Mercurial > templog
annotate web/settings.py @ 586:87c20b8c5472 default master
port to python3
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Mon, 09 Sep 2019 22:24:10 +0800 |
| parents | 03e540c3ec24 |
| children |
| rev | line source |
|---|---|
| 586 | 1 import gevent.event |
| 253 | 2 import fcntl |
| 3 | |
|
258
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
4 import binascii |
|
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
5 import os |
|
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
6 |
| 253 | 7 class Settings(object): |
| 8 RAND_SIZE = 15 # 120 bits | |
| 9 | |
| 10 """ Handles state updates from both the web UI and from the fridge client. | |
| 11 The fridge client is canonical. It provides the epoch (apart from 'startepoch'), that | |
| 12 is changed any time the fridge reloads its local config. The fridge only accepts | |
| 13 updates that have the same epoch. | |
| 14 | |
| 15 When the web UI changes it keeps the same epoch but generates a new tag. The fridge sends | |
| 16 its current known tag and waits for it to change. | |
| 17 | |
| 18 content is opaque, presently a dictionary of decoded json | |
| 19 """ | |
| 20 | |
| 21 def __init__(self): | |
| 22 self.event = gevent.event.Event() | |
| 23 self.contents = None | |
| 24 self.epoch = None | |
| 25 self.tag = None | |
| 26 | |
|
258
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
27 self.update(None, 'startepoch') |
| 253 | 28 |
| 29 def wait(self, epoch_tag = None, timeout = None): | |
| 30 """ returns false if the timeout was hit """ | |
| 31 if self.epoch_tag() != epoch_tag: | |
| 32 # has alredy changed | |
| 33 return True | |
| 34 return self.event.wait(timeout) | |
| 35 | |
| 36 def epoch_tag(self): | |
| 37 return '%s-%s' % (self.epoch, self.tag) | |
| 38 | |
| 39 def random(self): | |
| 586 | 40 return os.urandom(self.RAND_SIZE).hex() |
| 253 | 41 |
| 42 def update(self, contents, epoch = None): | |
| 43 """ replaces settings contents and updates waiters if changed """ | |
| 44 if epoch: | |
| 45 if self.epoch == epoch: | |
| 46 return | |
| 47 else: | |
| 48 self.epoch = epoch | |
| 49 | |
| 50 self.tag = self.random() | |
| 51 self.contents = contents | |
| 52 | |
| 53 self.event.set() | |
| 54 self.event.clear() | |
| 55 | |
| 56 def get(self): | |
| 57 """ Returns (contents, epoch-tag) """ | |
| 58 return self.contents, self.epoch_tag() | |
| 59 | |
| 60 | |
| 61 | |
| 62 | |
| 63 |