rippled/src/libxrpl/shamap/SHAMapInnerNode.cpp

#include <xrpl/shamap/SHAMapInnerNode.h>

#include <xrpl/basics/IntrusivePointer.h>    // IWYU pragma: keep
#include <xrpl/basics/IntrusivePointer.ipp>  // IWYU pragma: keep
#include <xrpl/basics/SHAMapHash.h>
#include <xrpl/basics/Slice.h>
#include <xrpl/basics/base_uint.h>
#include <xrpl/basics/contract.h>
#include <xrpl/basics/spinlock.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/protocol/HashPrefix.h>
#include <xrpl/protocol/Serializer.h>
#include <xrpl/protocol/digest.h>
#include <xrpl/shamap/SHAMapNodeID.h>
#include <xrpl/shamap/SHAMapTreeNode.h>
#include <xrpl/shamap/detail/TaggedPointer.h>
#include <xrpl/shamap/detail/TaggedPointer.ipp>

#include <cstddef>
#include <cstdint>
#include <mutex>
#include <optional>
#include <stdexcept>
#include <string>
#include <tuple>
#include <utility>

namespace xrpl {

SHAMapInnerNode::SHAMapInnerNode(std::uint32_t cowid, std::uint8_t numAllocatedChildren)
    : SHAMapTreeNode(cowid), hashesAndChildren_(numAllocatedChildren)
{
}

SHAMapInnerNode::~SHAMapInnerNode() = default;

void
SHAMapInnerNode::partialDestructor()
{
    intr_ptr::SharedPtr<SHAMapTreeNode>* children = nullptr;
    // structured bindings can't be captured in c++ 17; use tie instead
    std::tie(std::ignore, std::ignore, children) = hashesAndChildren_.getHashesAndChildren();
    iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) { children[indexNum].reset(); });
}

template <class F>
void
SHAMapInnerNode::iterChildren(F&& f) const
{
    hashesAndChildren_.iterChildren(isBranch_, std::forward<F>(f));
}

template <class F>
void
SHAMapInnerNode::iterNonEmptyChildIndexes(F&& f) const
{
    hashesAndChildren_.iterNonEmptyChildIndexes(isBranch_, std::forward<F>(f));
}

void
SHAMapInnerNode::resizeChildArrays(std::uint8_t toAllocate)
{
    hashesAndChildren_ = TaggedPointer(std::move(hashesAndChildren_), isBranch_, toAllocate);
}

std::optional<int>
SHAMapInnerNode::getChildIndex(int i) const
{
    return hashesAndChildren_.getChildIndex(isBranch_, i);
}

intr_ptr::SharedPtr<SHAMapTreeNode>
SHAMapInnerNode::clone(std::uint32_t cowid) const
{
    auto const branchCount = getBranchCount();
    auto const thisIsSparse = !hashesAndChildren_.isDense();
    auto p = intr_ptr::make_shared<SHAMapInnerNode>(cowid, branchCount);
    p->hash_ = hash_;
    p->isBranch_ = isBranch_;
    p->fullBelowGen_ = fullBelowGen_;
    SHAMapHash *cloneHashes = nullptr, *thisHashes = nullptr;
    intr_ptr::SharedPtr<SHAMapTreeNode>*cloneChildren = nullptr, *thisChildren = nullptr;
    // structured bindings can't be captured in c++ 17; use tie instead
    std::tie(std::ignore, cloneHashes, cloneChildren) =
        p->hashesAndChildren_.getHashesAndChildren();
    std::tie(std::ignore, thisHashes, thisChildren) = hashesAndChildren_.getHashesAndChildren();

    if (thisIsSparse)
    {
        int cloneChildIndex = 0;
        iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) {
            cloneHashes[cloneChildIndex++] = thisHashes[indexNum];
        });
    }
    else
    {
        iterNonEmptyChildIndexes(
            [&](auto branchNum, auto indexNum) { cloneHashes[branchNum] = thisHashes[indexNum]; });
    }

    spinlock sl(lock_);
    std::lock_guard const lock(sl);

