Exception Handling

class KombuError(Exception):
    """
    Common base class for all Kombu exceptions.
    
    All Kombu-specific exceptions inherit from this class,
    making it easy to catch any Kombu-related error.
    """

class OperationalError(KombuError):
    """
    Recoverable message transport connection error.
    
    Indicates a temporary error that may be resolved by retrying
    the operation, such as network connectivity issues or
    temporary broker unavailability.
    """

class SerializationError(KombuError):
    """
    Failed to serialize or deserialize message content.
    
    Base class for all serialization-related errors.
    """

class EncodeError(SerializationError):
    """
    Cannot encode object for serialization.
    
    Raised when an object cannot be serialized using the
    specified serialization method.
    """

class DecodeError(SerializationError):
    """
    Cannot decode serialized data.
    
    Raised when serialized data cannot be deserialized,
    either due to corruption or incompatible format.
    """

class NotBoundError(KombuError):
    """
    Trying to call channel method on unbound entity.
    
    Raised when attempting to perform operations on exchanges,
    queues, or other entities that haven't been bound to a channel.
    """

class MessageStateError(KombuError):
    """
    Message already acknowledged or in invalid state.
    
    Raised when attempting to acknowledge, reject, or requeue
    a message that has already been processed.
    """

class LimitExceeded(KombuError):
    """
    Generic limit exceeded error.
    
    Base class for various limit-related exceptions.
    """

class ConnectionLimitExceeded(LimitExceeded):
    """
    Maximum number of simultaneous connections exceeded.
    
    Raised when attempting to create more connections than
    allowed by broker or client configuration.
    """

class ChannelLimitExceeded(LimitExceeded):
    """
    Maximum number of channels per connection exceeded.
    
    Raised when attempting to create more channels than
    allowed per connection.
    """

class VersionMismatch(KombuError):
    """
    Library dependency version mismatch.
    
    Raised when required library versions are incompatible
    with current Kombu version or each other.
    """

class SerializerNotInstalled(SerializationError):
    """
    Required serialization library not installed.
    
    Raised when attempting to use a serializer (like msgpack
    or yaml) that requires additional packages not installed.
    """

class ContentDisallowed(KombuError):
    """
    Consumer doesn't accept this content type.
    
    Raised when attempting to deliver a message with content
    type not in the consumer's accept list.
    """

class InconsistencyError(KombuError):
    """
    Data or environment inconsistency detected.
    
    Raised when internal state inconsistencies are detected
    that may indicate configuration or data corruption issues.
    """

class HttpError(KombuError):
    """
    HTTP client error.
    
    Raised by HTTP-based transports when HTTP operations fail.
    """

def reraise(tp, value, tb=None):
    """
    Reraise exception with preserved traceback.
    
    Parameters:
    - tp (type): Exception type
    - value (Exception): Exception instance
    - tb (traceback): Traceback object (optional)
    
    Raises:
    The provided exception with preserved traceback information.
    """

from kombu import Connection, Producer, Consumer, Queue
from kombu.exceptions import (
    KombuError, OperationalError, SerializationError,
    NotBoundError, MessageStateError
)

def robust_message_handling():
    try:
        with Connection('redis://localhost:6379/0') as conn:
            queue = Queue('test_queue')
            
            # This might raise NotBoundError if queue not bound
            queue.declare(channel=conn.channel())
            
            producer = Producer(conn.channel())
            producer.publish({'message': 'hello'}, routing_key='test')
            
    except OperationalError as e:
        print(f"Connection/transport error: {e}")
        # Could implement retry logic here
        
    except SerializationError as e:
        print(f"Serialization error: {e}")
        # Handle serialization issues
        
    except NotBoundError as e:
        print(f"Entity not bound to channel: {e}")
        # Fix binding issues
        
    except KombuError as e:
        print(f"Generic Kombu error: {e}")
        # Handle any other Kombu-specific errors
        
    except Exception as e:
        print(f"Unexpected error: {e}")
        # Handle non-Kombu errors

from kombu import Connection, Consumer, Queue
from kombu.exceptions import MessageStateError, DecodeError

def safe_message_processor(body, message):
    """Process message with comprehensive error handling"""
    try:
        # Process the message
        result = process_business_logic(body)
        
