leader discovery fix and code cleaning
This commit is contained in:
Pierre
@@ -0,0 +1,260 @@
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"""
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LeaderClient - Client for reading leader info from meta-core
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This replaces the old LeaderDiscovery.py by delegating leader election
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to meta-core (Go sidecar) and just reading the results.
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Features:
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- Reads kv-leader.info file for leader URLs
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- Calls meta-core /urls API for current leader URLs
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- Watches for leader changes via file system watcher
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"""
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from __future__ import annotations
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import os
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import json
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import threading
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from dataclasses import dataclass
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from pathlib import Path
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from typing import Optional, Callable
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from urllib.request import urlopen, Request
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from urllib.error import URLError
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# Try to import watchdog for file watching (optional)
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try:
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from watchdog.observers import Observer
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from watchdog.events import FileSystemEventHandler
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WATCHDOG_AVAILABLE = True
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except ImportError:
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WATCHDOG_AVAILABLE = False
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Observer = None
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FileSystemEventHandler = object
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@dataclass
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class LeaderLockInfo:
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"""Leader lock file content format (kv-leader.info).
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Written by meta-core leader, read by other services.
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"""
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hostname: str
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base_url: str
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api_url: str # meta-core API URL (port 9000)
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redis_url: str
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webdav_url: str
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timestamp: int
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pid: int
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@dataclass
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class URLsResponse:
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"""Response from meta-core /urls API."""
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hostname: str
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base_url: str
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api_url: str
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redis_url: str
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webdav_url: str
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is_leader: bool
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class LockFileHandler(FileSystemEventHandler):
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"""File system event handler for lock file changes."""
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def __init__(self, callback: Callable[[], None], lock_filename: str):
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self.callback = callback
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self.lock_filename = lock_filename
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def on_modified(self, event):
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if event.src_path.endswith(self.lock_filename):
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self.callback()
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def on_created(self, event):
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if event.src_path.endswith(self.lock_filename):
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self.callback()
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def on_deleted(self, event):
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if event.src_path.endswith(self.lock_filename):
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self.callback()
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class LeaderClient:
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"""
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LeaderClient for meta-stremio.
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Reads leader info from kv-leader.info file written by meta-core.
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"""
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def __init__(
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self,
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meta_core_path: str,
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meta_core_url: Optional[str] = None
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):
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self.meta_core_path = meta_core_path
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self.meta_core_url = meta_core_url
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self.info_file_path = os.path.join(meta_core_path, 'locks', 'kv-leader.info')
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self.leader_info: Optional[LeaderLockInfo] = None
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self._file_observer = None
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self._on_change_callbacks: list[Callable[[], None]] = []
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self._stop_event = threading.Event()
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def get_leader_info(self) -> Optional[LeaderLockInfo]:
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"""Read leader info from the info file."""
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try:
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with open(self.info_file_path, 'r') as f:
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content = f.read()
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data = json.loads(content)
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self.leader_info = LeaderLockInfo(
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hostname=data.get('hostname', 'unknown'),
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base_url=data.get('baseUrl', ''),
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api_url=data.get('apiUrl', ''),
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redis_url=data.get('redisUrl', ''),
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webdav_url=data.get('webdavUrl', ''),
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timestamp=data.get('timestamp', 0),
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pid=data.get('pid', 0)
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)
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return self.leader_info
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except FileNotFoundError:
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print(f"[LeaderClient] Leader info file not found: {self.info_file_path}")
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return None
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except json.JSONDecodeError as e:
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print(f"[LeaderClient] Error parsing leader info: {e}")
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return None
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except Exception as e:
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print(f"[LeaderClient] Error reading leader info: {e}")
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return None
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def get_redis_url(self) -> Optional[str]:
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"""Get Redis URL from leader info."""
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info = self.get_leader_info()
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return info.redis_url if info else None
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def get_webdav_url(self) -> Optional[str]:
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"""Get WebDAV URL from leader info."""
