Mercurial > templog
annotate web/settings.py @ 284:8ea6c90774e3
add dependencies
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Wed, 23 Mar 2016 21:34:44 +0800 |
| parents | 03e540c3ec24 |
| children | 87c20b8c5472 |
| rev | line source |
|---|---|
| 253 | 1 import gevent |
| 2 import fcntl | |
| 3 import hashlib | |
| 4 | |
|
258
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
5 import binascii |
|
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
6 import os |
|
03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
7 |
| 253 | 8 class Settings(object): |
| 9 RAND_SIZE = 15 # 120 bits | |
| 10 | |
| 11 """ Handles state updates from both the web UI and from the fridge client. | |
| 12 The fridge client is canonical. It provides the epoch (apart from 'startepoch'), that | |
| 13 is changed any time the fridge reloads its local config. The fridge only accepts | |
| 14 updates that have the same epoch. | |
| 15 | |
| 16 When the web UI changes it keeps the same epoch but generates a new tag. The fridge sends | |
| 17 its current known tag and waits for it to change. | |
| 18 | |
| 19 content is opaque, presently a dictionary of decoded json | |
| 20 """ | |
| 21 | |
| 22 def __init__(self): | |
| 23 self.event = gevent.event.Event() | |
| 24 self.contents = None | |
| 25 self.epoch = None | |
| 26 self.tag = None | |
| 27 | |
|
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03e540c3ec24
fix server side long polling
Matt Johnston <matt@ucc.asn.au>
parents:
253
diff
changeset
|
28 self.update(None, 'startepoch') |
| 253 | 29 |
| 30 def wait(self, epoch_tag = None, timeout = None): | |
| 31 """ returns false if the timeout was hit """ | |
| 32 if self.epoch_tag() != epoch_tag: | |
| 33 # has alredy changed | |
| 34 return True | |
| 35 return self.event.wait(timeout) | |
| 36 | |
| 37 def epoch_tag(self): | |
| 38 return '%s-%s' % (self.epoch, self.tag) | |
| 39 | |
| 40 def random(self): | |
| 41 return binascii.hexlify(os.urandom(self.RAND_SIZE)) | |
| 42 | |
| 43 def update(self, contents, epoch = None): | |
| 44 """ replaces settings contents and updates waiters if changed """ | |
| 45 if epoch: | |
| 46 if self.epoch == epoch: | |
| 47 return | |
| 48 else: | |
| 49 self.epoch = epoch | |
| 50 | |
| 51 self.tag = self.random() | |
| 52 self.contents = contents | |
| 53 | |
| 54 self.event.set() | |
| 55 self.event.clear() | |
| 56 | |
| 57 def get(self): | |
| 58 """ Returns (contents, epoch-tag) """ | |
| 59 return self.contents, self.epoch_tag() | |
| 60 | |
| 61 | |
| 62 | |
| 63 | |
| 64 |