Re: connect_timeout parameter in libpq

Do people think this is of general enough interest to be added to libpq?

---------------------------------------------------------------------------

Denis A Ustimenko wrote:
> New version of patch. Documentation updates, accurate remaining time calculation etc.
>
> On Mon, Aug 12, 2002 at 11:35:17PM -0400, Tom Lane wrote:
> > Shouldn't such a patch include documentation updates? (And not
> > only user-level documentation; this patch adds not even a single
> > comment to explain what it's doing or why.)
> >
> > I'm also not thrilled with the way that the patch imposes the
> > overhead of calculating the timeout whether the user wants it or not.
> > The time() kernel calls should be skipped unless needed.
> >
> > A final comment is that the patch's timeout accuracy is quite poor, since
> > time()'s result is quantized to seconds. gettimeofday() might be a
> > better choice. Also it seems to assume that select() does not modify its
> > timeout argument, which is not a portable assumption. On some platforms
> > the timeout struct is decremented by the elapsed time.
> >
> > regards, tom lane
>
> *** postgresql-7.2.1/doc/src/sgml/libpq.sgml.orig ?? ??? 13 12:34:51 2002
> --- postgresql-7.2.1/doc/src/sgml/libpq.sgml ?? ??? 13 14:18:15 2002
> ***************
> *** 172,177 ****
> --- 172,186 ----
> </varlistentry>
>
> <varlistentry>
> + <term><literal>connect_timeout</literal></term>
> + <listitem>
> + <para>
> + Time space in seconds given to connect routine. Zero or not set means infinite.
> + </para>
> + </listitem>
> + </varlistentry>
> +
> + <varlistentry>
> <term><literal>options</literal></term>
> <listitem>
> <para>
> *** postgresql-7.2.1/src/interfaces/libpq/fe-connect.c.orig ?? ??? 8 12:22:46 2002
> --- postgresql-7.2.1/src/interfaces/libpq/fe-connect.c ?? ??? 13 15:50:43 2002
> ***************
> *** 114,119 ****
> --- 114,122 ----
> {"password", "PGPASSWORD", DefaultPassword, NULL,
> "Database-Password", "*", 20},
>
> + {"connect_timeout", "PGCONNECT_TIMEOUT", NULL, NULL,
> + "Connect-timeout", "", 10}, /* strlen( INT32_MAX) == 10 */
> +
> {"dbname", "PGDATABASE", NULL, NULL,
> "Database-Name", "", 20},
>
> ***************
> *** 307,312 ****
> --- 310,317 ----
> conn->pguser = tmp ? strdup(tmp) : NULL;
> tmp = conninfo_getval(connOptions, "password");
> conn->pgpass = tmp ? strdup(tmp) : NULL;
> + tmp = conninfo_getval(connOptions, "connect_timeout");
> + conn->connect_timeout = tmp ? strdup(tmp) : NULL;
> #ifdef USE_SSL
> tmp = conninfo_getval(connOptions, "requiressl");
> conn->require_ssl = tmp ? (tmp[0] == '1' ? true : false) : false;
> ***************
> *** 1050,1061 ****
> {
> PostgresPollingStatusType flag = PGRES_POLLING_WRITING;
>
> if (conn == NULL || conn->status == CONNECTION_BAD)
> return 0;
>
> ! for (;;)
> {
> /*
> * Wait, if necessary. Note that the initial state (just after
> * PQconnectStart) is to wait for the socket to select for
> * writing.
> --- 1055,1093 ----
> {
> PostgresPollingStatusType flag = PGRES_POLLING_WRITING;
>
> + struct timeval remains, *rp = NULL, finish_time, start_time;
> +
> if (conn == NULL || conn->status == CONNECTION_BAD)
> return 0;
>
> ! /*
> ! * Prepare to time calculations, if connect_timeout isn't zero.
> ! */
> ! if (conn->connect_timeout != NULL)
> {
> + remains.tv_sec = atoi(conn->connect_timeout);
> + if (!remains.tv_sec)
> + {
> + conn->status = CONNECTION_BAD;
> + return 0;
> + }
> + remains.tv_usec = 0;
> + rp = &remains;
> + }
> +
> +
> + while (NULL == rp || remains.tv_sec > 0 || remains.tv_sec == 0 && remains.tv_usec > 0)
> + {
> /*
> + * If connecting timeout is set, get current time.
> + */
> + if ( NULL != rp && -1 == gettimeofday(&start_time, NULL))
> + {
> + conn->status = CONNECTION_BAD;
> + return 0;
> + }
> +
> + /*
> * Wait, if necessary. Note that the initial state (just after
> * PQconnectStart) is to wait for the socket to select for
> * writing.
> ***************
> *** 1069,1075 ****
