pair<void*,uint64_t>
IOBufQueue::preallocateSlow(uint64_t min, uint64_t newAllocationSize,
uint64_t max) {
// Allocate a new buffer of the requested max size.
unique_ptr<IOBuf> newBuf(IOBuf::create(std::max(min, newAllocationSize)));
appendToChain(head_, std::move(newBuf), false);
IOBuf* last = head_->prev();
return make_pair(last->writableTail(),
std::min(max, last->tailroom()));
}
void
IOBufQueue::append(const void* buf, size_t len) {
auto src = static_cast<const uint8_t*>(buf);
while (len != 0) {
if ((head_ == nullptr) || head_->prev()->isSharedOne() ||
(head_->prev()->tailroom() == 0)) {
appendToChain(head_,
IOBuf::create(std::max(MIN_ALLOC_SIZE,
std::min(len, MAX_ALLOC_SIZE))),
false);
}
IOBuf* last = head_->prev();
uint64_t copyLen = std::min(len, (size_t)last->tailroom());
memcpy(last->writableTail(), src, copyLen);
src += copyLen;
last->append(copyLen);
chainLength_ += copyLen;
len -= copyLen;
}
}
