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Safely closes a global database driver connection and sets it to None, with error handling and logging.

Purpose

This function provides a clean shutdown mechanism for a Neo4j database driver connection. It ensures proper resource cleanup by closing the driver connection, logging the operation, and handling any exceptions that may occur during closure. The function manages a global _driver variable and guarantees it's set to None after closure attempts, preventing resource leaks and ensuring the application can safely terminate or reinitialize the connection.

Source Code

def close_driver() -> None:
    """Close the database driver if it exists."""
    global _driver
    
    if (_driver is not None):
        try:
            _driver.close()
            logger.info("Database connection closed")
        except Exception as e:
            logger.error(f"Error closing database connection: {e}")
        finally:
            _driver = None

Return Value

Type: None

Returns None. This function performs side effects (closing the driver and modifying the global _driver variable) but does not return any value.

Dependencies

• logging
• neo4j

Required Imports

import logging
from neo4j import Driver

Usage Example

import logging
from neo4j import GraphDatabase, Driver

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

# Initialize global driver
_driver = None

def close_driver() -> None:
    """Close the database driver if it exists."""
    global _driver
    
    if (_driver is not None):
        try:
            _driver.close()
            logger.info("Database connection closed")
        except Exception as e:
            logger.error(f"Error closing database connection: {e}")
        finally:
            _driver = None

# Example usage
_driver = GraphDatabase.driver("bolt://localhost:7687", auth=("neo4j", "password"))
# ... perform database operations ...
close_driver()  # Clean shutdown of database connection

Best Practices

• Always call this function before application shutdown to ensure proper resource cleanup
• This function should be called after all database operations are complete
• The function is idempotent - it can be safely called multiple times without side effects
• Ensure the global _driver variable is properly initialized before calling this function
• Use this in conjunction with a context manager or try-finally block to guarantee cleanup
• The function uses a finally block to ensure _driver is set to None even if closing fails
• Consider calling this function in signal handlers or application exit hooks for graceful shutdown

Tags

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