/* MVFFFreeSegs -- Free segments from given range
*
* Given a free range, attempts to find entire segments within
* it, and returns them to the arena, updating total size counter.
*
* This is usually called immediately after MVFFAddToFreeList.
* It is not combined with MVFFAddToFreeList because the latter
* is also called when new segments are added under MVFFAlloc.
*/
static void MVFFFreeSegs(MVFF mvff, Addr base, Addr limit)
{
Seg seg = NULL; /* suppress "may be used uninitialized" */
Arena arena;
Bool b;
Addr segLimit; /* limit of the current segment when iterating */
Addr segBase; /* base of the current segment when iterating */
Res res;
AVERT(MVFF, mvff);
AVER(base < limit);
/* Could profitably AVER that the given range is free, */
/* but the CBS doesn't provide that facility. */
if (AddrOffset(base, limit) < mvff->minSegSize)
return; /* not large enough for entire segments */
arena = PoolArena(MVFF2Pool(mvff));
b = SegOfAddr(&seg, arena, base);
AVER(b);
segBase = SegBase(seg);
segLimit = SegLimit(seg);
while(segLimit <= limit) { /* segment ends in range */
if (segBase >= base) { /* segment starts in range */
RangeStruct range, oldRange;
RangeInit(&range, segBase, segLimit);
res = CBSDelete(&oldRange, CBSOfMVFF(mvff), &range);
if (res == ResOK) {
mvff->free -= RangeSize(&range);
} else if (ResIsAllocFailure(res)) {
/* CBS ran out of memory for splay nodes, which must mean that
* there were fragments on both sides: see
* <design/cbs/#function.cbs.delete.fail>. Handle this by
* deleting the whole of oldRange (which requires no
* allocation) and re-inserting the fragments. */
RangeStruct oldRange2;
res = CBSDelete(&oldRange2, CBSOfMVFF(mvff), &oldRange);
AVER(res == ResOK);
AVER(RangesEqual(&oldRange2, &oldRange));
mvff->free -= RangeSize(&oldRange);
AVER(RangeBase(&oldRange) != segBase);
{
Addr leftBase = RangeBase(&oldRange);
Addr leftLimit = segBase;
res = MVFFAddToFreeList(&leftBase, &leftLimit, mvff);
}
AVER(RangeLimit(&oldRange) != segLimit);
{
Addr rightBase = segLimit;
Addr rightLimit = RangeLimit(&oldRange);
res = MVFFAddToFreeList(&rightBase, &rightLimit, mvff);
}
} else if (res == ResFAIL) {
/* Not found in the CBS: must be found in the Freelist. */
res = FreelistDelete(&oldRange, FreelistOfMVFF(mvff), &range);
AVER(res == ResOK);
mvff->free -= RangeSize(&range);
}
AVER(res == ResOK);
AVER(RangesNest(&oldRange, &range));
/* Can't free the segment earlier, because if it was on the
* Freelist rather than the CBS then it likely contains data
* that needs to be read in order to update the Freelist. */
SegFree(seg);
mvff->total -= RangeSize(&range);
}
/* Avoid calling SegNext if the next segment would fail */
/* the loop test, mainly because there might not be a */
/* next segment. */
if (segLimit == limit) /* segment ends at end of range */
break;
b = SegFindAboveAddr(&seg, arena, segBase);
AVER(b);
segBase = SegBase(seg);
segLimit = SegLimit(seg);
}
return;
}
static void allocate(FBMState state, Addr base, Addr limit)
{
Res res;
Index ib, il; /* Indexed for base and limit */
Bool isFree;
RangeStruct range, oldRange;
Addr outerBase, outerLimit; /* interval containing [ib, il) */
ib = indexOfAddr(state, base);
il = indexOfAddr(state, limit);
isFree = BTIsResRange(state->allocTable, ib, il);
NAllocateTried++;
if (isFree) {
Size left, right, total; /* Sizes of block and two fragments */
outerBase =
addrOfIndex(state, lastEdge(state->allocTable, ArraySize, ib));
outerLimit =
addrOfIndex(state, nextEdge(state->allocTable, ArraySize, il - 1));
left = AddrOffset(outerBase, base);
right = AddrOffset(limit, outerLimit);
total = AddrOffset(outerBase, outerLimit);
/* TODO: check these values */
UNUSED(left);
UNUSED(right);
UNUSED(total);
} else {
outerBase = outerLimit = NULL;
}
RangeInit(&range, base, limit);
switch (state->type) {
case FBMTypeCBS:
res = CBSDelete(&oldRange, state->the.cbs, &range);
break;
case FBMTypeFreelist:
res = FreelistDelete(&oldRange, state->the.fl, &range);
break;
default:
fail();
return;
}
if (verbose) {
printf("allocate: [%p,%p) -- %s\n",
(void *)base, (void *)limit, isFree ? "succeed" : "fail");
describe(state);
}
if (!isFree) {
die_expect((mps_res_t)res, MPS_RES_FAIL,
"Succeeded in deleting allocated block");
} else { /* isFree */
die_expect((mps_res_t)res, MPS_RES_OK,
"failed to delete free block");
Insist(RangeBase(&oldRange) == outerBase);
Insist(RangeLimit(&oldRange) == outerLimit);
NAllocateSucceeded++;
BTSetRange(state->allocTable, ib, il);
}
}
