Stop a raise inside a UDF block from deadlocking other threads - #731
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When a block registered with `Database#define_function` raised an exception, the connection was left holding sqlite's per-connection mutex. Any other thread that subsequently used the connection blocked forever while holding the GVL, wedging the entire process. The scalar function callback will now invoke the block under `rb_protect`, following the pattern established by the aggregate handlers in `aggregator.c`: a raise will be converted into `sqlite3_result_error` so that sqlite unwinds and releases its mutex normally, and `Statement#step` will re-raise the original exception to the caller.
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When a block registered with
Database#define_functionraised an exception, the connection was left holding sqlite's per-connection mutex. Any other thread that subsequently used the connection blocked forever while holding the GVL, wedging the entire process.The scalar function callback now invokes the block under
rb_protect, following the pattern established by the aggregate handlers inaggregator.c: a raise is converted intosqlite3_result_errorso that sqlite unwinds and releases its mutex normally, andStatement#stepre-raises the original exception to the caller.