regress.c

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/*------------------------------------------------------------------------
 *
 * regress.c
 *   Code for various C-language functions defined as part of the
 *   regression tests.
 *
 * This code is released under the terms of the PostgreSQL License.
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/test/regress/regress.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include <math.h>
#include <signal.h>

#include "access/detoast.h"
#include "access/htup_details.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "commands/sequence.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "executor/spi.h"
#include "miscadmin.h"
#include "nodes/supportnodes.h"
#include "optimizer/optimizer.h"
#include "optimizer/plancat.h"
#include "port/atomics.h"
#include "storage/spin.h"
#include "utils/builtins.h"
#include "utils/geo_decls.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/typcache.h"

#define EXPECT_TRUE(expr)   \
    do { \
        if (!(expr)) \
            elog(ERROR, \
                 "%s was unexpectedly false in file \"%s\" line %u", \
                 #expr, __FILE__, __LINE__); \
    } while (0)

#define EXPECT_EQ_U32(result_expr, expected_expr)   \
    do { \
        uint32      result = (result_expr); \
        uint32      expected = (expected_expr); \
        if (result != expected) \
            elog(ERROR, \
                 "%s yielded %u, expected %s in file \"%s\" line %u", \
                 #result_expr, result, #expected_expr, __FILE__, __LINE__); \
    } while (0)

#define EXPECT_EQ_U64(result_expr, expected_expr)   \
    do { \
        uint64      result = (result_expr); \
        uint64      expected = (expected_expr); \
        if (result != expected) \
            elog(ERROR, \
                 "%s yielded " UINT64_FORMAT ", expected %s in file \"%s\" line %u", \
                 #result_expr, result, #expected_expr, __FILE__, __LINE__); \
    } while (0)

#define LDELIM          '('
#define RDELIM          ')'
#define DELIM           ','

static void regress_lseg_construct(LSEG *lseg, Point *pt1, Point *pt2);

PG_MODULE_MAGIC;


/* return the point where two paths intersect, or NULL if no intersection. */
PG_FUNCTION_INFO_V1(interpt_pp);

Datum
interpt_pp(PG_FUNCTION_ARGS)
{
    PATH       *p1 = PG_GETARG_PATH_P(0);
    PATH       *p2 = PG_GETARG_PATH_P(1);
    int         i,
                j;
    LSEG        seg1,
                seg2;
    bool        found;          /* We've found the intersection */

    found = false;              /* Haven't found it yet */

    for (i = 0; i < p1->npts - 1 && !found; i++)
    {
        regress_lseg_construct(&seg1, &p1->p[i], &p1->p[i + 1]);
        for (j = 0; j < p2->npts - 1 && !found; j++)
        {
            regress_lseg_construct(&seg2, &p2->p[j], &p2->p[j + 1]);
            if (DatumGetBool(DirectFunctionCall2(lseg_intersect,
                                                 LsegPGetDatum(&seg1),
                                                 LsegPGetDatum(&seg2))))
                found = true;
        }
    }

    if (!found)
        PG_RETURN_NULL();

    /*
     * Note: DirectFunctionCall2 will kick out an error if lseg_interpt()
     * returns NULL, but that should be impossible since we know the two
     * segments intersect.
     */
    PG_RETURN_DATUM(DirectFunctionCall2(lseg_interpt,
                                        LsegPGetDatum(&seg1),
                                        LsegPGetDatum(&seg2)));
}


/* like lseg_construct, but assume space already allocated */
static void
regress_lseg_construct(LSEG *lseg, Point *pt1, Point *pt2)
{
    lseg->p[0].x = pt1->x;
    lseg->p[0].y = pt1->y;
    lseg->p[1].x = pt2->x;
    lseg->p[1].y = pt2->y;
}

PG_FUNCTION_INFO_V1(overpaid);

Datum
overpaid(PG_FUNCTION_ARGS)
{
    HeapTupleHeader tuple = PG_GETARG_HEAPTUPLEHEADER(0);
    bool        isnull;
    int32       salary;

    salary = DatumGetInt32(GetAttributeByName(tuple, "salary", &isnull));
    if (isnull)
        PG_RETURN_NULL();
    PG_RETURN_BOOL(salary > 699);
}

/* New type "widget"
 * This used to be "circle", but I added circle to builtins,
 *  so needed to make sure the names do not collide. - tgl 97/04/21
 */

typedef struct
{
    Point       center;
    double      radius;
} WIDGET;

PG_FUNCTION_INFO_V1(widget_in);
PG_FUNCTION_INFO_V1(widget_out);

