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Postgres FD Implementation
Commit 44e8a968 authored by Tom Lane's avatar Tom Lane
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Invent a new, more thread-safe version of PQrequestCancel, called PQcancel. 

Use this new function in psql.  Implement query cancellation in psql for
Windows.  Code by Magnus Hagander, documentation and minor editorialization
by Tom Lane.
parent 80559fa9
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Showing with 399 additions and 118 deletions
doc/src/sgml/libpq.sgml
View file @ 44e8a968
<!--
$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.166 2004/10/18 22:00:41 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.167 2004/10/30 23:09:59 tgl Exp $
-->
<chapter id="libpq">
......@@ -2569,49 +2569,11 @@ if <function>PQisBusy</function> returns false (0). It can also call
A client that uses
<function>PQsendQuery</function>/<function>PQgetResult</function> can
also attempt to cancel a command that is still being processed by the
server.<indexterm><primary>canceling</><secondary>SQL command</></>
<variablelist>
<varlistentry>
<term><function>PQrequestCancel</function><indexterm><primary>PQrequestCancel</></></term>
<listitem>
<para>
Requests that the server abandon
processing of the current command.
<synopsis>
int PQrequestCancel(PGconn *conn);
</synopsis>
</para>
<para>
The return value is 1 if the cancel request was successfully
dispatched and 0 if not. (If not, <function>PQerrorMessage</function> tells why not.)
Successful dispatch is no guarantee that the request will have any
effect, however. Regardless of the return value of <function>PQrequestCancel</function>,
the application must continue with the normal result-reading
sequence using <function>PQgetResult</function>. If the cancellation
is effective, the current command will terminate early and return
an error result. If the cancellation fails (say, because the
server was already done processing the command), then there will
be no visible result at all.
</para>
<para>
Note that if the current command is part of a transaction block, cancellation
will abort the whole transaction.
</para>
<para>
<function>PQrequestCancel</function> can safely be invoked from a signal handler.
So, it is also possible to use it in conjunction with plain
<function>PQexec</function>, if the decision to cancel can be made in a signal
handler. For example, <application>psql</application> invokes
<function>PQrequestCancel</function> from a <symbol>SIGINT</> signal handler, thus allowing
interactive cancellation of commands that it issues through <function>PQexec</function>.
</para>
</listitem>
</varlistentry>
</variablelist>
server; see <xref linkend="libpq-cancel">. But regardless of the return value
of <function>PQcancel</function>, the application must continue with the
normal result-reading sequence using <function>PQgetResult</function>.
A successful cancellation will simply cause the command to terminate
sooner than it would have otherwise.
</para>
<para>
......@@ -2699,6 +2661,125 @@ and then read the response as described above.
</sect1>
<sect1 id="libpq-cancel">
<title>Cancelling Queries in Progress</title>
<indexterm zone="libpq-cancel"><primary>canceling</><secondary>SQL command</></>
<para>
A client application can request cancellation of
a command that is still being processed by the
server, using the functions described in this section.
<variablelist>
<varlistentry>
<term><function>PQgetCancel</function><indexterm><primary>PQgetCancel</></></term>
<listitem>
<para>
Creates a data structure containing the information needed to cancel
a command issued through a particular database connection.
<synopsis>
PGcancel *PQgetCancel(PGconn *conn);
</synopsis>
</para>
<para>
<function>PQgetCancel</function> creates a
<structname>PGcancel</><indexterm><primary>PGcancel</></> object given
a <structname>PGconn</> connection object. It will return NULL if the
given <parameter>conn</> is NULL or an invalid connection. The
<structname>PGcancel</> object is an opaque structure that is not meant
to be accessed directly by the application; it can only be passed to
<function>PQcancel</function> or <function>PQfreeCancel</function>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><function>PQfreeCancel</function><indexterm><primary>PQfreeCancel</></></term>
<listitem>
<para>
Frees a data structure created by <function>PQgetCancel</function>.
