execqual.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		/* Need to prep callinfo structure */
		InitFunctionCallInfoData(fcinfo, &(fcache->func), 0, NULL, NULL);
		argDone = ExecEvalFuncArgs(&fcinfo, arguments, econtext);
		if (argDone == ExprEndResult)
		{
			/* input is an empty set, so return an empty set. */
			*isNull = true;
			if (isDone)
				*isDone = ExprEndResult;
			else
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("set-valued function called in context that cannot accept a set")));
			return (Datum) 0;
		}
		hasSetArg = (argDone != ExprSingleResult);
	}
	else
	{
		/* Copy callinfo from previous evaluation */
		memcpy(&fcinfo, &fcache->setArgs, sizeof(fcinfo));
		hasSetArg = fcache->setHasSetArg;
		/* Reset flag (we may set it again below) */
		fcache->setArgsValid = false;
	}

	/*
	 * If function returns set, prepare a resultinfo node for communication
	 */
	if (fcache->func.fn_retset)
	{
		fcinfo.resultinfo = (Node *) &rsinfo;
		rsinfo.type = T_ReturnSetInfo;
		rsinfo.econtext = econtext;
		rsinfo.expectedDesc = NULL;
		rsinfo.allowedModes = (int) SFRM_ValuePerCall;
		rsinfo.returnMode = SFRM_ValuePerCall;
		/* isDone is filled below */
		rsinfo.setResult = NULL;
		rsinfo.setDesc = NULL;
	}

	/*
	 * now return the value gotten by calling the function manager, passing
	 * the function the evaluated parameter values.
	 */
	if (fcache->func.fn_retset || hasSetArg)
	{
		/*
		 * We need to return a set result.	Complain if caller not ready to
		 * accept one.
		 */
		if (isDone == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));

		/*
		 * This loop handles the situation where we have both a set argument
		 * and a set-valued function.  Once we have exhausted the function's
		 * value(s) for a particular argument value, we have to get the next
		 * argument value and start the function over again. We might have to
		 * do it more than once, if the function produces an empty result set
		 * for a particular input value.
		 */
		for (;;)
		{
			/*
			 * If function is strict, and there are any NULL arguments, skip
			 * calling the function (at least for this set of args).
			 */
			bool		callit = true;

			if (fcache->func.fn_strict)
			{
				for (i = 0; i < fcinfo.nargs; i++)
				{
					if (fcinfo.argnull[i])
					{
						callit = false;
						break;
					}
				}
			}

			if (callit)
			{
				fcinfo.isnull = false;
				rsinfo.isDone = ExprSingleResult;
				result = FunctionCallInvoke(&fcinfo);
				*isNull = fcinfo.isnull;
				*isDone = rsinfo.isDone;
			}
			else
			{
				result = (Datum) 0;
				*isNull = true;
				*isDone = ExprEndResult;
			}

			if (*isDone != ExprEndResult)
			{
				/*
				 * Got a result from current argument.	If function itself
				 * returns set, save the current argument values to re-use on
				 * the next call.
				 */
				if (fcache->func.fn_retset && *isDone == ExprMultipleResult)
				{
					memcpy(&fcache->setArgs, &fcinfo, sizeof(fcinfo));
					fcache->setHasSetArg = hasSetArg;
					fcache->setArgsValid = true;
					/* Register cleanup callback if we didn't already */
					if (!fcache->shutdown_reg)
					{
						RegisterExprContextCallback(econtext,
													ShutdownFuncExpr,
													PointerGetDatum(fcache));
						fcache->shutdown_reg = true;
					}
				}

				/*
				 * Make sure we say we are returning a set, even if the
				 * function itself doesn't return sets.
				 */
				if (hasSetArg)
					*isDone = ExprMultipleResult;
				break;
			}

			/* Else, done with this argument */
			if (!hasSetArg)
				break;			/* input not a set, so done */

			/* Re-eval args to get the next element of the input set */
			argDone = ExecEvalFuncArgs(&fcinfo, arguments, econtext);

			if (argDone != ExprMultipleResult)
			{
				/* End of argument set, so we're done. */
				*isNull = true;
				*isDone = ExprEndResult;
				result = (Datum) 0;
				break;
			}