#define NARGS   3

Datum
widget_in(PG_FUNCTION_ARGS)
{
    char       *str = PG_GETARG_CSTRING(0);
    char       *p,
               *coord[NARGS];
    int         i;
    WIDGET     *result;

    for (i = 0, p = str; *p && i < NARGS && *p != RDELIM; p++)
    {
        if (*p == DELIM || (*p == LDELIM && i == 0))
            coord[i++] = p + 1;
    }

    if (i < NARGS)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                 errmsg("invalid input syntax for type %s: \"%s\"",
                        "widget", str)));

    result = (WIDGET *) palloc(sizeof(WIDGET));
    result->center.x = atof(coord[0]);
    result->center.y = atof(coord[1]);
    result->radius = atof(coord[2]);

    PG_RETURN_POINTER(result);
}

Datum
widget_out(PG_FUNCTION_ARGS)
{
    WIDGET     *widget = (WIDGET *) PG_GETARG_POINTER(0);
    char       *str = psprintf("(%g,%g,%g)",
                               widget->center.x, widget->center.y, widget->radius);

    PG_RETURN_CSTRING(str);
}

PG_FUNCTION_INFO_V1(pt_in_widget);

Datum
pt_in_widget(PG_FUNCTION_ARGS)
{
    Point      *point = PG_GETARG_POINT_P(0);
    WIDGET     *widget = (WIDGET *) PG_GETARG_POINTER(1);
    float8      distance;

    distance = DatumGetFloat8(DirectFunctionCall2(point_distance,
                                                  PointPGetDatum(point),
                                                  PointPGetDatum(&widget->center)));

    PG_RETURN_BOOL(distance < widget->radius);
}

PG_FUNCTION_INFO_V1(reverse_name);

Datum
reverse_name(PG_FUNCTION_ARGS)
{
    char       *string = PG_GETARG_CSTRING(0);
    int         i;
    int         len;
    char       *new_string;

    new_string = palloc0(NAMEDATALEN);
    for (i = 0; i < NAMEDATALEN && string[i]; ++i)
        ;
    if (i == NAMEDATALEN || !string[i])
        --i;
    len = i;
    for (; i >= 0; --i)
        new_string[len - i] = string[i];
    PG_RETURN_CSTRING(new_string);
}

PG_FUNCTION_INFO_V1(trigger_return_old);

Datum
trigger_return_old(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    HeapTuple   tuple;

    if (!CALLED_AS_TRIGGER(fcinfo))
        elog(ERROR, "trigger_return_old: not fired by trigger manager");

    tuple = trigdata->tg_trigtuple;

    return PointerGetDatum(tuple);
}

#define TTDUMMY_INFINITY    999999

static SPIPlanPtr splan = NULL;
static bool ttoff = false;

PG_FUNCTION_INFO_V1(ttdummy);

Datum
ttdummy(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    Trigger    *trigger;        /* to get trigger name */
    char      **args;           /* arguments */
    int         attnum[2];      /* fnumbers of start/stop columns */
    Datum       oldon,
                oldoff;
    Datum       newon,
                newoff;
    Datum      *cvals;          /* column values */
    char       *cnulls;         /* column nulls */
    char       *relname;        /* triggered relation name */
    Relation    rel;            /* triggered relation */
    HeapTuple   trigtuple;
    HeapTuple   newtuple = NULL;
    HeapTuple   rettuple;
    TupleDesc   tupdesc;        /* tuple description */
    int         natts;          /* # of attributes */
    bool        isnull;         /* to know is some column NULL or not */
    int         ret;
    int         i;

    if (!CALLED_AS_TRIGGER(fcinfo))
        elog(ERROR, "ttdummy: not fired by trigger manager");
    if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
        elog(ERROR, "ttdummy: must be fired for row");
    if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
        elog(ERROR, "ttdummy: must be fired before event");
    if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
        elog(ERROR, "ttdummy: cannot process INSERT event");
    if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
        newtuple = trigdata->tg_newtuple;

    trigtuple = trigdata->tg_trigtuple;

    rel = trigdata->tg_relation;
    relname = SPI_getrelname(rel);

