Re: Error on PQputline() - Mailing list pgsql-hackers

> -----Original Message-----
> From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
> Sent: Friday, May 17, 2002 4:38 PM
> To: Dann Corbit
> Cc: pgsql-hackers@postgresql.org
> Subject: Re: [HACKERS] Error on PQputline()
>
>
> "Dann Corbit" <DCorbit@connx.com> writes:
> >> You're running libpq with the nonblocking mode selected?
>
> > Actually no.  It should be the default mode for a connection made by
> > PQconnectdb().  That's what made the error so puzzling.
>
> I'm confused too.  For starters, I cannot find that error message
> string about 'A non-blocking socket operation could not be completed
> immediately' anywhere.  Got any idea what's producing that?  Exactly
> which version of libpq are you using, anyway?

7.1.3.  Sorry for running on fossil PostgreSQL.

/* ---------------------------------------------------------------------
*/
/* pqFlush: send any data waiting in the output buffer*/
int
pqFlush(PGconn *conn)
{char       *ptr = conn->outBuffer;int            len = conn->outCount;
if (conn->sock < 0){    printfPQExpBuffer(&conn->errorMessage,                      "pqFlush() --
connection not open\n");    return EOF;}
/* * don't try to send zero data, allows us to use this function
without * too much worry about overhead */if (len == 0)    return (0);
/* while there's still data to send */while (len > 0){    /* Prevent being SIGPIPEd if backend has closed the
connection. */
#ifndef WIN32    pqsigfunc    oldsighandler = pqsignal(SIGPIPE,
SIG_IGN);

#endif
    int            sent;

#ifdef USE_SSL    if (conn->ssl)        sent = SSL_write(conn->ssl, ptr, len);    else
#endif        sent = send(conn->sock, ptr, len, 0);

#ifndef WIN32    pqsignal(SIGPIPE, oldsighandler);
#endif
    if (sent < 0)    {
        /*         * Anything except EAGAIN or EWOULDBLOCK is
trouble. If it's         * EPIPE or ECONNRESET, assume we've lost the
backend         * connection permanently.         */        switch (errno)        {
#ifdef EAGAIN            case EAGAIN:                break;
#endif
#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK !=
EAGAIN))            case EWOULDBLOCK:                break;
#endif            case EINTR:                continue;
            case EPIPE:
#ifdef ECONNRESET            case ECONNRESET:
#endif
printfPQExpBuffer(&conn->errorMessage,
"pqFlush() -- backend closed the channel unexpectedly.\n"
"\tThis probably means the backend terminated abnormally"                       " before or while
processing the request.\n");
                /*                 * We used to close the socket
here, but that's a bad                 * idea since there might be
unread data waiting                 * (typically, a NOTICE message
from the backend                 * telling us it's committing
hara-kiri...).  Leave                 * the socket open until
pqReadData finds no more data                 * can be read.                 */                return EOF;
/*
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvv
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!
*/            default:
printfPQExpBuffer(&conn->errorMessage,                  "pqFlush() --  couldn't send
data: errno=%d\n%s\n",
errno, strerror(errno));                /* We don't assume it's a fatal
error... */                return EOF;
/*
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^^^^^^^
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!
*/        }    }    else    {        ptr += sent;        len -= sent;    }
    if (len > 0)    {        /* We didn't send it all, wait till we can send
more */
        /*         * if the socket is in non-blocking mode we may
need to abort         * here         */
#ifdef USE_SSL        /* can't do anything for our SSL users yet */        if (conn->ssl == NULL)        {
#endif            if (pqIsnonblocking(conn))            {                /* shift the contents of the
buffer */                memmove(conn->outBuffer, ptr,
len);                conn->outCount = len;                return EOF;            }
#ifdef USE_SSL        }
#endif
        if (pqWait(FALSE, TRUE, conn))            return EOF;    }}
conn->outCount = 0;
if (conn->Pfdebug)    fflush(conn->Pfdebug);
return 0;
}
> > "Would it be faster to write a file to disk and read it again on the
> > local host for the server or to send the calls via libpq client
> > messages?"
>
> Good question.  I'd recommend the messaging approach since it
> eliminates
> lots of headaches about file access privileges and so forth.  But on
> some platforms the overhead could be high.
>
>             regards, tom lane
>