class Paging:
def __init__(self, memory, instructions_per_frame, hdd):
self._memory = memory
self._instructions_per_frame = instructions_per_frame
self._frames = []
self._frame_manager = FrameManager(self._frames, hdd)
self._page_creator = PageCreator(instructions_per_frame)
self.generate_frames()
def assign_to_hdd(self, hdd, pcb):
self._page_creator.create(pcb, self._instructions_per_frame)
def memory_size(self):
return self._memory.size()
def get_amount_of_frames(self):
return len(self._frames)
def __can_create(self):
return self.memory_size() % self._instructions_per_frame == 0
def get_frame_for_current_instruction(self, pcb):
self._frame_manager.get_frames_of_pcb(pcb)
def generate_frames(self):
if self.__can_create():
self.__create_frames()
def __create_frames(self):
index = 0
print("Creating frames...")
for split in range(0, self.memory_size(), self._instructions_per_frame):
self._frames.append(Frame(index, split, split + self._instructions_per_frame - 1))
index += 1
def assign_to_memory(self, pcb):
if pcb.get_memory_policy_for_pcb().has_no_data():
self._page_creator.create(pcb, self._instructions_per_frame)
policy_result = self.pages_for_pcb(pcb)
return policy_result
def pages_for_pcb(self, pcb):
return self._frame_manager.map_page_to_frame(pcb)
def can_serve(self, pcb):
return self.get_amount_of_free_frames() >= self.frames_per_pcb(pcb)
def frames_per_pcb(self, pcb):
return pcb.get_amount_of_instructions() / self._page_creator.get_instructions_per_frame()
def get_amount_of_free_frames(self):
return len(FunctionsForLists.filterList(lambda f: not f.is_in_use(), self._frames))
def set_memory_manager(self, memory_manager):
self._memory_manager = memory_manager
def get_info_holder(self, program):
return PageHolder(program)
class FrameManagerTest(unittest.TestCase):
# Arrange
def setUp(self):
program = Program('Excel')
pageHolder = PageHolder(program)
self.frame1 = Frame(0, 9, -1)
self.frame2 = Frame(1, 9, -1)
self.frame3 = Frame(2, 9, -1)
self.frame4 = Frame(3, 9, -1)
self.frames = [self.frame1, self.frame2, self.frame3, self.frame4]
self.hdd = HDD(50)
self.frame_manager = FrameManager(self.frames, self.hdd)
self.page_creator = PageCreator()
self.pcb = PCB(0, 30, pageHolder)
self.page_creator.create(self.pcb, 5)
def test_whenIAssignAPCBTheFirstTime_ThenFrameManagerUsesTheFirstFrame(self):
# Pages
first_frame = self.frame_manager.get_frames()[0]
self.frame_manager.map_page_to_frame(self.pcb)
first_pcb_page = self.pcb.get_page_assigned_by_number(0)
self.assertEquals(first_frame.get_page(), first_pcb_page)
def test_whenTheFirstPCBPageIsUsedAndPCBIsAssigned_ThenFrameManagerUsesTheSecondFrame(self):
# Pages
first_pcb_page = self.pcb.get_page_assigned_by_number(0)
second_pcb_page =self.pcb.get_page_assigned_by_number(1)
self.frame_manager.map_page_to_frame(self.pcb)
first_pcb_page.set_used()
self.frame_manager.map_page_to_frame(self.pcb)
second_frame = self.frame_manager.get_frames()[1]
self.assertEquals(second_frame.get_page(), second_pcb_page)
def test_whenAllFramesAreUsedAndPCBAssignsOneMorePage_ThenTheYoungestFrameGetsEmpty(self):
# Pages
first_pcb_page = self.pcb.get_page_assigned_by_number(0)
second_pcb_page = self.pcb.get_page_assigned_by_number(1)
assert (second_pcb_page != None)
third_pcb_page = self.pcb.get_page_assigned_by_number(2)
forth_pcb_page = self.pcb.get_page_assigned_by_number(3)
fifth_pcb_page = self.pcb.get_page_assigned_by_number(4)
self.frame_manager.map_page_to_frame(self.pcb)
first_pcb_page.set_used()
self.frame_manager.map_page_to_frame(self.pcb)
second_pcb_page.set_used()
self.frame_manager.map_page_to_frame(self.pcb)
third_pcb_page.set_used()
self.frame_manager.map_page_to_frame(self.pcb)
forth_pcb_page.set_used()
forth_frame = self.frame_manager.get_frames()[3]
self.frame_manager.map_page_to_frame(self.pcb)
self.assertEqual(forth_frame.get_page(), fifth_pcb_page)