class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
#
# Your code here.
#
try:
self.rwlock.read_acquire()
return self.db.read()
finally:
self.rwlock.read_release()
# end my code
def write(self, fortune):
#
# Your code here.
#
try:
self.rwlock.write_acquire()
self.db.write(fortune)
finally:
self.rwlock.write_release()
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
#
# Your code here.
#
self.rwlock.read_acquire()
result = self.db.read()
self.rwlock.read_release()
return result
pass
def write(self, fortune):
#
# Your code here.
#
self.rwlock.write_acquire()
result = self.db.write(fortune)
self.rwlock.write_release()
return result
pass
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
# Acquire read lock before accessing critical data.
self.rwlock.read_acquire()
tmp = self.db.read()
# Release lock when finished with critical data.
self.rwlock.read_release()
return tmp
def write(self, fortune):
# Acquire write lock before accessing critical data.
self.rwlock.write_acquire()
self.db.write(fortune)
# Release lock when finished with critical data.
self.rwlock.write_release()
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
#
# Your code here.
#
self.rwlock.read_acquire()
result = self.db.read()
self.rwlock.read_release()
print(" \n Read to Database called! \n")
return result
pass
def write(self, fortune):
#
# Your code here.
#
print("WRITE GOT CALLED")
self.rwlock.write_acquire()
to_write = '\n'+fortune+'\n%'
result = self.db.write(to_write)
self.rwlock.write_release()
return "wrote:" + fortune
pass
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
""" Reading the database and utilizing the read-lock
:return result (read fortune from the database) """
self.rwlock.read_acquire()
try:
result = self.db.read()
finally:
self.rwlock.read_release()
return result
def write(self, fortune):
""" Writing to the database and utilizing the write-lock
:return result) """
self.rwlock.write_acquire()
try:
self.db.write(fortune[0])
finally:
self.rwlock.write_release()
return
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
# These act as wrappers for processes in the underlying database
def read(self):
#print("Server trying to read")
s=self.db.read();
#print("Server has read fortune:"+s)
return(s)
def write(self, fortune):
# We return the result of self.db.write even though this function has no return statement.
# This provides extensibility, since future versions may return some information such as a status code.
#print("trying to write fortune:" + fortune)
self.db.write(fortune)
#print("Server thinks it worked")
return("Successfully wrote fortune \""+fortune+"\" to database")
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
self.rwlock.read_acquire()
try:
result, status = self.db.read(), "success"
except:
result, status = Exception, "fail"
finally:
self.rwlock.read_release()
return result, status
def write(self, fortune):
self.rwlock.write_acquire()
try:
self.db.write(fortune)
result = "success"
except:
result = Exception
finally:
self.rwlock.write_release()
return result
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
#
return self.db.read()
#
def write(self, fortune):
#
self.db.write(fortune)
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
#
# Your code here.
#
# Remember the rule:
# 1. Open the lock
# 2. Perform action
# 3. Close the lock
# We do this so that if after opening the lock,
# the database can crash while performing the action
# So even if that happens, the lock should always be placed at the end
# Hence the 'finally'
try:
self.rwlock.read_acquire()
fortune = self.db.read()
finally:
self.rwlock.read_release()
return fortune
def write(self, fortune):
#
# Your code here.
#
# Remember the rule:
# 1. Open the lock
# 2. Perform action
# 3. Close the lock
# We do this so that if after opening the lock,
# the database can crash while performing the action
# So even if that happens, the lock should always be placed at the end
# Hence the 'finally'
try:
self.rwlock.write_acquire()
self.db.write(fortune)
finally:
self.rwlock.write_release()
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
def read(self):
#
# Your code here.
#
# Acquire the lock before reading, in order to
# prevent any writing operations during read.
self.rwlock.read_acquire()
try:
result = self.db.read()
finally:
# Release lock and return result when we are done.
self.rwlock.read_release()
return result
def write(self, fortune):
#
# Your code here
#
# Acquire the lock when writing, in order for no
# reading or writing from other threads to perform
# any operations during this write. Lock is released
# afterwards, and default value "NULL" is returned to
# indicate that everything went as it should.
self.rwlock.write_acquire()
try:
self.db.write(fortune)
finally:
self.rwlock.write_release()
return "NULL"
class Server(object):
"""Class that provides synchronous access to the database."""
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
# Public methods
# These act as wrappers for processes in the underlying database
def read(self):
#print("Server trying to read")
s = self.db.read()
#print("Server has read fortune:"+s)
return (s)
def write(self, fortune):
# We return the result of self.db.write even though this function has no return statement.
# This provides extensibility, since future versions may return some information such as a status code.
#print("trying to write fortune:" + fortune)
self.db.write(fortune)
#print("Server thinks it worked")
return ("Successfully wrote fortune \"" + fortune + "\" to database")
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
def __init__(self, db_file):
self.db = Database(db_file)
self.rwlock = ReadWriteLock()
dest="fortune",
help="Write a new fortune to the database.")
parser.add_argument("-i",
"--interactive",
action="store_true",
dest="interactive",
default=False,
help="Interactive session with the fortune database.")
opts = parser.parse_args()
# -----------------------------------------------------------------------------
# The main program
# -----------------------------------------------------------------------------
# Create the database object
db = Database("dbs/fortune.db")
if not opts.interactive:
# Run in the normal mode
if opts.fortune is not None:
db.write(opts.fortune)
else:
print(db.read())
else:
# Run in the interactive mode
def menu():
print("""\
Choose one of the following commands:
r :: read a random fortune from the database,
w <FORTUNE> :: write a new fortune into the database,
Client for a fortune database. It reads a random fortune from the database.
"""
arg_parser = OptionParser(description = description)
arg_parser.add_option("-w", "--write", metavar = "FORTUNE", dest = "fortune",
help = "Write a new fortune to the database.")
arg_parser.add_option("-i", "--interactive",
action = "store_true", dest = "interactive", default = False,
help = "Interactive session with the fortune database.")
opts, args = arg_parser.parse_args()
# ------------------------------------------------------------------------------
# The main program
# ------------------------------------------------------------------------------
# Create the database object
db = Database("dbs/fortune.db")
if not opts.interactive:
# Run in the normal mode
if opts.fortune is not None:
db.write(opts.fortune)
else:
print db.read()
else:
# Run in the interactive mode
def menu():
print (
"Choose one of the following commands:\n"
" r :: read a random fortune from the database,\n"
" w <FORTUNE> :: write a new fortune into the database,\n"