        # Acknowledge successful processing
        try:
            message.ack()
        except MessageStateError:
            print("Message already acknowledged")
            
    except DecodeError as e:
        print(f"Failed to decode message: {e}")
        # Reject malformed messages without requeue
        try:
            message.reject(requeue=False)
        except MessageStateError:
            pass  # Already processed
            
    except ValueError as e:
        print(f"Business logic error: {e}")
        # Requeue for retry
        try:
            message.reject(requeue=True)
        except MessageStateError:
            pass  # Already processed
            
    except Exception as e:
        print(f"Unexpected processing error: {e}")
        # Decide whether to requeue or reject
        try:
            message.reject(requeue=False)  # Don't requeue unknown errors
        except MessageStateError:
            pass

def process_business_logic(data):
    """Business logic that might fail"""
    if not isinstance(data, dict):
        raise ValueError("Expected dict data")
    
    if 'required_field' not in data:
        raise ValueError("Missing required field")
    
    return {'processed': True, 'result': data['required_field'] * 2}

# Usage
with Connection('redis://localhost:6379/0') as conn:
    queue = Queue('error_handling_queue')
    consumer = Consumer(conn.channel(), [queue], callbacks=[safe_message_processor])
    consumer.consume()
    
    # Process messages with error handling
    conn.drain_events(timeout=1.0)

from kombu import Connection
from kombu.exceptions import OperationalError, ConnectionLimitExceeded
import time
import random

def robust_connection_handler(broker_url, max_retries=5):
    """Handle connection with retry logic"""
    retry_count = 0
    backoff_base = 1
    
    while retry_count < max_retries:
        try:
            conn = Connection(broker_url)
            conn.connect()  # Explicit connection
            
            print("Connection established successfully")
            return conn
            
        except ConnectionLimitExceeded as e:
            print(f"Connection limit exceeded: {e}")
            # This might not be retryable
            time.sleep(backoff_base * (2 ** retry_count))
            retry_count += 1
            
        except OperationalError as e:
            print(f"Operational error (attempt {retry_count + 1}): {e}")
            
            # Exponential backoff with jitter
            sleep_time = backoff_base * (2 ** retry_count) + random.uniform(0, 1)
            print(f"Retrying in {sleep_time:.2f} seconds...")
            time.sleep(sleep_time)
            retry_count += 1
            
        except Exception as e:
            print(f"Unexpected connection error: {e}")
            break
    
    print(f"Failed to establish connection after {max_retries} attempts")
    return None

# Usage
conn = robust_connection_handler('redis://localhost:6379/0')
if conn:
    try:
        # Use connection
        with conn:
            # Perform operations
            pass
    finally:
        conn.close()

from kombu.serialization import dumps, loads, enable_insecure_serializers
from kombu.exceptions import EncodeError, DecodeError, SerializerNotInstalled

def safe_serialization_test():
    """Test serialization with error handling"""
    
    # Test data
    serializable_data = {'message': 'hello', 'number': 42}
    unserializable_data = {'function': lambda x: x}  # Functions can't be serialized with JSON
    
    # Test JSON serialization (safe)
    try:
        serialized, content_type, encoding = dumps(serializable_data, 'json')
        deserialized = loads(serialized, content_type, encoding)
        print(f"JSON serialization successful: {deserialized}")
    except EncodeError as e:
        print(f"JSON encode error: {e}")
    except DecodeError as e:
        print(f"JSON decode error: {e}")
    
    # Test with unserializable data
    try:
        serialized, content_type, encoding = dumps(unserializable_data, 'json')
    except EncodeError as e:
        print(f"Expected JSON encode error: {e}")
    
    # Test unavailable serializer
    try:
        enable_insecure_serializers(['nonexistent'])
        serialized, content_type, encoding = dumps(serializable_data, 'nonexistent')
    except SerializerNotInstalled as e:
        print(f"Serializer not available: {e}")
    except KeyError as e:
        print(f"Unknown serializer: {e}")
    
    # Test corrupted data
    try:
        corrupted_data = b'{"invalid": json'
        deserialized = loads(corrupted_data, 'application/json')
    except DecodeError as e:
        print(f"Expected decode error: {e}")

safe_serialization_test()

from kombu import Connection, Consumer, Queue
from kombu.exceptions import KombuError, OperationalError, SerializationError
import logging
import traceback
from datetime import datetime

# Setup logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class ErrorTrackingConsumer:
    def __init__(self, connection, queues):
        self.connection = connection
        self.queues = queues
        self.error_counts = {}
    
    def process_message(self, body, message):
        """Process message with detailed error tracking"""
        message_id = body.get('id', 'unknown')
        
        try:
            # Simulate processing
            if body.get('should_fail'):
                raise ValueError("Simulated processing failure")
            
            logger.info(f"Successfully processed message {message_id}")
            message.ack()
            
        except Exception as exc:
            self.handle_processing_error(exc, message, message_id)
    
    def handle_processing_error(self, exc, message, message_id):
        """Handle and log processing errors"""
        error_type = type(exc).__name__
        
