postgres.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,551 行 · 第 1/5 页

	{
		Query	   *query = (Query *) lfirst(portal->parseTrees);

		if (query->commandType == CMD_UTILITY &&
			query->utilityStmt != NULL &&
			IsA(query->utilityStmt, TransactionStmt))
		{
			TransactionStmt *stmt = (TransactionStmt *) query->utilityStmt;

			is_trans_stmt = true;
			if (stmt->kind == TRANS_STMT_COMMIT ||
				stmt->kind == TRANS_STMT_ROLLBACK)
				is_trans_exit = true;
		}
	}

	/*
	 * Create dest receiver in MessageContext (we don't want it in
	 * transaction context, because that may get deleted if portal
	 * contains VACUUM).
	 */
	receiver = CreateDestReceiver(dest, portal);

	/*
	 * Ensure we are in a transaction command (this should normally be the
	 * case already due to prior BIND).
	 */
	start_xact_command();

	/*
	 * If we are in aborted transaction state, the only portals we can
	 * actually run are those containing COMMIT or ROLLBACK commands.
	 */
	if (IsAbortedTransactionBlockState())
	{
		if (!is_trans_exit)
			ereport(ERROR,
					(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
					 errmsg("current transaction is aborted, "
					 "commands ignored until end of transaction block")));
	}

	/* Check for cancel signal before we start execution */
	CHECK_FOR_INTERRUPTS();

	/*
	 * Okay to run the portal.
	 */
	if (max_rows <= 0)
		max_rows = FETCH_ALL;

	completed = PortalRun(portal,
						  max_rows,
						  receiver,
						  receiver,
						  completionTag);

	(*receiver->rDestroy) (receiver);

	if (completed)
	{
		if (is_trans_stmt)
		{
			/*
			 * If this was a transaction control statement, commit it.	We
			 * will start a new xact command for the next command (if
			 * any).
			 */
			finish_xact_command();
		}
		else
		{
			/*
			 * We need a CommandCounterIncrement after every query, except
			 * those that start or end a transaction block.
			 */
			CommandCounterIncrement();
		}

		/* Send appropriate CommandComplete to client */
		EndCommand(completionTag, dest);
	}
	else
	{
		/* Portal run not complete, so send PortalSuspended */
		if (whereToSendOutput == Remote)
			pq_putemptymessage('s');
	}

	debug_query_string = NULL;
}

/*
 * exec_describe_statement_message
 *
 * Process a "Describe" message for a prepared statement
 */
static void
exec_describe_statement_message(const char *stmt_name)
{
	PreparedStatement *pstmt;
	TupleDesc	tupdesc;
	List	   *l;
	StringInfoData buf;

	/* Find prepared statement */
	if (stmt_name[0] != '\0')
		pstmt = FetchPreparedStatement(stmt_name, true);
	else
	{
		/* special-case the unnamed statement */
		pstmt = unnamed_stmt_pstmt;
		if (!pstmt)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_PSTATEMENT),
				   errmsg("unnamed prepared statement does not exist")));
	}

	if (whereToSendOutput != Remote)
		return;					/* can't actually do anything... */

	/*
	 * First describe the parameters...
	 */
	pq_beginmessage(&buf, 't'); /* parameter description message type */
	pq_sendint(&buf, length(pstmt->argtype_list), 2);

	foreach(l, pstmt->argtype_list)
	{
		Oid			ptype = lfirsto(l);

		pq_sendint(&buf, (int) ptype, 4);
	}
	pq_endmessage(&buf);

	/*
	 * Next send RowDescription or NoData to describe the result...
	 */
	tupdesc = FetchPreparedStatementResultDesc(pstmt);
	if (tupdesc)
	{
		List	   *targetlist;

		if (ChoosePortalStrategy(pstmt->query_list) == PORTAL_ONE_SELECT)
			targetlist = ((Query *) lfirst(pstmt->query_list))->targetList;
		else
			targetlist = NIL;
		SendRowDescriptionMessage(tupdesc, targetlist, NULL);
	}
	else
		pq_putemptymessage('n');	/* NoData */

}

/*
 * exec_describe_portal_message
 *
 * Process a "Describe" message for a portal
 */
static void
exec_describe_portal_message(const char *portal_name)
{
	Portal		portal;

	portal = GetPortalByName(portal_name);
	if (!PortalIsValid(portal))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_CURSOR),
				 errmsg("portal \"%s\" does not exist", portal_name)));

	if (whereToSendOutput != Remote)
		return;					/* can't actually do anything... */

	if (portal->tupDesc)
	{
		List	   *targetlist;

		if (portal->strategy == PORTAL_ONE_SELECT)
			targetlist = ((Query *) lfirst(portal->parseTrees))->targetList;
		else
			targetlist = NIL;
		SendRowDescriptionMessage(portal->tupDesc, targetlist,
								  portal->formats);
	}
	else
		pq_putemptymessage('n');	/* NoData */
}


