tclthreadalloc.c

tcl是工具命令语言

     */

    new = TclpAlloc(reqsize);
    if (new != NULL) {
	if (reqsize > blockPtr->b_reqsize) {
	    reqsize = blockPtr->b_reqsize;
	}
    	memcpy(new, ptr, reqsize);
    	TclpFree(ptr);
    }
    return new;
}


/*
 *----------------------------------------------------------------------
 *
 * TclThreadAllocObj --
 *
 *	Allocate a Tcl_Obj from the per-thread cache.
 *
 * Results:
 *	Pointer to uninitialized Tcl_Obj.
 *
 * Side effects:
 *	May move Tcl_Obj's from shared cached or allocate new Tcl_Obj's
 *  	if list is empty.
 *
 *----------------------------------------------------------------------
 */

Tcl_Obj *
TclThreadAllocObj(void)
{
    register Cache *cachePtr = TclpGetAllocCache();
    register int nmove;
    register Tcl_Obj *objPtr;
    Tcl_Obj *newObjsPtr;

    if (cachePtr == NULL) {
	cachePtr = GetCache();
    }

    /*
     * Get this thread's obj list structure and move
     * or allocate new objs if necessary.
     */
     
    if (cachePtr->nobjs == 0) {
    	Tcl_MutexLock(objLockPtr);
	nmove = sharedPtr->nobjs;
	if (nmove > 0) {
	    if (nmove > NOBJALLOC) {
		nmove = NOBJALLOC;
	    }
	    MoveObjs(sharedPtr, cachePtr, nmove);
	}
    	Tcl_MutexUnlock(objLockPtr);
	if (cachePtr->nobjs == 0) {
	    cachePtr->nobjs = nmove = NOBJALLOC;
	    newObjsPtr = malloc(sizeof(Tcl_Obj) * nmove);
	    if (newObjsPtr == NULL) {
		panic("alloc: could not allocate %d new objects", nmove);
	    }
	    while (--nmove >= 0) {
		objPtr = &newObjsPtr[nmove];
		objPtr->internalRep.otherValuePtr = cachePtr->firstObjPtr;
		cachePtr->firstObjPtr = objPtr;
	    }
	}
    }

    /*
     * Pop the first object.
     */

    objPtr = cachePtr->firstObjPtr;
    cachePtr->firstObjPtr = objPtr->internalRep.otherValuePtr;
    --cachePtr->nobjs;
    return objPtr;
}


/*
 *----------------------------------------------------------------------
 *
 * TclThreadFreeObj --
 *
 *	Return a free Tcl_Obj to the per-thread cache.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May move free Tcl_Obj's to shared list upon hitting high
 *  	water mark.
 *
 *----------------------------------------------------------------------
 */

void
TclThreadFreeObj(Tcl_Obj *objPtr)
{
    Cache *cachePtr = TclpGetAllocCache();

    if (cachePtr == NULL) {
	cachePtr = GetCache();
    }

    /*
     * Get this thread's list and push on the free Tcl_Obj.
     */
     
    objPtr->internalRep.otherValuePtr = cachePtr->firstObjPtr;
    cachePtr->firstObjPtr = objPtr;
    ++cachePtr->nobjs;
    
    /*
     * If the number of free objects has exceeded the high
     * water mark, move some blocks to the shared list.
     */
     
    if (cachePtr->nobjs > NOBJHIGH) {
	Tcl_MutexLock(objLockPtr);
	MoveObjs(cachePtr, sharedPtr, NOBJALLOC);
	Tcl_MutexUnlock(objLockPtr);
    }
}


/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetMemoryInfo --
 *
 *	Return a list-of-lists of memory stats.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *  	List appended to given dstring.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_GetMemoryInfo(Tcl_DString *dsPtr)
{
    Cache *cachePtr;
    char buf[200];
    int n;