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info = self.get_leader_info()
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return info.webdav_url if info else None
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def get_api_url(self) -> Optional[str]:
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"""Get meta-core API URL from leader info."""
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info = self.get_leader_info()
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return info.api_url if info else None
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def get_urls(self) -> Optional[URLsResponse]:
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"""Call meta-core /urls API to get current URLs."""
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# First try using configured meta_core_url
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api_url = self.meta_core_url
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# Fall back to reading from leader info
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if not api_url:
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info = self.get_leader_info()
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api_url = info.api_url if info else None
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if not api_url:
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print("[LeaderClient] No meta-core API URL available")
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return None
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try:
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url = f"{api_url}/urls"
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req = Request(url, headers={'Accept': 'application/json'})
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with urlopen(req, timeout=5) as response:
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if response.status != 200:
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print(f"[LeaderClient] Failed to get URLs: {response.status}")
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return None
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data = json.loads(response.read().decode())
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return URLsResponse(
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hostname=data.get('hostname', ''),
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base_url=data.get('baseUrl', ''),
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api_url=data.get('apiUrl', ''),
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redis_url=data.get('redisUrl', ''),
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webdav_url=data.get('webdavUrl', ''),
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is_leader=data.get('isLeader', False)
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)
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except URLError as e:
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print(f"[LeaderClient] Error calling /urls API: {e}")
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return None
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except Exception as e:
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print(f"[LeaderClient] Error getting URLs: {e}")
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return None
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def wait_for_leader(self, timeout_ms: int = 30000) -> LeaderLockInfo:
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"""Wait for leader info to be available."""
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import time
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start_time = time.time()
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poll_interval = 0.5 # 500ms
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while (time.time() - start_time) * 1000 < timeout_ms:
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info = self.get_leader_info()
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if info:
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print(f"[LeaderClient] Leader found: {info.hostname} at {info.redis_url}")
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return info
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print("[LeaderClient] Waiting for leader...")
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time.sleep(poll_interval)
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raise TimeoutError(f"No leader found within {timeout_ms}ms")
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def start_watching(self) -> None:
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"""Start watching for leader changes."""
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if not WATCHDOG_AVAILABLE:
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print("[LeaderClient] watchdog not available, file watching disabled")
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return
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try:
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lock_dir = os.path.dirname(self.info_file_path)
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handler = LockFileHandler(
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callback=self._on_file_change,
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lock_filename='kv-leader.info'
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)
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self._file_observer = Observer()
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self._file_observer.schedule(handler, lock_dir, recursive=False)
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self._file_observer.start()
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print(f"[LeaderClient] Watching for leader changes in {lock_dir}")
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except Exception as e:
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print(f"[LeaderClient] Could not start file watcher: {e}")
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def stop_watching(self) -> None:
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"""Stop watching for leader changes."""
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if self._file_observer:
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self._file_observer.stop()
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self._file_observer.join(timeout=2.0)
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self._file_observer = None
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print("[LeaderClient] Stopped watching for leader changes")
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def _on_file_change(self) -> None:
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"""Handle file change event."""
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print("[LeaderClient] Leader info changed, reloading...")
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self.get_leader_info()
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self._notify_change()
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def on_change(self, callback: Callable[[], None]) -> 'LeaderClient':
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"""Register callback for leader changes."""
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self._on_change_callbacks.append(callback)
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return self
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def _notify_change(self) -> None:
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"""Notify all change callbacks."""
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for callback in self._on_change_callbacks:
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try:
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callback()
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except Exception as e:
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print(f"[LeaderClient] Error in change callback: {e}")
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def get_cached_leader_info(self) -> Optional[LeaderLockInfo]:
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"""Get cached leader info (without re-reading file)."""
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return self.leader_info
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def close(self) -> None:
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"""Clean up resources."""
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self._stop_event.set()
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self.stop_watching()
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self._on_change_callbacks = []
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