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Postgres95 1.01 Distribution - Virgin Sources
This commit is contained in:
Marc G. Fournier
354
src/backend/tcop/dest.c
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354
src/backend/tcop/dest.c
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/*-------------------------------------------------------------------------
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*
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* dest.c--
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* support for various communication destinations - see lib/H/tcop/dest.h
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/tcop/dest.c,v 1.1.1.1 1996/07/09 06:21:59 scrappy Exp $
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*
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*-------------------------------------------------------------------------
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*/
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/*
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* INTERFACE ROUTINES
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* BeginCommand - prepare destination for tuples of the given type
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* EndCommand - tell destination that no more tuples will arrive
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* NullCommand - tell dest that the last of a query sequence was processed
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*
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* NOTES
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* These routines do the appropriate work before and after
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* tuples are returned by a query to keep the backend and the
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* "destination" portals synchronized.
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*
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*/
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#include <stdio.h> /* for sprintf() */
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#include "postgres.h"
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#include "access/htup.h"
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#include "libpq/libpq-be.h"
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#include "access/printtup.h"
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#include "utils/portal.h"
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#include "utils/elog.h"
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#include "utils/palloc.h"
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#include "executor/executor.h"
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#include "tcop/dest.h"
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#include "catalog/pg_type.h"
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#include "utils/mcxt.h"
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#include "commands/async.h"
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/* ----------------
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* output functions
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* ----------------
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*/
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void
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donothing(List *tuple, List *attrdesc)
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{
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}
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void (*DestToFunction(CommandDest dest))()
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{
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switch (dest) {
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case RemoteInternal:
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return printtup_internal;
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break;
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case Remote:
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return printtup;
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break;
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case Local:
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return be_printtup;
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break;
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case Debug:
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return debugtup;
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break;
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case None:
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default:
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return donothing;
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break;
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}
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/*
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* never gets here, but DECstation lint appears to be stupid...
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*/
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return donothing;
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}
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#define IS_INSERT_TAG(tag) (*tag == 'I' && *(tag+1) == 'N')
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/* ----------------
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* EndCommand - tell destination that no more tuples will arrive
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* ----------------
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*/
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void
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EndCommand(char *commandTag, CommandDest dest)
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{
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char buf[64];
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switch (dest) {
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case RemoteInternal:
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case Remote:
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/* ----------------
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* tell the fe that the query is over
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* ----------------
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*/
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pq_putnchar("C", 1);
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/* pq_putint(0, 4); */
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if (IS_INSERT_TAG(commandTag))
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{
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sprintf(buf, "%s %d", commandTag, GetAppendOid());
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pq_putstr(buf);
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}
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else
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pq_putstr(commandTag);
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pq_flush();
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break;
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case Local:
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case Debug:
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break;
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case CopyEnd:
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pq_putnchar("Z", 1);
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pq_flush();
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break;
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case None:
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default:
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break;
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}
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}
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/*
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* These are necessary to sync communications between fe/be processes doing
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* COPY rel TO stdout
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*
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* or
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*
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* COPY rel FROM stdin
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*
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*/
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void
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SendCopyBegin()
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{
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pq_putnchar("B", 1);
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/* pq_putint(0, 4); */
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pq_flush();
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}
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void
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ReceiveCopyBegin()
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{
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pq_putnchar("D", 1);
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/* pq_putint(0, 4); */
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pq_flush();
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}
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/* ----------------
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* NullCommand - tell dest that the last of a query sequence was processed
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*
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* Necessary to implement the hacky FE/BE interface to handle
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* multiple-return queries.
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* ----------------
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*/
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void
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NullCommand(CommandDest dest)
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{
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switch (dest) {
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case RemoteInternal:
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case Remote: {
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#if 0
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/* Do any asynchronous notification. If front end wants to poll,
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it can send null queries to call this function.