<synopsis>
void PQfreeCancel(PGcancel *cancel);
</synopsis>
</para>
<para>
<function>PQfreeCancel</function> frees a data object previously created
by <function>PQgetCancel</function>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><function>PQcancel</function><indexterm><primary>PQcancel</></></term>
<listitem>
<para>
Requests that the server abandon
processing of the current command.
<synopsis>
int PQcancel(PGcancel *cancel, char *errbuf, int errbufsize);
</synopsis>
</para>
<para>
The return value is 1 if the cancel request was successfully
dispatched and 0 if not. If not, <parameter>errbuf</> is filled with an error
message explaining why not. <parameter>errbuf</> must be a char array of size
<parameter>errbufsize</> (the recommended size is 256 bytes).
</para>
<para>
Successful dispatch is no guarantee that the request will have any effect,
however. If the cancellation is effective, the current command will terminate
early and return an error result. If the cancellation fails (say, because the
server was already done processing the command), then there will be no visible
result at all.
</para>
<para>
<function>PQcancel</function> can safely be invoked from a signal handler,
if the <parameter>errbuf</> is a local variable in the signal handler. The
<structname>PGcancel</> object is read-only as far as
<function>PQcancel</function> is concerned, so it can also be invoked from a
thread that is separate from the one manipulating the <structname>PGconn</>
object.
</para>
</listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
<term><function>PQrequestCancel</function><indexterm><primary>PQrequestCancel</></></term>
<listitem>
<para>
Requests that the server abandon
processing of the current command.
<synopsis>
int PQrequestCancel(PGconn *conn);
</synopsis>
</para>
<para>
<function>PQrequestCancel</function> is a deprecated variant of
<function>PQcancel</function>. It operates directly on the
<structname>PGconn</> object, and in case of failure stores the
error message in the <structname>PGconn</> object (whence it can be
retrieved by <function>PQerrorMessage</function>). Although the
functionality is the same, this approach creates hazards for multiple-thread
programs and signal handlers, since it is possible that overwriting the
<structname>PGconn</>'s error message will mess up the operation currently
in progress on the connection.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</sect1>
<sect1 id="libpq-fastpath">
<title>The Fast-Path Interface</title>
......@@ -3852,11 +3933,16 @@ passed around freely between threads.
</para>
<para>
The deprecated functions <function>PQoidStatus</function> and
<function>fe_setauthsvc</function> are not thread-safe and should not be
used in multithread programs. <function>PQoidStatus</function> can be
replaced by <function>PQoidValue</function>. There is no good reason to
call <function>fe_setauthsvc</function> at all.
The deprecated functions
<function>PQrequestCancel</function>,
<function>PQoidStatus</function> and
<function>fe_setauthsvc</function>
are not thread-safe and should not be used in multithread programs.
<function>PQrequestCancel</function> can be replaced by
<function>PQcancel</function>.
<function>PQoidStatus</function> can be replaced by
<function>PQoidValue</function>.
There is no good reason to call <function>fe_setauthsvc</function> at all.
</para>
<para>
......
src/bin/psql/common.c
View file @ 44e8a968
......@@ -3,7 +3,7 @@
*
* Copyright (c) 2000-2004, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/bin/psql/common.c,v 1.92 2004/10/10 23:37:40 neilc Exp $
* $PostgreSQL: pgsql/src/bin/psql/common.c,v 1.93 2004/10/30 23:10:50 tgl Exp $
*/
#include "postgres_fe.h"
#include "common.h"
......@@ -223,23 +223,33 @@ NoticeProcessor(void *arg, const char *message)
*
* Before we start a query, we enable a SIGINT signal catcher that sends a
* cancel request to the backend. Note that sending the cancel directly from
* the signal handler is safe because PQrequestCancel() is written to make it
* so. We use write() to print to stdout because it's better to use simple
* the signal handler is safe because PQcancel() is written to make it
* so. We use write() to print to stderr because it's better to use simple
* facilities in a signal handler.
