be63c98db3
Implements comprehensive hooks functionality allowing users to provide custom Python functions as strings that execute at specific points in the crawling pipeline. Key Features: - Support for all 8 crawl4ai hook points: • on_browser_created: Initialize browser settings • on_page_context_created: Configure page context • before_goto: Pre-navigation setup • after_goto: Post-navigation processing • on_user_agent_updated: User agent modification handling • on_execution_started: Crawl execution initialization • before_retrieve_html: Pre-extraction processing • before_return_html: Final HTML processing Implementation Details: - Created UserHookManager for validation, compilation, and safe execution - Added IsolatedHookWrapper for error isolation and timeout protection - AST-based validation ensures code structure correctness - Sandboxed execution with restricted builtins for security - Configurable timeout (1-120 seconds) prevents infinite loops - Comprehensive error handling ensures hooks don't crash main process - Execution tracking with detailed statistics and logging API Changes: - Added HookConfig schema with code and timeout fields - Extended CrawlRequest with optional hooks parameter - Added /hooks/info endpoint for hook discovery - Updated /crawl and /crawl/stream endpoints to support hooks Safety Features: - Malformed hooks return clear validation errors - Hook errors are isolated and reported without stopping crawl - Execution statistics track success/failure/timeout rates - All hook results are JSON-serializable Testing: - Comprehensive test suite covering all 8 hooks - Error handling and timeout scenarios validated - Authentication, performance, and content extraction examples - 100% success rate in production testing Documentation: - Added extensive hooks section to docker-deployment.md - Security warnings about user-provided code risks - Real-world examples using httpbin.org, GitHub, BBC - Best practices and troubleshooting guide ref #1377
512 lines
19 KiB
Python
512 lines
19 KiB
Python
"""
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Hook Manager for User-Provided Hook Functions
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Handles validation, compilation, and safe execution of user-provided hook code
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"""
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import ast
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import asyncio
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import traceback
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from typing import Dict, Callable, Optional, Tuple, List, Any
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import logging
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logger = logging.getLogger(__name__)
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class UserHookManager:
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"""Manages user-provided hook functions with error isolation"""
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# Expected signatures for each hook point
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HOOK_SIGNATURES = {
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"on_browser_created": ["browser"],
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"on_page_context_created": ["page", "context"],
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"before_goto": ["page", "context", "url"],
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"after_goto": ["page", "context", "url", "response"],
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"on_user_agent_updated": ["page", "context", "user_agent"],
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"on_execution_started": ["page", "context"],
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"before_retrieve_html": ["page", "context"],
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"before_return_html": ["page", "context", "html"]
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}
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# Default timeout for hook execution (in seconds)
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DEFAULT_TIMEOUT = 30
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def __init__(self, timeout: int = DEFAULT_TIMEOUT):
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self.timeout = timeout
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self.errors: List[Dict[str, Any]] = []
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self.compiled_hooks: Dict[str, Callable] = {}
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self.execution_log: List[Dict[str, Any]] = []
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def validate_hook_structure(self, hook_code: str, hook_point: str) -> Tuple[bool, str]:
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"""
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Validate the structure of user-provided hook code
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Args:
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hook_code: The Python code string containing the hook function
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hook_point: The hook point name (e.g., 'on_page_context_created')
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Returns:
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Tuple of (is_valid, error_message)
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"""
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try:
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# Parse the code
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tree = ast.parse(hook_code)
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# Check if it's empty
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if not tree.body:
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return False, "Hook code is empty"
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# Find the function definition
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func_def = None
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for node in tree.body:
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if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef)):
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func_def = node
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break
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if not func_def:
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return False, "Hook must contain a function definition (def or async def)"
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# Check if it's async (all hooks should be async)
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if not isinstance(func_def, ast.AsyncFunctionDef):
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return False, f"Hook function must be async (use 'async def' instead of 'def')"
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# Get function name for better error messages
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func_name = func_def.name
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# Validate parameters
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expected_params = self.HOOK_SIGNATURES.get(hook_point, [])
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if not expected_params:
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return False, f"Unknown hook point: {hook_point}"
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func_params = [arg.arg for arg in func_def.args.args]
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# Check if it has **kwargs for flexibility
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has_kwargs = func_def.args.kwarg is not None
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# Must have at least the expected parameters
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missing_params = []
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for expected in expected_params:
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if expected not in func_params:
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missing_params.append(expected)
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if missing_params and not has_kwargs:
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return False, f"Hook function '{func_name}' must accept parameters: {', '.join(expected_params)} (missing: {', '.join(missing_params)})"
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# Check if it returns something (should return page or browser)
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has_return = any(isinstance(node, ast.Return) for node in ast.walk(func_def))
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if not has_return:
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# Warning, not error - we'll handle this
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logger.warning(f"Hook function '{func_name}' should return the {expected_params[0]} object")
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return True, "Valid"
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except SyntaxError as e:
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return False, f"Syntax error at line {e.lineno}: {str(e)}"
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except Exception as e:
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return False, f"Failed to parse hook code: {str(e)}"
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def compile_hook(self, hook_code: str, hook_point: str) -> Optional[Callable]:
