functions.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

			dtuptypmod = -1;
		}
		else
		{
			/* function is declared to return RECORD */
			TupleDesc	tupDesc = fcache->junkFilter->jf_cleanTupType;

			if (tupDesc->tdtypeid == RECORDOID &&
				tupDesc->tdtypmod < 0)
				assign_record_type_typmod(tupDesc);
			dtuptype = tupDesc->tdtypeid;
			dtuptypmod = tupDesc->tdtypmod;
		}

		HeapTupleHeaderSetDatumLength(dtup, t_len);
		HeapTupleHeaderSetTypeId(dtup, dtuptype);
		HeapTupleHeaderSetTypMod(dtup, dtuptypmod);

		value = PointerGetDatum(dtup);
		fcinfo->isnull = false;
	}
	else
	{
		/*
		 * Returning a scalar, which we have to extract from the first column
		 * of the SELECT result, and then copy into result context if needed.
		 */
		value = slot_getattr(slot, 1, &(fcinfo->isnull));

		if (!fcinfo->isnull)
			value = datumCopy(value, fcache->typbyval, fcache->typlen);
	}

	MemoryContextSwitchTo(oldcontext);

	/*
	 * If this is a single valued function we have to end the function
	 * execution now.
	 */
	if (!fcinfo->flinfo->fn_retset)
		postquel_end(es);

	return value;
}

Datum
fmgr_sql(PG_FUNCTION_ARGS)
{
	MemoryContext oldcontext;
	SQLFunctionCachePtr fcache;
	ErrorContextCallback sqlerrcontext;
	execution_state *es;
	Datum		result = 0;

	/*
	 * Switch to context in which the fcache lives.  This ensures that
	 * parsetrees, plans, etc, will have sufficient lifetime.  The
	 * sub-executor is responsible for deleting per-tuple information.
	 */
	oldcontext = MemoryContextSwitchTo(fcinfo->flinfo->fn_mcxt);

	/*
	 * Setup error traceback support for ereport()
	 */
	sqlerrcontext.callback = sql_exec_error_callback;
	sqlerrcontext.arg = fcinfo->flinfo;
	sqlerrcontext.previous = error_context_stack;
	error_context_stack = &sqlerrcontext;

	/*
	 * Initialize fcache (build plans) if first time through.
	 */
	fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
	if (fcache == NULL)
	{
		init_sql_fcache(fcinfo->flinfo);
		fcache = (SQLFunctionCachePtr) fcinfo->flinfo->fn_extra;
	}
	es = fcache->func_state;

	/*
	 * Convert params to appropriate format if starting a fresh execution. (If
	 * continuing execution, we can re-use prior params.)
	 */
	if (es && es->status == F_EXEC_START)
		postquel_sub_params(fcache, fcinfo);

	/*
	 * Find first unfinished query in function.
	 */
	while (es && es->status == F_EXEC_DONE)
		es = es->next;

	/*
	 * Execute each command in the function one after another until we're
	 * executing the final command and get a result or we run out of commands.
	 */
	while (es)
	{
		result = postquel_execute(es, fcinfo, fcache, oldcontext);
		if (es->status != F_EXEC_DONE)
			break;
		es = es->next;
	}

	/*
	 * If we've gone through every command in this function, we are done.
	 */
	if (es == NULL)
	{
		/*
		 * Reset the execution states to start over again on next call.
		 */
		es = fcache->func_state;
		while (es)
		{
			es->status = F_EXEC_START;
			es = es->next;
		}

		/*
		 * Let caller know we're finished.
		 */
		if (fcinfo->flinfo->fn_retset)
		{
			ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;

			if (rsi && IsA(rsi, ReturnSetInfo))
				rsi->isDone = ExprEndResult;
			else
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("set-valued function called in context that cannot accept a set")));
			fcinfo->isnull = true;
			result = (Datum) 0;

			/* Deregister shutdown callback, if we made one */
			if (fcache->shutdown_reg)
			{
				UnregisterExprContextCallback(rsi->econtext,
											  ShutdownSQLFunction,
											  PointerGetDatum(fcache));
				fcache->shutdown_reg = false;
			}
		}

		error_context_stack = sqlerrcontext.previous;

		MemoryContextSwitchTo(oldcontext);

		return result;
	}

	/*
	 * If we got a result from a command within the function it has to be the
	 * final command.  All others shouldn't be returning anything.
	 */
	Assert(LAST_POSTQUEL_COMMAND(es));

	/*
	 * Let caller know we're not finished.
	 */
	if (fcinfo->flinfo->fn_retset)
	{
		ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;

		if (rsi && IsA(rsi, ReturnSetInfo))
			rsi->isDone = ExprMultipleResult;
		else
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));

		/*
		 * Ensure we will get shut down cleanly if the exprcontext is not run
		 * to completion.
		 */
		if (!fcache->shutdown_reg)
		{
			RegisterExprContextCallback(rsi->econtext,
										ShutdownSQLFunction,
										PointerGetDatum(fcache));
			fcache->shutdown_reg = true;
		}
	}

	error_context_stack = sqlerrcontext.previous;

