source: src/mlx/watchdog.py@ 919:2ce8ca39525b

python3
Last change on this file since 919:2ce8ca39525b was 919:2ce8ca39525b, checked in by István Váradi <ivaradi@…>, 4 years ago

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1# Watchdog
2
3#-----------------------------------------------------------------------------
4
5from threading import Thread, Lock
6
7import time
8
9#-----------------------------------------------------------------------------
10
11## @package mlx.watchdog
12#
13# Watchdog module. It implements a thread which wakes up regularly and checks
14# that none of its clients is left in a state for too long a time. If so, that
15# fact is logged.
16
17#-----------------------------------------------------------------------------
18
19class _ClientState(object):
20 """A client state.
21
22 It can be set or cleared. If set, there is a timeout associated with it. If
23 the timeout is over, the client state is logged. If it becomes clear later,
24 that fact is logged too."""
25 def __init__(self, timeout, name):
26 """Construct the client state with the given timeout and log text."""
27
28 self._lock = Lock()
29
30 self._timeout = timeout
31 self._name = name
32 self._nextTimeout = None
33 self._timedout = False
34
35 def set(self):
36 """Put the client into the set state."""
37 with self._lock:
38 if self._nextTimeout is None:
39 self._nextTimeout = time.time() + self._timeout
40
41 def clear(self):
42 """Put the client into the cleared state."""
43 with self._lock:
44 self._nextTimeout = None
45
46 def _check(self, t):
47 """Check the client state.
48
49 If it has timed out, and it has not been logged yet, it is logged. If
50 it is cleared, but had a timeout earlier, that fact is also logged."""
51 logTimeout = False
52 logCleared = False
53 with self._lock:
54 if self._nextTimeout is None:
55 logCleared = self._timedout
56 self._timedout = False
57 elif t>=self._nextTimeout:
58 logTimeout = not self._timedout
59 self._timedout = True
60
61 if logTimeout:
62 print("Watchdog client %s has timed out!" % (self._name))
63 elif logCleared:
64 print("Watchdog client %s has been cleared." % (self._name))
65
66#-----------------------------------------------------------------------------
67
68class Watchdog(Thread):
69 """The watchdog thread."""
70 _instance = None
71
72 WAKEUP_INTERVAL = 1.0
73
74 LOG_INTERVAL = 60.0
75
76 @staticmethod
77 def get():
78 """Get the only instance of the watchdog."""
79 return Watchdog._instance
80
81 def __init__(self):
82 """Construct the watchdog."""
83 assert self._instance is None
84
85 super(Watchdog, self).__init__()
86 self.daemon = True
87
88 self._lock = Lock()
89 self._clients = []
90
91 Watchdog._instance = self
92
93 def addClient(self, timeout, name):
94 """Add a client with the given timeout and name.
95
96 The new client is returned."""
97 client = _ClientState(timeout, name)
98 with self._lock:
99 self._clients.append(client)
100 return client
101
102 def run(self):
103 """Perform the client checks, then wait for WAKEUP_INTERVAL.
104
105 If LOG_INTERVAL elapses, put an entry in the debug log to confirm that
106 the watchdog still works."""
107
108 nextLogTime = time.time()
109 nextWakeupTime = nextLogTime + self.WAKEUP_INTERVAL
110
111 while True:
112 t = time.time()
113 while t>=nextWakeupTime:
114 nextWakeupTime += self.WAKEUP_INTERVAL
115
116 if t>=nextLogTime:
117 print("Watchdog.run: running")
118 while t>=nextLogTime:
119 nextLogTime += self.LOG_INTERVAL
120
121 self._checkClients(t)
122
123 t = time.time()
124 if t<nextWakeupTime:
125 time.sleep(nextWakeupTime - t)
126
127 def _checkClients(self, t):
128 """Check the clients."""
129 with self._lock:
130 clients = self._clients[:]
131
132 for client in clients:
133 client._check(t)
134
135#-----------------------------------------------------------------------------
136#-----------------------------------------------------------------------------
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