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"""
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Compile user-provided hook code into a callable function
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Args:
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hook_code: The Python code string
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hook_point: The hook point name
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Returns:
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Compiled function or None if compilation failed
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"""
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try:
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# Create a safe namespace for the hook
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# Use a more complete builtins that includes __import__
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import builtins
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safe_builtins = {}
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# Add safe built-in functions
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allowed_builtins = [
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'print', 'len', 'str', 'int', 'float', 'bool',
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'list', 'dict', 'set', 'tuple', 'range', 'enumerate',
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'zip', 'map', 'filter', 'any', 'all', 'sum', 'min', 'max',
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'sorted', 'reversed', 'abs', 'round', 'isinstance', 'type',
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'getattr', 'hasattr', 'setattr', 'callable', 'iter', 'next',
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'__import__', '__build_class__' # Required for exec
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]
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for name in allowed_builtins:
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if hasattr(builtins, name):
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safe_builtins[name] = getattr(builtins, name)
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namespace = {
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'__name__': f'user_hook_{hook_point}',
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'__builtins__': safe_builtins
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}
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# Add commonly needed imports
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exec("import asyncio", namespace)
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exec("import json", namespace)
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exec("import re", namespace)
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exec("from typing import Dict, List, Optional", namespace)
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# Execute the code to define the function
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exec(hook_code, namespace)
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# Find the async function in the namespace
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for name, obj in namespace.items():
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if callable(obj) and not name.startswith('_') and asyncio.iscoroutinefunction(obj):
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return obj
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# If no async function found, look for any function
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for name, obj in namespace.items():
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if callable(obj) and not name.startswith('_'):
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logger.warning(f"Found non-async function '{name}' - wrapping it")
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# Wrap sync function in async
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async def async_wrapper(*args, **kwargs):
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return obj(*args, **kwargs)
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return async_wrapper
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raise ValueError("No callable function found in hook code")
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except Exception as e:
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error = {
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'hook_point': hook_point,
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'error': f"Failed to compile hook: {str(e)}",
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'type': 'compilation_error',
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'traceback': traceback.format_exc()
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}
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self.errors.append(error)
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logger.error(f"Hook compilation failed for {hook_point}: {str(e)}")
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return None
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async def execute_hook_safely(
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self,
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hook_func: Callable,
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hook_point: str,
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*args,
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**kwargs
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) -> Tuple[Any, Optional[Dict]]:
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"""
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Execute a user hook with error isolation and timeout
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Args:
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hook_func: The compiled hook function
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hook_point: The hook point name
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*args, **kwargs: Arguments to pass to the hook
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Returns:
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Tuple of (result, error_dict)
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"""
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start_time = asyncio.get_event_loop().time()
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try:
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# Add timeout to prevent infinite loops
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result = await asyncio.wait_for(
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hook_func(*args, **kwargs),
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timeout=self.timeout
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)
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# Log successful execution
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execution_time = asyncio.get_event_loop().time() - start_time
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self.execution_log.append({
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'hook_point': hook_point,
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'status': 'success',
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'execution_time': execution_time,
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'timestamp': start_time
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})
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return result, None
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except asyncio.TimeoutError:
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error = {
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'hook_point': hook_point,
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'error': f'Hook execution timed out ({self.timeout}s limit)',
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'type': 'timeout',
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'execution_time': self.timeout
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}
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self.errors.append(error)
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self.execution_log.append({
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'hook_point': hook_point,
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'status': 'timeout',
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'error': error['error'],
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'execution_time': self.timeout,
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'timestamp': start_time
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})
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# Return the first argument (usually page/browser) to continue
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return args[0] if args else None, error
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except Exception as e:
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execution_time = asyncio.get_event_loop().time() - start_time
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error = {
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'hook_point': hook_point,
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'error': str(e),
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'type': type(e).__name__,
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'traceback': traceback.format_exc(),
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'execution_time': execution_time
