test_slru.c

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/*--------------------------------------------------------------------------
 *
 * test_slru.c
 *      Test correctness of SLRU functions.
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/test/modules/test_slru/test_slru.c
 *
 * -------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include "access/slru.h"
#include "access/transam.h"
#include "miscadmin.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/shmem.h"
#include "utils/builtins.h"
 
PG_MODULE_MAGIC;
 
/*
 * SQL-callable entry points
 */
PG_FUNCTION_INFO_V1(test_slru_page_write);
PG_FUNCTION_INFO_V1(test_slru_page_writeall);
PG_FUNCTION_INFO_V1(test_slru_page_read);
PG_FUNCTION_INFO_V1(test_slru_page_readonly);
PG_FUNCTION_INFO_V1(test_slru_page_exists);
PG_FUNCTION_INFO_V1(test_slru_page_sync);
PG_FUNCTION_INFO_V1(test_slru_page_delete);
PG_FUNCTION_INFO_V1(test_slru_page_truncate);
PG_FUNCTION_INFO_V1(test_slru_delete_all);
 
/* Number of SLRU page slots */
#define NUM_TEST_BUFFERS        16
 
/* SLRU control lock */
LWLock      TestSLRULock;
#define TestSLRULock (&TestSLRULock)
 
static SlruCtlData TestSlruCtlData;
#define TestSlruCtl         (&TestSlruCtlData)
 
static shmem_request_hook_type prev_shmem_request_hook = NULL;
static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
 
static bool
test_slru_scan_cb(SlruCtl ctl, char *filename, int segpage, void *data)
{
    elog(NOTICE, "Calling test_slru_scan_cb()");
    return SlruScanDirCbDeleteAll(ctl, filename, segpage, data);
}
 
Datum
test_slru_page_write(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
    char       *data = text_to_cstring(PG_GETARG_TEXT_PP(1));
    int         slotno;
 
    LWLockAcquire(TestSLRULock, LW_EXCLUSIVE);
 
    slotno = SimpleLruZeroPage(TestSlruCtl, pageno);
 
    /* these should match */
    Assert(TestSlruCtl->shared->page_number[slotno] == pageno);
 
    /* mark the page as dirty so as it would get written */
    TestSlruCtl->shared->page_dirty[slotno] = true;
    TestSlruCtl->shared->page_status[slotno] = SLRU_PAGE_VALID;
 
    /* write given data to the page, up to the limit of the page */
    strncpy(TestSlruCtl->shared->page_buffer[slotno], data,
            BLCKSZ - 1);
 
    SimpleLruWritePage(TestSlruCtl, slotno);
    LWLockRelease(TestSLRULock);
 
    PG_RETURN_VOID();
}
 
Datum
test_slru_page_writeall(PG_FUNCTION_ARGS)
{
    SimpleLruWriteAll(TestSlruCtl, true);
    PG_RETURN_VOID();
}
 
Datum
test_slru_page_read(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
    bool        write_ok = PG_GETARG_BOOL(1);
    char       *data = NULL;
    int         slotno;
 
    /* find page in buffers, reading it if necessary */
    LWLockAcquire(TestSLRULock, LW_EXCLUSIVE);
    slotno = SimpleLruReadPage(TestSlruCtl, pageno,
                               write_ok, InvalidTransactionId);
    data = (char *) TestSlruCtl->shared->page_buffer[slotno];
    LWLockRelease(TestSLRULock);
 
    PG_RETURN_TEXT_P(cstring_to_text(data));
}
 
Datum
test_slru_page_readonly(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
    char       *data = NULL;
    int         slotno;
 
    /* find page in buffers, reading it if necessary */
    slotno = SimpleLruReadPage_ReadOnly(TestSlruCtl,
                                        pageno,
                                        InvalidTransactionId);
    Assert(LWLockHeldByMe(TestSLRULock));
    data = (char *) TestSlruCtl->shared->page_buffer[slotno];
    LWLockRelease(TestSLRULock);
 
