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RFA: auto-retry TCP connections, take 2
- From: Sandra Loosemore <sandra at codesourcery dot com>
- To: gdb-patches at sourceware dot org
- Cc: Joel Brobecker <brobecker at adacore dot com>, drow at false dot org
- Date: Tue, 30 Dec 2008 16:02:21 -0500
- Subject: RFA: auto-retry TCP connections, take 2
Here's a new patch, revised per the previous discussion to rename the new
commands. Moving them out of "set/show remote" into a new "set/show tcp" prefix
cleaned up the implementation logic a bit, so it's probably the right choice.
The rest of the patch, with the actual retry/timeout logic, is unchanged from
the previous version.
OK to check in?
-Sandra
2008-12-30 Sandra Loosemore <sandra@codesourcery.com>
gdb/
* ser-tcp.c: Adjust includes.
(tcp_set_cmdlist, tcp_show_cmdlist): Declare.
(tcp_auto_retry, tcp_retry_limit): Declare.
(TIMEOUT): Remove, in favor of tcp_retry_limit.
(POLL_INTERVAL): Increase to 5, in favor of backoff logic.
(wait_for_connect): New function.
(net_open): Use it. Add auto-retry logic.
(set_tcp_cmd, show_tcp_cmd): New functions.
(_initialize_ser_tcp): Initialize new "set/show tcp auto-retry"
and "set/show tcp connect-timeout" commands.
* NEWS: Document new commands.
gdb/doc/
* gdb.texinfo (Remote Configuration): Document new
"set/show tcp auto-retry" and "set/show tcp connect-timeout"
commands.
Index: gdb/NEWS
===================================================================
RCS file: /cvs/src/src/gdb/NEWS,v
retrieving revision 1.296
diff -r1.296 NEWS
171a172,179
> set tcp auto-retry (on|off)
> show tcp auto-retry
> set tcp connect-timeout
> show tcp connect-timeout
> These commands allow GDB to retry failed TCP connections to a remote stub
> with a specified timeout period; this is useful if the stub is launched
> in parallel with GDB but may not be ready to accept connections immediately.
>
Index: gdb/ser-tcp.c
===================================================================
RCS file: /cvs/src/src/gdb/ser-tcp.c,v
retrieving revision 1.30
diff -r1.30 ser-tcp.c
24a25,27
> #include "gdbcmd.h"
> #include "cli/cli-decode.h"
> #include "cli/cli-setshow.h"
51a55
> #include "gdb_select.h"
59,60c63,75
< /* seconds to wait for connect */
< #define TIMEOUT 15
---
> /* For "set tcp" and "show tcp". */
>
> static struct cmd_list_element *tcp_set_cmdlist;
> static struct cmd_list_element *tcp_show_cmdlist;
>
> /* Whether to auto-retry refused connections. */
>
> static int tcp_auto_retry = 1;
>
> /* Timeout period for connections, in seconds. */
>
> static int tcp_retry_limit = 15;
>
62c77,149
< #define POLL_INTERVAL 2
---
>
> #define POLL_INTERVAL 5
>
> /* Helper function to wait a while. If SCB is non-null, wait on its
> file descriptor. Otherwise just wait on a timeout, updating *POLLS.
> Returns -1 on timeout or interrupt, otherwise the value of select. */
>
> static int
> wait_for_connect (struct serial *scb, int *polls)
> {
> struct timeval t;
> int n;
>
> /* While we wait for the connect to complete,
> poll the UI so it can update or the user can
> interrupt. */
> if (deprecated_ui_loop_hook && deprecated_ui_loop_hook (0))
> {
> errno = EINTR;
> return -1;
> }
>
> /* Check for timeout. */
> if (*polls > tcp_retry_limit * POLL_INTERVAL)
> {
> errno = ETIMEDOUT;
> return -1;
> }
>
> /* Back off to polling once per second after the first POLL_INTERVAL
> polls. */
> if (*polls < POLL_INTERVAL)
> {
> t.tv_sec = 0;
> t.tv_usec = 1000000 / POLL_INTERVAL;
> }
> else
> {
> t.tv_sec = 1;
> t.tv_usec = 0;
> }
>
> if (scb)
> {
> fd_set rset, wset, eset;
> FD_ZERO (&rset);
> FD_SET (scb->fd, &rset);
> wset = rset;
> eset = rset;
>
> /* POSIX systems return connection success or failure by signalling
> wset. Windows systems return success in wset and failure in
> eset.
