Branch data     Line data    Source code

       1                 :             : /*--------------------------------------------------------------------------
       2                 :             :  *
       3                 :             :  * regress_injection.c
       4                 :             :  *      Functions supporting test-specific subject matter.
       5                 :             :  *
       6                 :             :  * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
       7                 :             :  * Portions Copyright (c) 1994, Regents of the University of California
       8                 :             :  *
       9                 :             :  * IDENTIFICATION
      10                 :             :  *      src/test/modules/injection_points/regress_injection.c
      11                 :             :  *
      12                 :             :  * -------------------------------------------------------------------------
      13                 :             :  */
      14                 :             : 
      15                 :             : #include "postgres.h"
      16                 :             : 
      17                 :             : #include "access/table.h"
      18                 :             : #include "fmgr.h"
      19                 :             : #include "miscadmin.h"
      20                 :             : #include "postmaster/autovacuum.h"
      21                 :             : #include "storage/procarray.h"
      22                 :             : #include "utils/rel.h"
      23                 :             : #include "utils/xid8.h"
      24                 :             : 
      25                 :             : /*
      26                 :             :  * removable_cutoff - for syscache-update-pruned.spec
      27                 :             :  *
      28                 :             :  * Wrapper around GetOldestNonRemovableTransactionId().  In general, this can
      29                 :             :  * move backward.  runningcheck=false isolation tests can reasonably prevent
      30                 :             :  * that.  For the causes of backward movement, see
      31                 :             :  * postgr.es/m/CAEze2Wj%2BV0kTx86xB_YbyaqTr5hnE_igdWAwuhSyjXBYscf5-Q%40mail.gmail.com
      32                 :             :  * and the header comment for ComputeXidHorizons().  One can assume this
      33                 :             :  * doesn't move backward if one (a) passes a shared catalog as the argument
      34                 :             :  * and (b) arranges for concurrent activity not to reach AbortTransaction().
      35                 :             :  * Non-runningcheck tests can control most concurrent activity, except
      36                 :             :  * autovacuum and the isolationtester control connection.  AbortTransaction()
      37                 :             :  * in those would justify test failure.  Seeing autoanalyze can allocate an
      38                 :             :  * XID in any database, (a) ensures we'll consistently not ignore those XIDs.
      39                 :             :  */
      40                 :          50 : PG_FUNCTION_INFO_V1(removable_cutoff);
      41                 :             : Datum
      42                 :           9 : removable_cutoff(PG_FUNCTION_ARGS)
      43                 :             : {
      44                 :           9 :     Relation    rel = NULL;
      45                 :             :     TransactionId xid;
      46                 :             :     FullTransactionId next_fxid_before,
      47                 :             :                 next_fxid;
      48                 :             : 
      49                 :             :     /* could take other relkinds callee takes, but we've not yet needed it */
      50         [ +  - ]:           9 :     if (!PG_ARGISNULL(0))
      51                 :           9 :         rel = table_open(PG_GETARG_OID(0), AccessShareLock);
      52                 :             : 
      53   [ +  -  -  +  :           9 :     if (rel != NULL && !rel->rd_rel->relisshared && autovacuum_start_daemon)
                   -  - ]
      54         [ #  # ]:           0 :         elog(WARNING,
      55                 :             :              "removable_cutoff(non-shared-rel) can move backward under autovacuum=on");
      56                 :             : 
      57                 :             :     /*
      58                 :             :      * No lock or snapshot necessarily prevents oldestXid from advancing past
      59                 :             :      * "xid" while this function runs.  That concerns us only in that we must
      60                 :             :      * not ascribe "xid" to the wrong epoch.  (That may never arise in
      61                 :             :      * isolation testing, but let's set a good example.)  As a crude solution,
      62                 :             :      * retry until nextXid doesn't change.
      63                 :             :      */
      64                 :           9 :     next_fxid = ReadNextFullTransactionId();
      65                 :             :     do
      66                 :             :     {
      67         [ -  + ]:           9 :         CHECK_FOR_INTERRUPTS();
      68                 :           9 :         next_fxid_before = next_fxid;
      69                 :           9 :         xid = GetOldestNonRemovableTransactionId(rel);
      70                 :           9 :         next_fxid = ReadNextFullTransactionId();
      71         [ -  + ]:           9 :     } while (!FullTransactionIdEquals(next_fxid, next_fxid_before));
      72                 :             : 
      73         [ +  - ]:           9 :     if (rel)
      74                 :           9 :         table_close(rel, AccessShareLock);
      75                 :             : 
      76                 :           9 :     PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromAllowableAt(next_fxid,
      77                 :             :                                                                  xid));
      78                 :             : }