    /* check if TT is OFF for this relation */
    if (ttoff)                  /* OFF - nothing to do */
    {
        pfree(relname);
        return PointerGetDatum((newtuple != NULL) ? newtuple : trigtuple);
    }

    trigger = trigdata->tg_trigger;

    if (trigger->tgnargs != 2)
        elog(ERROR, "ttdummy (%s): invalid (!= 2) number of arguments %d",
             relname, trigger->tgnargs);

    args = trigger->tgargs;
    tupdesc = rel->rd_att;
    natts = tupdesc->natts;

    for (i = 0; i < 2; i++)
    {
        attnum[i] = SPI_fnumber(tupdesc, args[i]);
        if (attnum[i] <= 0)
            elog(ERROR, "ttdummy (%s): there is no attribute %s",
                 relname, args[i]);
        if (SPI_gettypeid(tupdesc, attnum[i]) != INT4OID)
            elog(ERROR, "ttdummy (%s): attribute %s must be of integer type",
                 relname, args[i]);
    }

    oldon = SPI_getbinval(trigtuple, tupdesc, attnum[0], &isnull);
    if (isnull)
        elog(ERROR, "ttdummy (%s): %s must be NOT NULL", relname, args[0]);

    oldoff = SPI_getbinval(trigtuple, tupdesc, attnum[1], &isnull);
    if (isnull)
        elog(ERROR, "ttdummy (%s): %s must be NOT NULL", relname, args[1]);

    if (newtuple != NULL)       /* UPDATE */
    {
        newon = SPI_getbinval(newtuple, tupdesc, attnum[0], &isnull);
        if (isnull)
            elog(ERROR, "ttdummy (%s): %s must be NOT NULL", relname, args[0]);
        newoff = SPI_getbinval(newtuple, tupdesc, attnum[1], &isnull);
        if (isnull)
            elog(ERROR, "ttdummy (%s): %s must be NOT NULL", relname, args[1]);

        if (oldon != newon || oldoff != newoff)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("ttdummy (%s): you cannot change %s and/or %s columns (use set_ttdummy)",
                            relname, args[0], args[1])));

        if (newoff != TTDUMMY_INFINITY)
        {
            pfree(relname);     /* allocated in upper executor context */
            return PointerGetDatum(NULL);
        }
    }
    else if (oldoff != TTDUMMY_INFINITY)    /* DELETE */
    {
        pfree(relname);
        return PointerGetDatum(NULL);
    }

    newoff = DirectFunctionCall1(nextval, CStringGetTextDatum("ttdummy_seq"));
    /* nextval now returns int64; coerce down to int32 */
    newoff = Int32GetDatum((int32) DatumGetInt64(newoff));

    /* Connect to SPI manager */
    if ((ret = SPI_connect()) < 0)
        elog(ERROR, "ttdummy (%s): SPI_connect returned %d", relname, ret);

    /* Fetch tuple values and nulls */
    cvals = (Datum *) palloc(natts * sizeof(Datum));
    cnulls = (char *) palloc(natts * sizeof(char));
    for (i = 0; i < natts; i++)
    {
        cvals[i] = SPI_getbinval((newtuple != NULL) ? newtuple : trigtuple,
                                 tupdesc, i + 1, &isnull);
        cnulls[i] = (isnull) ? 'n' : ' ';
    }

    /* change date column(s) */
    if (newtuple)               /* UPDATE */
    {
        cvals[attnum[0] - 1] = newoff;  /* start_date eq current date */
        cnulls[attnum[0] - 1] = ' ';
        cvals[attnum[1] - 1] = TTDUMMY_INFINITY;    /* stop_date eq INFINITY */
        cnulls[attnum[1] - 1] = ' ';
    }
    else
        /* DELETE */
    {
        cvals[attnum[1] - 1] = newoff;  /* stop_date eq current date */
        cnulls[attnum[1] - 1] = ' ';
    }

    /* if there is no plan ... */
    if (splan == NULL)
    {
        SPIPlanPtr  pplan;
        Oid        *ctypes;
        char       *query;

        /* allocate space in preparation */
        ctypes = (Oid *) palloc(natts * sizeof(Oid));
        query = (char *) palloc(100 + 16 * natts);

        /*
         * Construct query: INSERT INTO _relation_ VALUES ($1, ...)
         */
        sprintf(query, "INSERT INTO %s VALUES (", relname);
        for (i = 1; i <= natts; i++)
        {
            sprintf(query + strlen(query), "$%d%s",
                    i, (i < natts) ? ", " : ")");
            ctypes[i - 1] = SPI_gettypeid(tupdesc, i);
        }

        /* Prepare plan for query */
        pplan = SPI_prepare(query, natts, ctypes);
        if (pplan == NULL)
            elog(ERROR, "ttdummy (%s): SPI_prepare returned %s", relname, SPI_result_code_string(SPI_result));

        if (SPI_keepplan(pplan))
            elog(ERROR, "ttdummy (%s): SPI_keepplan failed", relname);

        splan = pplan;
    }

    ret = SPI_execp(splan, cvals, cnulls, 0);

    if (ret < 0)
        elog(ERROR, "ttdummy (%s): SPI_execp returned %d", relname, ret);