        # Track error counts
        self.error_counts[error_type] = self.error_counts.get(error_type, 0) + 1
        
        # Log error details
        logger.error(f"Processing error for message {message_id}: {exc}")
        logger.error(f"Error type: {error_type}")
        logger.error(f"Total {error_type} errors: {self.error_counts[error_type]}")
        
        # Log stack trace for debugging
        logger.debug(traceback.format_exc())
        
        # Handle different error types
        if isinstance(exc, SerializationError):
            logger.error("Serialization error - rejecting message")
            message.reject(requeue=False)
            
        elif isinstance(exc, ValueError):
            logger.warning("Business logic error - requeuing for retry")
            message.reject(requeue=True)
            
        elif isinstance(exc, KombuError):
            logger.error("Kombu-specific error - investigating")
            message.reject(requeue=False)
            
        else:
            logger.error("Unknown error type - rejecting without requeue")
            message.reject(requeue=False)
    
    def run(self):
        """Main consumer loop with connection error handling"""
        while True:
            try:
                consumer = Consumer(
                    self.connection.channel(),
                    self.queues,
                    callbacks=[self.process_message]
                )
                
                consumer.consume()
                
                while True:
                    self.connection.drain_events(timeout=1.0)
                    
            except OperationalError as e:
                logger.error(f"Connection error: {e}")
                logger.info("Attempting to reconnect...")
                time.sleep(5)
                continue
                
            except KeyboardInterrupt:
                logger.info("Shutting down consumer...")
                break
                
            except Exception as e:
                logger.error(f"Unexpected error: {e}")
                logger.error(traceback.format_exc())
                break
        
        # Print final error summary
        if self.error_counts:
            logger.info("Error summary:")
            for error_type, count in self.error_counts.items():
                logger.info(f"  {error_type}: {count} occurrences")

# Usage
if __name__ == '__main__':
    with Connection('redis://localhost:6379/0') as conn:
        queue = Queue('error_tracking_queue')
        consumer = ErrorTrackingConsumer(conn, [queue])
        consumer.run()

from kombu.exceptions import KombuError

class CustomProcessingError(KombuError):
    """Custom error for application-specific failures"""
    def __init__(self, message, error_code=None, retry_after=None):
        super().__init__(message)
        self.error_code = error_code
        self.retry_after = retry_after

class DataValidationError(CustomProcessingError):
    """Error for data validation failures"""
    pass

class ExternalServiceError(CustomProcessingError):
    """Error for external service failures"""
    pass

def process_with_custom_errors(body, message):
    """Process message with custom error types"""
    try:
        # Validate data
        if not body.get('user_id'):
            raise DataValidationError(
                "Missing user_id field",
                error_code='MISSING_USER_ID'
            )
        
        # Call external service
        if body.get('external_service_down'):
            raise ExternalServiceError(
                "External service unavailable",
                error_code='SERVICE_DOWN',
                retry_after=300  # Retry after 5 minutes
            )
        
        # Process successfully
        message.ack()
        
    except DataValidationError as e:
        logger.error(f"Validation error: {e} (code: {e.error_code})")
        message.reject(requeue=False)  # Don't retry validation errors
        
    except ExternalServiceError as e:
        logger.warning(f"Service error: {e} (retry after: {e.retry_after}s)")
        message.reject(requeue=True)  # Retry service errors
        
    except CustomProcessingError as e:
        logger.error(f"Custom processing error: {e}")
        message.reject(requeue=False)
        
    except Exception as e:
        logger.error(f"Unexpected error: {e}")
        message.reject(requeue=False)

from kombu import Connection
from kombu.exceptions import KombuError
import sys

def debug_kombu_exceptions():
    """Demonstrate exception information and debugging"""
    
    try:
        # Simulate various Kombu errors
        conn = Connection('invalid://broker:9999')
        conn.connect()
        
    except KombuError as e:
        print("Kombu Exception Details:")
        print(f"  Type: {type(e).__name__}")
        print(f"  Message: {str(e)}")
        print(f"  Module: {e.__class__.__module__}")
        
        # Print exception hierarchy
        print("  Exception hierarchy:")
        for cls in type(e).__mro__:
            if cls == object:
                break
            print(f"    {cls.__name__}")
        
        # Print traceback for debugging
        import traceback
        print("  Traceback:")
        traceback.print_exc()
        
    except Exception as e:
        print(f"Non-Kombu exception: {type(e).__name__}: {e}")

debug_kombu_exceptions()