	MemoryContextSwitchTo(oldcontext);

	return result;
}


/*
 * error context callback to let us supply a call-stack traceback
 */
static void
sql_exec_error_callback(void *arg)
{
	FmgrInfo   *flinfo = (FmgrInfo *) arg;
	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) flinfo->fn_extra;
	HeapTuple	func_tuple;
	Form_pg_proc functup;
	char	   *fn_name;
	int			syntaxerrposition;

	/* Need access to function's pg_proc tuple */
	func_tuple = SearchSysCache(PROCOID,
								ObjectIdGetDatum(flinfo->fn_oid),
								0, 0, 0);
	if (!HeapTupleIsValid(func_tuple))
		return;					/* shouldn't happen */
	functup = (Form_pg_proc) GETSTRUCT(func_tuple);
	fn_name = NameStr(functup->proname);

	/*
	 * If there is a syntax error position, convert to internal syntax error
	 */
	syntaxerrposition = geterrposition();
	if (syntaxerrposition > 0)
	{
		bool		isnull;
		Datum		tmp;
		char	   *prosrc;

		tmp = SysCacheGetAttr(PROCOID, func_tuple, Anum_pg_proc_prosrc,
							  &isnull);
		if (isnull)
			elog(ERROR, "null prosrc");
		prosrc = DatumGetCString(DirectFunctionCall1(textout, tmp));
		errposition(0);
		internalerrposition(syntaxerrposition);
		internalerrquery(prosrc);
		pfree(prosrc);
	}

	/*
	 * Try to determine where in the function we failed.  If there is a query
	 * with non-null QueryDesc, finger it.	(We check this rather than looking
	 * for F_EXEC_RUN state, so that errors during ExecutorStart or
	 * ExecutorEnd are blamed on the appropriate query; see postquel_start and
	 * postquel_end.)
	 */
	if (fcache)
	{
		execution_state *es;
		int			query_num;

		es = fcache->func_state;
		query_num = 1;
		while (es)
		{
			if (es->qd)
			{
				errcontext("SQL function \"%s\" statement %d",
						   fn_name, query_num);
				break;
			}
			es = es->next;
			query_num++;
		}
		if (es == NULL)
		{
			/*
			 * couldn't identify a running query; might be function entry,
			 * function exit, or between queries.
			 */
			errcontext("SQL function \"%s\"", fn_name);
		}
	}
	else
	{
		/* must have failed during init_sql_fcache() */
		errcontext("SQL function \"%s\" during startup", fn_name);
	}

	ReleaseSysCache(func_tuple);
}


/*
 * callback function in case a function-returning-set needs to be shut down
 * before it has been run to completion
 */
static void
ShutdownSQLFunction(Datum arg)
{
	SQLFunctionCachePtr fcache = (SQLFunctionCachePtr) DatumGetPointer(arg);
	execution_state *es = fcache->func_state;

	while (es != NULL)
	{
		/* Shut down anything still running */
		if (es->status == F_EXEC_RUN)
			postquel_end(es);
		/* Reset states to START in case we're called again */
		es->status = F_EXEC_START;
		es = es->next;
	}

	/* execUtils will deregister the callback... */
	fcache->shutdown_reg = false;
}


/*
 * check_sql_fn_retval() -- check return value of a list of sql parse trees.
 *
 * The return value of a sql function is the value returned by
 * the final query in the function.  We do some ad-hoc type checking here
 * to be sure that the user is returning the type he claims.
 *
 * This is normally applied during function definition, but in the case
 * of a function with polymorphic arguments, we instead apply it during
 * function execution startup.	The rettype is then the actual resolved
 * output type of the function, rather than the declared type.	(Therefore,
 * we should never see ANYARRAY or ANYELEMENT as rettype.)
 *
 * The return value is true if the function returns the entire tuple result
 * of its final SELECT, and false otherwise.  Note that because we allow
 * "SELECT rowtype_expression", this may be false even when the declared
 * function return type is a rowtype.
 *
 * If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
 * to convert the function's tuple result to the correct output tuple type.
 * Whenever the result value is false (ie, the function isn't returning a
 * tuple result), *junkFilter is set to NULL.
 */
bool
check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
					JunkFilter **junkFilter)
{
	Query	   *parse;
	int			cmd;
	List	   *tlist;
	ListCell   *tlistitem;
	int			tlistlen;
	char		fn_typtype;
	Oid			restype;

	if (junkFilter)
		*junkFilter = NULL;		/* default result */

	/* guard against empty function body; OK only if void return type */
	if (queryTreeList == NIL)
	{
		if (rettype != VOIDOID)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
			 errmsg("return type mismatch in function declared to return %s",
					format_type_be(rettype)),
				 errdetail("Function's final statement must be a SELECT.")));
		return false;
	}

	/* find the final query */
	parse = (Query *) lfirst(list_tail(queryTreeList));

	cmd = parse->commandType;
	tlist = parse->targetList;

