Re: [HACKERS] LIBPQ patches ...

On Sat, 8 Jan 2000, Bruce Momjian wrote:

> Looks fine. I have talked to someone about doing no-blocking
> connections in the past. Maybe this the same person.
>
> I will let someone else comment on whether the protocol changes are
> correct.

Okay, if I haven't heard anything major by Sunday, I'm going to include
these, whic still gives us a month before beta (well, not quite, but
close) and then the beta period in order to clean it up...

>
>
> >
> > Does anyone have anything against me applying this to the current source
> > tree?
> >
> >
> > Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy
> > Systems Administrator @ hub.org
> > primary: scrappy(at)hub(dot)org secondary: scrappy(at){freebsd|postgresql}.org
> >
> > ---------- Forwarded message ----------
> > Date: Fri, 17 Dec 1999 13:51:50 -0800 (PST)
> > From: Alfred Perlstein <bright(at)wintelcom(dot)net>
> > To: The Hermit Hacker <scrappy(at)hub(dot)org>
> > Subject: Re: pctrackd updates and such
> >
> > On Fri, 17 Dec 1999, The Hermit Hacker wrote:
> >
> > >
> > > Okay, first thing...can you redo these as context diffs? We generally
> > > refuse *any* patches that aren't context...
> >
> > sure.
> >
> > >
> > > Second, are these against a reasonably current snapshot of PostgreSQL
> > > (aka. the upcoming v7), or v6.5.3 release? If v6.5.3, we're gonna need to
> > > get these v7.x ready before we can commit them...
> >
> > they are against a checked out cvs copy as of a couple days ago,
> > and should apply cleanly to what's in the current repo.
> >
> > > Once both of the above conditions are in place, and after I get back from
> > > BC, I'll work on getting these into the v7.0 release...or, at least,
> > > talked/commented about if there are any objections...
> > >
> > > I'm outta here for 10 days...Happy Holidays and talk with ya when I get
> > > back...
> >
> > ok, cool see you soon. :)
> >
> > -Alfred
> >
> > don't forget the problem with sending queries that may occur:
> >
> > i'm not sure if handlesendfailure() can cope with only sending
> > a 'Q' to the backend, we may have to work out reservations or
> > something for space, another idea would be to implement a
> > pqWritev() of some sort that would take an array of pointers
> > and lengths to send to the backend and only allow any data to
> > go into the backend if the entire string can fit.
> >
> > then again, handlesendfailure may work, but doing reservations
> > for the send buffer seems cleaner...
> >
> > diff's contexted against pgsql-'current':
> >
> >
> > Index: fe-connect.c
> > ===================================================================
> > RCS file: /home/pgcvs/pgsql/src/interfaces/libpq/fe-connect.c,v
> > retrieving revision 1.108
> > diff -u -c -r1.108 fe-connect.c
> > cvs diff: conflicting specifications of output style
> > *** fe-connect.c 1999/12/02 00:26:15 1.108
> > --- fe-connect.c 1999/12/14 09:42:24
> > ***************
> > *** 595,625 ****
> > return 0;
> > }
> >
> > -
> > - /* ----------
> > - * connectMakeNonblocking -
> > - * Make a connection non-blocking.
> > - * Returns 1 if successful, 0 if not.
> > - * ----------
> > - */
> > - static int
> > - connectMakeNonblocking(PGconn *conn)
> > - {
> > - #ifndef WIN32
> > - if (fcntl(conn->sock, F_SETFL, O_NONBLOCK) < 0)
> > - #else
> > - if (ioctlsocket(conn->sock, FIONBIO, &on) != 0)
> > - #endif
> > - {
> > - printfPQExpBuffer(&conn->errorMessage,
> > - "connectMakeNonblocking -- fcntl() failed: errno=%d\n%s\n",
> > - errno, strerror(errno));
> > - return 0;
> > - }
> > -
> > - return 1;
> > - }
> > -
> > /* ----------
> > * connectNoDelay -
> > * Sets the TCP_NODELAY socket option.
> > --- 595,600 ----
> > ***************
> > *** 792,798 ****
> > * Ewan Mellor <eem21(at)cam(dot)ac(dot)uk>.
> > * ---------- */
> > #if (!defined(WIN32) || defined(WIN32_NON_BLOCKING_CONNECTIONS)) && !defined(USE_SSL)
> > ! if (!connectMakeNonblocking(conn))
> > goto connect_errReturn;
> > #endif
> >
> > --- 767,773 ----
> > * Ewan Mellor <eem21(at)cam(dot)ac(dot)uk>.
