tclalloc.c

tcl是工具命令语言

 *
 *	Allocate more memory to the indicated bucket.
 *
 *	Assumes Mutex is already held.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Attempts to get more memory from the system.
 *
 *----------------------------------------------------------------------
 */

static void
MoreCore(bucket)
    int bucket;		/* What bucket to allocat to. */
{
    register union overhead *op;
    register long sz;		/* size of desired block */
    long amt;			/* amount to allocate */
    int nblks;			/* how many blocks we get */
    struct block *blockPtr;

    /*
     * sbrk_size <= 0 only for big, FLUFFY, requests (about
     * 2^30 bytes on a VAX, I think) or for a negative arg.
     */
    sz = 1 << (bucket + 3);
    ASSERT(sz > 0);

    amt = MAXMALLOC;
    nblks = amt / sz;
    ASSERT(nblks*sz == amt);

    blockPtr = (struct block *) TclpSysAlloc((unsigned) 
	    (sizeof(struct block) + amt), 1);
    /* no more room! */
    if (blockPtr == NULL) {
	return;
    }
    blockPtr->nextPtr = blockList;
    blockList = blockPtr;

    op = (union overhead *) (blockPtr + 1);
    
    /*
     * Add new memory allocated to that on
     * free list for this hash bucket.
     */
    nextf[bucket] = op;
    while (--nblks > 0) {
	op->ov_next = (union overhead *)((caddr_t)op + sz);
	op = (union overhead *)((caddr_t)op + sz);
    }
    op->ov_next = (union overhead *)NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpFree --
 *
 *	Free memory.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TclpFree(cp)
    char *cp;		/* Pointer to memory to free. */
{   
    register long size;
    register union overhead *op;
    struct block *bigBlockPtr;

    if (cp == NULL) {
	return;
    }

    Tcl_MutexLock(allocMutexPtr);
    op = (union overhead *)((caddr_t)cp - sizeof (union overhead));

    ASSERT(op->ov_magic0 == MAGIC);		/* make sure it was in use */
    ASSERT(op->ov_magic1 == MAGIC);
    if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC) {
	Tcl_MutexUnlock(allocMutexPtr);
	return;
    }

    RANGE_ASSERT(op->ov_rmagic == RMAGIC);
    RANGE_ASSERT(*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
    size = op->ov_index;
    if ( size == 0xff ) {
#ifdef MSTATS
	nmalloc[NBUCKETS]--;
#endif
	bigBlockPtr = (struct block *) op - 1;
	bigBlockPtr->prevPtr->nextPtr = bigBlockPtr->nextPtr;
	bigBlockPtr->nextPtr->prevPtr = bigBlockPtr->prevPtr;
	TclpSysFree(bigBlockPtr);
	Tcl_MutexUnlock(allocMutexPtr);
	return;
    }
    ASSERT(size < NBUCKETS);
    op->ov_next = nextf[size];	/* also clobbers ov_magic */
    nextf[size] = op;
#ifdef MSTATS
    nmalloc[size]--;
#endif
    Tcl_MutexUnlock(allocMutexPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpRealloc --
 *
 *	Reallocate memory.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

char *
TclpRealloc(cp, nbytes)
    char *cp;			/* Pointer to alloced block. */
    unsigned int nbytes;	/* New size of memory. */
{   
    int i;
    union overhead *op;
    struct block *bigBlockPtr;
    int expensive;
    unsigned long maxsize;

    if (cp == NULL) {
	return (TclpAlloc(nbytes));
    }

    Tcl_MutexLock(allocMutexPtr);

    op = (union overhead *)((caddr_t)cp - sizeof (union overhead));

    ASSERT(op->ov_magic0 == MAGIC);		/* make sure it was in use */
    ASSERT(op->ov_magic1 == MAGIC);
    if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC) {
	Tcl_MutexUnlock(allocMutexPtr);
	return NULL;
    }

    RANGE_ASSERT(op->ov_rmagic == RMAGIC);
    RANGE_ASSERT(*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
    i = op->ov_index;

