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In the continuing saga of FE/BE protocol revisions, add reporting of

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initial values and runtime changes in selected parameters.  This gets
rid of the need for an initial 'select pg_client_encoding()' query in
libpq, bringing us back to one message transmitted in each direction
for a standard connection startup.  To allow server version to be sent
using the same GUC mechanism that handles other parameters, invent the
concept of a never-settable GUC parameter: you can 'show server_version'
but it's not settable by any GUC input source.  Create 'lc_collate' and
'lc_ctype' never-settable parameters so that people can find out these
settings without need for pg_controldata.  (These side ideas were all
discussed some time ago in pgsql-hackers, but not yet implemented.)
This commit is contained in:
Tom Lane
2003-04-25 19:45:10 +00:00
parent a2190c9eb6
commit 9cbaf72177
13 changed files with 412 additions and 478 deletions
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53
src/interfaces/libpq/fe-exec.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.132 2003/04/25 01:24:00 momjian Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.133 2003/04/25 19:45:09 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -21,6 +21,8 @@
#include "libpq-fe.h"
#include "libpq-int.h"
#include "mb/pg_wchar.h"
#ifdef WIN32
#include "win32.h"
#else
@ -54,6 +56,7 @@ static void handleSendFailure(PGconn *conn);
static void handleSyncLoss(PGconn *conn, char id, int msgLength);
static int getRowDescriptions(PGconn *conn);
static int getAnotherTuple(PGconn *conn, int binary);
static int getParameterStatus(PGconn *conn);
static int getNotify(PGconn *conn);
/* ---------------
@ -950,6 +953,11 @@ parseInput(PGconn *conn)
*
* However, if the state is IDLE then we got trouble; we need to deal
* with the unexpected message somehow.
*
* ParameterStatus ('S') messages are a special case: in IDLE state
* we must process 'em (this case could happen if a new value was
* adopted from config file due to SIGHUP), but otherwise we hold
* off until BUSY state.
*/
if (id == 'A')
{
@ -970,6 +978,7 @@ parseInput(PGconn *conn)
/*
* Unexpected message in IDLE state; need to recover somehow.
* ERROR messages are displayed using the notice processor;
* ParameterStatus is handled normally;
* anything else is just dropped on the floor after displaying
* a suitable warning notice. (An ERROR is very possibly the
* backend telling us why it is about to close the connection,
@ -980,6 +989,11 @@ parseInput(PGconn *conn)
if (pqGetErrorNotice(conn, false /* treat as notice */))
return;
}
else if (id == 'S')
{
if (getParameterStatus(conn))
return;
}
else
{
snprintf(noticeWorkspace, sizeof(noticeWorkspace),
@ -1021,6 +1035,10 @@ parseInput(PGconn *conn)
PGRES_EMPTY_QUERY);
conn->asyncStatus = PGASYNC_READY;
break;
case 'S': /* parameter status */
if (getParameterStatus(conn))
return;
break;
case 'K': /* secret key data from the backend */
/*
@ -1671,6 +1689,35 @@ fail:
return EOF;
}
/*
* Attempt to read a ParameterStatus message.
* This is possible in several places, so we break it out as a subroutine.
* Entry: 'S' message type and length have already been consumed.
* Exit: returns 0 if successfully consumed message.
* returns EOF if not enough data.
*/
static int
getParameterStatus(PGconn *conn)
{
/* Get the parameter name */
if (pqGets(&conn->workBuffer, conn))
return EOF;
/* Is it one we care about? */
if (strcmp(conn->workBuffer.data, "client_encoding") == 0)
{
if (pqGets(&conn->workBuffer, conn))
return EOF;
conn->client_encoding = pg_char_to_encoding(conn->workBuffer.data);
}
else
{
/* Uninteresting parameter, ignore it */
if (pqGets(&conn->workBuffer, conn))
return EOF;
}
return 0;
}
/*
* Attempt to read a Notify response message.
* This is possible in several places, so we break it out as a subroutine.
@ -2249,6 +2296,10 @@ PQfn(PGconn *conn,
if (conn->result)
return prepareAsyncResult(conn);
return PQmakeEmptyPGresult(conn, status);
case 'S': /* parameter status */
if (getParameterStatus(conn))
continue;
break;
default:
/* The backend violates the protocol. */
printfPQExpBuffer(&conn->errorMessage,