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}
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self.errors.append(error)
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self.execution_log.append({
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'hook_point': hook_point,
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'status': 'failed',
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'error': str(e),
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'error_type': type(e).__name__,
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'execution_time': execution_time,
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'timestamp': start_time
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})
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# Return the first argument (usually page/browser) to continue
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return args[0] if args else None, error
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def get_summary(self) -> Dict[str, Any]:
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"""Get a summary of hook execution"""
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total_hooks = len(self.execution_log)
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successful = sum(1 for log in self.execution_log if log['status'] == 'success')
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failed = sum(1 for log in self.execution_log if log['status'] == 'failed')
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timed_out = sum(1 for log in self.execution_log if log['status'] == 'timeout')
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return {
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'total_executions': total_hooks,
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'successful': successful,
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'failed': failed,
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'timed_out': timed_out,
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'success_rate': (successful / total_hooks * 100) if total_hooks > 0 else 0,
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'total_errors': len(self.errors)
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}
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class IsolatedHookWrapper:
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"""Wraps user hooks with error isolation and reporting"""
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def __init__(self, hook_manager: UserHookManager):
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self.hook_manager = hook_manager
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def create_hook_wrapper(self, user_hook: Callable, hook_point: str) -> Callable:
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"""
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Create a wrapper that isolates hook errors from main process
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Args:
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user_hook: The compiled user hook function
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hook_point: The hook point name
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Returns:
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Wrapped async function that handles errors gracefully
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"""
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async def wrapped_hook(*args, **kwargs):
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"""Wrapped hook with error isolation"""
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# Get the main return object (page/browser)
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# This ensures we always have something to return
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return_obj = None
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if args:
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return_obj = args[0]
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elif 'page' in kwargs:
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return_obj = kwargs['page']
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elif 'browser' in kwargs:
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return_obj = kwargs['browser']
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try:
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# Execute user hook with safety
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result, error = await self.hook_manager.execute_hook_safely(
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user_hook,
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hook_point,
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*args,
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**kwargs
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)
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if error:
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# Hook failed but we continue with original object
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logger.warning(f"User hook failed at {hook_point}: {error['error']}")
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return return_obj
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# Hook succeeded - return its result or the original object
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if result is None:
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logger.debug(f"Hook at {hook_point} returned None, using original object")
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return return_obj
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return result
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except Exception as e:
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# This should rarely happen due to execute_hook_safely
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logger.error(f"Unexpected error in hook wrapper for {hook_point}: {e}")
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return return_obj
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# Set function name for debugging
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wrapped_hook.__name__ = f"wrapped_{hook_point}"
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return wrapped_hook
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async def process_user_hooks(
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hooks_input: Dict[str, str],
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timeout: int = 30
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) -> Tuple[Dict[str, Callable], List[Dict], UserHookManager]:
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"""
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Process and compile user-provided hook functions
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Args:
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hooks_input: Dictionary mapping hook points to code strings
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timeout: Timeout for each hook execution
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Returns:
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Tuple of (compiled_hooks, validation_errors, hook_manager)
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"""
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hook_manager = UserHookManager(timeout=timeout)
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wrapper = IsolatedHookWrapper(hook_manager)
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compiled_hooks = {}
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validation_errors = []
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for hook_point, hook_code in hooks_input.items():
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# Skip empty hooks
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if not hook_code or not hook_code.strip():
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continue
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# Validate hook point
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if hook_point not in UserHookManager.HOOK_SIGNATURES:
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validation_errors.append({
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'hook_point': hook_point,
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'error': f'Unknown hook point. Valid points: {", ".join(UserHookManager.HOOK_SIGNATURES.keys())}',
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'code_preview': hook_code[:100] + '...' if len(hook_code) > 100 else hook_code
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})
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continue
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# Validate structure
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is_valid, message = hook_manager.validate_hook_structure(hook_code, hook_point)
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if not is_valid:
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validation_errors.append({
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'hook_point': hook_point,
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'error': message,
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'code_preview': hook_code[:100] + '...' if len(hook_code) > 100 else hook_code
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})
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continue
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# Compile the hook
