src/backend/utils/adt/xid.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * xid.c
   4  *        POSTGRES transaction identifier and command identifier datatypes.
   5  *
   6  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL$
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include <limits.h>
  18
  19 #include "access/transam.h"
  20 #include "access/xact.h"
  21 #include "libpq/pqformat.h"
  22 #include "utils/builtins.h"
  23
  24 #define PG_GETARG_TRANSACTIONID(n)      DatumGetTransactionId(PG_GETARG_DATUM(n))
  25 #define PG_RETURN_TRANSACTIONID(x)      return TransactionIdGetDatum(x)
  26
  27 #define PG_GETARG_COMMANDID(n)          DatumGetCommandId(PG_GETARG_DATUM(n))
  28 #define PG_RETURN_COMMANDID(x)          return CommandIdGetDatum(x)
  29
  30
  31 Datum
  32 xidin(PG_FUNCTION_ARGS)
  33 {
  34         char       *str = PG_GETARG_CSTRING(0);
  35
  36         PG_RETURN_TRANSACTIONID((TransactionId) strtoul(str, NULL, 0));
  37 }
  38
  39 Datum
  40 xidout(PG_FUNCTION_ARGS)
  41 {
  42         TransactionId transactionId = PG_GETARG_TRANSACTIONID(0);
  43
  44         /* maximum 32 bit unsigned integer representation takes 10 chars */
  45         char       *str = palloc(11);
  46
  47         snprintf(str, 11, "%lu", (unsigned long) transactionId);
  48
  49         PG_RETURN_CSTRING(str);
  50 }
  51
  52 /*
  53  *              xidrecv                 - converts external binary format to xid
  54  */
  55 Datum
  56 xidrecv(PG_FUNCTION_ARGS)
  57 {
  58         StringInfo      buf = (StringInfo) PG_GETARG_POINTER(0);
  59
  60         PG_RETURN_TRANSACTIONID((TransactionId) pq_getmsgint(buf, sizeof(TransactionId)));
  61 }
  62
  63 /*
  64  *              xidsend                 - converts xid to binary format
  65  */
  66 Datum
  67 xidsend(PG_FUNCTION_ARGS)
  68 {
  69         TransactionId arg1 = PG_GETARG_TRANSACTIONID(0);
  70         StringInfoData buf;
  71
  72         pq_begintypsend(&buf);
  73         pq_sendint(&buf, arg1, sizeof(arg1));
  74         PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
  75 }
  76
  77 /*
  78  *              xideq                   - are two xids equal?
  79  */
  80 Datum
  81 xideq(PG_FUNCTION_ARGS)
  82 {
  83         TransactionId xid1 = PG_GETARG_TRANSACTIONID(0);
  84         TransactionId xid2 = PG_GETARG_TRANSACTIONID(1);
  85
  86         PG_RETURN_BOOL(TransactionIdEquals(xid1, xid2));
  87 }
  88
  89 /*
  90  *              xid_age                 - compute age of an XID (relative to current xact)
  91  */
  92 Datum
  93 xid_age(PG_FUNCTION_ARGS)
  94 {
  95         TransactionId xid = PG_GETARG_TRANSACTIONID(0);
  96         TransactionId now = GetTopTransactionId();
  97
  98         /* Permanent XIDs are always infinitely old */
  99         if (!TransactionIdIsNormal(xid))
 100                 PG_RETURN_INT32(INT_MAX);
 101
 102         PG_RETURN_INT32((int32) (now - xid));
 103 }
 104
 105
 106 /*****************************************************************************
 107  *       COMMAND IDENTIFIER ROUTINES                                                                                     *
 108  *****************************************************************************/
 109
 110 /*
 111  *              cidin   - converts CommandId to internal representation.
 112  */
 113 Datum
 114 cidin(PG_FUNCTION_ARGS)
 115 {
 116         char       *s = PG_GETARG_CSTRING(0);
 117         CommandId       c;
 118
 119         c = atoi(s);
 120
 121         PG_RETURN_COMMANDID(c);
 122 }
 123
 124 /*
 125  *              cidout  - converts a cid to external representation.
 126  */
 127 Datum
 128 cidout(PG_FUNCTION_ARGS)
 129 {
 130         CommandId       c = PG_GETARG_COMMANDID(0);
 131         char       *result = (char *) palloc(16);
 132
 133         snprintf(result, 16, "%u", (unsigned int) c);
 134         PG_RETURN_CSTRING(result);
 135 }
 136
 137 /*
 138  *              cidrecv                 - converts external binary format to cid
 139  */
 140 Datum
 141 cidrecv(PG_FUNCTION_ARGS)
 142 {
 143         StringInfo      buf = (StringInfo) PG_GETARG_POINTER(0);
 144
 145         PG_RETURN_COMMANDID((CommandId) pq_getmsgint(buf, sizeof(CommandId)));
 146 }
 147
 148 /*
 149  *              cidsend                 - converts cid to binary format
 150  */
 151 Datum
 152 cidsend(PG_FUNCTION_ARGS)
 153 {
 154         CommandId       arg1 = PG_GETARG_COMMANDID(0);
 155         StringInfoData buf;
 156
 157         pq_begintypsend(&buf);
 158         pq_sendint(&buf, arg1, sizeof(arg1));
 159         PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 160 }
 161
 162 Datum
 163 cideq(PG_FUNCTION_ARGS)
 164 {
 165         CommandId       arg1 = PG_GETARG_COMMANDID(0);
 166         CommandId       arg2 = PG_GETARG_COMMANDID(1);
 167
 168         PG_RETURN_BOOL(arg1 == arg2);
 169 }