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experimental watch_prefix with new timeout mechanism added

master
_ahmedbilal 3 years ago
parent
commit
9abc74e387
  1. 63
      etcd_wrapper.py

63
etcd_wrapper.py

@ -3,6 +3,7 @@ import json
import signal
import threading
import time
import queue
from collections import namedtuple
from dataclasses import dataclass
@ -52,41 +53,49 @@ class Etcd3Wrapper(object):
yield EtcdEntry(*entry[::-1], value_in_json=value_in_json)
# def watch_prefix(self, *args, timeout=0, value_in_json=False, **kwargs):
# def raise_timeout(signum, frame):
# raise TimeoutError("timeout")
# r, _ = self.client.watch_prefix(*args, **kwargs)
# if timeout > 0:
# signal.signal(signal.SIGALRM, raise_timeout)
# while True:
# try:
# if timeout > 0:
# signal.alarm(timeout)
# r, _ = self.client.watch_prefix(*args, **kwargs)
# signal.alarm(timeout)
# for event in r:
# signal.alarm(0)
# # if e.value is None don't propagate its value
# if event.value is None:
# continue
# event = EtcdEntry(event, event.value, value_in_json=value_in_json)
# signal.alarm(timeout)
# yield event
# if event.value:
# event = EtcdEntry(event, event.value, value_in_json=value_in_json)
# signal.alarm(timeout)
# yield event
# else:
# signal.alarm(timeout)
# except TimeoutError:
# _value = {"status": "TIMEOUT"}
# yield EtcdEntry(PseudoEtcdMeta(key=b"TIMEOUT"), value=str.encode(json.dumps(_value)))
def watch_prefix(self, key_prefix, timeout=0, value_in_json=False, **kwargs):
def watch_prefix(self, key_prefix, timeout,
value_in_json=False, **kwargs):
q = queue.Queue()
r, _ = self.client.watch_prefix(key_prefix, **kwargs)
if timeout > 0:
t = threading.Thread(target=create_timeout_event,
args=(timeout, key_prefix, self.client))
t.start()
for event in r:
if event.value:
event = EtcdEntry(event, event.value, value_in_json=value_in_json)
yield event
def create_timeout_event(timeout, key_prefix, etcd_client):
while True:
time.sleep(timeout)
_value = {"status": "TIMEOUT", "last_timeout": datetime.utcnow().isoformat()}
_key = path.join(f"{key_prefix}", "TIMEOUT")
etcd_client.put(_key.encode("utf-8"), json.dumps(_value))
t = threading.Thread(target=watch_prefix_generator,
args=(value_in_json, r, q))
t.start()
while True:
try:
v = q.get(timeout=timeout)
yield v
except queue.Empty:
_value = {"status": "TIMEOUT"}
e = EtcdEntry(PseudoEtcdMeta(key=b"TIMEOUT"), value=str.encode(json.dumps(_value)))
yield e
def watch_prefix_generator(value_in_json, generator, q):
for event in generator:
if event.value:
event = EtcdEntry(event, event.value)
q.put(event)

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