def read_file_from_server(file_name, cache):
# 1 - Check the DS, see if the file exist; get file id and file server id, and version
response_from_directory_server = requests.get(
Sff.create_url(DIRECTORY_SERVER_DETAILS[0],
DIRECTORY_SERVER_DETAILS[1]),
params={'file_name': file_name},
json={'client_id': cache.client_id})
not_locked = response_from_directory_server.json()['lock']
file_server_id = response_from_directory_server.json()['file_server_id']
print not_locked
if not_locked and file_server_id is not None:
file_to_read = "Cache{}/".format(cache.client_id) + file_name + '.txt'
file_name += '.txt'
print 'file name client has requested {}'.format(file_name)
file_id, file_server_id, version, file_server_details = Sff.get_file_details_from_DS(
response_from_directory_server)
# update cache if (1) The file is not in the cache (2) the copy in the cache is out of date
if cache.get_key_to_file(
file_name) is None or version > cache.get_version_of_file(
file_name):
# getting file details
Sff.print_file_details(file_name, file_id, file_server_id, version)
# check and see if the file details are up to date - if they are ignore, else update cache
if file_server_details is not None and file_id is not None:
response_from_directory_server = requests.get(
Sff.create_url(file_server_details[0],
file_server_details[1]),
params={
'file_id': file_id,
'file_server_id': file_server_id
})
# update cache
print "Updating data in the cache..."
data = response_from_directory_server.json()['file_str']
print data
cache.update_data_in_cache(file_to_read, data)
if not os.path.exists(file_to_read):
print "ERROR: file {} does not exists in cache or on the server....\n Please enter a" \
" valid file name or create a new file...\n".format(file_name)
return
open_file = open(file_to_read, 'r')
dat = open_file.read()
open_file.close()
open_text_editor(file_to_read)
data_to_cache = open(file_to_read, 'r').read()
if dat is not data_to_cache: # if the data in the file is updated, update the data in the cache, else continue
print "adding data to the cache\nLocation {}".format(file_name)
cache.add_cache_entry(file_name,
cache.set_version_of_file(file_name),
data_to_cache)
else:
print "file is locked come back later..."
def write_file_to_server(file_name, cache):
file_name_ = file_name + '.txt'
key_in_cache = cache.get_key_to_file(file_name_)
is_file_in_cache = cache.get_cache_entry(file_name_)
if key_in_cache is not None and is_file_in_cache is not None:
# I have a file in the cache
response_from_directory_server = requests.get(
Sff.create_url(DIRECTORY_SERVER_DETAILS[0],
DIRECTORY_SERVER_DETAILS[1]),
params={'file_name': file_name},
json={'client_id': cache.client_id})
file_id, file_server_id, version, file_server_details = Sff.get_file_details_from_DS(
response_from_directory_server)
Sff.print_file_details(file_name, file_id, file_server_id, version)
# get details for the server my file is on
print "Trying to obtain a lock on file {} for client {}...".format(
file_name, cache.client_id)
# try to lock file on server
response_from_locking_server = requests.get(Sff.create_url(
DIRECTORY_SERVER_DETAILS[0], DIRECTORY_SERVER_DETAILS[1],
'lock_server'),
json={
'client_id':
cache.client_id,
'file_id':
file_id,
'file_server_id':
file_server_id
})
# if I can lock this file...
if response_from_locking_server.json()['lock']:
print "Lock has been received for client{} for file: {}".format(
cache.client_id, file_name)
file_to_read = "Cache{}/".format(cache.client_id) + file_name_
open_file = open(file_to_read, 'r')
dat = open_file.read()
open_file.close()
open_text_editor(file_to_read)
file_ = open(file_to_read, 'r')
data_to_send = file_.read()
file_.close()
if dat is not data_to_send: # if the data in the file is updated
# update the cache
cache.update_data_in_cache(file_name_, data_to_send)
# update the file on the server
requests.post(Sff.create_url(file_server_details[0],
file_server_details[1]),
json={
'file_id': file_id,
'data': data_to_send,
'server_id': file_server_id,
'file_name': file_name,
'version': str(datetime.datetime.now())
})
print "unlocking client{} from file .\n".format(
cache.client_id, file_id)
requests.delete(Sff.create_url(DIRECTORY_SERVER_DETAILS[0],
DIRECTORY_SERVER_DETAILS[1],
'lock_server'),
json={
'client_id': cache.client_id,
'file_id': file_id,
'file_server_id': file_server_id
})
print "File has been unlocked by locking server!"
elif not response_from_locking_server.json()['lock']:
print 'The file is locked by another client - Try again later...'
else:
print "Data is not in cache/stored locally! - To be able to write the file to a server, first read it and" \
" make changes"