    if (thisIsSparse)
    {
        int cloneChildIndex = 0;
        iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) {
            cloneChildren[cloneChildIndex++] = thisChildren[indexNum];
        });
    }
    else
    {
        iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) {
            cloneChildren[branchNum] = thisChildren[indexNum];
        });
    }

    return p;
}

intr_ptr::SharedPtr<SHAMapTreeNode>
SHAMapInnerNode::makeFullInner(Slice data, SHAMapHash const& hash, bool hashValid)
{
    // A full inner node is serialized as 16 256-bit hashes, back to back:
    if (data.size() != branchFactor * uint256::bytes)
        Throw<std::runtime_error>("Invalid FI node");

    auto ret = intr_ptr::make_shared<SHAMapInnerNode>(0, branchFactor);

    SerialIter si(data);

    auto hashes = ret->hashesAndChildren_.getHashes();

    for (int i = 0; i < branchFactor; ++i)
    {
        hashes[i].as_uint256() = si.getBitString<256>();

        if (hashes[i].isNonZero())
            ret->isBranch_ |= (1 << i);
    }

    ret->resizeChildArrays(ret->getBranchCount());

    if (hashValid)
    {
        ret->hash_ = hash;
    }
    else
    {
        ret->updateHash();
    }

    return ret;
}

intr_ptr::SharedPtr<SHAMapTreeNode>
SHAMapInnerNode::makeCompressedInner(Slice data)
{
    // A compressed inner node is serialized as a series of 33 byte chunks,
    // representing a one byte "position" and a 256-bit hash:
    constexpr std::size_t chunkSize = uint256::bytes + 1;

    if (auto const s = data.size(); (s % chunkSize != 0) || (s > chunkSize * branchFactor))
        Throw<std::runtime_error>("Invalid CI node");

    SerialIter si(data);

    auto ret = intr_ptr::make_shared<SHAMapInnerNode>(0, branchFactor);

    auto hashes = ret->hashesAndChildren_.getHashes();

    while (!si.empty())
    {
        auto const hash = si.getBitString<256>();
        auto const pos = si.get8();

        if (pos >= branchFactor)
            Throw<std::runtime_error>("invalid CI node");

        hashes[pos].as_uint256() = hash;

        if (hashes[pos].isNonZero())
            ret->isBranch_ |= (1 << pos);
    }

    ret->resizeChildArrays(ret->getBranchCount());
    ret->updateHash();
    return ret;
}

void
SHAMapInnerNode::updateHash()
{
    uint256 nh;
    if (isBranch_ != 0)
    {
        sha512_half_hasher h;
        using beast::hash_append;
        hash_append(h, HashPrefix::innerNode);
        iterChildren([&](SHAMapHash const& hh) { hash_append(h, hh); });
        nh = static_cast<typename sha512_half_hasher::result_type>(h);
    }
    hash_ = SHAMapHash{nh};
}

void
SHAMapInnerNode::updateHashDeep()
{
    SHAMapHash* hashes = nullptr;
    intr_ptr::SharedPtr<SHAMapTreeNode>* children = nullptr;
    // structured bindings can't be captured in c++ 17; use tie instead
    std::tie(std::ignore, hashes, children) = hashesAndChildren_.getHashesAndChildren();
    iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) {
        if (auto p = children[indexNum].get())
            hashes[indexNum] = p->getHash();
    });
    updateHash();
}

void
SHAMapInnerNode::serializeForWire(Serializer& s) const
{
    XRPL_ASSERT(!isEmpty(), "xrpl::SHAMapInnerNode::serializeForWire : is non-empty");

