pgrowlocks.c File Reference

#include "postgres.h"
#include "access/heapam.h"
#include "access/multixact.h"
#include "access/relscan.h"
#include "access/tableam.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "catalog/pg_am_d.h"
#include "catalog/pg_authid.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/procarray.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/varlena.h"

Include dependency graph for pgrowlocks.c:

Go to the source code of this file.

Macros
#define	NCHARS   32
#define	Atnum_tid   0
#define	Atnum_xmax   1
#define	Atnum_ismulti   2
#define	Atnum_xids   3
#define	Atnum_modes   4
#define	Atnum_pids   5

Functions
	PG_FUNCTION_INFO_V1 (pgrowlocks)
Datum	pgrowlocks (PG_FUNCTION_ARGS)

Variables
	PG_MODULE_MAGIC

Macro Definition Documentation

Atnum_ismulti

#define Atnum_ismulti   2

Definition at line 59 of file pgrowlocks.c.

Atnum_modes

#define Atnum_modes   4

Definition at line 61 of file pgrowlocks.c.

Atnum_pids

#define Atnum_pids   5

Definition at line 62 of file pgrowlocks.c.

Atnum_tid

#define Atnum_tid   0

Definition at line 57 of file pgrowlocks.c.

Atnum_xids

#define Atnum_xids   3

Definition at line 60 of file pgrowlocks.c.

Atnum_xmax

#define Atnum_xmax   1

Definition at line 58 of file pgrowlocks.c.

NCHARS

#define NCHARS   32

Definition at line 55 of file pgrowlocks.c.

Function Documentation

PG_FUNCTION_INFO_V1()

PG_FUNCTION_INFO_V1

(

pgrowlocks

)

pgrowlocks()

Datum pgrowlocks

(

PG_FUNCTION_ARGS

)

Definition at line 65 of file pgrowlocks.c.

{
    text       *relname = PG_GETARG_TEXT_PP(0);
    ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
    AttInMetadata *attinmeta;
    Relation    rel;
    RangeVar   *relrv;
    TableScanDesc scan;
    HeapScanDesc hscan;
    HeapTuple   tuple;
    AclResult   aclresult;
    char      **values;
 
    SetSingleFuncCall(fcinfo, 0);
 
    /* Access the table */
    relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
    rel = relation_openrv(relrv, AccessShareLock);
 
    if (rel->rd_rel->relam != HEAP_TABLE_AM_OID)
        ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                        errmsg("only heap AM is supported")));
 
    if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is a partitioned table",
                        RelationGetRelationName(rel)),
                 errdetail("Partitioned tables do not contain rows.")));
    else if (rel->rd_rel->relkind != RELKIND_RELATION)
        ereport(ERROR,
                (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                 errmsg("\"%s\" is not a table",
                        RelationGetRelationName(rel))));
 
    /*
     * check permissions: must have SELECT on table or be in
     * pg_stat_scan_tables
     */
    aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
                                  ACL_SELECT);
    if (aclresult != ACLCHECK_OK)
        aclresult = has_privs_of_role(GetUserId(), ROLE_PG_STAT_SCAN_TABLES) ? ACLCHECK_OK : ACLCHECK_NO_PRIV;
 
    if (aclresult != ACLCHECK_OK)
        aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind),
                       RelationGetRelationName(rel));
 
    /* Scan the relation */
    scan = table_beginscan(rel, GetActiveSnapshot(), 0, NULL);
    hscan = (HeapScanDesc) scan;
 
    attinmeta = TupleDescGetAttInMetadata(rsinfo->setDesc);
 
    values = (char **) palloc(rsinfo->setDesc->natts * sizeof(char *));
 
    while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
    {
        TM_Result   htsu;
        TransactionId xmax;
        uint16      infomask;
 
        /* must hold a buffer lock to call HeapTupleSatisfiesUpdate */
        LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
 
        htsu = HeapTupleSatisfiesUpdate(tuple,
                                        GetCurrentCommandId(false),
                                        hscan->rs_cbuf);
        xmax = HeapTupleHeaderGetRawXmax(tuple->t_data);
        infomask = tuple->t_data->t_infomask;
 
        /*
         * A tuple is locked if HTSU returns BeingModified.
         */
        if (htsu == TM_BeingModified)
        {
            values[Atnum_tid] = (char *) DirectFunctionCall1(tidout,
                                                             PointerGetDatum(&tuple->t_self));
 
            values[Atnum_xmax] = palloc(NCHARS * sizeof(char));
            snprintf(values[Atnum_xmax], NCHARS, "%u", xmax);
            if (infomask & HEAP_XMAX_IS_MULTI)
            {
                MultiXactMember *members;
                int         nmembers;
                bool        first = true;
                bool        allow_old;
 
                values[Atnum_ismulti] = pstrdup("true");
 
                allow_old = HEAP_LOCKED_UPGRADED(infomask);
                nmembers = GetMultiXactIdMembers(xmax, &members, allow_old,
                                                 false);
                if (nmembers == -1)
                {
                    values[Atnum_xids] = "{0}";
                    values[Atnum_modes] = "{transient upgrade status}";
                    values[Atnum_pids] = "{0}";
                }
                else
                {
                    int         j;
 
                    values[Atnum_xids] = palloc(NCHARS * nmembers);
                    values[Atnum_modes] = palloc(NCHARS * nmembers);
                    values[Atnum_pids] = palloc(NCHARS * nmembers);
 
                    strcpy(values[Atnum_xids], "{");
                    strcpy(values[Atnum_modes], "{");
                    strcpy(values[Atnum_pids], "{");
 
                    for (j = 0; j < nmembers; j++)
                    {
                        char        buf[NCHARS];
 