    /* Tuple to return to upper Executor ... */
    if (newtuple)               /* UPDATE */
        rettuple = SPI_modifytuple(rel, trigtuple, 1, &(attnum[1]), &newoff, NULL);
    else                        /* DELETE */
        rettuple = trigtuple;

    SPI_finish();               /* don't forget say Bye to SPI mgr */

    pfree(relname);

    return PointerGetDatum(rettuple);
}

PG_FUNCTION_INFO_V1(set_ttdummy);

Datum
set_ttdummy(PG_FUNCTION_ARGS)
{
    int32       on = PG_GETARG_INT32(0);

    if (ttoff)                  /* OFF currently */
    {
        if (on == 0)
            PG_RETURN_INT32(0);

        /* turn ON */
        ttoff = false;
        PG_RETURN_INT32(0);
    }

    /* ON currently */
    if (on != 0)
        PG_RETURN_INT32(1);

    /* turn OFF */
    ttoff = true;

    PG_RETURN_INT32(1);
}


/*
 * Type int44 has no real-world use, but the regression tests use it
 * (under the alias "city_budget").  It's a four-element vector of int4's.
 */

/*
 *      int44in         - converts "num, num, ..." to internal form
 *
 *      Note: Fills any missing positions with zeroes.
 */
PG_FUNCTION_INFO_V1(int44in);

Datum
int44in(PG_FUNCTION_ARGS)
{
    char       *input_string = PG_GETARG_CSTRING(0);
    int32      *result = (int32 *) palloc(4 * sizeof(int32));
    int         i;

    i = sscanf(input_string,
               "%d, %d, %d, %d",
               &result[0],
               &result[1],
               &result[2],
               &result[3]);
    while (i < 4)
        result[i++] = 0;

    PG_RETURN_POINTER(result);
}

/*
 *      int44out        - converts internal form to "num, num, ..."
 */
PG_FUNCTION_INFO_V1(int44out);

Datum
int44out(PG_FUNCTION_ARGS)
{
    int32      *an_array = (int32 *) PG_GETARG_POINTER(0);
    char       *result = (char *) palloc(16 * 4);

    snprintf(result, 16 * 4, "%d,%d,%d,%d",
             an_array[0],
             an_array[1],
             an_array[2],
             an_array[3]);

    PG_RETURN_CSTRING(result);
}

PG_FUNCTION_INFO_V1(make_tuple_indirect);
Datum
make_tuple_indirect(PG_FUNCTION_ARGS)
{
    HeapTupleHeader rec = PG_GETARG_HEAPTUPLEHEADER(0);
    HeapTupleData tuple;
    int         ncolumns;
    Datum      *values;
    bool       *nulls;

    Oid         tupType;
    int32       tupTypmod;
    TupleDesc   tupdesc;

    HeapTuple   newtup;

    int         i;

    MemoryContext old_context;

    /* Extract type info from the tuple itself */
    tupType = HeapTupleHeaderGetTypeId(rec);
    tupTypmod = HeapTupleHeaderGetTypMod(rec);
    tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
    ncolumns = tupdesc->natts;

    /* Build a temporary HeapTuple control structure */
    tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
    ItemPointerSetInvalid(&(tuple.t_self));
    tuple.t_tableOid = InvalidOid;
    tuple.t_data = rec;

    values = (Datum *) palloc(ncolumns * sizeof(Datum));
    nulls = (bool *) palloc(ncolumns * sizeof(bool));

    heap_deform_tuple(&tuple, tupdesc, values, nulls);

    old_context = MemoryContextSwitchTo(TopTransactionContext);

    for (i = 0; i < ncolumns; i++)
    {
        struct varlena *attr;
        struct varlena *new_attr;
        struct varatt_indirect redirect_pointer;

        /* only work on existing, not-null varlenas */
        if (TupleDescAttr(tupdesc, i)->attisdropped ||
            nulls[i] ||
            TupleDescAttr(tupdesc, i)->attlen != -1)
            continue;

        attr = (struct varlena *) DatumGetPointer(values[i]);

        /* don't recursively indirect */
        if (VARATT_IS_EXTERNAL_INDIRECT(attr))
            continue;

        /* copy datum, so it still lives later */
        if (VARATT_IS_EXTERNAL_ONDISK(attr))
            attr = detoast_external_attr(attr);
        else
        {
            struct varlena *oldattr = attr;

            attr = palloc0(VARSIZE_ANY(oldattr));
            memcpy(attr, oldattr, VARSIZE_ANY(oldattr));
        }

