sqlite3_busy_handler

sqlite3_busy_handler is a callback function in SQLite that is used to handle database busy errors. When two or more processes try to access the same database at the same time, SQLite returns a busy error. In such cases, the busy handler function is called to allow the application to retry the operation after a certain amount of time or to cancel the operation altogether.

The syntax of sqlite3_busy_handler is as follows:

int sqlite3_busy_handler(sqlite3* db, int (*callback)(void*, int), void* data);

Here, db is a pointer to the SQLite database that needs to be monitored for busy errors. The callback function is the user-defined function that will be called when a busy error occurs. The data parameter is a pointer to user-defined data that will be passed to the callback function.

The callback function should return 0 to retry the operation, or non-zero to cancel the operation. The callback function can also use the data parameter to pass additional information to the application.

The sqlite3_busy_handler function can be used to implement custom retry logic for the application when it encounters busy errors. By default, SQLite will retry the operation indefinitely until it succeeds or until the application cancels the operation. However, this can cause performance issues in high-concurrency environments. Therefore, using a custom busy handler can help to manage these issues and improve the overall performance of the application.