> > * ---------- */
> > #if (!defined(WIN32) || defined(WIN32_NON_BLOCKING_CONNECTIONS)) && !defined(USE_SSL)
> > ! if (PQsetnonblocking(conn, TRUE) != 0)
> > goto connect_errReturn;
> > #endif
> >
> > ***************
> > *** 904,910 ****
> > /* This makes the connection non-blocking, for all those cases which forced us
> > not to do it above. */
> > #if (defined(WIN32) && !defined(WIN32_NON_BLOCKING_CONNECTIONS)) || defined(USE_SSL)
> > ! if (!connectMakeNonblocking(conn))
> > goto connect_errReturn;
> > #endif
> >
> > --- 879,885 ----
> > /* This makes the connection non-blocking, for all those cases which forced us
> > not to do it above. */
> > #if (defined(WIN32) && !defined(WIN32_NON_BLOCKING_CONNECTIONS)) || defined(USE_SSL)
> > ! if (PQsetnonblocking(conn, TRUE) != 0)
> > goto connect_errReturn;
> > #endif
> >
> > ***************
> > *** 1702,1707 ****
> > --- 1677,1683 ----
> > conn->inBuffer = (char *) malloc(conn->inBufSize);
> > conn->outBufSize = 8 * 1024;
> > conn->outBuffer = (char *) malloc(conn->outBufSize);
> > + conn->nonblocking = FALSE;
> > initPQExpBuffer(&conn->errorMessage);
> > initPQExpBuffer(&conn->workBuffer);
> > if (conn->inBuffer == NULL ||
> > ***************
> > *** 1811,1816 ****
> > --- 1787,1793 ----
> > conn->lobjfuncs = NULL;
> > conn->inStart = conn->inCursor = conn->inEnd = 0;
> > conn->outCount = 0;
> > + conn->nonblocking = FALSE;
> >
> > }
> >
> > Index: fe-exec.c
> > ===================================================================
> > RCS file: /home/pgcvs/pgsql/src/interfaces/libpq/fe-exec.c,v
> > retrieving revision 1.86
> > diff -u -c -r1.86 fe-exec.c
> > cvs diff: conflicting specifications of output style
> > *** fe-exec.c 1999/11/11 00:10:14 1.86
> > --- fe-exec.c 1999/12/14 05:55:11
> > ***************
> > *** 13,18 ****
> > --- 13,19 ----
> > */
> > #include <errno.h>
> > #include <ctype.h>
> > + #include <fcntl.h>
> >
> > #include "postgres.h"
> > #include "libpq-fe.h"
> > ***************
> > *** 24,30 ****
> > #include <unistd.h>
> > #endif
> >
> > -
> > /* keep this in same order as ExecStatusType in libpq-fe.h */
> > const char *const pgresStatus[] = {
> > "PGRES_EMPTY_QUERY",
> > --- 25,30 ----
> > ***************
> > *** 574,580 ****
> > --- 574,588 ----
> > * we will NOT block waiting for more input.
> > */
> > if (pqReadData(conn) < 0)
> > + {
> > + /*
> > + * try to flush the send-queue otherwise we may never get a
> > + * resonce for something that may not have already been sent
> > + * because it's in our write buffer!
> > + */
> > + pqFlush(conn);
> > return 0;
> > + }
> > /* Parsing of the data waits till later. */
> > return 1;
> > }
> > ***************
> > *** 1088,1095 ****
> > --- 1096,1112 ----
> > {
> > PGresult *result;
> > PGresult *lastResult;
> > + bool savedblocking;
> >
> > /*
> > + * we assume anyone calling PQexec wants blocking behaviour,
> > + * we force the blocking status of the connection to blocking
> > + * for the duration of this function and restore it on return
> > + */
> > + savedblocking = PQisnonblocking(conn);
> > + PQsetnonblocking(conn, FALSE);
> > +
> > + /*
> > * Silently discard any prior query result that application didn't
> > * eat. This is probably poor design, but it's here for backward
> > * compatibility.