        /* build indirection Datum */
        new_attr = (struct varlena *) palloc0(INDIRECT_POINTER_SIZE);
        redirect_pointer.pointer = attr;
        SET_VARTAG_EXTERNAL(new_attr, VARTAG_INDIRECT);
        memcpy(VARDATA_EXTERNAL(new_attr), &redirect_pointer,
               sizeof(redirect_pointer));

        values[i] = PointerGetDatum(new_attr);
    }

    newtup = heap_form_tuple(tupdesc, values, nulls);
    pfree(values);
    pfree(nulls);
    ReleaseTupleDesc(tupdesc);

    MemoryContextSwitchTo(old_context);

    /*
     * We intentionally don't use PG_RETURN_HEAPTUPLEHEADER here, because that
     * would cause the indirect toast pointers to be flattened out of the
     * tuple immediately, rendering subsequent testing irrelevant.  So just
     * return the HeapTupleHeader pointer as-is.  This violates the general
     * rule that composite Datums shouldn't contain toast pointers, but so
     * long as the regression test scripts don't insert the result of this
     * function into a container type (record, array, etc) it should be OK.
     */
    PG_RETURN_POINTER(newtup->t_data);
}

PG_FUNCTION_INFO_V1(regress_putenv);

Datum
regress_putenv(PG_FUNCTION_ARGS)
{
    MemoryContext oldcontext;
    char       *envbuf;

    if (!superuser())
        elog(ERROR, "must be superuser to change environment variables");

    oldcontext = MemoryContextSwitchTo(TopMemoryContext);
    envbuf = text_to_cstring((text *) PG_GETARG_POINTER(0));
    MemoryContextSwitchTo(oldcontext);

    if (putenv(envbuf) != 0)
        elog(ERROR, "could not set environment variable: %m");

    PG_RETURN_VOID();
}

/* Sleep until no process has a given PID. */
PG_FUNCTION_INFO_V1(wait_pid);

Datum
wait_pid(PG_FUNCTION_ARGS)
{
    int         pid = PG_GETARG_INT32(0);

    if (!superuser())
        elog(ERROR, "must be superuser to check PID liveness");

    while (kill(pid, 0) == 0)
    {
        CHECK_FOR_INTERRUPTS();
        pg_usleep(50000);
    }

    if (errno != ESRCH)
        elog(ERROR, "could not check PID %d liveness: %m", pid);

    PG_RETURN_VOID();
}

static void
test_atomic_flag(void)
{
    pg_atomic_flag flag;

    pg_atomic_init_flag(&flag);
    EXPECT_TRUE(pg_atomic_unlocked_test_flag(&flag));
    EXPECT_TRUE(pg_atomic_test_set_flag(&flag));
    EXPECT_TRUE(!pg_atomic_unlocked_test_flag(&flag));
    EXPECT_TRUE(!pg_atomic_test_set_flag(&flag));
    pg_atomic_clear_flag(&flag);
    EXPECT_TRUE(pg_atomic_unlocked_test_flag(&flag));
    EXPECT_TRUE(pg_atomic_test_set_flag(&flag));
    pg_atomic_clear_flag(&flag);
}

static void
test_atomic_uint32(void)
{
    pg_atomic_uint32 var;
    uint32      expected;
    int         i;

    pg_atomic_init_u32(&var, 0);
    EXPECT_EQ_U32(pg_atomic_read_u32(&var), 0);
    pg_atomic_write_u32(&var, 3);
    EXPECT_EQ_U32(pg_atomic_read_u32(&var), 3);
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, pg_atomic_read_u32(&var) - 2),
                  3);
    EXPECT_EQ_U32(pg_atomic_fetch_sub_u32(&var, 1), 4);
    EXPECT_EQ_U32(pg_atomic_sub_fetch_u32(&var, 3), 0);
    EXPECT_EQ_U32(pg_atomic_add_fetch_u32(&var, 10), 10);
    EXPECT_EQ_U32(pg_atomic_exchange_u32(&var, 5), 10);
    EXPECT_EQ_U32(pg_atomic_exchange_u32(&var, 0), 5);

