void HashCollection::shrink(uint32_t oldCap /* = 0 */) {
assert(isCapacityTooHigh() && (oldCap == 0 || oldCap < cap()));
assert(m_size <= posLimit() && posLimit() <= cap());
dropImmCopy();
uint32_t newCap;
if (oldCap != 0) {
// If an old capacity was specified, use that
newCap = oldCap;
// .. unless the old capacity is too small, in which case we use the
// smallest capacity that is large enough to hold the current number
// of elements.
for (; newCap < m_size; newCap <<= 1) {}
assert(newCap == computeMaxElms(folly::nextPowTwo<uint64_t>(newCap) - 1));
} else {
if (m_size == 0 && nextKI() == 0) {
decRefArr(m_arr);
m_arr = staticEmptyDictArrayAsMixed();
return;
}
// If no old capacity was provided, we compute the largest capacity
// where m_size/cap() is less than or equal to 0.5 for good hysteresis
size_t doubleSz = size_t(m_size) * 2;
uint32_t capThreshold = (doubleSz < size_t(MaxSize)) ? doubleSz : MaxSize;
for (newCap = SmallSize * 2; newCap < capThreshold; newCap <<= 1) {}
}
assert(SmallSize <= newCap && newCap <= MaxSize);
assert(m_size <= newCap);
auto* oldAd = arrayData();
if (!oldAd->cowCheck()) {
// If the buffer's refcount is 1, we can teleport the elements
// to a new buffer
auto oldBuf = data();
auto oldUsed = posLimit();
auto oldNextKI = nextKI();
auto arr = MixedArray::asMixed(MixedArray::MakeReserveDict(newCap));
auto data = mixedData(arr);
m_arr = arr;
auto table = (int32_t*)(data + size_t(newCap));
auto table_mask = tableMask();
arr->m_size = m_size;
setPosLimit(m_size);
setNextKI(oldNextKI);
for (uint32_t frPos = 0, toPos = 0; toPos < m_size; ++toPos, ++frPos) {
frPos = skipTombstonesNoBoundsCheck(frPos, oldUsed, oldBuf);
copyElm(oldBuf[frPos], data[toPos]);
*findForNewInsert(table, table_mask, data[toPos].probe()) = toPos;
}
oldAd->setZombie();
decRefArr(oldAd);
} else {
// For cases where the buffer's refcount is greater than 1, call
// resizeHelper()
resizeHelper(newCap);
}
assert(canMutateBuffer());
assert(m_immCopy.isNull());
assert(!isCapacityTooHigh() || newCap == oldCap);
}
ALWAYS_INLINE
typename std::enable_if<
std::is_base_of<BaseMap, TMap>::value, Object>::type
BaseMap::php_skip(const Variant& n) {
if (!n.isInteger()) {
SystemLib::throwInvalidArgumentExceptionObject(
"Parameter n must be an integer");
}
int64_t len = n.toInt64();
if (len <= 0) {
// We know the resulting Map will simply be a copy of this Map,
// so we can just call Clone() and return early here.
return Object::attach(TMap::Clone(this));
}
auto map = req::make<TMap>();
if (len >= m_size) {
// We know the resulting Map will be empty, so we can return
// early here.
return Object{std::move(map)};
}
size_t sz = size_t(m_size) - size_t(len);
assert(sz);
map->reserve(sz);
map->setSize(sz);
map->setPosLimit(sz);
uint32_t frPos = nthElmPos(len);
auto table = map->hashTab();
auto mask = map->tableMask();
for (uint32_t toPos = 0; toPos < sz; ++toPos, ++frPos) {
frPos = skipTombstonesNoBoundsCheck(frPos);
auto& toE = map->data()[toPos];
dupElm(data()[frPos], toE);
*findForNewInsert(table, mask, toE.probe()) = toPos;
if (toE.hasIntKey()) {
map->updateNextKI(toE.ikey);
} else {
assert(toE.hasStrKey());
map->updateIntLikeStrKeys(toE.skey);
}
}
return Object{std::move(map)};
}
ALWAYS_INLINE
typename std::enable_if<
std::is_base_of<BaseMap, TMap>::value, Object>::type
BaseMap::php_slice(const Variant& start, const Variant& len) {
int64_t istart;
int64_t ilen;
if (!start.isInteger() || (istart = start.toInt64()) < 0) {
SystemLib::throwInvalidArgumentExceptionObject(
"Parameter start must be a non-negative integer");
}
if (!len.isInteger() || (ilen = len.toInt64()) < 0) {
SystemLib::throwInvalidArgumentExceptionObject(
"Parameter len must be a non-negative integer");
}
size_t skipAmt = std::min<size_t>(istart, m_size);
size_t sz = std::min<size_t>(ilen, size_t(m_size) - skipAmt);
auto map = req::make<TMap>();
map->reserve(sz);
map->setSize(sz);
map->setPosLimit(sz);
uint32_t frPos = nthElmPos(skipAmt);
auto table = map->hashTab();
auto mask = map->tableMask();
for (uint32_t toPos = 0; toPos < sz; ++toPos, ++frPos) {
frPos = skipTombstonesNoBoundsCheck(frPos);
auto& toE = map->data()[toPos];
dupElm(data()[frPos], toE);
*findForNewInsert(table, mask, toE.probe()) = toPos;
if (toE.hasIntKey()) {
map->updateNextKI(toE.ikey);
} else {
assert(toE.hasStrKey());
map->updateIntLikeStrKeys(toE.skey);
}
}
return Object{std::move(map)};
}