from __future__ import annotations
import time
import numpy as np
test_claim_vector = [8, 5, 9, 7]
test_allocated_res_table = [
[2, 0, 1, 1],
[0, 1, 2, 1],
[4, 0, 0, 3],
[0, 2, 1, 0],
[1, 0, 3, 0],
]
test_maximum_claim_table = [
[3, 2, 1, 4],
[0, 2, 5, 2],
[5, 1, 0, 5],
[1, 5, 3, 0],
[3, 0, 3, 3],
]
class BankersAlgorithm:
def __init__(
self,
claim_vector: list[int],
allocated_resources_table: list[list[int]],
maximum_claim_table: list[list[int]],
) -> None:
""" :param claim_vector: A nxn/nxm list depicting the amount of each resources (eg. memory, interface, semaphores, etc.) available. :param allocated_resources_table: A nxn/nxm list depicting the amount of each resource each process is currently holding :param maximum_claim_table: A nxn/nxm list depicting how much of each resource the system currently has available """
self.__claim_vector = claim_vector
self.__allocated_resources_table = allocated_resources_table
self.__maximum_claim_table = maximum_claim_table
def __processes_resource_summation(self) -> list[int]:
""" Check for allocated resources in line with each resource in the claim vector """
return [
sum(p_item[i] for p_item in self.__allocated_resources_table)
for i in range(len(self.__allocated_resources_table[0]))
]
def __available_resources(self) -> list[int]:
""" Check for available resources in line with each resource in the claim vector """
return np.array(self.__claim_vector) - np.array(
self.__processes_resource_summation()
)
def __need(self) -> list[list[int]]:
""" Implement safety checker that calculates the needs by ensuring that max_claim[i][j] - alloc_table[i][j] <= avail[j] """
return [
list(np.array(self.__maximum_claim_table[i]) - np.array(allocated_resource))
for i, allocated_resource in enumerate(self.__allocated_resources_table)
]
def __need_index_manager(self) -> dict[int, list[int]]:
return {
self.__need().index(i): i for i in self.__need()}
def main(self, **kwargs) -> None:
need_list = self.__need()
alloc_resources_table = self.__allocated_resources_table
available_resources = self.__available_resources()
need_index_manager = self.__need_index_manager()
for kw, val in kwargs.items():
if kw and val is True:
self.__pretty_data()
print("_" * 50 + "\n")
while need_list:
safe = False
for each_need in need_list:
execution = True
for index, need in enumerate(each_need):
if need > available_resources[index]:
execution = False
break
if execution:
safe = True
# get the original index of the process from ind_ctrl db
for original_need_index, need_clone in need_index_manager.items():
if each_need == need_clone:
process_number = original_need_index
print(f"Process {
process_number + 1} is executing.")
# remove the process run from stack
need_list.remove(each_need)
# update available/freed resources stack
available_resources = np.array(available_resources) + np.array(
alloc_resources_table[process_number]
)
print(
"Updated available resource stack for processes: "
+ " ".join([str(x) for x in available_resources])
)
break
if safe:
print("The process is in a safe state.\n")
else:
print("System in unsafe state. Aborting...\n")
break
def __pretty_data(self):
""" Properly align display of the algorithm's solution """
print(" " * 9 + "Allocated Resource Table")
for item in self.__allocated_resources_table:
print(
f"P{
self.__allocated_resources_table.index(item) + 1}"
+ " ".join(f"{
it:>8}" for it in item)
+ "\n"
)
print(" " * 9 + "System Resource Table")
for item in self.__maximum_claim_table:
print(
f"P{
self.__maximum_claim_table.index(item) + 1}"
+ " ".join(f"{
it:>8}" for it in item)
+ "\n"
)
print(
"Current Usage by Active Processes: "
+ " ".join(str(x) for x in self.__claim_vector)
)
print(
"Initial Available Resources: "
+ " ".join(str(x) for x in self.__available_resources())
)
time.sleep(1)
if __name__ == "__main__":
import doctest
doctest.testmod()