    /* test around numerical limits */
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, INT_MAX), 0);
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, INT_MAX), INT_MAX);
    pg_atomic_fetch_add_u32(&var, 2);   /* wrap to 0 */
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, PG_INT16_MAX), 0);
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, PG_INT16_MAX + 1),
                  PG_INT16_MAX);
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, PG_INT16_MIN),
                  2 * PG_INT16_MAX + 1);
    EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&var, PG_INT16_MIN - 1),
                  PG_INT16_MAX);
    pg_atomic_fetch_add_u32(&var, 1);   /* top up to UINT_MAX */
    EXPECT_EQ_U32(pg_atomic_read_u32(&var), UINT_MAX);
    EXPECT_EQ_U32(pg_atomic_fetch_sub_u32(&var, INT_MAX), UINT_MAX);
    EXPECT_EQ_U32(pg_atomic_read_u32(&var), (uint32) INT_MAX + 1);
    EXPECT_EQ_U32(pg_atomic_sub_fetch_u32(&var, INT_MAX), 1);
    pg_atomic_sub_fetch_u32(&var, 1);
    expected = PG_INT16_MAX;
    EXPECT_TRUE(!pg_atomic_compare_exchange_u32(&var, &expected, 1));
    expected = PG_INT16_MAX + 1;
    EXPECT_TRUE(!pg_atomic_compare_exchange_u32(&var, &expected, 1));
    expected = PG_INT16_MIN;
    EXPECT_TRUE(!pg_atomic_compare_exchange_u32(&var, &expected, 1));
    expected = PG_INT16_MIN - 1;
    EXPECT_TRUE(!pg_atomic_compare_exchange_u32(&var, &expected, 1));

    /* fail exchange because of old expected */
    expected = 10;
    EXPECT_TRUE(!pg_atomic_compare_exchange_u32(&var, &expected, 1));

    /* CAS is allowed to fail due to interrupts, try a couple of times */
    for (i = 0; i < 1000; i++)
    {
        expected = 0;
        if (!pg_atomic_compare_exchange_u32(&var, &expected, 1))
            break;
    }
    if (i == 1000)
        elog(ERROR, "atomic_compare_exchange_u32() never succeeded");
    EXPECT_EQ_U32(pg_atomic_read_u32(&var), 1);
    pg_atomic_write_u32(&var, 0);

    /* try setting flagbits */
    EXPECT_TRUE(!(pg_atomic_fetch_or_u32(&var, 1) & 1));
    EXPECT_TRUE(pg_atomic_fetch_or_u32(&var, 2) & 1);
    EXPECT_EQ_U32(pg_atomic_read_u32(&var), 3);
    /* try clearing flagbits */
    EXPECT_EQ_U32(pg_atomic_fetch_and_u32(&var, ~2) & 3, 3);
    EXPECT_EQ_U32(pg_atomic_fetch_and_u32(&var, ~1), 1);
    /* no bits set anymore */
    EXPECT_EQ_U32(pg_atomic_fetch_and_u32(&var, ~0), 0);
}

static void
test_atomic_uint64(void)
{
    pg_atomic_uint64 var;
    uint64      expected;
    int         i;

    pg_atomic_init_u64(&var, 0);
    EXPECT_EQ_U64(pg_atomic_read_u64(&var), 0);
    pg_atomic_write_u64(&var, 3);
    EXPECT_EQ_U64(pg_atomic_read_u64(&var), 3);
    EXPECT_EQ_U64(pg_atomic_fetch_add_u64(&var, pg_atomic_read_u64(&var) - 2),
                  3);
    EXPECT_EQ_U64(pg_atomic_fetch_sub_u64(&var, 1), 4);
    EXPECT_EQ_U64(pg_atomic_sub_fetch_u64(&var, 3), 0);
    EXPECT_EQ_U64(pg_atomic_add_fetch_u64(&var, 10), 10);
    EXPECT_EQ_U64(pg_atomic_exchange_u64(&var, 5), 10);
    EXPECT_EQ_U64(pg_atomic_exchange_u64(&var, 0), 5);

    /* fail exchange because of old expected */
    expected = 10;
    EXPECT_TRUE(!pg_atomic_compare_exchange_u64(&var, &expected, 1));

    /* CAS is allowed to fail due to interrupts, try a couple of times */
    for (i = 0; i < 100; i++)
    {
        expected = 0;
        if (!pg_atomic_compare_exchange_u64(&var, &expected, 1))
            break;
    }
    if (i == 100)
        elog(ERROR, "atomic_compare_exchange_u64() never succeeded");
    EXPECT_EQ_U64(pg_atomic_read_u64(&var), 1);

    pg_atomic_write_u64(&var, 0);