*
* On win32, the signal cancelling happens on a separate thread, because
* that's how SetConsoleCtrlHandler works. The PQcancel function is safe
* for this (unlike PQrequestCancel). However, a CRITICAL_SECTION is required
* to protect the PGcancel structure against being changed while the other
* thread is using it.
*/
static PGconn *volatile cancelConn = NULL;
static PGcancel *cancelConn = NULL;
#ifdef WIN32
static CRITICAL_SECTION cancelConnLock;
#endif
volatile bool cancel_pressed = false;
#define write_stderr(str) write(fileno(stderr), str, strlen(str))
#ifndef WIN32
#define write_stderr(String) write(fileno(stderr), String, strlen(String))
#ifndef WIN32
void
handle_sigint(SIGNAL_ARGS)
{
int save_errno = errno;
char errbuf[256];
/* Don't muck around if prompting for a password. */
if (prompt_state)
......@@ -250,17 +260,60 @@ handle_sigint(SIGNAL_ARGS)
cancel_pressed = true;
if (PQrequestCancel(cancelConn))
if (PQcancel(cancelConn, errbuf, sizeof(errbuf)))
write_stderr("Cancel request sent\n");
else
{
write_stderr("Could not send cancel request: ");
write_stderr(PQerrorMessage(cancelConn));
write_stderr(errbuf);
}
errno = save_errno; /* just in case the write changed it */
}
#endif /* not WIN32 */
#else /* WIN32 */
static BOOL WINAPI
consoleHandler(DWORD dwCtrlType)
{
char errbuf[256];
if (dwCtrlType == CTRL_C_EVENT ||
dwCtrlType == CTRL_BREAK_EVENT)
{
if (prompt_state)
return TRUE;
/* Perform query cancel */
EnterCriticalSection(&cancelConnLock);
if (cancelConn != NULL)
{
cancel_pressed = true;
if (PQcancel(cancelConn, errbuf, sizeof(errbuf)))
write_stderr("Cancel request sent\n");
else
{
write_stderr("Could not send cancel request: ");
write_stderr(errbuf);
}
}
LeaveCriticalSection(&cancelConnLock);
return TRUE;
}
else
/* Return FALSE for any signals not being handled */
return FALSE;
}
void
setup_cancel_handler(void)
{
InitializeCriticalSection(&cancelConnLock);
SetConsoleCtrlHandler(consoleHandler, TRUE);
}
#endif /* WIN32 */
/* ConnectionUp
......@@ -327,20 +380,42 @@ CheckConnection(void)
static void
SetCancelConn(void)
{
cancelConn = pset.db;
#ifdef WIN32
EnterCriticalSection(&cancelConnLock);
#endif
/* Free the old one if we have one */
if (cancelConn != NULL)
PQfreeCancel(cancelConn);
cancelConn = PQgetCancel(pset.db);
#ifdef WIN32
LeaveCriticalSection(&cancelConnLock);
#endif
}
/*
* ResetCancelConn
*
* Set cancelConn to NULL. I don't know what this means exactly, but it saves
* having to export the variable.
* Free the current cancel connection, if any, and set to NULL.
*/
void
ResetCancelConn(void)
{
#ifdef WIN32
EnterCriticalSection(&cancelConnLock);
#endif
if (cancelConn)
PQfreeCancel(cancelConn);
cancelConn = NULL;
#ifdef WIN32
LeaveCriticalSection(&cancelConnLock);
#endif
}
......
src/bin/psql/common.h
View file @ 44e8a968
......@@ -3,7 +3,7 @@
*
* Copyright (c) 2000-2004, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/bin/psql/common.h,v 1.39 2004/08/29 04:13:02 momjian Exp $
* $PostgreSQL: pgsql/src/bin/psql/common.h,v 1.40 2004/10/30 23:10:50 tgl Exp $
*/
#ifndef COMMON_H
#define COMMON_H
......@@ -48,7 +48,9 @@ extern void ResetCancelConn(void);
#ifndef WIN32
extern void handle_sigint(SIGNAL_ARGS);
#endif /* not WIN32 */
#else
extern void setup_cancel_handler(void);
#endif
extern PGresult *PSQLexec(const char *query, bool start_xact);
......
