Function setup_param_list

src/pl/plpgsql/src/pl_exec.c:6185–6231

* Create a ParamListInfo to pass to SPI * * We use a single ParamListInfo struct for all SPI calls made to evaluate * PLpgSQL_exprs in this estate. It contains no per-param data, just hook * functions, so it's effectively read-only for SPI. * * An exception from pure read-only-ness is that the parserSetupArg points * to the specific PLpgSQL_expr being evaluated. This is not an issue for

 * that seems like a waste of memory.)
 */
static ParamListInfo
setup_param_list(PLpgSQL_execstate *estate, PLpgSQL_expr *expr)
{
	ParamListInfo paramLI;

	/*
	 * We must have created the SPIPlan already (hence, query text has been
	 * parsed/analyzed at least once); else we cannot rely on expr->paramnos.
	 */
	Assert(expr->plan != NULL);

	/*
	 * We only need a ParamListInfo if the expression has parameters.  In
	 * principle we should test with bms_is_empty(), but we use a not-null
	 * test because it's faster.  In current usage bits are never removed from
	 * expr->paramnos, only added, so this test is correct anyway.
	 */
	if (expr->paramnos)
	{
		/* Use the common ParamListInfo */
		paramLI = estate->paramLI;

		/*
		 * Set up link to active expr where the hook functions can find it.
		 * Callers must save and restore parserSetupArg if there is any chance
		 * that they are interrupting an active use of parameters.
		 */
		paramLI->parserSetupArg = (void *) expr;

		/*
		 * Also make sure this is set before parser hooks need it.  There is
		 * no need to save and restore, since the value is always correct once
		 * set.  (Should be set already, but let's be sure.)
		 */
		expr->func = estate->func;
	}
	else
	{
		/*
		 * Expression requires no parameters.  Be sure we represent this case
		 * as a NULL ParamListInfo, so that plancache.c knows there is no
		 * point in a custom plan.
		 */
		paramLI = NULL;
	}
	return paramLI;
}

/*
 * plpgsql_param_fetch		paramFetch callback for dynamic parameter fetch