/*
 * Convenience routines for starting/committing a single command.
 */
static void
start_xact_command(void)
{
	if (!xact_started)
	{
		ereport(DEBUG3,
				(errmsg_internal("StartTransactionCommand")));
		StartTransactionCommand();

		/* Set statement timeout running, if any */
		if (StatementTimeout > 0)
			enable_sig_alarm(StatementTimeout, true);

		xact_started = true;
	}
}

static void
finish_xact_command(void)
{
	if (xact_started)
	{
		/* Invoke IMMEDIATE constraint triggers */
		DeferredTriggerEndQuery();

		/* Cancel any active statement timeout before committing */
		disable_sig_alarm(true);

		/* Now commit the command */
		ereport(DEBUG3,
				(errmsg_internal("CommitTransactionCommand")));

		CommitTransactionCommand();

#ifdef MEMORY_CONTEXT_CHECKING
		/* Check all memory contexts that weren't freed during commit */
		/* (those that were, were checked before being deleted) */
		MemoryContextCheck(TopMemoryContext);
#endif

#ifdef SHOW_MEMORY_STATS
		/* Print mem stats after each commit for leak tracking */
		if (ShowStats)
			MemoryContextStats(TopMemoryContext);
#endif

		xact_started = false;
	}
}


/* --------------------------------
 *		signal handler routines used in PostgresMain()
 * --------------------------------
 */

/*
 * quickdie() occurs when signalled SIGQUIT by the postmaster.
 *
 * Some backend has bought the farm,
 * so we need to stop what we're doing and exit.
 */
void
quickdie(SIGNAL_ARGS)
{
	PG_SETMASK(&BlockSig);

	/*
	 * Ideally this should be ereport(FATAL), but then we'd not get
	 * control back (perhaps could fix by doing local sigsetjmp?)
	 */
	ereport(WARNING,
			(errcode(ERRCODE_CRASH_SHUTDOWN),
		errmsg("terminating connection because of crash of another server process"),
	   errdetail("The postmaster has commanded this server process to roll back"
				 " the current transaction and exit, because another"
				 " server process exited abnormally and possibly corrupted"
				 " shared memory."),
			 errhint("In a moment you should be able to reconnect to the"
					 " database and repeat your command.")));

	/*
	 * DO NOT proc_exit() -- we're here because shared memory may be
	 * corrupted, so we don't want to try to clean up our transaction.
	 * Just nail the windows shut and get out of town.
	 *
	 * Note we do exit(1) not exit(0).	This is to force the postmaster into
	 * a system reset cycle if some idiot DBA sends a manual SIGQUIT to a
	 * random backend.	This is necessary precisely because we don't clean
	 * up our shared memory state.
	 */
	exit(1);
}

/*
 * Shutdown signal from postmaster: abort transaction and exit
 * at soonest convenient time
 */
void
die(SIGNAL_ARGS)
{
	int			save_errno = errno;

	/* Don't joggle the elbow of proc_exit */
	if (!proc_exit_inprogress)
	{
		InterruptPending = true;
		ProcDiePending = true;

		/*
		 * If it's safe to interrupt, and we're waiting for input or a
		 * lock, service the interrupt immediately
		 */
		if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
			CritSectionCount == 0)
		{
			/* bump holdoff count to make ProcessInterrupts() a no-op */
			/* until we are done getting ready for it */
			InterruptHoldoffCount++;
			DisableNotifyInterrupt();
			/* Make sure CheckDeadLock won't run while shutting down... */
			LockWaitCancel();
			InterruptHoldoffCount--;
			ProcessInterrupts();
		}
	}

	errno = save_errno;
}

/*
 * Timeout or shutdown signal from postmaster during client authentication.
 * Simply exit(0).
 *
 * XXX: possible future improvement: try to send a message indicating
 * why we are disconnecting.  Problem is to be sure we don't block while
 * doing so, nor mess up the authentication message exchange.
 */
void
authdie(SIGNAL_ARGS)
{
	exit(0);
}

/*
 * Query-cancel signal from postmaster: abort current transaction
 * at soonest convenient time
 */
static void
StatementCancelHandler(SIGNAL_ARGS)
{
	int			save_errno = errno;

	/*
	 * Don't joggle the elbow of proc_exit, nor an already-in-progress
	 * abort
	 */
	if (!proc_exit_inprogress && !InError)
	{
		InterruptPending = true;
		QueryCancelPending = true;

		/*
		 * If it's safe to interrupt, and we're waiting for a lock,
		 * service the interrupt immediately.  No point in interrupting if
		 * we're waiting for input, however.
		 */
		if (ImmediateInterruptOK && InterruptHoldoffCount == 0 &&
			CritSectionCount == 0)
		{
			/* bump holdoff count to make ProcessInterrupts() a no-op */
			/* until we are done getting ready for it */
			InterruptHoldoffCount++;
			if (LockWaitCancel())
			{
				DisableNotifyInterrupt();
				InterruptHoldoffCount--;
				ProcessInterrupts();
			}
			else
				InterruptHoldoffCount--;
		}
	}

	errno = save_errno;
}

/* signal handler for floating point exception */
static void
FloatExceptionHandler(SIGNAL_ARGS)
{
	ereport(ERROR,
			(errcode(ERRCODE_FLOATING_POINT_EXCEPTION),
			 errmsg("floating-point exception"),
		   errdetail("An invalid floating-point operation was signaled. "
					 "This probably means an out-of-range result or an "
					 "invalid operation, such as division by zero.")));
}