			/*
			 * If we reach here, loop around to run the function on the new
			 * argument.
			 */
		}
	}
	else
	{
		/*
		 * Non-set case: much easier.
		 *
		 * We change the ExprState function pointer to use the simpler
		 * ExecMakeFunctionResultNoSets on subsequent calls.  This amounts to
		 * assuming that no argument can return a set if it didn't do so the
		 * first time.
		 */
		fcache->xprstate.evalfunc = (ExprStateEvalFunc) ExecMakeFunctionResultNoSets;

		if (isDone)
			*isDone = ExprSingleResult;

		/*
		 * If function is strict, and there are any NULL arguments, skip
		 * calling the function and return NULL.
		 */
		if (fcache->func.fn_strict)
		{
			for (i = 0; i < fcinfo.nargs; i++)
			{
				if (fcinfo.argnull[i])
				{
					*isNull = true;
					return (Datum) 0;
				}
			}
		}
		fcinfo.isnull = false;
		result = FunctionCallInvoke(&fcinfo);
		*isNull = fcinfo.isnull;
	}

	return result;
}

/*
 *		ExecMakeFunctionResultNoSets
 *
 * Simplified version of ExecMakeFunctionResult that can only handle
 * non-set cases.  Hand-tuned for speed.
 */
static Datum
ExecMakeFunctionResultNoSets(FuncExprState *fcache,
							 ExprContext *econtext,
							 bool *isNull,
							 ExprDoneCond *isDone)
{
	ListCell   *arg;
	Datum		result;
	FunctionCallInfoData fcinfo;
	int			i;

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	if (isDone)
		*isDone = ExprSingleResult;

	/* inlined, simplified version of ExecEvalFuncArgs */
	i = 0;
	foreach(arg, fcache->args)
	{
		ExprState  *argstate = (ExprState *) lfirst(arg);

		fcinfo.arg[i] = ExecEvalExpr(argstate,
									 econtext,
									 &fcinfo.argnull[i],
									 NULL);
		i++;
	}

	InitFunctionCallInfoData(fcinfo, &(fcache->func), i, NULL, NULL);

	/*
	 * If function is strict, and there are any NULL arguments, skip calling
	 * the function and return NULL.
	 */
	if (fcache->func.fn_strict)
	{
		while (--i >= 0)
		{
			if (fcinfo.argnull[i])
			{
				*isNull = true;
				return (Datum) 0;
			}
		}
	}
	/* fcinfo.isnull = false; */	/* handled by InitFunctionCallInfoData */
	result = FunctionCallInvoke(&fcinfo);
	*isNull = fcinfo.isnull;

	return result;
}


/*
 *		ExecMakeTableFunctionResult
 *
 * Evaluate a table function, producing a materialized result in a Tuplestore
 * object.	*returnDesc is set to the tupledesc actually returned by the
 * function, or NULL if it didn't provide one.
 */
Tuplestorestate *
ExecMakeTableFunctionResult(ExprState *funcexpr,
							ExprContext *econtext,
							TupleDesc expectedDesc,
							TupleDesc *returnDesc)
{
	Tuplestorestate *tupstore = NULL;
	TupleDesc	tupdesc = NULL;
	Oid			funcrettype;
	bool		returnsTuple;
	bool		returnsSet = false;
	FunctionCallInfoData fcinfo;
	ReturnSetInfo rsinfo;
	HeapTupleData tmptup;
	MemoryContext callerContext;
	MemoryContext oldcontext;
	bool		direct_function_call;
	bool		first_time = true;

	callerContext = CurrentMemoryContext;

	funcrettype = exprType((Node *) funcexpr->expr);

	returnsTuple = (funcrettype == RECORDOID ||
					get_typtype(funcrettype) == 'c');

	/*
	 * Prepare a resultinfo node for communication.  We always do this even if
	 * not expecting a set result, so that we can pass expectedDesc.  In the
	 * generic-expression case, the expression doesn't actually get to see the
	 * resultinfo, but set it up anyway because we use some of the fields as
	 * our own state variables.
	 */
	InitFunctionCallInfoData(fcinfo, NULL, 0, NULL, (Node *) &rsinfo);
	rsinfo.type = T_ReturnSetInfo;
	rsinfo.econtext = econtext;
	rsinfo.expectedDesc = expectedDesc;
	rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize);
	rsinfo.returnMode = SFRM_ValuePerCall;
	/* isDone is filled below */
	rsinfo.setResult = NULL;
	rsinfo.setDesc = NULL;