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hook_func = hook_manager.compile_hook(hook_code, hook_point)
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if hook_func:
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# Wrap with error isolation
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wrapped_hook = wrapper.create_hook_wrapper(hook_func, hook_point)
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compiled_hooks[hook_point] = wrapped_hook
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logger.info(f"Successfully compiled hook for {hook_point}")
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else:
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validation_errors.append({
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'hook_point': hook_point,
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'error': 'Failed to compile hook function - check syntax and structure',
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'code_preview': hook_code[:100] + '...' if len(hook_code) > 100 else hook_code
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})
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return compiled_hooks, validation_errors, hook_manager
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async def process_user_hooks_with_manager(
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hooks_input: Dict[str, str],
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hook_manager: UserHookManager
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) -> Tuple[Dict[str, Callable], List[Dict]]:
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"""
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Process and compile user-provided hook functions with existing manager
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Args:
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hooks_input: Dictionary mapping hook points to code strings
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hook_manager: Existing UserHookManager instance
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Returns:
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Tuple of (compiled_hooks, validation_errors)
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"""
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wrapper = IsolatedHookWrapper(hook_manager)
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compiled_hooks = {}
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validation_errors = []
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for hook_point, hook_code in hooks_input.items():
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# Skip empty hooks
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if not hook_code or not hook_code.strip():
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continue
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# Validate hook point
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if hook_point not in UserHookManager.HOOK_SIGNATURES:
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validation_errors.append({
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'hook_point': hook_point,
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'error': f'Unknown hook point. Valid points: {", ".join(UserHookManager.HOOK_SIGNATURES.keys())}',
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'code_preview': hook_code[:100] + '...' if len(hook_code) > 100 else hook_code
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})
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continue
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# Validate structure
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is_valid, message = hook_manager.validate_hook_structure(hook_code, hook_point)
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if not is_valid:
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validation_errors.append({
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'hook_point': hook_point,
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'error': message,
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'code_preview': hook_code[:100] + '...' if len(hook_code) > 100 else hook_code
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})
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continue
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# Compile the hook
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hook_func = hook_manager.compile_hook(hook_code, hook_point)
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if hook_func:
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# Wrap with error isolation
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wrapped_hook = wrapper.create_hook_wrapper(hook_func, hook_point)
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compiled_hooks[hook_point] = wrapped_hook
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logger.info(f"Successfully compiled hook for {hook_point}")
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else:
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validation_errors.append({
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'hook_point': hook_point,
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'error': 'Failed to compile hook function - check syntax and structure',
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'code_preview': hook_code[:100] + '...' if len(hook_code) > 100 else hook_code
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})
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return compiled_hooks, validation_errors
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async def attach_user_hooks_to_crawler(
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crawler, # AsyncWebCrawler instance
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user_hooks: Dict[str, str],
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timeout: int = 30,
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hook_manager: Optional[UserHookManager] = None
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) -> Tuple[Dict[str, Any], UserHookManager]:
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"""
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Attach user-provided hooks to crawler with full error reporting
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Args:
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crawler: AsyncWebCrawler instance
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user_hooks: Dictionary mapping hook points to code strings
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timeout: Timeout for each hook execution
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hook_manager: Optional existing UserHookManager instance
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Returns:
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Tuple of (status_dict, hook_manager)
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"""
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# Use provided hook_manager or create a new one
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if hook_manager is None:
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hook_manager = UserHookManager(timeout=timeout)
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# Process hooks with the hook_manager
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compiled_hooks, validation_errors = await process_user_hooks_with_manager(
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user_hooks, hook_manager
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)
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# Log validation errors
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if validation_errors:
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logger.warning(f"Hook validation errors: {validation_errors}")
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# Attach successfully compiled hooks
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attached_hooks = []
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for hook_point, wrapped_hook in compiled_hooks.items():
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try:
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crawler.crawler_strategy.set_hook(hook_point, wrapped_hook)
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attached_hooks.append(hook_point)
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logger.info(f"Attached hook to {hook_point}")
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except Exception as e:
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logger.error(f"Failed to attach hook to {hook_point}: {e}")
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validation_errors.append({
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'hook_point': hook_point,
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'error': f'Failed to attach hook: {str(e)}'
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})
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status = 'success' if not validation_errors else ('partial' if attached_hooks else 'failed')
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status_dict = {
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'status': status,
|
|
'attached_hooks': attached_hooks,
|
|
'validation_errors': validation_errors,
|
|
'total_hooks_provided': len(user_hooks),
|
|
'successfully_attached': len(attached_hooks),
|
|
'failed_validation': len(validation_errors)
|
|
}
|
|
|
|
return status_dict, hook_manager |