new, simpler, cleaner, experimental timeout mechanism

This commit is contained in:
ahmadbilalkhalid 2019-07-25 16:54:06 +05:00
parent 615a070918
commit b198048ed8

View file

@ -1,9 +1,13 @@
import etcd3
import json
import signal
import threading
import time
from dataclasses import dataclass
from collections import namedtuple
from dataclasses import dataclass
from datetime import datetime
from os import path
PseudoEtcdMeta = namedtuple("PseudoEtcdMeta", ["key"])
@ -47,26 +51,42 @@ class Etcd3Wrapper(object):
for entry in r:
yield EtcdEntry(*entry[::-1], value_in_json=value_in_json)
def watch_prefix(self, *args, timeout=0, value_in_json=False, **kwargs):
# def watch_prefix(self, *args, timeout=0, value_in_json=False, **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)
# 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
# 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):
r, _ = self.client.watch_prefix(key_prefix, **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)
t = threading.Thread(target=create_timeout_event,
args=(timeout, key_prefix, self.client))
t.start()
for event in r:
# 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)
yield event
except TimeoutError:
_value = {"status": "TIMEOUT"}
yield EtcdEntry(PseudoEtcdMeta(key=b"TIMEOUT"), value=str.encode(json.dumps(_value)))
for event in r:
if event.value:
event = EtcdEntry(event, event.value, value_in_json=value_in_json)
yield event
def raise_timeout(signum, frame):
_ = signum, frame
raise TimeoutError()
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, _value, value_in_json=True)