src/bin/psql/mainloop.c
View file @ 44e8a968
......@@ -3,7 +3,7 @@
*
* Copyright (c) 2000-2004, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/bin/psql/mainloop.c,v 1.64 2004/08/29 05:06:54 momjian Exp $
* $PostgreSQL: pgsql/src/bin/psql/mainloop.c,v 1.65 2004/10/30 23:10:50 tgl Exp $
*/
#include "postgres_fe.h"
#include "mainloop.h"
......@@ -121,7 +121,10 @@ MainLoop(FILE *source)
* ready
*/
pqsignal(SIGINT, handle_sigint); /* control-C => cancel */
#endif /* not WIN32 */
#else /* WIN32 */
setup_cancel_handler();
#endif
fflush(stdout);
......
src/interfaces/libpq/exports.txt
View file @ 44e8a968
# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.2 2004/10/18 22:00:42 tgl Exp $
# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.3 2004/10/30 23:11:26 tgl Exp $
# Functions to be exported by libpq DLLs
PQconnectdb 1
PQsetdbLogin 2
......@@ -119,3 +119,6 @@ pg_valid_server_encoding 116
pqsignal 117
PQprepare 118
PQsendPrepare 119
PQgetCancel 120
PQfreeCancel 121
PQcancel 122
src/interfaces/libpq/fe-connect.c
View file @ 44e8a968
......@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.288 2004/10/29 19:30:02 momjian Exp $
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.289 2004/10/30 23:11:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -2189,19 +2189,55 @@ PQresetPoll(PGconn *conn)
return PGRES_POLLING_FAILED;
}
/*
* PQcancelGet: get a PGcancel structure corresponding to a connection.
*
* A copy is needed to be able to cancel a running query from a different
* thread. If the same structure is used all structure members would have
* to be individually locked (if the entire structure was locked, it would
* be impossible to cancel a synchronous query becuase the structure would
* have to stay locked for the duration of the query).
*/
PGcancel *
PQgetCancel(PGconn *conn)
{
PGcancel *cancel;
if (!conn)
return NULL;
if (conn->sock < 0)
return NULL;
cancel = malloc(sizeof(PGcancel));
if (cancel == NULL)
return NULL;
memcpy(&cancel->raddr, &conn->raddr, sizeof(SockAddr));
cancel->be_pid = conn->be_pid;
cancel->be_key = conn->be_key;
return cancel;
}
/* PQfreeCancel: free a cancel structure */
void
PQfreeCancel(PGcancel *cancel)
{
if (cancel)
free(cancel);
}
/*
* PQrequestCancel: attempt to request cancellation of the current operation.
* PQcancel and PQrequestCancel: attempt to request cancellation of the
* current operation.
*
* The return value is TRUE if the cancel request was successfully
* dispatched, FALSE if not (in which case conn->errorMessage is set).
* dispatched, FALSE if not (in which case an error message is available).
* Note: successful dispatch is no guarantee that there will be any effect at
* the backend. The application must read the operation result as usual.
*
* XXX it was a bad idea to have the error message returned in
* conn->errorMessage, since it could overwrite a message already there.
* Would be better to return it in a char array passed by the caller.
*
* CAUTION: we want this routine to be safely callable from a signal handler
* (for example, an application might want to call it in a SIGINT handler).
* This means we cannot use any C library routine that might be non-reentrant.
......@@ -2210,59 +2246,40 @@ PQresetPoll(PGconn *conn)
* error messages with strcpy/strcat is tedious but should be quite safe.
* We also save/restore errno in case the signal handler support doesn't.
