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Viewing changes to src/backend/utils/adt/xid.c

  • Committer: Bazaar Package Importer
  • Author(s): Martin Pitt
  • Date: 2011-05-11 10:41:53 UTC
  • Revision ID: james.westby@ubuntu.com-20110511104153-psbh2o58553fv1m0
Tags: upstream-9.1~beta1
Import upstream version 9.1~beta1

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src/backend/utils/adt/xid.c
 
1
/*-------------------------------------------------------------------------
 
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 *
 
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 * xid.c
 
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 *        POSTGRES transaction identifier and command identifier datatypes.
 
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 *
 
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 * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
 
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 * Portions 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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 *        src/backend/utils/adt/xid.c
 
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 *
 
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 *-------------------------------------------------------------------------
 
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 */
 
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#include "postgres.h"
 
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#include <limits.h>
 
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#include "access/transam.h"
 
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#include "access/xact.h"
 
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#include "libpq/pqformat.h"
 
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#include "utils/builtins.h"
 
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#define PG_GETARG_TRANSACTIONID(n)      DatumGetTransactionId(PG_GETARG_DATUM(n))
 
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#define PG_RETURN_TRANSACTIONID(x)      return TransactionIdGetDatum(x)
 
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#define PG_GETARG_COMMANDID(n)          DatumGetCommandId(PG_GETARG_DATUM(n))
 
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#define PG_RETURN_COMMANDID(x)          return CommandIdGetDatum(x)
 
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Datum
 
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xidin(PG_FUNCTION_ARGS)
 
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{
 
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        char       *str = PG_GETARG_CSTRING(0);
 
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        PG_RETURN_TRANSACTIONID((TransactionId) strtoul(str, NULL, 0));
 
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}
 
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Datum
 
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xidout(PG_FUNCTION_ARGS)
 
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{
 
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        TransactionId transactionId = PG_GETARG_TRANSACTIONID(0);
 
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        /* maximum 32 bit unsigned integer representation takes 10 chars */
 
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        char       *str = palloc(11);
 
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        snprintf(str, 11, "%lu", (unsigned long) transactionId);
 
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        PG_RETURN_CSTRING(str);
 
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}
 
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/*
 
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 *              xidrecv                 - converts external binary format to xid
 
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 */
 
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Datum
 
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xidrecv(PG_FUNCTION_ARGS)
 
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{
 
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        StringInfo      buf = (StringInfo) PG_GETARG_POINTER(0);
 
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        PG_RETURN_TRANSACTIONID((TransactionId) pq_getmsgint(buf, sizeof(TransactionId)));
 
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}
 
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/*
 
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 *              xidsend                 - converts xid to binary format
 
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 */
 
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Datum
 
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xidsend(PG_FUNCTION_ARGS)
 
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{
 
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        TransactionId arg1 = PG_GETARG_TRANSACTIONID(0);
 
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        StringInfoData buf;
 
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        pq_begintypsend(&buf);
 
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        pq_sendint(&buf, arg1, sizeof(arg1));
 
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        PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 
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}
 
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/*
 
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 *              xideq                   - are two xids equal?
 
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 */
 
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Datum
 
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xideq(PG_FUNCTION_ARGS)
 
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{
 
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        TransactionId xid1 = PG_GETARG_TRANSACTIONID(0);
 
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        TransactionId xid2 = PG_GETARG_TRANSACTIONID(1);
 
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        PG_RETURN_BOOL(TransactionIdEquals(xid1, xid2));
 
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}
 
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/*
 
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 *              xid_age                 - compute age of an XID (relative to current xact)
 
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 */
 
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Datum
 
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xid_age(PG_FUNCTION_ARGS)
 
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{
 
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        TransactionId xid = PG_GETARG_TRANSACTIONID(0);
 
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        TransactionId now = GetTopTransactionId();
 
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        /* Permanent XIDs are always infinitely old */
 
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        if (!TransactionIdIsNormal(xid))
 
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                PG_RETURN_INT32(INT_MAX);
 
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        PG_RETURN_INT32((int32) (now - xid));
 
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}
 
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/*
 
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 * xidComparator
 
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 *              qsort comparison function for XIDs
 
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 *
 
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 * We can't use wraparound comparison for XIDs because that does not respect
 
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 * the triangle inequality!  Any old sort order will do.
 
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 */
 
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int
 
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xidComparator(const void *arg1, const void *arg2)
 
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{
 
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        TransactionId xid1 = *(const TransactionId *) arg1;
 
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        TransactionId xid2 = *(const TransactionId *) arg2;
 
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        if (xid1 > xid2)
 
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                return 1;
 
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        if (xid1 < xid2)
 
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                return -1;
 
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        return 0;
 
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}
 
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/*****************************************************************************
 
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 *       COMMAND IDENTIFIER ROUTINES                                                                                     *
 
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 *****************************************************************************/
 
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/*
 
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 *              cidin   - converts CommandId to internal representation.
 
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 */
 
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Datum
 
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cidin(PG_FUNCTION_ARGS)
 
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{
 
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        char       *s = PG_GETARG_CSTRING(0);
 
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        CommandId       c;
 
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        c = atoi(s);
 
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        PG_RETURN_COMMANDID(c);
 
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}
 
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/*
 
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 *              cidout  - converts a cid to external representation.
 
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 */
 
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Datum
 
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cidout(PG_FUNCTION_ARGS)
 
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{
 
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        CommandId       c = PG_GETARG_COMMANDID(0);
 
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        char       *result = (char *) palloc(16);
 
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        snprintf(result, 16, "%u", (unsigned int) c);
 
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        PG_RETURN_CSTRING(result);
 
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}
 
155
 
 
156
/*
 
157
 *              cidrecv                 - converts external binary format to cid
 
158
 */
 
159
Datum
 
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cidrecv(PG_FUNCTION_ARGS)
 
161
{
 
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        StringInfo      buf = (StringInfo) PG_GETARG_POINTER(0);
 
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164
        PG_RETURN_COMMANDID((CommandId) pq_getmsgint(buf, sizeof(CommandId)));
 
165
}
 
166
 
 
167
/*
 
168
 *              cidsend                 - converts cid to binary format
 
169
 */
 
170
Datum
 
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cidsend(PG_FUNCTION_ARGS)
 
172
{
 
173
        CommandId       arg1 = PG_GETARG_COMMANDID(0);
 
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        StringInfoData buf;
 
175
 
 
176
        pq_begintypsend(&buf);
 
177
        pq_sendint(&buf, arg1, sizeof(arg1));
 
178
        PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 
179
}
 
180
 
 
181
Datum
 
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cideq(PG_FUNCTION_ARGS)
 
183
{
 
184
        CommandId       arg1 = PG_GETARG_COMMANDID(0);
 
185
        CommandId       arg2 = PG_GETARG_COMMANDID(1);
 
186
 
 
187
        PG_RETURN_BOOL(arg1 == arg2);
 
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}