(self, base, path):
_base = base.strip('/')
_path = path.strip('/')
if _path.startswith(_base):
_path = _path[len(_base):]
return _path.strip('/')
# GET downloads a file to the client
def _get_handler(self, conn, input):
filename = self._dir + input
if not os.path.isfile(filename):
conn.send(Response.NO_EXIST)
else:
f = open(filename, "rb")
conn.send_file(f)
f.close()
conn.shutdown(socket.SHUT_WR)
conn.close()
# XPUT uploads a file (either adding a new file or overwriting an existing one) WITHOUT forwarding it to the
# replication set. this is used to stop PUT messages circling through the network forever
def _xput_handler(self, conn, input):
filepath = os.path.dirname(input)
if not os.path.isdir(self._dir + filepath):
conn.send(Response.NO_EXIST)
return False
conn.send(Response.OK)
# check if the file existed or not before overwriting
exists = os.path.isfile(self._dir + input)
f = open(self._dir + input, "wb")
conn.recv_file(f)
f.close()
conn.send(Response.OK)
if not exists:
self._advertise_buffer.add(input, ObjectBuffer.Type.file)
return True
# PUT uploads a file (either adding a new file or overwriting an existing one)
def _put_handler(self, conn, input):
# perform the usual replication-less xput first
success = self._xput_handler(conn, input)
# now add this put operation to the replication buffer if it was a successful xput (ie the client didn't try
# to put a file to an invalid directory)
if success:
self._replication_buffer.add(input, ObjectBuffer.Type.file)
# XMKDIR creates a directory in the node WITHOUT forwarding it to the replication set
def _xmkdir_handler(self, conn, input):
newdir = str(self._dir + input.strip('/'))
basedir = os.path.dirname(newdir)
if not os.path.isdir(basedir):
conn.send(Response.NO_EXIST)
return False
else:
try:
os.makedirs(newdir)
conn.send(Response.OK)
self._advertise_buffer.add(input.strip('/'), ObjectBuffer.Type.directory)
return True
except Exception as e:
if e.errno != errno.EEXIST:
raise
else:
conn.send(Response.EXISTS)
return False
# MKDIR creates a directory in the node
def _mkdir_handler(self, conn, input):
success = self._xmkdir_handler(conn, input)
if success:
self._replication_buffer.add(input.strip('/'), ObjectBuffer.Type.directory)
# XDELETE deletes a file or directory *recursively* in the node WITHOUT forwarding it to the replication set
def _xdelete_handler(self, conn, input):
object = str(self._dir + input).rstrip('/')
if os.path.isdir(object):
shutil.rmtree(object)
conn.send(Response.OK)
self._advertise_buffer.add(input, ObjectBuffer.Type.deleteDirectory)
elif os.path.isfile(object):
os.remove(object)
conn.send(Response.OK)
self._advertise_buffer.add(input, ObjectBuffer.Type.deleteFile)
else:
conn.send(Response.NO_EXIST)
return False
return True
#DELETE deletes a file or directory recursively
def _delete_handler(self, conn, input):
success = self._xdelete_handler(conn, input)
if success:
isfile = os.path.isfile(self._dir + input)
repl_type = ObjectBuffer.Type.deleteFile if isfile else ObjectBuffer.Type.deleteDirectory
self._replication_buffer.add(input, repl_type)
# called whenever the server receives data
def _request_handler(self, conn):
try:
# no initial request can be longer than 8096 bytes
data = conn.recv(8096)
input = data.split()
# invoke respective handlers for the input command
if input[0] == "GET":
self._get_handler(conn, input[1])
elif input[0] == "XPUT":
self._xput_handler(conn, input[1])
elif input[0] == "PUT":
self._put_handler(conn, input[1])
elif input[0] == "XMKDIR":
self._xmkdir_handler(conn, input[1])
elif input[0] == "MKDIR":
self._mkdir_handler(conn, input[1])
elif input[0] == "XDELETE":
self._xdelete_handler(conn, input[1])
elif input[0] == "DELETE":
self._delete_handler(conn, input[1])
else:
conn.send(Response.INVALID_COMMAND)
conn.close()
except Exception as e:
conn.send(Response.ERROR + " " + str(e))
conn.close()
def _init_advertise(self, server, host, port, adv_host, adv_port):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
s.connect((adv_host, adv_port))
except Exception as e:
if e.errno == errno.ECONNREFUSED:
print "*!* ERROR: Unable to connect to " + server + "!"
print "*!* Node and " + server + " are *NOT* in sync!"
else:
print e
return None
s.send("ADVERTISE "+host+" "+str(port))
data = s.recv(1024)
if data != Response.OK:
print "Received unusual response from " + server + ": " + data + ". Attempting to continue anyway."
return s
# advertise *all* files in the Nodes filesystem to the DirectoryServer
def _directory_server_advertisement(self, host, port, ds_host, ds_port):
print "Advertising to Directory Server..."
s = self._init_advertise("Directory Server", host, port, ds_host, ds_port)
if s is None:
return
# repeatedly send advertisement messages of the structure of the server filesystem
for (dirpath, dirnames, filenames) in os.walk(self._dir):
advertisement = Advertisement(self._relative_path(self._dir, dirpath), dirnames, filenames)
s.send(advertisement.to_json())
data = s.recv(1024)
if data != Response.OK:
print "Received unusual response from Directory Server: "+data+". Attempting to continue anyway."
s.close()
print "Advertisement complete: Node and Directory Server in sync."
