epics-base/modules/libcom/src/freeList/freeListLib.c

/*************************************************************************\
* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
*     National Laboratory.
* Copyright (c) 2002 The Regents of the University of California, as
*     Operator of Los Alamos National Laboratory.
* SPDX-License-Identifier: EPICS
* EPICS Base is distributed subject to a Software License Agreement found
* in file LICENSE that is included with this distribution.
\*************************************************************************/
/* Author:  Marty Kraimer Date:    04-19-94 */

#include <string.h>
#include <stdlib.h>
#include <stddef.h>

#include "valgrind/valgrind.h"

#ifndef NVALGRIND
/* buffer around allocations to detect out of bounds access */
#define REDZONE sizeof(double)
#else
#define REDZONE 0
#endif

#include "cantProceed.h"
#include "epicsMutex.h"
#include "freeList.h"
#include "adjustment.h"
#include "errlog.h"
#include "epicsString.h"
#include "epicsAtomic.h"
#include "epicsExport.h"

/* Bypass free list and directly call malloc() every time? */
int freeListBypass
#ifdef EPICS_FREELIST_DEBUG
    = 1;
#else
    = 2; /* checks environment $EPICS_FREELIST_BYPASS */
#endif

epicsExportAddress(int, freeListBypass);

typedef struct allocMem {
    struct allocMem     *next;
    void                *memory;
}allocMem;
typedef struct {
    int         size;
    int         nmalloc;
    void        *head;
    allocMem    *mallochead;
    size_t      nBlocksAvailable;
    epicsMutexId lock;
}FREELISTPVT;

LIBCOM_API void epicsStdCall 
    freeListInitPvt(void **ppvt,int size,int nmalloc)
{
    FREELISTPVT *pfl;
    int bypass = epicsAtomicGetIntT(&freeListBypass);

    if(bypass==2) {
        const char *str = getenv("EPICS_FREELIST_BYPASS");

        if(str && epicsStrCaseCmp(str, "YES")==0) {
            bypass = 1;
        } else if(!str || str[0]=='\0' || epicsStrCaseCmp(str, "NO")==0) {
            bypass = 0;
        } else {
            errlogPrintf(ERL_WARNING " EPICS_FREELIST_BYPASS expected to be YES, NO, or empty.  Not \"%s\"\n", str);
        }
        epicsAtomicSetIntT(&freeListBypass, bypass);
    }

    pfl = callocMustSucceed(1,sizeof(FREELISTPVT), "freeListInitPvt");
    pfl->size = adjustToWorstCaseAlignment(size);
    if(!bypass)
        pfl->nmalloc = nmalloc; /* nmalloc==0 to bypass */
    pfl->head = NULL;
    pfl->mallochead = NULL;
    pfl->nBlocksAvailable = 0u;
    pfl->lock = epicsMutexMustCreate();
    *ppvt = (void *)pfl;
    VALGRIND_CREATE_MEMPOOL(pfl, REDZONE, 0);
}

LIBCOM_API void * epicsStdCall freeListCalloc(void *pvt)
{
    FREELISTPVT *pfl = pvt;
    void        *ptemp;

    if(!pfl->nmalloc)
        ptemp = calloc(1u, pfl->size);
    else if(!!(ptemp = freeListMalloc(pvt)))
        memset((char *)ptemp,0,pfl->size);
    return(ptemp);
}

LIBCOM_API void * epicsStdCall freeListMalloc(void *pvt)
{
    FREELISTPVT *pfl = pvt;
    void        *ptemp;
    void        **ppnext;
    allocMem    *pallocmem;
    int         i;

    if(!pfl->nmalloc)
        return malloc(pfl->size);

    epicsMutexMustLock(pfl->lock);
    ptemp = pfl->head;
    if(ptemp==0) {
        /* layout of each block. nmalloc+1 REDZONEs for nmallocs.
         * The first sizeof(void*) bytes are used to store a pointer
         * to the next free block.
         *
         * | RED | size0 ------ | RED | size1 | ... | RED |
         * |     | next | ----- |
         */
        ptemp = (void *)malloc(pfl->nmalloc*(pfl->size+REDZONE)+REDZONE);
        if(ptemp==0) {
            epicsMutexUnlock(pfl->lock);
            return(0);
        }
        pallocmem = (allocMem *)calloc(1,sizeof(allocMem));
        if(pallocmem==0) {
            epicsMutexUnlock(pfl->lock);
            free(ptemp);
            return(0);
        }
        pallocmem->memory = ptemp; /* real allocation */
        ptemp = REDZONE + (char *) ptemp; /* skip first REDZONE */
        if(pfl->mallochead)
            pallocmem->next = pfl->mallochead;
        pfl->mallochead = pallocmem;
        for(i=0; i<pfl->nmalloc; i++) {
            ppnext = ptemp;
            VALGRIND_MEMPOOL_ALLOC(pfl, ptemp, sizeof(void*));
            *ppnext = pfl->head;
            pfl->head = ptemp;
            ptemp = ((char *)ptemp) + pfl->size+REDZONE;
        }
        ptemp = pfl->head;
        pfl->nBlocksAvailable += pfl->nmalloc;
    }
    ppnext = pfl->head;
    pfl->head = *ppnext;
    pfl->nBlocksAvailable--;
    epicsMutexUnlock(pfl->lock);
    VALGRIND_MEMPOOL_FREE(pfl, ptemp);
    VALGRIND_MEMPOOL_ALLOC(pfl, ptemp, pfl->size);
    return(ptemp);
}

LIBCOM_API void epicsStdCall freeListFree(void *pvt,void*pmem)
{
    FREELISTPVT *pfl = pvt;
    void        **ppnext;

    if(!pfl->nmalloc) {
        free(pmem);
        return;
    }

    VALGRIND_MEMPOOL_FREE(pvt, pmem);
    VALGRIND_MEMPOOL_ALLOC(pvt, pmem, sizeof(void*));

    epicsMutexMustLock(pfl->lock);
    ppnext = pmem;
    *ppnext = pfl->head;
    pfl->head = pmem;
    pfl->nBlocksAvailable++;
    epicsMutexUnlock(pfl->lock);
}

LIBCOM_API void epicsStdCall freeListCleanup(void *pvt)
{
    FREELISTPVT *pfl = pvt;
    allocMem    *phead;
    allocMem    *pnext;

    VALGRIND_DESTROY_MEMPOOL(pvt);

    phead = pfl->mallochead;
    while(phead) {
        pnext = phead->next;
        free(phead->memory);
        free(phead);
        phead = pnext;
    }
    epicsMutexDestroy(pfl->lock);
    free(pvt);
}

LIBCOM_API size_t epicsStdCall freeListItemsAvail(void *pvt)
{
    FREELISTPVT *pfl = pvt;
    size_t nBlocksAvailable;
    epicsMutexMustLock(pfl->lock);
    nBlocksAvailable = pfl->nBlocksAvailable;
    epicsMutexUnlock(pfl->lock);
    return nBlocksAvailable;
}