                        if (!first)
                        {
                            strcat(values[Atnum_xids], ",");
                            strcat(values[Atnum_modes], ",");
                            strcat(values[Atnum_pids], ",");
                        }
                        snprintf(buf, NCHARS, "%u", members[j].xid);
                        strcat(values[Atnum_xids], buf);
                        switch (members[j].status)
                        {
                            case MultiXactStatusUpdate:
                                snprintf(buf, NCHARS, "Update");
                                break;
                            case MultiXactStatusNoKeyUpdate:
                                snprintf(buf, NCHARS, "No Key Update");
                                break;
                            case MultiXactStatusForUpdate:
                                snprintf(buf, NCHARS, "For Update");
                                break;
                            case MultiXactStatusForNoKeyUpdate:
                                snprintf(buf, NCHARS, "For No Key Update");
                                break;
                            case MultiXactStatusForShare:
                                snprintf(buf, NCHARS, "Share");
                                break;
                            case MultiXactStatusForKeyShare:
                                snprintf(buf, NCHARS, "Key Share");
                                break;
                        }
                        strcat(values[Atnum_modes], buf);
                        snprintf(buf, NCHARS, "%d",
                                 BackendXidGetPid(members[j].xid));
                        strcat(values[Atnum_pids], buf);
 
                        first = false;
                    }
 
                    strcat(values[Atnum_xids], "}");
                    strcat(values[Atnum_modes], "}");
                    strcat(values[Atnum_pids], "}");
                }
            }
            else
            {
                values[Atnum_ismulti] = pstrdup("false");
 
                values[Atnum_xids] = palloc(NCHARS * sizeof(char));
                snprintf(values[Atnum_xids], NCHARS, "{%u}", xmax);
 
                values[Atnum_modes] = palloc(NCHARS);
                if (infomask & HEAP_XMAX_LOCK_ONLY)
                {
                    if (HEAP_XMAX_IS_SHR_LOCKED(infomask))
                        snprintf(values[Atnum_modes], NCHARS, "{For Share}");
                    else if (HEAP_XMAX_IS_KEYSHR_LOCKED(infomask))
                        snprintf(values[Atnum_modes], NCHARS, "{For Key Share}");
                    else if (HEAP_XMAX_IS_EXCL_LOCKED(infomask))
                    {
                        if (tuple->t_data->t_infomask2 & HEAP_KEYS_UPDATED)
                            snprintf(values[Atnum_modes], NCHARS, "{For Update}");
                        else
                            snprintf(values[Atnum_modes], NCHARS, "{For No Key Update}");
                    }
                    else
                        /* neither keyshare nor exclusive bit it set */
                        snprintf(values[Atnum_modes], NCHARS,
                                 "{transient upgrade status}");
                }
                else
                {
                    if (tuple->t_data->t_infomask2 & HEAP_KEYS_UPDATED)
                        snprintf(values[Atnum_modes], NCHARS, "{Update}");
                    else
                        snprintf(values[Atnum_modes], NCHARS, "{No Key Update}");
                }
 
                values[Atnum_pids] = palloc(NCHARS * sizeof(char));
                snprintf(values[Atnum_pids], NCHARS, "{%d}",
                         BackendXidGetPid(xmax));
            }
 
            LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
 
            /* build a tuple */
            tuple = BuildTupleFromCStrings(attinmeta, values);
            tuplestore_puttuple(rsinfo->setResult, tuple);
        }
        else
        {
            LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_UNLOCK);
        }
    }
 
    table_endscan(scan);
    table_close(rel, AccessShareLock);
    return (Datum) 0;
}

References AccessShareLock, ACL_SELECT, aclcheck_error(), ACLCHECK_NO_PRIV, ACLCHECK_OK, Atnum_ismulti, Atnum_modes, Atnum_pids, Atnum_tid, Atnum_xids, Atnum_xmax, BackendXidGetPid(), buf, BUFFER_LOCK_SHARE, BUFFER_LOCK_UNLOCK, BuildTupleFromCStrings(), DirectFunctionCall1, ereport, errcode(), errdetail(), errmsg(), ERROR, ForwardScanDirection, get_relkind_objtype(), GetActiveSnapshot(), GetCurrentCommandId(), GetMultiXactIdMembers(), GetUserId(), has_privs_of_role(), heap_getnext(), HEAP_KEYS_UPDATED, HEAP_LOCKED_UPGRADED, HEAP_XMAX_IS_EXCL_LOCKED, HEAP_XMAX_IS_KEYSHR_LOCKED, HEAP_XMAX_IS_MULTI, HEAP_XMAX_IS_SHR_LOCKED, HEAP_XMAX_LOCK_ONLY, HeapTupleHeaderGetRawXmax, HeapTupleSatisfiesUpdate(), j, LockBuffer(), makeRangeVarFromNameList(), MultiXactStatusForKeyShare, MultiXactStatusForNoKeyUpdate, MultiXactStatusForShare, MultiXactStatusForUpdate, MultiXactStatusNoKeyUpdate, MultiXactStatusUpdate, TupleDescData::natts, NCHARS, palloc(), pg_class_aclcheck(), PG_GETARG_TEXT_PP, PointerGetDatum, pstrdup(), relation_openrv(), RelationGetRelationName, RelationGetRelid, relname, ReturnSetInfo::setDesc, ReturnSetInfo::setResult, SetSingleFuncCall(), snprintf, status(), table_beginscan(), table_close(), table_endscan(), textToQualifiedNameList(), tidout(), TM_BeingModified, TupleDescGetAttInMetadata(), tuplestore_puttuple(), and values.

Variable Documentation

PG_MODULE_MAGIC

PG_MODULE_MAGIC

Definition at line 45 of file pgrowlocks.c.