	/*
	 * The last query must be a SELECT if and only if return type isn't VOID.
	 */
	if (rettype == VOIDOID)
	{
		if (cmd == CMD_SELECT)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
			 errmsg("return type mismatch in function declared to return %s",
					format_type_be(rettype)),
			 errdetail("Function's final statement must not be a SELECT.")));
		return false;
	}

	/* by here, the function is declared to return some type */
	if (cmd != CMD_SELECT)
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
			 errmsg("return type mismatch in function declared to return %s",
					format_type_be(rettype)),
				 errdetail("Function's final statement must be a SELECT.")));

	/*
	 * Count the non-junk entries in the result targetlist.
	 */
	tlistlen = ExecCleanTargetListLength(tlist);

	fn_typtype = get_typtype(rettype);

	if (fn_typtype == 'b' || fn_typtype == 'd')
	{
		/*
		 * For base-type returns, the target list should have exactly one
		 * entry, and its type should agree with what the user declared. (As
		 * of Postgres 7.2, we accept binary-compatible types too.)
		 */
		if (tlistlen != 1)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
			 errmsg("return type mismatch in function declared to return %s",
					format_type_be(rettype)),
				 errdetail("Final SELECT must return exactly one column.")));

		restype = exprType((Node *) ((TargetEntry *) linitial(tlist))->expr);
		if (!IsBinaryCoercible(restype, rettype))
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
			 errmsg("return type mismatch in function declared to return %s",
					format_type_be(rettype)),
					 errdetail("Actual return type is %s.",
							   format_type_be(restype))));
	}
	else if (fn_typtype == 'c' || rettype == RECORDOID)
	{
		/* Returns a rowtype */
		TupleDesc	tupdesc;
		int			tupnatts;	/* physical number of columns in tuple */
		int			tuplogcols; /* # of nondeleted columns in tuple */
		int			colindex;	/* physical column index */

		/*
		 * If the target list is of length 1, and the type of the varnode in
		 * the target list matches the declared return type, this is okay.
		 * This can happen, for example, where the body of the function is
		 * 'SELECT func2()', where func2 has the same return type as the
		 * function that's calling it.
		 */
		if (tlistlen == 1)
		{
			restype = exprType((Node *) ((TargetEntry *) linitial(tlist))->expr);
			if (IsBinaryCoercible(restype, rettype))
				return false;	/* NOT returning whole tuple */
		}

		/* Is the rowtype fixed, or determined only at runtime? */
		if (get_func_result_type(func_id, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
		{
			/*
			 * Assume we are returning the whole tuple. Crosschecking against
			 * what the caller expects will happen at runtime.
			 */
			if (junkFilter)
				*junkFilter = ExecInitJunkFilter(tlist, false, NULL);
			return true;
		}
		Assert(tupdesc);

		/*
		 * Verify that the targetlist matches the return tuple type. We scan
		 * the non-deleted attributes to ensure that they match the datatypes
		 * of the non-resjunk columns.
		 */
		tupnatts = tupdesc->natts;
		tuplogcols = 0;			/* we'll count nondeleted cols as we go */
		colindex = 0;

		foreach(tlistitem, tlist)
		{
			TargetEntry *tle = (TargetEntry *) lfirst(tlistitem);
			Form_pg_attribute attr;
			Oid			tletype;
			Oid			atttype;

			if (tle->resjunk)
				continue;

			do
			{
				colindex++;
				if (colindex > tupnatts)
					ereport(ERROR,
							(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
							 errmsg("return type mismatch in function declared to return %s",
									format_type_be(rettype)),
					   errdetail("Final SELECT returns too many columns.")));
				attr = tupdesc->attrs[colindex - 1];
			} while (attr->attisdropped);
			tuplogcols++;

			tletype = exprType((Node *) tle->expr);
			atttype = attr->atttypid;
			if (!IsBinaryCoercible(tletype, atttype))
				ereport(ERROR,
						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
						 errmsg("return type mismatch in function declared to return %s",
								format_type_be(rettype)),
						 errdetail("Final SELECT returns %s instead of %s at column %d.",
								   format_type_be(tletype),
								   format_type_be(atttype),
								   tuplogcols)));
		}

		for (;;)
		{
			colindex++;
			if (colindex > tupnatts)
				break;
			if (!tupdesc->attrs[colindex - 1]->attisdropped)
				tuplogcols++;
		}

		if (tlistlen != tuplogcols)
			ereport(ERROR,
					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
			 errmsg("return type mismatch in function declared to return %s",
					format_type_be(rettype)),
					 errdetail("Final SELECT returns too few columns.")));

		/* Set up junk filter if needed */
		if (junkFilter)
			*junkFilter = ExecInitJunkFilterConversion(tlist,
												CreateTupleDescCopy(tupdesc),
													   NULL);

		/* Report that we are returning entire tuple result */
		return true;
	}
	else if (rettype == ANYARRAYOID || rettype == ANYELEMENTOID)
	{
		/* This should already have been caught ... */
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
				 errmsg("cannot determine result data type"),
				 errdetail("A function returning \"anyarray\" or \"anyelement\" must have at least one argument of either type.")));
	}
	else
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
				 errmsg("return type %s is not supported for SQL functions",
						format_type_be(rettype))));

	return false;
}