>
> We must call select here, rather than gdb_select, because
> the serial structure has not yet been initialized - the
> MinGW select wrapper will not know that this FD refers
> to a socket. */
> n = select (scb->fd + 1, &rset, &wset, &eset, &t);
> }
> else
> /* Use gdb_select here, since we have no file descriptors, and on
> Windows, plain select doesn't work in that case. */
> n = gdb_select (0, NULL, NULL, NULL, &t);
>
> /* If we didn't time out, only count it as one poll. */
> if (n > 0 || *polls < POLL_INTERVAL)
> (*polls)++;
> else
> (*polls) += POLL_INTERVAL;
>
> return n;
> }
78a166
> int polls = 0;
110a199,205
> sockaddr.sin_family = PF_INET;
> sockaddr.sin_port = htons (port);
> memcpy (&sockaddr.sin_addr.s_addr, hostent->h_addr,
> sizeof (struct in_addr));
>
> retry:
>
119,123d213
< sockaddr.sin_family = PF_INET;
< sockaddr.sin_port = htons (port);
< memcpy (&sockaddr.sin_addr.s_addr, hostent->h_addr,
< sizeof (struct in_addr));
<
131c221,222
< if (n < 0
---
> if (n < 0)
> {
133,135c224
< /* Under Windows, calling "connect" with a non-blocking socket
< results in WSAEWOULDBLOCK, not WSAEINPROGRESS. */
< && WSAGetLastError() != WSAEWOULDBLOCK
---
> int err = WSAGetLastError();
137c226
< && errno != EINPROGRESS
---
> int err = errno;
139,140c228,231
< )
< {
---
>
> /* Maybe we're waiting for the remote target to become ready to
> accept connections. */
> if (tcp_auto_retry
142c233,235
< errno = WSAGetLastError();
---
> && err == WSAECONNREFUSED
> #else
> && err == ECONNREFUSED
144,146c237,241
< net_close (scb);
< return -1;
< }
---
> && wait_for_connect (NULL, &polls) >= 0)
> {
> close (scb->fd);
> goto retry;
> }
148,154c243,256
< if (n)
< {
< /* looks like we need to wait for the connect */
< struct timeval t;
< fd_set rset, wset, eset;
< int polls = 0;
< FD_ZERO (&rset);
---
> if (
> #ifdef USE_WIN32API
> /* Under Windows, calling "connect" with a non-blocking socket
> results in WSAEWOULDBLOCK, not WSAEINPROGRESS. */
> err != WSAEWOULDBLOCK
> #else
> err != EINPROGRESS
> #endif
> )
> {
> errno = err;
> net_close (scb);
> return -1;
> }
155a258
> /* looks like we need to wait for the connect */
158,186c261
< /* While we wait for the connect to complete,
< poll the UI so it can update or the user can
< interrupt. */
< if (deprecated_ui_loop_hook)
< {
< if (deprecated_ui_loop_hook (0))
< {
< errno = EINTR;
< net_close (scb);
< return -1;
< }
< }
<
< FD_SET (scb->fd, &rset);
< wset = rset;
< eset = rset;
< t.tv_sec = 0;
< t.tv_usec = 1000000 / POLL_INTERVAL;
<
< /* POSIX systems return connection success or failure by signalling
< wset. Windows systems return success in wset and failure in
< eset.