    /* try setting flagbits */
    EXPECT_TRUE(!(pg_atomic_fetch_or_u64(&var, 1) & 1));
    EXPECT_TRUE(pg_atomic_fetch_or_u64(&var, 2) & 1);
    EXPECT_EQ_U64(pg_atomic_read_u64(&var), 3);
    /* try clearing flagbits */
    EXPECT_EQ_U64((pg_atomic_fetch_and_u64(&var, ~2) & 3), 3);
    EXPECT_EQ_U64(pg_atomic_fetch_and_u64(&var, ~1), 1);
    /* no bits set anymore */
    EXPECT_EQ_U64(pg_atomic_fetch_and_u64(&var, ~0), 0);
}

/*
 * Perform, fairly minimal, testing of the spinlock implementation.
 *
 * It's likely worth expanding these to actually test concurrency etc, but
 * having some regularly run tests is better than none.
 */
static void
test_spinlock(void)
{
    /*
     * Basic tests for spinlocks, as well as the underlying operations.
     *
     * We embed the spinlock in a struct with other members to test that the
     * spinlock operations don't perform too wide writes.
     */
    {
        struct test_lock_struct
        {
            char        data_before[4];
            slock_t     lock;
            char        data_after[4];
        } struct_w_lock;

        memcpy(struct_w_lock.data_before, "abcd", 4);
        memcpy(struct_w_lock.data_after, "ef12", 4);

        /* test basic operations via the SpinLock* API */
        SpinLockInit(&struct_w_lock.lock);
        SpinLockAcquire(&struct_w_lock.lock);
        SpinLockRelease(&struct_w_lock.lock);

        /* test basic operations via underlying S_* API */
        S_INIT_LOCK(&struct_w_lock.lock);
        S_LOCK(&struct_w_lock.lock);
        S_UNLOCK(&struct_w_lock.lock);

        /* and that "contended" acquisition works */
        s_lock(&struct_w_lock.lock, "testfile", 17, "testfunc");
        S_UNLOCK(&struct_w_lock.lock);

        /*
         * Check, using TAS directly, that a single spin cycle doesn't block
         * when acquiring an already acquired lock.
         */
#ifdef TAS
        S_LOCK(&struct_w_lock.lock);

        if (!TAS(&struct_w_lock.lock))
            elog(ERROR, "acquired already held spinlock");

#ifdef TAS_SPIN
        if (!TAS_SPIN(&struct_w_lock.lock))
            elog(ERROR, "acquired already held spinlock");
#endif                          /* defined(TAS_SPIN) */

        S_UNLOCK(&struct_w_lock.lock);
#endif                          /* defined(TAS) */

        /*
         * Verify that after all of this the non-lock contents are still
         * correct.
         */
        if (memcmp(struct_w_lock.data_before, "abcd", 4) != 0)
            elog(ERROR, "padding before spinlock modified");
        if (memcmp(struct_w_lock.data_after, "ef12", 4) != 0)
            elog(ERROR, "padding after spinlock modified");
    }

    /*
     * Ensure that allocating more than INT32_MAX emulated spinlocks
     * works. That's interesting because the spinlock emulation uses a 32bit
     * integer to map spinlocks onto semaphores. There've been bugs...
     */
#ifndef HAVE_SPINLOCKS
    {
        /*
         * Initialize enough spinlocks to advance counter close to
         * wraparound. It's too expensive to perform acquire/release for each,
         * as those may be syscalls when the spinlock emulation is used (and
         * even just atomic TAS would be expensive).
         */
        for (uint32 i = 0; i < INT32_MAX - 100000; i++)
        {
            slock_t lock;

            SpinLockInit(&lock);
        }

        for (uint32 i = 0; i < 200000; i++)
        {
            slock_t lock;

            SpinLockInit(&lock);

            SpinLockAcquire(&lock);
            SpinLockRelease(&lock);
            SpinLockAcquire(&lock);
            SpinLockRelease(&lock);
        }
    }
#endif
}

/*
 * Verify that performing atomic ops inside a spinlock isn't a
 * problem. Realistically that's only going to be a problem when both
 * --disable-spinlocks and --disable-atomics are used, but it's cheap enough
 * to just always test.
 *
 * The test works by initializing enough atomics that we'd conflict if there
 * were an overlap between a spinlock and an atomic by holding a spinlock
 * while manipulating more than NUM_SPINLOCK_SEMAPHORES atomics.
 *
 * NUM_TEST_ATOMICS doesn't really need to be more than
 * NUM_SPINLOCK_SEMAPHORES, but it seems better to test a bit more
 * extensively.
 */
static void
test_atomic_spin_nest(void)
{
    slock_t lock;
#define NUM_TEST_ATOMICS (NUM_SPINLOCK_SEMAPHORES + NUM_ATOMICS_SEMAPHORES + 27)
    pg_atomic_uint32 atomics32[NUM_TEST_ATOMICS];
    pg_atomic_uint64 atomics64[NUM_TEST_ATOMICS];