    Tcl_MutexLock(listLockPtr);
    cachePtr = firstCachePtr;
    while (cachePtr != NULL) {
	Tcl_DStringStartSublist(dsPtr);
	if (cachePtr == sharedPtr) {
    	    Tcl_DStringAppendElement(dsPtr, "shared");
	} else {
	    sprintf(buf, "thread%d", (int) cachePtr->owner);
    	    Tcl_DStringAppendElement(dsPtr, buf);
	}
	for (n = 0; n < NBUCKETS; ++n) {
    	    sprintf(buf, "%d %d %d %d %d %d %d",
		(int) binfo[n].blocksize,
		cachePtr->buckets[n].nfree,
		cachePtr->buckets[n].nget,
		cachePtr->buckets[n].nput,
		cachePtr->buckets[n].nrequest,
		cachePtr->buckets[n].nlock,
		cachePtr->buckets[n].nwait);
	    Tcl_DStringAppendElement(dsPtr, buf);
	}
	Tcl_DStringEndSublist(dsPtr);
	    cachePtr = cachePtr->nextPtr;
    }
    Tcl_MutexUnlock(listLockPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * MoveObjs --
 *
 *	Move Tcl_Obj's between caches.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *  	None.
 *
 *----------------------------------------------------------------------
 */

static void
MoveObjs(Cache *fromPtr, Cache *toPtr, int nmove)
{
    register Tcl_Obj *objPtr = fromPtr->firstObjPtr;
    Tcl_Obj *fromFirstObjPtr = objPtr;

    toPtr->nobjs += nmove;
    fromPtr->nobjs -= nmove;

    /*
     * Find the last object to be moved; set the next one
     * (the first one not to be moved) as the first object
     * in the 'from' cache.
     */

    while (--nmove) {
	objPtr = objPtr->internalRep.otherValuePtr;
    }
    fromPtr->firstObjPtr = objPtr->internalRep.otherValuePtr;    

    /*
     * Move all objects as a block - they are already linked to
     * each other, we just have to update the first and last.
     */

    objPtr->internalRep.otherValuePtr = toPtr->firstObjPtr;
    toPtr->firstObjPtr = fromFirstObjPtr;
}


/*
 *----------------------------------------------------------------------
 *
 *  Block2Ptr, Ptr2Block --
 *
 *	Convert between internal blocks and user pointers.
 *
 * Results:
 *	User pointer or internal block.
 *
 * Side effects:
 *	Invalid blocks will abort the server.
 *
 *----------------------------------------------------------------------
 */

static char *
Block2Ptr(Block *blockPtr, int bucket, unsigned int reqsize) 
{
    register void *ptr;

    blockPtr->b_magic1 = blockPtr->b_magic2 = MAGIC;
    blockPtr->b_bucket = bucket;
    blockPtr->b_reqsize = reqsize;
    ptr = ((void *) (blockPtr + 1));
#if RCHECK
    ((unsigned char *)(ptr))[reqsize] = MAGIC;
#endif
    return (char *) ptr;
}

static Block *
Ptr2Block(char *ptr)
{
    register Block *blockPtr;

    blockPtr = (((Block *) ptr) - 1);
    if (blockPtr->b_magic1 != MAGIC
#if RCHECK
	|| ((unsigned char *) ptr)[blockPtr->b_reqsize] != MAGIC
#endif
	|| blockPtr->b_magic2 != MAGIC) {
	panic("alloc: invalid block: %p: %x %x %x\n",
	    blockPtr, blockPtr->b_magic1, blockPtr->b_magic2,
	    ((unsigned char *) ptr)[blockPtr->b_reqsize]);
    }
    return blockPtr;
}


/*
 *----------------------------------------------------------------------
 *
 *  LockBucket, UnlockBucket --
 *
 *	Set/unset the lock to access a bucket in the shared cache.
 *
 * Results:
 *  	None.
 *
 * Side effects:
 *	Lock activity and contention are monitored globally and on
 *  	a per-cache basis.
 *
 *----------------------------------------------------------------------
 */

static void
LockBucket(Cache *cachePtr, int bucket)
{
#if 0
    if (Tcl_MutexTryLock(binfo[bucket].lockPtr) != TCL_OK) {
	Tcl_MutexLock(binfo[bucket].lockPtr);
    	++cachePtr->buckets[bucket].nwait;
    	++sharedPtr->buckets[bucket].nwait;
    }
#else
    Tcl_MutexLock(binfo[bucket].lockPtr);
#endif
    ++cachePtr->buckets[bucket].nlock;
    ++sharedPtr->buckets[bucket].nlock;
}


static void
UnlockBucket(Cache *cachePtr, int bucket)
{
    Tcl_MutexUnlock(binfo[bucket].lockPtr);
}


/*
 *----------------------------------------------------------------------
 *
 *  PutBlocks --
 *
 *	Return unused blocks to the shared cache.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
PutBlocks(Cache *cachePtr, int bucket, int nmove)
{
    register Block *lastPtr, *firstPtr;
    register int n = nmove;