# advertise this Node to the replication manager, letting it know that this Node exists
def _replication_manager_advertisement(self, host, port, rm_host, rm_port):
print "Advertising to Replication Manager..."
s = self._init_advertise("Replication Manager", host, port, rm_host, rm_port)
if s is None:
return
s.close()
print "Advertisement complete: Node and Replication Manager in sync."
# perform a full advertise to the Directory Server and Replication Manager. this is done at startup
def _full_advertise(self, host, port, ds_host, ds_port, rm_host, rm_port):
self._directory_server_advertisement(host, port, ds_host, ds_port)
self._replication_manager_advertisement(host, port, rm_host, rm_port)
# this manages batch updates of advertisements to the directory server. it runs in its own thread, and will sleep
# on a condition variable until data becomes available in the buffer to send to the directory server
def _incremental_advertise(self, host, port, ds_host, ds_port):
while True:
# sleep on condition variable
while self._advertise_buffer.is_empty():
self._advertise_cv.acquire()
self._advertise_cv.wait()
self._advertise_cv.release()
time.sleep(Interval.ADVERTISE)
# if the pc reaches here, this thread has been woken to send an incremental advertise and clear the buffer
s = self._init_advertise("Directory Server", host, port, ds_host, ds_port)
if s is None:
return
self._advertise_cv.acquire()
messages = self._advertise_buffer.get_all()
for message in messages:
s.send(message.to_json())
data = s.recv(1024)
if data != Response.OK:
print "Received unusual response from Directory Server: "+data+". Attempting to continue anyway."
self._advertise_buffer.clear()
self._advertise_cv.release()
s.close()
print "Advertisement complete: Node and Directory Server in sync."
# find out which other Nodes are in the same replication set as this Node
def _get_replication_set(self, host, port, rm_host, rm_port):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
s.connect((rm_host, rm_port))
except Exception as e:
if e.errno == errno.ECONNREFUSED:
print "*!* ERROR: Unable to connect to ReplicationManager!"
print "*!* Node and ReplicationManager are *NOT* in sync!"
else:
print e
return None
s.send("LOOKUP "+host+" "+str(port))
data = s.recv(1024)
s.close()
if len(data):
arr = data.split(" ")[1:] # remove the first element ("OK"), the rest of the elements are the replicants
locations = []
for item in arr:
parts = item.split(":")
loc = Location(parts[0], parts[1])
locations.append(loc)
return locations
return None
# incrementally send batch updates to each Node in the replication set, *peer to peer*
def _replication_manager_update(self, host, port, rm_host, rm_port):
while True:
# sleep on condition variable
while self._replication_buffer.is_empty():
self._replication_cv.acquire()
self._replication_cv.wait()
self._replication_cv.release()
time.sleep(Interval.ADVERTISE)
self._replication_cv.acquire()
# flush the buffer and then release the lock so request handler threads waiting on the lock can continue
adv_list = self._replication_buffer.get_all()
self._replication_buffer.clear()
self._replication_cv.release()
# get the replication set
set = self._get_replication_set(host, port, rm_host, rm_port)
if set is None:
continue
for loc in set:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((loc.host, int(loc.port)))
conn = ConnectionHelper(s)
for item in adv_list:
for dir in item.dirnames:
s.send("XMKDIR "+dir)
data = s.recv(1024)
if data != Response.OK:
print "Received unusual response from replication peer "+loc.host+":"+loc.port
for file in item.filenames:
s.send("XPUT "+file)
data = s.recv(1024)
if data != Response.OK:
print "Received unusual response from replication peer "+loc.host+":"+loc.port
continue # abort XPUT operation
f = open(self._dir + item.dirpath + "/" + file, "rb")
conn.send_file(f)
for i in item.deletelist:
s.send("XDELETE "+i)
data = s.recv(1024)
if data != Response.OK:
print "Received unusual response from replication peer "+loc.host+":"+loc.port
conn.close()
def __init__(self, dir, host, port, ds_host, ds_port, rm_host, rm_port):
self._dir = dir
# append a slash to the end of the home directory if it's not passed in
if self._dir[len(self._dir)-1] != '/':
self._dir += '/'
# initialise the condition variable and buffer for the incremental advertise thread
self._advertise_cv = threading.Condition()
self._advertise_buffer = ObjectBuffer(self._advertise_cv)
# initialise the condition variable and buffer for the replication forwarder
self._replication_cv = threading.Condition()
self._replication_buffer = ObjectBuffer(self._replication_cv)
# do an initial full advertisement (to the directory server and replication manager) before the threadpool init
self._full_advertise(host, port, ds_host, ds_port, rm_host, rm_port)
# now initialise the node's listening threadpool with 10 threads
self._server = TCPServer(port, 10, self._request_handler)
t = threading.Thread(target=self._incremental_advertise, args=(host, port, ds_host, ds_port,))
t.daemon = True
t.start()
t = threading.Thread(target=self._replication_manager_update, args=(host, port, rm_host, rm_port,))
t.daemon = True
t.start()
self._server.start()
print "Node server started successfully."