    SpinLockInit(&lock);

    for (int i = 0; i < NUM_TEST_ATOMICS; i++)
    {
        pg_atomic_init_u32(&atomics32[i], 0);
        pg_atomic_init_u64(&atomics64[i], 0);
    }

    /* just so it's not all zeroes */
    for (int i = 0; i < NUM_TEST_ATOMICS; i++)
    {
        EXPECT_EQ_U32(pg_atomic_fetch_add_u32(&atomics32[i], i), 0);
        EXPECT_EQ_U64(pg_atomic_fetch_add_u64(&atomics64[i], i), 0);
    }

    /* test whether we can do atomic op with lock held */
    SpinLockAcquire(&lock);
    for (int i = 0; i < NUM_TEST_ATOMICS; i++)
    {
        EXPECT_EQ_U32(pg_atomic_fetch_sub_u32(&atomics32[i], i), i);
        EXPECT_EQ_U32(pg_atomic_read_u32(&atomics32[i]), 0);
        EXPECT_EQ_U64(pg_atomic_fetch_sub_u64(&atomics64[i], i), i);
        EXPECT_EQ_U64(pg_atomic_read_u64(&atomics64[i]), 0);
    }
    SpinLockRelease(&lock);
}
#undef NUM_TEST_ATOMICS

PG_FUNCTION_INFO_V1(test_atomic_ops);
Datum
test_atomic_ops(PG_FUNCTION_ARGS)
{
    test_atomic_flag();

    test_atomic_uint32();

    test_atomic_uint64();

    /*
     * Arguably this shouldn't be tested as part of this function, but it's
     * closely enough related that that seems ok for now.
     */
    test_spinlock();

    test_atomic_spin_nest();

    PG_RETURN_BOOL(true);
}

PG_FUNCTION_INFO_V1(test_fdw_handler);
Datum
test_fdw_handler(PG_FUNCTION_ARGS)
{
    elog(ERROR, "test_fdw_handler is not implemented");
    PG_RETURN_NULL();
}

PG_FUNCTION_INFO_V1(test_support_func);
Datum
test_support_func(PG_FUNCTION_ARGS)
{
    Node       *rawreq = (Node *) PG_GETARG_POINTER(0);
    Node       *ret = NULL;

    if (IsA(rawreq, SupportRequestSelectivity))
    {
        /*
         * Assume that the target is int4eq; that's safe as long as we don't
         * attach this to any other boolean-returning function.
         */
        SupportRequestSelectivity *req = (SupportRequestSelectivity *) rawreq;
        Selectivity s1;

        if (req->is_join)
            s1 = join_selectivity(req->root, Int4EqualOperator,
                                  req->args,
                                  req->inputcollid,
                                  req->jointype,
                                  req->sjinfo);
        else
            s1 = restriction_selectivity(req->root, Int4EqualOperator,
                                         req->args,
                                         req->inputcollid,
                                         req->varRelid);

        req->selectivity = s1;
        ret = (Node *) req;
    }

    if (IsA(rawreq, SupportRequestCost))
    {
        /* Provide some generic estimate */
        SupportRequestCost *req = (SupportRequestCost *) rawreq;

        req->startup = 0;
        req->per_tuple = 2 * cpu_operator_cost;
        ret = (Node *) req;
    }

    if (IsA(rawreq, SupportRequestRows))
    {
        /*
         * Assume that the target is generate_series_int4; that's safe as long
         * as we don't attach this to any other set-returning function.
         */
        SupportRequestRows *req = (SupportRequestRows *) rawreq;

        if (req->node && IsA(req->node, FuncExpr))  /* be paranoid */
        {
            List       *args = ((FuncExpr *) req->node)->args;
            Node       *arg1 = linitial(args);
            Node       *arg2 = lsecond(args);

            if (IsA(arg1, Const) &&
                !((Const *) arg1)->constisnull &&
                IsA(arg2, Const) &&
                !((Const *) arg2)->constisnull)
            {
                int32       val1 = DatumGetInt32(((Const *) arg1)->constvalue);
                int32       val2 = DatumGetInt32(((Const *) arg2)->constvalue);

                req->rows = val2 - val1 + 1;
                ret = (Node *) req;
            }
        }
    }

    PG_RETURN_POINTER(ret);
}

PG_FUNCTION_INFO_V1(test_opclass_options_func);
Datum
test_opclass_options_func(PG_FUNCTION_ARGS)
{
    PG_RETURN_NULL();
}