    // If the node is sparse, then only send non-empty branches:
    if (getBranchCount() < 12)
    {
        // compressed node
        auto hashes = hashesAndChildren_.getHashes();
        iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) {
            s.addBitString(hashes[indexNum].as_uint256());
            s.add8(branchNum);
        });
        s.add8(wireTypeCompressedInner);
    }
    else
    {
        iterChildren([&](SHAMapHash const& hh) { s.addBitString(hh.as_uint256()); });
        s.add8(wireTypeInner);
    }
}

void
SHAMapInnerNode::serializeWithPrefix(Serializer& s) const
{
    XRPL_ASSERT(!isEmpty(), "xrpl::SHAMapInnerNode::serializeWithPrefix : is non-empty");

    s.add32(HashPrefix::innerNode);
    iterChildren([&](SHAMapHash const& hh) { s.addBitString(hh.as_uint256()); });
}

std::string
SHAMapInnerNode::getString(SHAMapNodeID const& id) const
{
    std::string ret = SHAMapTreeNode::getString(id);
    auto hashes = hashesAndChildren_.getHashes();
    iterNonEmptyChildIndexes([&](auto branchNum, auto indexNum) {
        ret += "\nb";
        ret += std::to_string(branchNum);
        ret += " = ";
        ret += to_string(hashes[indexNum]);
    });
    return ret;
}

// We are modifying an inner node
void
SHAMapInnerNode::setChild(int m, intr_ptr::SharedPtr<SHAMapTreeNode> child)
{
    XRPL_ASSERT(
        (m >= 0) && (m < branchFactor), "xrpl::SHAMapInnerNode::setChild : valid branch input");
    XRPL_ASSERT(cowid_, "xrpl::SHAMapInnerNode::setChild : nonzero cowid");
    XRPL_ASSERT(child.get() != this, "xrpl::SHAMapInnerNode::setChild : valid child input");

    auto const dstIsBranch = [&] {
        if (child)
        {
            return isBranch_ | (1u << m);
        }

        return isBranch_ & ~(1u << m);
    }();

    auto const dstToAllocate = popcnt16(dstIsBranch);
    // change hashesAndChildren to remove the element, or make room for the
    // added element, if necessary
    hashesAndChildren_ =
        TaggedPointer(std::move(hashesAndChildren_), isBranch_, dstIsBranch, dstToAllocate);

    isBranch_ = dstIsBranch;

    if (child)
    {
        auto const childIndex =
            *getChildIndex(m);  // NOLINT(bugprone-unchecked-optional-access) isBranch_ set above
        auto [_, hashes, children] = hashesAndChildren_.getHashesAndChildren();
        hashes[childIndex].zero();
        children[childIndex] = std::move(child);
    }

    hash_.zero();

    XRPL_ASSERT(
        getBranchCount() <= hashesAndChildren_.capacity(),
        "xrpl::SHAMapInnerNode::setChild : maximum branch count");
}

// finished modifying, now make shareable
void
SHAMapInnerNode::shareChild(int m, intr_ptr::SharedPtr<SHAMapTreeNode> const& child)
{
    XRPL_ASSERT(
        (m >= 0) && (m < branchFactor), "xrpl::SHAMapInnerNode::shareChild : valid branch input");
    XRPL_ASSERT(cowid_, "xrpl::SHAMapInnerNode::shareChild : nonzero cowid");
    XRPL_ASSERT(child, "xrpl::SHAMapInnerNode::shareChild : non-null child input");
    XRPL_ASSERT(child.get() != this, "xrpl::SHAMapInnerNode::shareChild : valid child input");

    XRPL_ASSERT(!isEmptyBranch(m), "xrpl::SHAMapInnerNode::shareChild : non-empty branch input");
    // NOLINTNEXTLINE(bugprone-unchecked-optional-access) assert above
    hashesAndChildren_.getChildren()[*getChildIndex(m)] = child;
}

SHAMapTreeNode*
SHAMapInnerNode::getChildPointer(int branch)
{
    XRPL_ASSERT(
        branch >= 0 && branch < branchFactor,
        "xrpl::SHAMapInnerNode::getChildPointer : valid branch input");
    XRPL_ASSERT(
        !isEmptyBranch(branch), "xrpl::SHAMapInnerNode::getChildPointer : non-empty branch input");

    auto const index =
        *getChildIndex(branch);  // NOLINT(bugprone-unchecked-optional-access) assert above

    packed_spinlock sl(lock_, index);
    std::lock_guard const lock(sl);
    return hashesAndChildren_.getChildren()[index].get();
}

