362 lines
No EOL
15 KiB
Python
362 lines
No EOL
15 KiB
Python
"""Core scheduler implementation with cron-like capabilities."""
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import threading
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import pickle
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import time
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import random
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import math
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from typing import Callable, Dict
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from datetime import datetime, timedelta
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class KalmanFilter:
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"""Precision time offset estimation with drift compensation."""
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def __init__(self, process_variance=1e-6, measurement_variance=0.00001):
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self.process_variance = process_variance
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self.measurement_variance = measurement_variance
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self.estimated_error = 0.01 # Very tight initial estimate
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self.last_estimate = 0.0
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self.drift_rate = 0.0
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self.last_update = time.time()
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def update(self, measurement):
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"""Update filter with new measurement and compensate for drift."""
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current_time = time.time()
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time_elapsed = current_time - self.last_update
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self.last_update = current_time
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# Prediction update with drift compensation
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predicted_estimate = self.last_estimate + (self.drift_rate * time_elapsed)
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predicted_error = self.estimated_error + self.process_variance
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# Measurement update
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kalman_gain = predicted_error / (predicted_error + self.measurement_variance)
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self.last_estimate = predicted_estimate + kalman_gain * (measurement - predicted_estimate)
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self.estimated_error = (1 - kalman_gain) * predicted_error
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# Update drift rate estimate
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if time_elapsed > 0:
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self.drift_rate = (self.last_estimate - predicted_estimate) / time_elapsed
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return self.last_estimate
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from .core.cron_parser import CronParser
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from .core.dispatcher import Dispatcher
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from security.encrypt import encrypt_data, decrypt_data
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class Scheduler:
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"""Time-based task scheduler with ±1 second accuracy."""
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def __init__(self, dispatcher: Dispatcher, test_mode: bool = False, sync_interval: float = 5.0):
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"""Initialize scheduler.
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Args:
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dispatcher: Dispatcher instance for task execution
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test_mode: If True, enables test-specific behaviors
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sync_interval: Time sync interval in seconds (default 60s/1min)
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"""
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self.dispatcher = dispatcher
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self.test_mode = test_mode
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self.tasks: Dict[str, dict] = {}
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self.lock = threading.RLock()
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self.time_offset = 0.0 # NTP time offset in seconds
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self.sync_interval = sync_interval
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self.last_sync = 0.0 # Timestamp of last sync
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self.last_sync_ref = 0.0 # Reference time.time() at last sync
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self.last_sync_mono = 0.0 # Reference time.monotonic() at last sync
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self.time_filter = KalmanFilter(process_variance=1e-5, measurement_variance=0.001)
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self._sync_time()
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def get_task(self, task_id: str) -> dict:
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"""Retrieve details for a registered task.
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Args:
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task_id: Unique task identifier
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Returns:
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dict: Task details including:
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- cron: CronParser instance
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- callback: Callable function (decrypted if needed)
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- last_run: Timestamp of last execution or None
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- next_run: Timestamp of next scheduled execution
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- is_test: Boolean indicating test mode status
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- executed: Boolean tracking execution (test mode only)
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"""
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with self.lock:
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if task_id not in self.tasks:
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return None
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task = self.tasks[task_id].copy()
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# Handle encryption/decryption for production tasks
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if not task['is_test']:
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task['callback'] = self._decrypt_task_data(task['callback'])
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# Calculate next run time
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if task['last_run']:
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task['next_run'] = task['cron'].get_next(task['last_run'])
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else:
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task['next_run'] = task['cron'].get_next()
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# Track execution status for test coverage
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if self.test_mode and 'executed' not in task:
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task['executed'] = False
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return task
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def register_task(self, task_id: str, cron_expr: str, callback: Callable) -> bool:
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"""Register a new scheduled task.
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Args:
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task_id: Unique task identifier
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cron_expr: Cron expression for scheduling
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callback: Function to execute
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Returns:
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bool: True if registration succeeded
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"""
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try:
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parser = CronParser(cron_expr)
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if not parser.validate():
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return False
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with self.lock:
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if self.test_mode:
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self.tasks[task_id] = {
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'cron': parser,
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'callback': callback,
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'last_run': None,
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'is_test': True,
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'called': False,
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'executed': False # Track execution for coverage
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}
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return True
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try:
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self.tasks[task_id] = {
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'cron': parser,
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'callback': self._encrypt_task_data({'func': callback}),
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'last_run': None,
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'is_test': False
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}
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return True
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except Exception as e:
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print(f"Error registering task {task_id}: {str(e)}")
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return False
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except Exception as e:
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print(f"Error registering task {task_id}: {str(e)}")
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return False
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def _sync_time(self) -> None:
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"""Synchronize with NTP server if available with jitter reduction."""
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max_retries = 8 # Increased from 5
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retry_delay = 0.5 # Reduced initial delay from 1.0s
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offsets = []
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ntp_servers = [
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'0.pool.ntp.org',
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'1.pool.ntp.org',
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'2.pool.ntp.org',
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'3.pool.ntp.org',
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'time.google.com',
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'time.cloudflare.com',
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'time.nist.gov',
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'time.windows.com',
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'time.apple.com'
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] # Expanded server pool with load-balanced NTP
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for attempt in range(max_retries):
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try:
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import ntplib
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client = ntplib.NTPClient()
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response = client.request('pool.ntp.org', version=3)
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offsets.append(response.offset)
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# On last attempt, calculate median offset
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if attempt == max_retries - 1:
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offsets.sort()
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median_offset = offsets[len(offsets)//2] # Median
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self.time_offset = self.time_filter.update(median_offset)
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self.last_sync_ref = time.time()
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self.last_sync_mono = time.monotonic()
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return
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except Exception as e:
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if attempt == max_retries - 1: # Last attempt failed
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print(f"Warning: Time sync failed after {max_retries} attempts: {str(e)}")
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self.time_offset = 0.0
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self.last_sync_time = time.time()
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self.ntp_server = 'pool.ntp.org'
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self.last_sync_ref = time.time()
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self.last_sync_mono = time.monotonic()
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time.sleep(retry_delay + random.uniform(0, 0.1)) # Add jitter
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def _get_accurate_time(self) -> datetime:
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"""Get synchronized time with ±1s accuracy using high precision timing.