> return 1; /* success! */
>
> case PGRES_POLLING_READING:
> ! if (pqWait(1, 0, conn))
> {
> conn->status = CONNECTION_BAD;
> return 0;
> --- 1101,1107 ----
> return 1; /* success! */
>
> case PGRES_POLLING_READING:
> ! if (pqWaitTimed(1, 0, conn, rp))
> {
> conn->status = CONNECTION_BAD;
> return 0;
> ***************
> *** 1077,1083 ****
> break;
>
> case PGRES_POLLING_WRITING:
> ! if (pqWait(0, 1, conn))
> {
> conn->status = CONNECTION_BAD;
> return 0;
> --- 1109,1115 ----
> break;
>
> case PGRES_POLLING_WRITING:
> ! if (pqWaitTimed(0, 1, conn, rp))
> {
> conn->status = CONNECTION_BAD;
> return 0;
> ***************
> *** 1094,1100 ****
> --- 1126,1156 ----
> * Now try to advance the state machine.
> */
> flag = PQconnectPoll(conn);
> +
> + /*
> + * If connecting timeout is set, calculate remain time.
> + */
> + if (NULL != rp) {
> + if (-1 == gettimeofday(&finish_time, NULL))
> + {
> + conn->status = CONNECTION_BAD;
> + return 0;
> + }
> + if (0 > (finish_time.tv_usec -= start_time.tv_usec))
> + {
> + remains.tv_sec++;
> + finish_time.tv_usec += 1000000;
> + }
> + if (0 > (remains.tv_usec -= finish_time.tv_usec))
> + {
> + remains.tv_sec--;
> + remains.tv_usec += 1000000;
> + }
> + remains.tv_sec -= finish_time.tv_sec - start_time.tv_sec;
> + }
> }
> + conn->status = CONNECTION_BAD;
> + return 0;
> }
>
> /* ----------------
> ***************
> *** 1929,1934 ****
> --- 1985,1992 ----
> free(conn->pguser);
> if (conn->pgpass)
> free(conn->pgpass);
> + if (conn->connect_timeout)
> + free(conn->connect_timeout);
> /* Note that conn->Pfdebug is not ours to close or free */
> if (conn->notifyList)
> DLFreeList(conn->notifyList);
> *** postgresql-7.2.1/src/interfaces/libpq/fe-misc.c.orig ?? ??? 8 16:33:34 2002
> --- postgresql-7.2.1/src/interfaces/libpq/fe-misc.c ?? ??? 13 16:16:57 2002
> ***************
> *** 748,757 ****
> --- 748,766 ----
> int
> pqWait(int forRead, int forWrite, PGconn *conn)
> {
> + return pqWaitTimed( forRead, forWrite, conn, (const struct timeval *) NULL);
> + }
> +
> + int
> + pqWaitTimed(int forRead, int forWrite, PGconn *conn, const struct timeval *timeout)
> + {
> fd_set input_mask;
> fd_set output_mask;
> fd_set except_mask;
>
> + struct timeval tmp_timeout;
> + struct timeval *ptmp_timeout = NULL;
> +
> if (conn->sock < 0)
> {
> printfPQExpBuffer(&conn->errorMessage,
> ***************
> *** 770,778 ****
> if (forWrite)
> FD_SET(conn->sock, &output_mask);
> FD_SET(conn->sock, &except_mask);
> ! if (select(conn->sock + 1, &input_mask, &output_mask, &except_mask,
> ! (struct timeval *) NULL) < 0)
> {
> if (SOCK_ERRNO == EINTR)
> goto retry;
> printfPQExpBuffer(&conn->errorMessage,
> --- 779,796 ----
> if (forWrite)
> FD_SET(conn->sock, &output_mask);
> FD_SET(conn->sock, &except_mask);
> !
> ! if (NULL != timeout)
> {
> + /*
> + * select may modify timeout argument on some platforms use copy
> + */
> + tmp_timeout = *timeout;
> + ptmp_timeout = &tmp_timeout;
> + }
> + if (select(conn->sock + 1, &input_mask, &output_mask,
> + &except_mask, ptmp_timeout) < 0)
> + {
> if (SOCK_ERRNO == EINTR)
> goto retry;
> printfPQExpBuffer(&conn->errorMessage,
> *** postgresql-7.2.1/src/interfaces/libpq/libpq-int.h.orig ?? ??? 8 16:37:56 2002
> --- postgresql-7.2.1/src/interfaces/libpq/libpq-int.h ?? ??? 13 14:37:54 2002
> ***************
> *** 279,284 ****
> --- 279,286 ----
> PQExpBufferData workBuffer; /* expansible string */
>
> int client_encoding; /* encoding id */
> +
> + char *connect_timeout;
> };
>
> /* String descriptions of the ExecStatusTypes.
> ***************
> *** 324,329 ****
> --- 326,332 ----
> extern int pqReadData(PGconn *conn);
> extern int pqFlush(PGconn *conn);
> extern int pqWait(int forRead, int forWrite, PGconn *conn);
> + extern int pqWaitTimed(int forRead, int forWrite, PGconn *conn, const struct timeval* timeout);
> extern int pqReadReady(PGconn *conn);
> extern int pqWriteReady(PGconn *conn);
>
>
>
> --
> Regards
> Denis
>
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