79 lines
3 KiB
Python
79 lines
3 KiB
Python
"""Persistent finite campaign budget; only caller holding Campaign.lock may mutate."""
|
|
import fcntl
|
|
import json
|
|
import os
|
|
from pathlib import Path
|
|
|
|
MODES = ('control', 'private_standard', 'private_mosaic')
|
|
ACTIONS = {'D1': 'reconfiguration', 'D2': 'reconfiguration',
|
|
'D3': 'migration', 'D5': 'migration'}
|
|
LIMITS = {'reconfiguration': 6, 'migration': 6, 'camera_pair': 1}
|
|
|
|
|
|
def read(lab):
|
|
path = Path(lab) / 'dynamic-campaign-budget.json'
|
|
if not path.exists():
|
|
if any((Path(lab) / 'runs').glob('*-dynamic-*')):
|
|
raise ValueError('missing ledger in existing campaign; no reset')
|
|
return {'version': 1, 'runs': [], 'reservations': []}
|
|
state = json.loads(path.read_text())
|
|
if state['version'] != 1 or len(state['runs']) != len(set(state['runs'])):
|
|
raise ValueError('invalid campaign runs/version')
|
|
if any(m not in MODES for m in state['runs']):
|
|
raise ValueError('invalid mode')
|
|
seen = set()
|
|
for r in state['reservations']:
|
|
key = (r['mode'], r['action'])
|
|
if key in seen or r['mode'] not in state['runs'] or r['action'] not in ACTIONS:
|
|
raise ValueError('invalid/duplicate persisted reservation')
|
|
seen.add(key)
|
|
return state
|
|
|
|
|
|
def write(lab, state):
|
|
# WHY: reservations survive launch failure and restart; never refund.
|
|
# CONTRACT: lock is held across write, launch, cleanup; atomic replacement.
|
|
# INVARIANT: preserve every old entry, persist before IPC is launched.
|
|
path = Path(lab) / 'dynamic-campaign-budget.json'
|
|
tmp = path.with_suffix('.tmp')
|
|
with tmp.open('w') as f:
|
|
f.write(json.dumps(state, indent=2) + '\n')
|
|
f.flush()
|
|
os.fsync(f.fileno())
|
|
tmp.replace(path)
|
|
fd = os.open(path.parent, os.O_RDONLY | os.O_DIRECTORY)
|
|
try:
|
|
os.fsync(fd)
|
|
finally:
|
|
os.close(fd)
|
|
|
|
|
|
class Campaign:
|
|
def __init__(self, lab):
|
|
self.lab = Path(lab)
|
|
self.lock = (self.lab / 'dynamic-campaign.lock').open('a')
|
|
fcntl.flock(self.lock, fcntl.LOCK_EX | fcntl.LOCK_NB)
|
|
|
|
def begin(self, mode):
|
|
state = read(self.lab)
|
|
if mode not in MODES or mode in state['runs']:
|
|
raise ValueError('mode already attempted or invalid; no dynamic replay')
|
|
state['runs'].append(mode)
|
|
write(self.lab, state)
|
|
|
|
|
|
def reserve(lab, mode, action):
|
|
# CONTRACT: generated child runs under its parent's exclusive campaign lock.
|
|
state = read(lab)
|
|
if mode not in state['runs'] or action not in ACTIONS:
|
|
raise ValueError('unregistered mode/action')
|
|
if any(r['mode'] == mode and r['action'] == action for r in state['reservations']):
|
|
raise ValueError('action budget exhausted for mode')
|
|
kind = ACTIONS[action]
|
|
if sum(ACTIONS[r['action']] == kind for r in state['reservations']) >= LIMITS[kind]:
|
|
raise ValueError('campaign budget exhausted')
|
|
import time
|
|
state['reservations'].append({'mode': mode, 'action': action,
|
|
'reserved_ns': time.monotonic_ns()})
|
|
write(lab, state)
|
|
return state
|