/* SIGHUP: set flag to re-read config file at next convenient time */
static void
SigHupHandler(SIGNAL_ARGS)
{
	got_SIGHUP = true;
}


/*
 * ProcessInterrupts: out-of-line portion of CHECK_FOR_INTERRUPTS() macro
 *
 * If an interrupt condition is pending, and it's safe to service it,
 * then clear the flag and accept the interrupt.  Called only when
 * InterruptPending is true.
 */
void
ProcessInterrupts(void)
{
	/* OK to accept interrupt now? */
	if (InterruptHoldoffCount != 0 || CritSectionCount != 0)
		return;
	InterruptPending = false;
	if (ProcDiePending)
	{
		ProcDiePending = false;
		QueryCancelPending = false;		/* ProcDie trumps QueryCancel */
		ImmediateInterruptOK = false;	/* not idle anymore */
		DisableNotifyInterrupt();
		ereport(FATAL,
				(errcode(ERRCODE_ADMIN_SHUTDOWN),
		 errmsg("terminating connection due to administrator command")));
	}
	if (QueryCancelPending)
	{
		QueryCancelPending = false;
		ImmediateInterruptOK = false;	/* not idle anymore */
		DisableNotifyInterrupt();
		ereport(ERROR,
				(errcode(ERRCODE_QUERY_CANCELED),
				 errmsg("canceling query due to user request")));
	}
	/* If we get here, do nothing (probably, QueryCancelPending was reset) */
}


static void
usage(char *progname)
{
	printf(gettext("%s is the PostgreSQL stand-alone backend.  It is not\nintended to be used by normal users.\n\n"), progname);

	printf(gettext("Usage:\n  %s [OPTION]... [DBNAME]\n\n"), progname);
	printf(gettext("Options:\n"));
#ifdef USE_ASSERT_CHECKING
	printf(gettext("  -A 1|0          enable/disable run-time assert checking\n"));
#endif
	printf(gettext("  -B NBUFFERS     number of shared buffers\n"));
	printf(gettext("  -c NAME=VALUE   set run-time parameter\n"));
	printf(gettext("  -d 0-5          debugging level (0 is off)\n"));
	printf(gettext("  -D DATADIR      database directory\n"));
	printf(gettext("  -e              use European date input format (DMY)\n"));
	printf(gettext("  -E              echo query before execution\n"));
	printf(gettext("  -F              turn fsync off\n"));
	printf(gettext("  -N              do not use newline as interactive query delimiter\n"));
	printf(gettext("  -o FILENAME     send stdout and stderr to given file\n"));
	printf(gettext("  -P              disable system indexes\n"));
	printf(gettext("  -s              show statistics after each query\n"));
	printf(gettext("  -S SORT-MEM     set amount of memory for sorts (in kbytes)\n"));
	printf(gettext("  --describe-config  describe configuration parameters, then exit\n"));
	printf(gettext("  --help          show this help, then exit\n"));
	printf(gettext("  --version       output version information, then exit\n"));
	printf(gettext("\nDeveloper options:\n"));
	printf(gettext("  -f s|i|n|m|h    forbid use of some plan types\n"));
	printf(gettext("  -i              do not execute queries\n"));
	printf(gettext("  -O              allow system table structure changes\n"));
	printf(gettext("  -t pa|pl|ex     show timings after each query\n"));
	printf(gettext("  -W NUM          wait NUM seconds to allow attach from a debugger\n"));
	printf(gettext("\nReport bugs to <[e-mail]>.\n"));
}



/* ----------------------------------------------------------------
 * PostgresMain
 *	   postgres main loop -- all backends, interactive or otherwise start here
 *
 * argc/argv are the command line arguments to be used.  (When being forked
 * by the postmaster, these are not the original argv array of the process.)
 * username is the (possibly authenticated) PostgreSQL user name to be used
 * for the session.
 * ----------------------------------------------------------------
 */
int
PostgresMain(int argc, char *argv[], const char *username)
{
	int			flag;
	const char *dbname = NULL;
	char	   *potential_DataDir = NULL;
	bool		secure;
	int			errs = 0;
	int			debug_flag = 0;
	GucContext	ctx,
				debug_context;
	GucSource	gucsource;
	char	   *tmp;
	int			firstchar;
	StringInfoData	input_message;
	volatile bool send_rfq = true;

	/*
	 * Catch standard options before doing much else.  This even works on
	 * systems without getopt_long.
	 */
	if (!IsUnderPostmaster && argc > 1)
	{
		if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
		{
			usage(argv[0]);
			exit(0);
		}
		if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)