class DirectoryServer:
# keeps directory location names consistent throughout the directory structure
def _sanitise_location(self, loc):
if not loc.startswith('/'):
loc = '/' + loc
return loc.rstrip('/')
# respond to advertisements, which are updates from Nodes. Nodes send these updates when their filesystems have
# changed
def _advertise_handler(self, conn, host, port):
conn.send(Response.OK)
data = conn.recv(8096)
while data:
data = json.loads(data)
self._tree.add(host, port, data["dirnames"], data["filenames"], data["dirpath"], data["deletelist"])
conn.send(Response.OK)
data = conn.recv(8096)
# respond to a request from a client to get the location of a file. it will try to respond with a random location
# (if the file is stored in multiple Nodes) to try to balance load between Nodes.
def _get_handler(self, conn, location):
node = self._tree.find(location)
if node is None:
conn.send(Response.NO_EXIST)
elif isinstance(node, DT.Directory):
conn.send(Response.IS_DIRECTORY)
else:
conn.send(Response.OK + " " + node.random_loc()+" "+location)
# respond to a request from a client who wants to upload a new file. the DirectoryServer will choose a server for
# the client to upload the file to.
def _put_handler(self, conn, location):
location = self._sanitise_location(location)
parent = os.path.dirname(location)
pnode = self._tree.find(parent)
if pnode is None:
conn.send(Response.ERROR)
return
child = self._tree.find(location)
if child is None:
# pick the server with the least amount of objects in the hierarchy
loc = pnode.hlocs[len(pnode.hlocs)-1]
conn.send(Response.OK + " " + loc.get_string())
return
# pick a random (existing) child location
conn.send(Response.OK + " " + child.random_loc())
# respond to a request from a client who wants to create a new directory. the DirectoryServer will choose a server
# for the client to create the new directory in.
def _mkdir_handler(self, conn, location):
location = self._sanitise_location(location)
parent = os.path.dirname(location)
child = location[len(parent)-1:].strip('/')
pnode = self._tree.find(parent)
if pnode is None:
conn.send(Response.ERROR)
return
if pnode.get_child(child) is not None:
conn.send(Response.EXISTS)
return
# pick the server with the least amount of objects in the hierarchy
loc = pnode.hlocs[len(pnode.hlocs)-1]
conn.send(Response.OK + " " + loc.get_string())
# respond to a client request to list all items in a current location. similar to 'ls' in linux.
def _list_handler(self, conn, location):
node = self._tree.find(location)
if node is None:
conn.send(Response.NO_EXIST)
elif not isinstance(node, DT.Directory):
conn.send(Response.CANT_LIST)
else:
children = []
for child in node.children:
children.append(child.name)
conn.send(str(children))
def _request_handler(self, conn):
try:
# no initial request can be longer than 8096 bytes
data = conn.recv(8096)
input = data.split(" ")
# invoke respective handlers for the input command
if input[0] == "ADVERTISE":
self._advertise_handler(conn, input[1], input[2])
print "Received ADVERTISE from "+input[1]+":"+input[2]
elif input[0] == "GET":
self._get_handler(conn, input[1])
elif input[0] == "PUT":
self._put_handler(conn, input[1])
elif input[0] == "MKDIR":
self._mkdir_handler(conn, input[1])
elif input[0] == "LIST":
self._list_handler(conn, input[1])
elif input[0] == "PRINT":
self._tree.pretty_print(input[1])
else:
conn.send("INVALID_COMMAND")
conn.close()
except Exception as e:
exc_type, exc_obj, exc_tb = sys.exc_info()
fname = os.path.split(exc_tb.tb_frame.f_code.co_filename)[1]
print exc_type.__name__ + " " + fname + ":" + str(exc_tb.tb_lineno) + " " + str(e)
conn.send(Response.ERROR)
conn.close()
def __init__(self, port):
self._port = port
self._server = TCPServer(self._port, 10, self._request_handler)
self._tree = DT.DirectoryTree()
self._server.start()