> > ***************
> > *** 1102,1115 ****
> > PQclear(result);
> > printfPQExpBuffer(&conn->errorMessage,
> > "PQexec: you gotta get out of a COPY state yourself.\n");
> > ! return NULL;
> > }
> > PQclear(result);
> > }
> >
> > /* OK to send the message */
> > if (!PQsendQuery(conn, query))
> > ! return NULL;
> >
> > /*
> > * For backwards compatibility, return the last result if there are
> > --- 1119,1133 ----
> > PQclear(result);
> > printfPQExpBuffer(&conn->errorMessage,
> > "PQexec: you gotta get out of a COPY state yourself.\n");
> > ! /* restore blocking status */
> > ! goto errout;
> > }
> > PQclear(result);
> > }
> >
> > /* OK to send the message */
> > if (!PQsendQuery(conn, query))
> > ! goto errout;
> >
> > /*
> > * For backwards compatibility, return the last result if there are
> > ***************
> > *** 1142,1148 ****
> > --- 1160,1172 ----
> > result->resultStatus == PGRES_COPY_OUT)
> > break;
> > }
> > +
> > + PQsetnonblocking(conn, savedblocking);
> > return lastResult;
> > +
> > + errout:
> > + PQsetnonblocking(conn, savedblocking);
> > + return NULL;
> > }
> >
> >
> > ***************
> > *** 1431,1438 ****
> > "PQendcopy() -- I don't think there's a copy in progress.\n");
> > return 1;
> > }
> >
> > ! (void) pqFlush(conn); /* make sure no data is waiting to be sent */
> >
> > /* Return to active duty */
> > conn->asyncStatus = PGASYNC_BUSY;
> > --- 1455,1468 ----
> > "PQendcopy() -- I don't think there's a copy in progress.\n");
> > return 1;
> > }
> > +
> > + /* make sure no data is waiting to be sent */
> > + if (pqFlush(conn))
> > + return (1);
> >
> > ! /* non blocking connections may have to abort at this point. */
> > ! if (PQisnonblocking(conn) && PQisBusy(conn))
> > ! return (1);
> >
> > /* Return to active duty */
> > conn->asyncStatus = PGASYNC_BUSY;
> > ***************
> > *** 2025,2028 ****
> > --- 2055,2126 ----
> > return 1;
> > else
> > return 0;
> > + }
> > +
> > + /* PQsetnonblocking:
> > + sets the PGconn's database connection non-blocking if the arg is TRUE
> > + or makes it non-blocking if the arg is FALSE, this will not protect
> > + you from PQexec(), you'll only be safe when using the non-blocking
> > + API
> > + Needs to be called only on a connected database connection.
> > + */
> > +
> > + int
> > + PQsetnonblocking(PGconn *conn, int arg)
> > + {
> > + int fcntlarg;
> > +
> > + arg = (arg == TRUE) ? 1 : 0;
> > + if (arg == conn->nonblocking)
> > + return (0);
> > +
> > + #ifdef USE_SSL
> > + if (conn->ssl)
> > + {
> > + printfPQExpBuffer(&conn->errorMessage,
> > + "PQsetnonblocking() -- not supported when using SSL\n");
> > + return (-1);
> > + }
> > + #endif /* USE_SSL */
> > +
> > + #ifndef WIN32
> > + fcntlarg = fcntl(conn->sock, F_GETFL, 0);
> > + if (fcntlarg == -1)
> > + return (-1);
> > +
> > + if ((arg == TRUE &&
> > + fcntl(conn->sock, F_SETFL, fcntlarg | O_NONBLOCK) == -1) ||
> > + (arg == FALSE &&
> > + fcntl(conn->sock, F_SETFL, fcntlarg & ~O_NONBLOCK) == -1))
> > + #else
> > + fcntlarg = arg;
> > + if (ioctlsocket(conn->sock, FIONBIO, &fcntlarg) != 0)
> > + #endif
> > + {
> > + printfPQExpBuffer(&conn->errorMessage,
> > + "PQsetblocking() -- unable to set nonblocking status to %s\n",
> > + arg == TRUE ? "TRUE" : "FALSE");
> > + return (-1);
> > + }
> > +
> > + conn->nonblocking = arg;
> > + return (0);
> > + }
> > +
> > + /* return the blocking status of the database connection, TRUE == nonblocking,
> > + FALSE == blocking
> > + */
> > + int
> > + PQisnonblocking(PGconn *conn)
> > + {
> > +
> > + return (conn->nonblocking);
> > + }
> > +
> > + /* try to force data out, really only useful for non-blocking users */
> > + int
> > + PQflush(PGconn *conn)
> > + {
> > +
> > + return (pqFlush(conn));
> > }
> > Index: fe-misc.c
> > ===================================================================
> > RCS file: /home/pgcvs/pgsql/src/interfaces/libpq/fe-misc.c,v
> > retrieving revision 1.33
> > diff -u -c -r1.33 fe-misc.c
> > cvs diff: conflicting specifications of output style
> > *** fe-misc.c 1999/11/30 03:08:19 1.33
> > --- fe-misc.c 1999/12/14 08:21:09
> > ***************
> > *** 86,91 ****
> > --- 86,119 ----
> > {
> > size_t avail = Max(conn->outBufSize - conn->outCount, 0);
> >
> > + /*
> > + * if we are non-blocking and the send queue is too full to buffer this
> > + * request then try to flush some and return an error
> > + */
> > + if (PQisnonblocking(conn) && nbytes > avail && pqFlush(conn))
> > + {
> > + /*
> > + * even if the flush failed we may still have written some
> > + * data, recalculate the size of the send-queue relative
> > + * to the amount we have to send, we may be able to queue it
> > + * afterall even though it's not sent to the database it's
> > + * ok, any routines that check the data coming from the
> > + * database better call pqFlush() anyway.