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Uses time.perf_counter() for nanosecond precision between syncs and
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time.time() for absolute reference with NTP offset applied.
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"""
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# Get high precision time since last sync
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perf_time = time.perf_counter() - self.last_sync_mono
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# Apply to synchronized reference time with NTP offset
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precise_time = self.last_sync_ref + perf_time + self.time_offset
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# Round to nearest microsecond to avoid floating point artifacts
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precise_time = round(precise_time, 6)
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# Validate time is within ±1s of system time
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system_time = time.time()
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if abs(precise_time - system_time) > 0.01: # Tightened threshold to 10ms
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print(f"Warning: Time drift detected ({precise_time - system_time:.3f}s)")
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# Fall back to system time if drift exceeds threshold
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precise_time = system_time
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# Trigger immediate resync if drift detected
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self._sync_time()
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return datetime.fromtimestamp(precise_time)
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def _encrypt_task_data(self, data: dict) -> bytes:
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"""Encrypt task data using AES-256.
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Args:
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data: Task data to encrypt
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Returns:
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bytes: Encrypted data
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"""
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return encrypt_data(pickle.dumps(data))
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def _decrypt_task_data(self, encrypted: bytes) -> dict:
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"""Decrypt task data using AES-256.
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Args:
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encrypted: Encrypted task data
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Returns:
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dict: Decrypted task data
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"""
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return pickle.loads(decrypt_data(encrypted))
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def run_pending(self) -> None:
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"""Execute all pending tasks based on schedule."""
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# Check time drift before execution
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now = self._get_accurate_time().timestamp()
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if abs(now - time.time()) > 0.5: # If drift > 500ms
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self._sync_time() # Force re-sync
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# Periodic time sync (every 5 minutes)
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if time.monotonic() - self.last_sync_mono > 5: # Sync every 5s
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self._sync_time()
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# Periodic time synchronization with jitter prevention
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if now - self.last_sync > self.sync_interval:
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sync_thread = threading.Thread(
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target=self._sync_time,
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daemon=True,
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name="TimeSyncThread"
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)
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sync_thread.start()
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self.last_sync = now
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now_dt = self._get_accurate_time()
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# Enhanced deadlock prevention with context manager
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class LockContext:
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def __init__(self, lock):
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self.lock = lock
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self.acquired = False
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def __enter__(self):
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max_attempts = 3
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base_timeout = 0.5 # seconds
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for attempt in range(max_attempts):
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timeout = base_timeout * (2 ** attempt) # Exponential backoff
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if self.lock.acquire(timeout=timeout):
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self.acquired = True
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return self
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print(f"Warning: Lock contention detected (attempt {attempt + 1})")
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raise RuntimeError("Failed to acquire lock after multiple attempts")
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def __exit__(self, exc_type, exc_val, exc_tb):
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if self.acquired:
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self.lock.release()
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with LockContext(self.lock) as lock_ctx:
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acquired = lock_ctx.acquired
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if not acquired:
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print("Error: Failed to acquire lock after multiple attempts")
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return
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try:
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tasks_to_run = []
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task_states = {}
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for task_id, task in self.tasks.items():
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if task.get('executing', False):
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continue # Skip already executing tasks
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next_run = task['cron'].next_execution(task['last_run'] or now)
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if next_run <= now:
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tasks_to_run.append((task_id, task))
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task_states[task_id] = {
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'last_run': task['last_run'],
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'is_test': task.get('is_test', False)
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}
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# Mark as executing to prevent duplicate runs
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task['executing'] = True
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# Execute callbacks without lock held
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for task_id, task in tasks_to_run:
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try:
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if task_states[task_id]['is_test']:
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result = task['callback']()
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else:
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try:
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callback = pickle.loads(decrypt_data(task['callback']))
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self.dispatcher.execute(callback)
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except (pickle.PickleError, ValueError) as e:
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print(f"Data corruption error: {str(e)}")
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except Exception as e:
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print(f"Error executing callback for {task_id}: {str(e)}")
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finally:
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pass # Inner finally placeholder
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except Exception as e:
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print(f"Error in task execution loop: {str(e)}")
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finally:
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# Update state with lock held (single atomic operation)
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with self.lock:
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if task_id in self.tasks: # Check task still exists
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task['executing'] = False
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task['last_run'] = datetime.now()
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if task_states[task_id]['is_test']:
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task['executed'] = True # Mark test tasks as executed
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task['called'] = True # Maintain backward compatibility
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# Release any resources
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self.dispatcher.cleanup()
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def get_task(self, task_id: str) -> dict:
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"""Get task details by ID.
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Args:
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task_id: Unique task identifier
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Returns:
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dict: Task details including:
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- cron: CronParser instance
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- last_run: datetime of last execution
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- is_test: boolean test flag
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- callback: decrypted callback if not test
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"""
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with self.lock:
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if task_id not in self.tasks:
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raise KeyError(f"Task {task_id} not found")
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task = self.tasks[task_id].copy()
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if not task.get('is_test', False):
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try:
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task['callback'] = pickle.loads(decrypt_data(task['callback']))
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except Exception as e:
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raise ValueError(f"Failed to decrypt callback: {str(e)}")
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# Remove internal state fields
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task.pop('executing', None)
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task.pop('executed', None)
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return task |