Age Owner Branch data TLA 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 : : */
414 noah@leadboat.com 40 :CBC 46 : PG_FUNCTION_INFO_V1(removable_cutoff);
41 : : Datum
42 : 10 : removable_cutoff(PG_FUNCTION_ARGS)
43 : : {
44 : 10 : 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 [ + - ]: 10 : if (!PG_ARGISNULL(0))
51 : 10 : rel = table_open(PG_GETARG_OID(0), AccessShareLock);
52 : :
58 heikki.linnakangas@i 53 [ + - - + : 10 : if (rel != NULL && !rel->rd_rel->relisshared && autovacuum_start_daemon)
- - ]
340 noah@leadboat.com 54 [ # # ]:UBC 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 : : */
414 noah@leadboat.com 64 :CBC 10 : next_fxid = ReadNextFullTransactionId();
65 : : do
66 : : {
67 [ - + ]: 10 : CHECK_FOR_INTERRUPTS();
68 : 10 : next_fxid_before = next_fxid;
69 : 10 : xid = GetOldestNonRemovableTransactionId(rel);
70 : 10 : next_fxid = ReadNextFullTransactionId();
71 [ - + ]: 10 : } while (!FullTransactionIdEquals(next_fxid, next_fxid_before));
72 : :
73 [ + - ]: 10 : if (rel)
74 : 10 : table_close(rel, AccessShareLock);
75 : :
76 : 10 : PG_RETURN_FULLTRANSACTIONID(FullTransactionIdFromAllowableAt(next_fxid,
77 : : xid));
78 : : }
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