    /*
     * If the block isn't in a bin, just realloc it.
     */

    if (i == 0xff) {
	struct block *prevPtr, *nextPtr;
	bigBlockPtr = (struct block *) op - 1;
	prevPtr = bigBlockPtr->prevPtr;
	nextPtr = bigBlockPtr->nextPtr;
	bigBlockPtr = (struct block *) TclpSysRealloc(bigBlockPtr, 
		sizeof(struct block) + OVERHEAD + nbytes);
	if (bigBlockPtr == NULL) {
	    Tcl_MutexUnlock(allocMutexPtr);
	    return NULL;
	}

	if (prevPtr->nextPtr != bigBlockPtr) {
	    /*
	     * If the block has moved, splice the new block into the list where
	     * the old block used to be. 
	     */

	    prevPtr->nextPtr = bigBlockPtr;
	    nextPtr->prevPtr = bigBlockPtr;
	}

	op = (union overhead *) (bigBlockPtr + 1);
#ifdef MSTATS
	nmalloc[NBUCKETS]++;
#endif
#ifdef RCHECK
	/*
	 * Record allocated size of block and update magic number bounds.
	 */

	op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
	*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
	Tcl_MutexUnlock(allocMutexPtr);
	return (char *)(op+1);
    }
    maxsize = 1 << (i+3);
    expensive = 0;
    if ( nbytes + OVERHEAD > maxsize ) {
	expensive = 1;
    } else if ( i > 0 && nbytes + OVERHEAD < (maxsize/2) ) {
	expensive = 1;
    }

    if (expensive) {
	void *newp;

	Tcl_MutexUnlock(allocMutexPtr);

	newp = TclpAlloc(nbytes);
	if ( newp == NULL ) {
	    return NULL;
	}
	maxsize -= OVERHEAD;
	if ( maxsize < nbytes )
	    nbytes = maxsize;
	memcpy((VOID *) newp, (VOID *) cp, (size_t) nbytes);
	TclpFree(cp);
	return newp;
    }
    
    /*
     * Ok, we don't have to copy, it fits as-is
     */
#ifdef RCHECK
    op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
    *(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
    Tcl_MutexUnlock(allocMutexPtr);
    return(cp);
}

/*
 *----------------------------------------------------------------------
 *
 * mstats --
 *
 *	Prints two lines of numbers, one showing the length of the 
 *	free list for each size category, the second showing the 
 *	number of mallocs - frees for each size category.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

#ifdef MSTATS
void
mstats(s)
    char *s;	/* Where to write info. */
{
    register int i, j;
    register union overhead *p;
    int totfree = 0,
	totused = 0;

    Tcl_MutexLock(allocMutexPtr);
    fprintf(stderr, "Memory allocation statistics %s\nTclpFree:\t", s);
    for (i = 0; i < NBUCKETS; i++) {
	for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
	    fprintf(stderr, " %d", j);
	totfree += j * (1 << (i + 3));
    }
    fprintf(stderr, "\nused:\t");
    for (i = 0; i < NBUCKETS; i++) {
	fprintf(stderr, " %d", nmalloc[i]);
	totused += nmalloc[i] * (1 << (i + 3));
    }
    fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n",
	    totused, totfree);
    fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n", 
	    MAXMALLOC, nmalloc[NBUCKETS]);
    Tcl_MutexUnlock(allocMutexPtr);
}
#endif

#else  /* !USE_TCLALLOC */

/*
 *----------------------------------------------------------------------
 *
 * TclpAlloc --
 *
 *	Allocate more memory.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

char *
TclpAlloc(nbytes)
    unsigned int nbytes;	/* Number of bytes to allocate. */
{
    return (char*) malloc(nbytes);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpFree --
 *
 *	Free memory.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
TclpFree(cp)
    char *cp;		/* Pointer to memory to free. */
{   
    free(cp);
    return;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpRealloc --
 *
 *	Reallocate memory.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

char *
TclpRealloc(cp, nbytes)
    char *cp;			/* Pointer to alloced block. */
    unsigned int nbytes;	/* New size of memory. */
{   
    return (char*) realloc(cp, nbytes);
}

#endif /* !USE_TCLALLOC */
#endif /* !TCL_THREADS */