	/*
	 * Normally the passed expression tree will be a FuncExprState, since the
	 * grammar only allows a function call at the top level of a table
	 * function reference.	However, if the function doesn't return set then
	 * the planner might have replaced the function call via constant-folding
	 * or inlining.  So if we see any other kind of expression node, execute
	 * it via the general ExecEvalExpr() code; the only difference is that we
	 * don't get a chance to pass a special ReturnSetInfo to any functions
	 * buried in the expression.
	 */
	if (funcexpr && IsA(funcexpr, FuncExprState) &&
		IsA(funcexpr->expr, FuncExpr))
	{
		FuncExprState *fcache = (FuncExprState *) funcexpr;
		ExprDoneCond argDone;

		/*
		 * This path is similar to ExecMakeFunctionResult.
		 */
		direct_function_call = true;

		/*
		 * Initialize function cache if first time through
		 */
		if (fcache->func.fn_oid == InvalidOid)
		{
			FuncExpr   *func = (FuncExpr *) fcache->xprstate.expr;

			init_fcache(func->funcid, fcache, econtext->ecxt_per_query_memory);
		}
		returnsSet = fcache->func.fn_retset;

		/*
		 * Evaluate the function's argument list.
		 *
		 * Note: ideally, we'd do this in the per-tuple context, but then the
		 * argument values would disappear when we reset the context in the
		 * inner loop.	So do it in caller context.  Perhaps we should make a
		 * separate context just to hold the evaluated arguments?
		 */
		fcinfo.flinfo = &(fcache->func);
		argDone = ExecEvalFuncArgs(&fcinfo, fcache->args, econtext);
		/* We don't allow sets in the arguments of the table function */
		if (argDone != ExprSingleResult)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));

		/*
		 * If function is strict, and there are any NULL arguments, skip
		 * calling the function and act like it returned NULL (or an empty
		 * set, in the returns-set case).
		 */
		if (fcache->func.fn_strict)
		{
			int			i;

			for (i = 0; i < fcinfo.nargs; i++)
			{
				if (fcinfo.argnull[i])
					goto no_function_result;
			}
		}
	}
	else
	{
		/* Treat funcexpr as a generic expression */
		direct_function_call = false;
	}

	/*
	 * Switch to short-lived context for calling the function or expression.
	 */
	MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);

	/*
	 * Loop to handle the ValuePerCall protocol (which is also the same
	 * behavior needed in the generic ExecEvalExpr path).
	 */
	for (;;)
	{
		Datum		result;
		HeapTuple	tuple;

		CHECK_FOR_INTERRUPTS();

		/*
		 * reset per-tuple memory context before each call of the function or
		 * expression. This cleans up any local memory the function may leak
		 * when called.
		 */
		ResetExprContext(econtext);

		/* Call the function or expression one time */
		if (direct_function_call)
		{
			fcinfo.isnull = false;
			rsinfo.isDone = ExprSingleResult;
			result = FunctionCallInvoke(&fcinfo);
		}
		else
		{
			result = ExecEvalExpr(funcexpr, econtext,
								  &fcinfo.isnull, &rsinfo.isDone);
		}

		/* Which protocol does function want to use? */
		if (rsinfo.returnMode == SFRM_ValuePerCall)
		{
			/*
			 * Check for end of result set.
			 */
			if (rsinfo.isDone == ExprEndResult)
				break;

			/*
			 * Can't do anything very useful with NULL rowtype values. For a
			 * function returning set, we consider this a protocol violation
			 * (but another alternative would be to just ignore the result and
			 * "continue" to get another row).	For a function not returning
			 * set, we fall out of the loop; we'll cons up an all-nulls result
			 * row below.
			 */
			if (returnsTuple && fcinfo.isnull)
			{
				if (!returnsSet)
					break;
				ereport(ERROR,
						(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
						 errmsg("function returning set of rows cannot return null value")));
			}

			/*
			 * If first time through, build tupdesc and tuplestore for result
			 */
			if (first_time)
			{
				oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
				if (returnsTuple)
				{
					/*
					 * Use the type info embedded in the rowtype Datum to look
					 * up the needed tupdesc.  Make a copy for the query.
					 */
					HeapTupleHeader td;

					td = DatumGetHeapTupleHeader(result);
					tupdesc = lookup_rowtype_tupdesc(HeapTupleHeaderGetTypeId(td),
											   HeapTupleHeaderGetTypMod(td));
					tupdesc = CreateTupleDescCopy(tupdesc);
				}
				else
				{