Method readString

src/storage/overflow_file.cpp:19–45

namespace storage {

std::string OverflowFileHandle::readString(TransactionType trxType, const string_t& str) const {
    if (string_t::isShortString(str.len)) {
        return str.getAsShortString();
    }
    PageCursor cursor;
    TypeUtils::decodeOverflowPtr(str.overflowPtr, cursor.pageIdx, cursor.elemPosInPage);
    std::string retVal;
    retVal.reserve(str.len);
    int32_t remainingLength = str.len;
    while (remainingLength > 0) {
        auto numBytesToReadInPage =
            std::min(static_cast<uint32_t>(remainingLength), END_OF_PAGE - cursor.elemPosInPage);
        auto startPosInSrc = retVal.size();
        read(trxType, cursor.pageIdx, [&](uint8_t* frame) {
            // Replace rather than append, since optimistic read may call the function multiple
            // times
            retVal.replace(startPosInSrc, numBytesToReadInPage,
                std::string_view(reinterpret_cast<const char*>(frame) + cursor.elemPosInPage,
                    numBytesToReadInPage));
            cursor.pageIdx = *reinterpret_cast<page_idx_t*>(frame + END_OF_PAGE);
        });
        remainingLength -= numBytesToReadInPage;
        // After the first page we always start reading from the beginning of the page.
        cursor.elemPosInPage = 0;
    }
    return retVal;
}

bool OverflowFileHandle::equals(TransactionType trxType, std::string_view keyToLookup,
    const string_t& keyInEntry) const {