    /*
     * Before acquiring the lock, walk the block list to find
     * the last block to be moved.
     */

    firstPtr = lastPtr = cachePtr->buckets[bucket].firstPtr;
    while (--n > 0) {
	lastPtr = lastPtr->b_next;
    }
    cachePtr->buckets[bucket].firstPtr = lastPtr->b_next;
    cachePtr->buckets[bucket].nfree -= nmove;

    /*
     * Aquire the lock and place the list of blocks at the front
     * of the shared cache bucket.
     */

    LockBucket(cachePtr, bucket);
    lastPtr->b_next = sharedPtr->buckets[bucket].firstPtr;
    sharedPtr->buckets[bucket].firstPtr = firstPtr;
    sharedPtr->buckets[bucket].nfree += nmove;
    UnlockBucket(cachePtr, bucket);
}


/*
 *----------------------------------------------------------------------
 *
 *  GetBlocks --
 *
 *	Get more blocks for a bucket.
 *
 * Results:
 *	1 if blocks where allocated, 0 otherwise.
 *
 * Side effects:
 *	Cache may be filled with available blocks.
 *
 *----------------------------------------------------------------------
 */

static int
GetBlocks(Cache *cachePtr, int bucket)
{
    register Block *blockPtr;
    register int n;
    register size_t size;

    /*
     * First, atttempt to move blocks from the shared cache.  Note
     * the potentially dirty read of nfree before acquiring the lock
     * which is a slight performance enhancement.  The value is
     * verified after the lock is actually acquired.
     */
     
    if (cachePtr != sharedPtr && sharedPtr->buckets[bucket].nfree > 0) {
	LockBucket(cachePtr, bucket);
	if (sharedPtr->buckets[bucket].nfree > 0) {

	    /*
	     * Either move the entire list or walk the list to find
	     * the last block to move.
	     */

	    n = binfo[bucket].nmove;
	    if (n >= sharedPtr->buckets[bucket].nfree) {
		cachePtr->buckets[bucket].firstPtr =
		    sharedPtr->buckets[bucket].firstPtr;
		cachePtr->buckets[bucket].nfree =
		    sharedPtr->buckets[bucket].nfree;
		sharedPtr->buckets[bucket].firstPtr = NULL;
		sharedPtr->buckets[bucket].nfree = 0;
	    } else {
		blockPtr = sharedPtr->buckets[bucket].firstPtr;
		cachePtr->buckets[bucket].firstPtr = blockPtr;
		sharedPtr->buckets[bucket].nfree -= n;
		cachePtr->buckets[bucket].nfree = n;
		while (--n > 0) {
    		    blockPtr = blockPtr->b_next;
		}
		sharedPtr->buckets[bucket].firstPtr = blockPtr->b_next;
		blockPtr->b_next = NULL;
	    }
	}
	UnlockBucket(cachePtr, bucket);
    }
    
    if (cachePtr->buckets[bucket].nfree == 0) {

	/*
	 * If no blocks could be moved from shared, first look for a
	 * larger block in this cache to split up.
	 */

    	blockPtr = NULL;
	n = NBUCKETS;
	size = 0; /* lint */
	while (--n > bucket) {
    	    if (cachePtr->buckets[n].nfree > 0) {
		size = binfo[n].blocksize;
		blockPtr = cachePtr->buckets[n].firstPtr;
		cachePtr->buckets[n].firstPtr = blockPtr->b_next;
		--cachePtr->buckets[n].nfree;
		break;
	    }
	}

	/*
	 * Otherwise, allocate a big new block directly.
	 */

	if (blockPtr == NULL) {
	    size = MAXALLOC;
	    blockPtr = malloc(size);
	    if (blockPtr == NULL) {
		return 0;
	    }
	}

	/*
	 * Split the larger block into smaller blocks for this bucket.
	 */

	n = size / binfo[bucket].blocksize;
	cachePtr->buckets[bucket].nfree = n;
	cachePtr->buckets[bucket].firstPtr = blockPtr;
	while (--n > 0) {
	    blockPtr->b_next = (Block *) 
		((char *) blockPtr + binfo[bucket].blocksize);
	    blockPtr = blockPtr->b_next;
	}
	blockPtr->b_next = NULL;
    }
    return 1;
}

#endif /* TCL_THREADS */