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import time, contextlib, struct, json | |
import uwsgi | |
def token_bucket(interval, burst=1): | |
token_fmt = '>dL' | |
token_len = struct.calcsize(token_fmt) | |
token_get = lambda: struct.unpack(token_fmt, uwsgi.sharedarea_read(0, token_len)) | |
token_set = lambda *v: uwsgi.sharedarea_write(0, struct.pack(token_fmt, *v)) | |
token_set(time.monotonic(), burst) | |
assert uwsgi.sharedarea_read(0, token_len), 'Enable uwsgi --sharedarea plz' | |
@contextlib.contextmanager | |
def token_check(): | |
uwsgi.sharedarea_wlock() | |
try: yield (token_get, token_set) | |
finally: uwsgi.sharedarea_unlock() | |
rate = interval**-1 | |
def get_delay(grab=1): | |
ts = time.monotonic() | |
with token_check() as (tget, tset): | |
ts_sync, tokens = tget() | |
ts_sync, tokens = ts, min(burst, tokens + (ts - ts_sync) * rate) | |
if tokens >= grab: delay, tokens = 0, tokens - grab | |
else: delay = (grab - tokens) / rate | |
tset(ts_sync, tokens) | |
return delay | |
return get_delay | |
# interval, burst = uwsgi.opt[...] | |
interval, burst = 3600, 10 # hardcoded 10 req/h | |
get_delay = token_bucket(interval, burst) | |
def application(env, start_response): | |
start_response('200 OK', [('Content-Type','application/json')]) | |
return [json.dumps(dict(delay=get_delay()))] |
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