from mosaic import *
OS2023(9)

slideshow('9.1')

demo('pc-mutex', 'c/pc-mutex.c', libs=['thread.h', 'thread-sync.h'])

slideshow('9.2')

demo('pc-cv', 'c/pc-cv.c', libs=['thread.h', 'thread-sync.h'])

model('m/cv-if.py', check=True)

 1N, Tp, Tc = 1, 2, 2
 2
 3def Tproduce(nm):
 4  while heap.mutex != 'Yes':
 5    sys_sched()
 6  heap.mutex = 'No'
 7  sys_sched()
 8  
 9  if not (heap.count < N):
10    heap.blocked.append(nm)
11    heap.mutex = 'Yes'
12    sys_sched()
13    while nm in heap.blocked:
14      sys_sched()
15    while heap.mutex != 'Yes':
16      sys_sched()
17    heap.mutex = 'No'
18    sys_sched()
19
20  heap.count += 1
21  sys_sched()
22  sys_write('(')
23  sys_sched()
24
25  if heap.blocked:
26    r = sys_choose([i for i, _ in enumerate(heap.blocked)])
27    heap.blocked.pop(r)
28
29  heap.mutex = 'Yes'
30
31def Tconsume(nm):
32  while heap.mutex != 'Yes':
33    sys_sched()
34  heap.mutex = 'No'
35  sys_sched()
36  
37  if not (heap.count > 0):
38    heap.blocked.append(nm)
39    heap.mutex = 'Yes'
40    sys_sched()
41    while nm in heap.blocked:
42      sys_sched()
43    while heap.mutex != 'Yes':
44      sys_sched()
45    heap.mutex = 'No'
46    sys_sched()
47
48  heap.count -= 1
49  sys_sched()
50  sys_write(')')
51  sys_sched()
52
53  if heap.blocked:
54    r = sys_choose([i for i, _ in enumerate(heap.blocked)])
55    heap.blocked.pop(r)
56
57  heap.mutex = 'Yes'
58
59def main():
60  heap.count = 0
61  heap.mutex = 'Yes'
62  heap.blocked = []
63
64  for i in range(Tp):
65    sys_spawn(Tproduce, f'Tp{i+1}')
66  for i in range(Tc):
67    sys_spawn(Tconsume, f'Tc{i+1}')
68
69# Outputs:
70# ()()
71# ())(

demo('pc-cv-while', 'c/pc-cv-while.c', libs=['thread.h', 'thread-sync.h'])

model('m/cv-broadcast.py', check=True)

 1N, Tp, Tc = 2, 2, 2
 2
 3def Tproduce(nm):
 4  while heap.mutex != 'Yes':
 5    sys_sched()
 6  heap.mutex = 'No'
 7  sys_sched()
 8  
 9  while not (heap.count < N):
10    heap.blocked.append(nm)
11    heap.mutex = 'Yes'
12    sys_sched()
13    while nm in heap.blocked:
14      sys_sched()
15    while heap.mutex != 'Yes':
16      sys_sched()
17    heap.mutex = 'No'
18    sys_sched()
19
20  heap.count += 1
21  sys_sched()
22  sys_write('(')
23  sys_sched()
24  heap.blocked = []
25  sys_sched()
26  heap.mutex = 'Yes'
27
28def Tconsume(nm):
29  while heap.mutex != 'Yes':
30    sys_sched()
31  heap.mutex = 'No'
32  sys_sched()
33  
34  while not (heap.count > 0):
35    heap.blocked.append(nm)
36    heap.mutex = 'Yes'
37    sys_sched()
38    while nm in heap.blocked:
39      sys_sched()
40    while heap.mutex != 'Yes':
41      sys_sched()
42    heap.mutex = 'No'
43    sys_sched()
44
45  heap.count -= 1
46  sys_sched()
47  sys_write(')')
48  sys_sched()
49  heap.blocked = []
50  sys_sched()
51  heap.mutex = 'Yes'
52
53def main():
54  heap.count = 0
55  heap.mutex = 'Yes'
56  heap.blocked = []
57
58  for i in range(Tp):
59    sys_spawn(Tproduce, f'Tp{i+1}')
60  for i in range(Tc):
61    sys_spawn(Tconsume, f'Tc{i+1}')
62
63# Outputs:
64# (())
65# ()()

slideshow('9.3')

demo('fish', 'c/fish.c', libs=['thread.h', 'thread-sync.h'])

WAIT_UNTIL(cond) with (mutex) {
  // cond 在此时成立
  work();
}

9. 并发控制：同步 (1)¶

Take-away Messages¶

课后习题/编程作业¶

1. 阅读材料¶

2. 编程实践¶

3. 实验作业¶