test_lwlock_tranches.c

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/*--------------------------------------------------------------------------
 *
 * test_lwlock_tranches.c
 *      Test code for LWLock tranches allocated by extensions.
 *
 * Copyright (c) 2025-2026, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *      src/test/modules/test_lwlock_tranches/test_lwlock_tranches.c
 *
 * -------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "fmgr.h"
#include "miscadmin.h"
#include "storage/lwlock.h"
#include "utils/builtins.h"
#include "utils/wait_classes.h"
 
PG_MODULE_MAGIC;
 
static shmem_request_hook_type prev_shmem_request_hook;
static void test_lwlock_tranches_shmem_request(void);
 
void
_PG_init(void)
{
    prev_shmem_request_hook = shmem_request_hook;
    shmem_request_hook = test_lwlock_tranches_shmem_request;
}
 
static void
test_lwlock_tranches_shmem_request(void)
{
    if (prev_shmem_request_hook)
        prev_shmem_request_hook();
 
    /*
     * Request some tranches with RequestNamedLWLockTranche() for
     * test_startup_lwlocks()
     */
    RequestNamedLWLockTranche("test_lwlock_tranches_startup", 1);
    RequestNamedLWLockTranche("test_lwlock_tranches_startup10", 10);
}
 
/*
 * Test locks requested with RequestNamedLWLockTranche
 */
PG_FUNCTION_INFO_V1(test_startup_lwlocks);
Datum
test_startup_lwlocks(PG_FUNCTION_ARGS)
{
    LWLockPadded *lwlock_startup;
    LWLockPadded *lwlock_startup10;
 
    /* Check that the locks can be used */
    lwlock_startup = GetNamedLWLockTranche("test_lwlock_tranches_startup");
    lwlock_startup10 = GetNamedLWLockTranche("test_lwlock_tranches_startup10");
 
    LWLockAcquire(&lwlock_startup->lock, LW_EXCLUSIVE);
    for (int i = 0; i < 10; i++)
        LWLockAcquire(&lwlock_startup10[i].lock, LW_EXCLUSIVE);
 
    LWLockRelease(&lwlock_startup->lock);
    for (int i = 0; i < 10; i++)
        LWLockRelease(&lwlock_startup10[i].lock);
 
    /*
     * Check that GetLWLockIdentifier() returns the expected value for
     * tranches
     */
    if (strcmp("test_lwlock_tranches_startup",
               GetLWLockIdentifier(PG_WAIT_LWLOCK, LWTRANCHE_FIRST_USER_DEFINED)) != 0)
        elog(ERROR, "incorrect startup lock tranche name");
    if (strcmp("test_lwlock_tranches_startup10",
               GetLWLockIdentifier(PG_WAIT_LWLOCK, LWTRANCHE_FIRST_USER_DEFINED + 1)) != 0)
        elog(ERROR, "incorrect startup lock tranche name");
 
    PG_RETURN_VOID();
}
 
/*
 * Wrapper for LWLockNewTrancheId().
 */
PG_FUNCTION_INFO_V1(test_lwlock_tranche_create);
Datum
test_lwlock_tranche_create(PG_FUNCTION_ARGS)
{
    char       *tranche_name = PG_ARGISNULL(0) ? NULL : TextDatumGetCString(PG_GETARG_DATUM(0));
    int         tranche_id;
 
    tranche_id = LWLockNewTrancheId(tranche_name);
 
    PG_RETURN_INT32(tranche_id);
}
 
/*
 * Wrapper for GetNamedLWLockTranche().
 */
PG_FUNCTION_INFO_V1(test_lwlock_tranche_lookup);
Datum
test_lwlock_tranche_lookup(PG_FUNCTION_ARGS)
{
    char       *tranche_name = TextDatumGetCString(PG_GETARG_DATUM(0));
 
    (void) GetNamedLWLockTranche(tranche_name);
 
    PG_RETURN_VOID();
}
 
PG_FUNCTION_INFO_V1(test_lwlock_get_lwlock_identifier);
Datum
test_lwlock_get_lwlock_identifier(PG_FUNCTION_ARGS)
{
    int         eventId = PG_GETARG_INT32(0);
    const char *tranche_name;
 
    tranche_name = GetLWLockIdentifier(PG_WAIT_LWLOCK, eventId);
 
    if (tranche_name)
        PG_RETURN_TEXT_P(cstring_to_text(tranche_name));
    else
        PG_RETURN_NULL();
}
 
/*
 * Wrapper for LWLockInitialize().
 */
PG_FUNCTION_INFO_V1(test_lwlock_initialize);
Datum
test_lwlock_initialize(PG_FUNCTION_ARGS)
{
    int         tranche_id = PG_GETARG_INT32(0);
    LWLock      lock;
 
    LWLockInitialize(&lock, tranche_id);
 
    PG_RETURN_VOID();
}