    PG_RETURN_TEXT_P(cstring_to_text(data));
}
 
Datum
test_slru_page_exists(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
    bool        found;
 
    LWLockAcquire(TestSLRULock, LW_EXCLUSIVE);
    found = SimpleLruDoesPhysicalPageExist(TestSlruCtl, pageno);
    LWLockRelease(TestSLRULock);
 
    PG_RETURN_BOOL(found);
}
 
Datum
test_slru_page_sync(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
    FileTag     ftag;
    char        path[MAXPGPATH];
 
    /* note that this flushes the full file a segment is located in */
    ftag.segno = pageno / SLRU_PAGES_PER_SEGMENT;
    SlruSyncFileTag(TestSlruCtl, &ftag, path);
 
    elog(NOTICE, "Called SlruSyncFileTag() for segment %u on path %s",
         ftag.segno, path);
 
    PG_RETURN_VOID();
}
 
Datum
test_slru_page_delete(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
    FileTag     ftag;
 
    ftag.segno = pageno / SLRU_PAGES_PER_SEGMENT;
    SlruDeleteSegment(TestSlruCtl, ftag.segno);
 
    elog(NOTICE, "Called SlruDeleteSegment() for segment %u", ftag.segno);
 
    PG_RETURN_VOID();
}
 
Datum
test_slru_page_truncate(PG_FUNCTION_ARGS)
{
    int         pageno = PG_GETARG_INT32(0);
 
    SimpleLruTruncate(TestSlruCtl, pageno);
    PG_RETURN_VOID();
}
 
Datum
test_slru_delete_all(PG_FUNCTION_ARGS)
{
    /* this calls SlruScanDirCbDeleteAll() internally, ensuring deletion */
    SlruScanDirectory(TestSlruCtl, test_slru_scan_cb, NULL);
 
    PG_RETURN_VOID();
}
 
/*
 * Module load callbacks and initialization.
 */
 
static void
test_slru_shmem_request(void)
{
    if (prev_shmem_request_hook)
        prev_shmem_request_hook();
 
    /* reserve shared memory for the test SLRU */
    RequestAddinShmemSpace(SimpleLruShmemSize(NUM_TEST_BUFFERS, 0));
}
 
static bool
test_slru_page_precedes_logically(int page1, int page2)
{
    return page1 < page2;
}
 
static void
test_slru_shmem_startup(void)
{
    const char  slru_dir_name[] = "pg_test_slru";
    int         test_tranche_id;
 
    if (prev_shmem_startup_hook)
        prev_shmem_startup_hook();
 
    /*
     * Create the SLRU directory if it does not exist yet, from the root of
     * the data directory.
     */
    (void) MakePGDirectory(slru_dir_name);
 
    /* initialize the SLRU facility */
    test_tranche_id = LWLockNewTrancheId();
    LWLockRegisterTranche(test_tranche_id, "test_slru_tranche");
    LWLockInitialize(TestSLRULock, test_tranche_id);
 
    TestSlruCtl->PagePrecedes = test_slru_page_precedes_logically;
    SimpleLruInit(TestSlruCtl, "TestSLRU",
                  NUM_TEST_BUFFERS, 0, TestSLRULock, slru_dir_name,
                  test_tranche_id, SYNC_HANDLER_NONE);
}
 
void
_PG_init(void)
{
    if (!process_shared_preload_libraries_in_progress)
        ereport(ERROR,
                (errmsg("cannot load \"%s\" after startup", "test_slru"),
                 errdetail("\"%s\" must be loaded with shared_preload_libraries.",
                           "test_slru")));
 
    prev_shmem_request_hook = shmem_request_hook;
    shmem_request_hook = test_slru_shmem_request;
 
    prev_shmem_startup_hook = shmem_startup_hook;
    shmem_startup_hook = test_slru_shmem_startup;
}