I do ot how the code working ? would yu explain it ? from threading import Thread, Lock from datetime import datetime import time # 2 shared_resource = "" lock = Lock() # 1 modify_readers = Lock(); n_readers = 0; # 3 fifo_lock = Lock() def wait(): time.sleep(2) ###
I do ot how the code working ? would yu explain it ?
from threading import Thread, Lock
from datetime import datetime
import time
# 2
shared_resource = ""
lock = Lock()
# 1
modify_readers = Lock();
n_readers = 0;
# 3
fifo_lock = Lock()
def wait():
time.sleep(2)
###
def acquire_reader():
global n_readers, modify_readers, fifo_lock
fifo_lock.acquire()
modify_readers.acquire()
fifo_lock.release()
n_readers += 1;
if(n_readers == 1): lock.acquire()
modify_readers.release()
###
def release_reader():
global n_readers, modify_readers, fifo_lock
modify_readers.acquire()
n_readers -= 1;
if(n_readers == 0): lock.release()
modify_readers.release()
###
def write_normal():
while True:
global shared_resource, fifo_lock
fifo_lock.acquire()
lock.acquire()
fifo_lock.release()
print("Writing normal")
shared_resource = datetime.now()
lock.release()
wait()
###
def write_reverse():
while True:
global shared_resource, fifo_lock
fifo_lock.acquire()
lock.acquire()
fifo_lock.release()
print("Writing reverse")
shared_resource = str(datetime.now() )[::-1]
lock.release()
wait()
###
def read():
while True:
global shared_resource
acquire_reader();
#print("Reading")
print(shared_resource);
release_reader();
wait()
###
w1 = Thread(target=write_normal)
w2 = Thread(target=write_reverse)
r1 = Thread(target=read)
r2 = Thread(target=read)
r3 = Thread(target=read)
w1.start();
w2.start();
#print("Writers running.")
r1.start();
r2.start();
r3.start();
#print("Readers running.")
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