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*/
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PQNotifyList *nPtr;
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MemoryContext orig;
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if (notifyContext == NULL) {
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notifyContext = CreateGlobalMemory("notify");
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}
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orig = MemoryContextSwitchTo((MemoryContext)notifyContext);
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for (nPtr = PQnotifies() ;
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nPtr != NULL;
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nPtr = (PQNotifyList *)SLGetSucc(&nPtr->Node)) {
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pq_putnchar("A",1);
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pq_putint(0, 4);
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pq_putstr(nPtr->relname);
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pq_putint(nPtr->be_pid,4);
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PQremoveNotify(nPtr);
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}
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pq_flush();
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PQcleanNotify(); /* garbage collect */
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(void) MemoryContextSwitchTo(orig);
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#endif
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/* ----------------
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* tell the fe that the last of the queries has finished
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* ----------------
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*/
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/* pq_putnchar("I", 1); */
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pq_putstr("I");
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/* pq_putint(0, 4);*/
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pq_flush();
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}
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break;
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case Local:
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case Debug:
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case None:
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default:
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break;
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}
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}
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/* ----------------
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* BeginCommand - prepare destination for tuples of the given type
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* ----------------
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*/
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void
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BeginCommand(char *pname,
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int operation,
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TupleDesc tupdesc,
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bool isIntoRel,
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bool isIntoPortal,
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char *tag,
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CommandDest dest)
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{
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PortalEntry *entry;
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AttributeTupleForm *attrs = tupdesc->attrs;
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int natts = tupdesc->natts;
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int i;
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char *p;
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switch (dest) {
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case RemoteInternal:
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case Remote:
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/* ----------------
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* if this is a "retrieve portal" query, just return
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* because nothing needs to be sent to the fe.
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* ----------------
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*/
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ResetAppendOid();
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if (isIntoPortal)
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return;
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/* ----------------
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* if portal name not specified for remote query,
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* use the "blank" portal.
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* ----------------
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*/
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if (pname == NULL)
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pname = "blank";
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/* ----------------
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* send fe info on tuples we're about to send
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* ----------------
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*/
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pq_flush();
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pq_putnchar("P", 1); /* new portal.. */
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pq_putstr(pname); /* portal name */
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/* ----------------
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* if this is a retrieve, then we send back the tuple
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* descriptor of the tuples. "retrieve into" is an
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* exception because no tuples are returned in that case.
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* ----------------
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*/
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if (operation == CMD_SELECT && !isIntoRel) {
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pq_putnchar("T", 1); /* type info to follow.. */
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pq_putint(natts, 2); /* number of attributes in tuples */
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for (i = 0; i < natts; ++i) {
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pq_putstr(attrs[i]->attname.data);/* if 16 char name oops.. */
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pq_putint((int) attrs[i]->atttypid, 4);
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pq_putint(attrs[i]->attlen, 2);
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}
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}
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pq_flush();
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break;
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case Local:
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/* ----------------
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* prepare local portal buffer for query results
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* and setup result for PQexec()
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* ----------------
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*/
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entry = be_currentportal();
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if (pname != NULL)
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pbuf_setportalinfo(entry, pname);
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if (operation == CMD_SELECT && !isIntoRel) {
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be_typeinit(entry, tupdesc, natts);
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p = (char *) palloc(strlen(entry->name)+2);
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p[0] = 'P';
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strcpy(p+1,entry->name);
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} else {
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p = (char *) palloc(strlen(tag)+2);
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p[0] = 'C';
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strcpy(p+1,tag);
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}
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entry->result = p;
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break;
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case Debug:
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/* ----------------
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* show the return type of the tuples
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* ----------------
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*/
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if (pname == NULL)
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pname = "blank";
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showatts(pname, tupdesc);
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break;
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case None:
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default:
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break;
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}
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}
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static Oid AppendOid;
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void
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ResetAppendOid()
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{
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AppendOid = InvalidOid;
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}
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#define MULTI_TUPLE_APPEND -1
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void
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UpdateAppendOid(Oid newoid)
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{
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/*
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* First update after AppendOid was reset (at command beginning).
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*/
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if (AppendOid == InvalidOid)
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AppendOid = newoid;
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/*
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* Already detected a multiple tuple append, return a void oid ;)
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*/
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else if (AppendOid == MULTI_TUPLE_APPEND)
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return;
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/*
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* Oid has been assigned once before, tag this as a multiple tuple
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* append.
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*/
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else
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AppendOid = MULTI_TUPLE_APPEND;
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}
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Oid
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GetAppendOid()
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{
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if (AppendOid == MULTI_TUPLE_APPEND)
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return InvalidOid;
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return AppendOid;
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}
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