*
* NOTE: this routine must not generate any error message longer than
* INITIAL_EXPBUFFER_SIZE (currently 256), since we dare not try to
* expand conn->errorMessage!
* internal_cancel() is an internal helper function to make code-sharing
* between the two versions of the cancel function possible.
*/
int
PQrequestCancel(PGconn *conn)
static int
internal_cancel(SockAddr *raddr, int be_pid, int be_key,
char *errbuf, int errbufsize)
{
int save_errno = SOCK_ERRNO;
int tmpsock = -1;
char sebuf[256];
int maxlen;
struct
{
uint32 packetlen;
CancelRequestPacket cp;
} crp;
/* Check we have an open connection */
if (!conn)
return FALSE;
if (conn->sock < 0)
{
strcpy(conn->errorMessage.data,
"PQrequestCancel() -- connection is not open\n");
conn->errorMessage.len = strlen(conn->errorMessage.data);
#ifdef WIN32
WSASetLastError(save_errno);
#else
errno = save_errno;
#endif
return FALSE;
}
/*
* We need to open a temporary connection to the postmaster. Use the
* information saved by connectDB to do this with only kernel calls.
* We need to open a temporary connection to the postmaster. Do
* this with only kernel calls.
*/
if ((tmpsock = socket(conn->raddr.addr.ss_family, SOCK_STREAM, 0)) < 0)
if ((tmpsock = socket(raddr->addr.ss_family, SOCK_STREAM, 0)) < 0)
{
strcpy(conn->errorMessage.data,
"PQrequestCancel() -- socket() failed: ");
StrNCpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
goto cancel_errReturn;
}
retry3:
if (connect(tmpsock, (struct sockaddr *) & conn->raddr.addr,
conn->raddr.salen) < 0)
if (connect(tmpsock, (struct sockaddr *) & raddr->addr,
raddr->salen) < 0)
{
if (SOCK_ERRNO == EINTR)
/* Interrupted system call - we'll just try again */
goto retry3;
strcpy(conn->errorMessage.data,
"PQrequestCancel() -- connect() failed: ");
StrNCpy(errbuf, "PQcancel() -- connect() failed: ", errbufsize);
goto cancel_errReturn;
}
......@@ -2274,8 +2291,8 @@ retry3:
crp.packetlen = htonl((uint32) sizeof(crp));
crp.cp.cancelRequestCode = (MsgType) htonl(CANCEL_REQUEST_CODE);
crp.cp.backendPID = htonl(conn->be_pid);
crp.cp.cancelAuthCode = htonl(conn->be_key);
crp.cp.backendPID = htonl(be_pid);
crp.cp.cancelAuthCode = htonl(be_key);
retry4:
if (send(tmpsock, (char *) &crp, sizeof(crp), 0) != (int) sizeof(crp))
......@@ -2283,8 +2300,7 @@ retry4:
if (SOCK_ERRNO == EINTR)
/* Interrupted system call - we'll just try again */
goto retry4;
strcpy(conn->errorMessage.data,
"PQrequestCancel() -- send() failed: ");
StrNCpy(errbuf, "PQcancel() -- send() failed: ", errbufsize);
goto cancel_errReturn;
}
......@@ -2316,21 +2332,90 @@ retry5:
return TRUE;
cancel_errReturn:
strcat(conn->errorMessage.data, SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
strcat(conn->errorMessage.data, "\n");
conn->errorMessage.len = strlen(conn->errorMessage.data);
if (tmpsock >= 0)
/*
* Make sure we don't overflow the error buffer. Leave space for
* the \n at the end, and for the terminating zero.
*/
maxlen = errbufsize - strlen(errbuf) - 2;
if (maxlen >= 0)
{
strncat(errbuf, SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)),
maxlen);
strcat(errbuf, "\n");
}
if (tmpsock >= 0)
closesocket(tmpsock);
#ifdef WIN32
WSASetLastError(save_errno);
WSASetLastError(save_errno);
#else
errno = save_errno;
errno = save_errno;
#endif
}
return FALSE;
}
/*
* PQcancel: request query cancel
*
* Returns TRUE if able to send the cancel request, FALSE if not.