> > + */
> > + if (nbytes > Max(conn->outBufSize - conn->outCount, 0))
> > + {
> > + printfPQExpBuffer(&conn->errorMessage,
> > + "pqPutBytes -- pqFlush couldn't flush enough"
> > + " data: space available: %d, space needed %d\n",
> > + Max(conn->outBufSize - conn->outCount, 0), nbytes);
> > + return EOF;
> > + }
> > + }
> > +
> > + /*
> > + * the non-blocking code above makes sure that this isn't true,
> > + * essentially this is no-op
> > + */
> > while (nbytes > avail)
> > {
> > memcpy(conn->outBuffer + conn->outCount, s, avail);
> > ***************
> > *** 548,553 ****
> > --- 576,589 ----
> > 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. */
> > ***************
> > *** 556,561 ****
> > --- 592,598 ----
> > #endif
> >
> > int sent;
> > +
> > #ifdef USE_SSL
> > if (conn->ssl)
> > sent = SSL_write(conn->ssl, ptr, len);
> > ***************
> > *** 585,590 ****
> > --- 622,629 ----
> > case EWOULDBLOCK:
> > break;
> > #endif
> > + case EINTR:
> > + continue;
> >
> > case EPIPE:
> > #ifdef ECONNRESET
> > ***************
> > *** 616,628 ****
> > ptr += sent;
> > len -= sent;
> > }
> > if (len > 0)
> > {
> > /* We didn't send it all, wait till we can send more */
> >
> > - /* At first glance this looks as though it should block. I think
> > - * that it will be OK though, as long as the socket is
> > - * non-blocking. */
> > if (pqWait(FALSE, TRUE, conn))
> > return EOF;
> > }
> > --- 655,685 ----
> > 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;
> > }
> > Index: libpq-fe.h
> > ===================================================================
> > RCS file: /home/pgcvs/pgsql/src/interfaces/libpq/libpq-fe.h,v
> > retrieving revision 1.53
> > diff -u -c -r1.53 libpq-fe.h
> > cvs diff: conflicting specifications of output style
> > *** libpq-fe.h 1999/11/30 03:08:19 1.53
> > --- libpq-fe.h 1999/12/14 01:30:01
> > ***************
> > *** 269,274 ****
> > --- 269,281 ----
> > extern int PQputnbytes(PGconn *conn, const char *buffer, int nbytes);
> > extern int PQendcopy(PGconn *conn);
> >
> > + /* Set blocking/nonblocking connection to the backend */
> > + extern int PQsetnonblocking(PGconn *conn, int arg);
> > + extern int PQisnonblocking(PGconn *conn);
> > +
> > + /* Force the write buffer to be written (or at least try) */
> > + extern int PQflush(PGconn *conn);
> > +
> > /*
> > * "Fast path" interface --- not really recommended for application
> > * use
> > Index: libpq-int.h
> > ===================================================================
> > RCS file: /home/pgcvs/pgsql/src/interfaces/libpq/libpq-int.h,v
> > retrieving revision 1.14
> > diff -u -c -r1.14 libpq-int.h
> > cvs diff: conflicting specifications of output style
> > *** libpq-int.h 1999/11/30 03:08:19 1.14
> > --- libpq-int.h 1999/12/14 01:30:01
> > ***************
> > *** 215,220 ****
> > --- 215,223 ----
> > int inEnd; /* offset to first position after avail
> > * data */
> >
> > + int nonblocking; /* whether this connection is using a blocking
> > + * socket to the backend or not */
> > +
> > /* Buffer for data not yet sent to backend */
> > char *outBuffer; /* currently allocated buffer */
> > int outBufSize; /* allocated size of buffer */
> >
> >
> >
> >
> >
> > ************
> >
>
>
> --
> Bruce Momjian | http://www.op.net/~candle
> maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
> + If your life is a hard drive, | 830 Blythe Avenue
> + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
>

Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy
Systems Administrator @ hub.org
primary: scrappy(at)hub(dot)org secondary: scrappy(at){freebsd|postgresql}.org