intr_ptr::SharedPtr<SHAMapTreeNode>
SHAMapInnerNode::getChild(int branch)
{
    XRPL_ASSERT(
        branch >= 0 && branch < branchFactor,
        "xrpl::SHAMapInnerNode::getChild : valid branch input");
    XRPL_ASSERT(!isEmptyBranch(branch), "xrpl::SHAMapInnerNode::getChild : non-empty branch input");

    auto const index =
        *getChildIndex(branch);  // NOLINT(bugprone-unchecked-optional-access) assert above

    packed_spinlock sl(lock_, index);
    std::lock_guard const lock(sl);
    return hashesAndChildren_.getChildren()[index];
}

SHAMapHash const&
SHAMapInnerNode::getChildHash(int m) const
{
    XRPL_ASSERT(
        (m >= 0) && (m < branchFactor), "xrpl::SHAMapInnerNode::getChildHash : valid branch input");
    if (auto const i = getChildIndex(m))
        return hashesAndChildren_.getHashes()[*i];

    return zeroSHAMapHash;
}

intr_ptr::SharedPtr<SHAMapTreeNode>
SHAMapInnerNode::canonicalizeChild(int branch, intr_ptr::SharedPtr<SHAMapTreeNode> node)
{
    XRPL_ASSERT(
        branch >= 0 && branch < branchFactor,
        "xrpl::SHAMapInnerNode::canonicalizeChild : valid branch input");
    XRPL_ASSERT(node != nullptr, "xrpl::SHAMapInnerNode::canonicalizeChild : valid node input");
    XRPL_ASSERT(
        !isEmptyBranch(branch),
        "xrpl::SHAMapInnerNode::canonicalizeChild : non-empty branch input");
    auto const childIndex =
        *getChildIndex(branch);  // NOLINT(bugprone-unchecked-optional-access) assert above
    auto [_, hashes, children] = hashesAndChildren_.getHashesAndChildren();
    XRPL_ASSERT(
        node->getHash() == hashes[childIndex],
        "xrpl::SHAMapInnerNode::canonicalizeChild : node and branch inputs "
        "hash do match");

    packed_spinlock sl(lock_, childIndex);
    std::lock_guard const lock(sl);

    if (children[childIndex])
    {
        // There is already a node hooked up, return it
        node = children[childIndex];
    }
    else
    {
        // Hook this node up
        children[childIndex] = node;
    }
    return node;
}

void
SHAMapInnerNode::invariants(bool is_root) const
{
    [[maybe_unused]] unsigned count = 0;
    auto [numAllocated, hashes, children] = hashesAndChildren_.getHashesAndChildren();

    if (numAllocated != branchFactor)
    {
        auto const branchCount = getBranchCount();
        for (int i = 0; i < branchCount; ++i)
        {
            XRPL_ASSERT(
                hashes[i].isNonZero(),
                "xrpl::SHAMapInnerNode::invariants : nonzero hash in branch");
            if (children[i] != nullptr)
                children[i]->invariants();
            ++count;
        }
    }
    else
    {
        for (int i = 0; i < branchFactor; ++i)
        {
            if (hashes[i].isNonZero())
            {
                XRPL_ASSERT(
                    (isBranch_ & (1 << i)),
                    "xrpl::SHAMapInnerNode::invariants : valid branch when "
                    "nonzero hash");
                if (children[i] != nullptr)
                    children[i]->invariants();
                ++count;
            }
            else
            {
                XRPL_ASSERT(
                    (isBranch_ & (1 << i)) == 0,
                    "xrpl::SHAMapInnerNode::invariants : valid branch when "
                    "zero hash");
            }
        }
    }

    if (!is_root)
    {
        XRPL_ASSERT(hash_.isNonZero(), "xrpl::SHAMapInnerNode::invariants : nonzero hash");
        XRPL_ASSERT(count >= 1, "xrpl::SHAMapInnerNode::invariants : minimum count");
    }
    XRPL_ASSERT(
        (count == 0) ? hash_.isZero() : hash_.isNonZero(),
        "xrpl::SHAMapInnerNode::invariants : hash and count do match");
}

}  // namespace xrpl