*
* On failure, an error message is stored in *errbuf, which must be of size
* errbufsize (recommended size is 256 bytes). *errbuf is not changed on
* success return.
*/
int
PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
{
if (!cancel)
{
StrNCpy(errbuf, "PQcancel() -- no cancel object supplied", errbufsize);
return FALSE;
}
return internal_cancel(&cancel->raddr, cancel->be_pid, cancel->be_key,
errbuf, errbufsize);
}
/*
* PQrequestCancel: old, not thread-safe function for requesting query cancel
*
* Returns TRUE if able to send the cancel request, FALSE if not.
*
* On failure, the error message is saved in conn->errorMessage; this means
* that this can't be used when there might be other active operations on
* the connection object.
*
* NOTE: error messages will be cut off at the current size of the
* error message buffer, since we dare not try to expand conn->errorMessage!
*/
int
PQrequestCancel(PGconn *conn)
{
int r;
/* Check we have an open connection */
if (!conn)
return FALSE;
if (conn->sock < 0)
{
StrNCpy(conn->errorMessage.data,
"PQrequestCancel() -- connection is not open\n",
conn->errorMessage.maxlen);
conn->errorMessage.len = strlen(conn->errorMessage.data);
return FALSE;
}
r = internal_cancel(&conn->raddr, conn->be_pid, conn->be_key,
conn->errorMessage.data, conn->errorMessage.maxlen);
if (!r)
conn->errorMessage.len = strlen(conn->errorMessage.data);
return r;
}
/*
* pqPacketSend() -- convenience routine to send a message to server.
......
src/interfaces/libpq/libpq-fe.h
View file @ 44e8a968
......@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.112 2004/10/18 22:00:42 tgl Exp $
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.113 2004/10/30 23:11:27 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -116,6 +116,12 @@ typedef struct pg_conn PGconn;
*/
typedef struct pg_result PGresult;
/* PGcancel encapsulates the information needed to cancel a running
* query on an existing connection.
* The contents of this struct are not supposed to be known to applications.
*/
typedef struct pg_cancel PGcancel;
/* PGnotify represents the occurrence of a NOTIFY message.
* Ideally this would be an opaque typedef, but it's so simple that it's
* unlikely to change.
......@@ -234,7 +240,16 @@ extern PostgresPollingStatusType PQresetPoll(PGconn *conn);
/* Synchronous (blocking) */
extern void PQreset(PGconn *conn);
/* request a cancel structure */
extern PGcancel *PQgetCancel(PGconn *conn);
/* free a cancel structure */
extern void PQfreeCancel(PGcancel *cancel);
/* issue a cancel request */
extern int PQcancel(PGcancel *cancel, char *errbuf, int errbufsize);
/* backwards compatible version of PQcancel; not thread-safe */
extern int PQrequestCancel(PGconn *conn);
/* Accessor functions for PGconn objects */
......
src/interfaces/libpq/libpq-int.h
View file @ 44e8a968
......@@ -12,7 +12,7 @@
* Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.95 2004/10/18 22:00:42 tgl Exp $
* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.96 2004/10/30 23:11:27 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -346,6 +346,18 @@ struct pg_conn
PQExpBufferData workBuffer; /* expansible string */
};
/* PGcancel stores all data necessary to cancel a connection. A copy of this
* data is required to safely cancel a connection running on a different
* thread.
*/
struct pg_cancel
{
SockAddr raddr; /* Remote address */
int be_pid; /* PID of backend --- needed for cancels */
int be_key; /* key of backend --- needed for cancels */
};
/* String descriptions of the ExecStatusTypes.
* direct use of this array is deprecated; call PQresStatus() instead.
*/
......
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