<
< We must call select here, rather than gdb_select, because
< the serial structure has not yet been initialized - the
< MinGW select wrapper will not know that this FD refers
< to a socket. */
< n = select (scb->fd + 1, &rset, &wset, &eset, &t);
< polls++;
---
> n = wait_for_connect (scb, &polls);
188,189c263,264
< while (n == 0 && polls <= TIMEOUT * POLL_INTERVAL);
< if (n < 0 || polls > TIMEOUT * POLL_INTERVAL)
---
> while (n == 0);
> if (n < 0)
191,192d265
< if (polls > TIMEOUT * POLL_INTERVAL)
< errno = ETIMEDOUT;
209a283,294
> /* Maybe the target still isn't ready to accept the connection. */
> if (tcp_auto_retry
> #ifdef USE_WIN32API
> && err == WSAECONNREFUSED
> #else
> && err == ECONNREFUSED
> #endif
> && wait_for_connect (NULL, &polls) >= 0)
> {
> close (scb->fd);
> goto retry;
> }
266a352,366
> /* Support for "set tcp" and "show tcp" commands. */
>
> static void
> set_tcp_cmd (char *args, int from_tty)
> {
> help_list (tcp_set_cmdlist, "set tcp ", -1, gdb_stdout);
> }
>
> static void
> show_tcp_cmd (char *args, int from_tty)
> {
> help_list (tcp_show_cmdlist, "show tcp ", -1, gdb_stdout);
> }
>
>
273d372
< return;
299a399,423
>
> add_prefix_cmd ("tcp", class_maintenance, set_tcp_cmd, _("\
> TCP protocol specific variables\n\
> Configure variables specific to remote TCP connections"),
> &tcp_set_cmdlist, "set tcp ",
> 0 /* allow-unknown */, &setlist);
> add_prefix_cmd ("tcp", class_maintenance, show_tcp_cmd, _("\
> TCP protocol specific variables\n\
> Configure variables specific to remote TCP connections"),
> &tcp_show_cmdlist, "show tcp ",
> 0 /* allow-unknown */, &showlist);
>
> add_setshow_boolean_cmd ("auto-retry", class_obscure,
> &tcp_auto_retry, _("\
> Set auto-retry on socket connect"), _("\
> Show auto-retry on socket connect"),
> NULL, NULL, NULL,
> &tcp_set_cmdlist, &tcp_show_cmdlist);
>
> add_setshow_uinteger_cmd ("connect-timeout", class_obscure,
> &tcp_retry_limit, _("\
> Set timeout limit for socket connection"), _("\
> Show timeout limit for socket connection"),
> NULL, NULL, NULL,
> &tcp_set_cmdlist, &tcp_show_cmdlist);
Index: gdb/doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.541
diff -r1.541 gdb.texinfo
14208a14209,14238
>
> @kindex set tcp
> @kindex show tcp
> @item set tcp auto-retry on
> @cindex auto-retry, for remote TCP target
> Enable auto-retry for remote TCP connections. This is useful if the remote
> debugging agent is launched in parallel with @value{GDBN}; there is a race
> condition because the agent may not become ready to accept the connection
> before @value{GDBN} attempts to connect. When auto-retry is
> enabled, if the initial attempt to connect fails, @value{GDBN} reattempts
> to establish the connection using the timeout specified by
> @code{set tcp connect-timeout}.
>
> @item set tcp auto-retry off
> Do not auto-retry failed TCP connections.
>
> @item show tcp auto-retry
> Show the current auto-retry setting.
>
> @item set tcp connect-timeout @var{seconds}
> @cindex connection timeout, for remote TCP target
> @cindex timeout, for remote target connection
> Set the timeout for establishing a TCP connection to the remote target to
> @var{seconds}. The timeout affects both polling to retry failed connections
> (enabled by @code{set tcp auto-retry on}) and waiting for connections
> that are merely slow to complete, and represents an approximate cumulative
> value.
>
> @item show tcp connect-timeout
> Show the current connection timeout setting.