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slight simplification to CurveTrees::hash_layer

This commit is contained in:
j-berman 2024-05-22 16:21:12 -07:00
parent 9e68475ebd
commit 26009ba5f1
1 changed files with 24 additions and 28 deletions
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52
src/fcmp/curve_trees.h
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@ -298,21 +298,19 @@ private:
const typename C::Chunk &new_children,
const std::size_t chunk_width,
const bool child_layer_last_hash_updated,
const LastChunkData<C> *last_chunk_ptr) const
const LastChunkData<C> *last_chunk_ptr,
const std::size_t offset) const
{
// If no last chunk exists, we can get a new parent
if (last_chunk_ptr == nullptr)
return get_new_parent<C>(curve, new_children);
std::vector<typename C::Scalar> prior_children;
std::size_t offset = last_chunk_ptr->child_offset;
if (child_layer_last_hash_updated)
{
// If the last chunk has updated children in it, then we need to get the delta to the old children, and
// subtract the offset by 1 since we're updating the prior last hash
// If the last chunk has updated children in it, then we need to get the delta to the old children
prior_children.emplace_back(curve.clone(last_chunk_ptr->last_child));
offset = offset > 0 ? (offset - 1) : (chunk_width - 1);
// Extend prior children by zeroes for any additional new children, since they must be new
if (new_children.size() > 1)
@ -354,36 +352,29 @@ private:
CHECK_AND_ASSERT_THROW_MES(!children.hashes.empty(), "empty children hashes");
std::size_t offset = (last_parent_chunk_ptr == nullptr) ? 0 : last_parent_chunk_ptr->child_offset;
// TODO: try to simplify the approach to avoid edge cases
// If we're adding new children to an existing last chunk, then we need to pull the parent start idx back 1
// since we'll be updating the existing parent hash of the last chunk
if (offset > 0)
{
CHECK_AND_ASSERT_THROW_MES(parents_out.start_idx > 0, "parent start idx should be > 0");
--parents_out.start_idx;
}
// If the child layer had its existing last hash updated, then we'll need to use the last hash's prior
// version in order to update the existing last parent hash in this layer
// If the child layer had its existing last hash updated (if the new children start at the last element in
// the child layer), then we'll need to use the last hash's prior version in order to update the existing
// last parent hash in this layer
bool child_layer_last_hash_updated = (last_parent_chunk_ptr == nullptr)
? false
: last_parent_chunk_ptr->child_layer_size == (children.start_idx + 1);
if (offset == 0 && child_layer_last_hash_updated)
{
CHECK_AND_ASSERT_THROW_MES(parents_out.start_idx > 0, "parent start idx should be > 0");
--parents_out.start_idx;
}
std::size_t offset = (last_parent_chunk_ptr == nullptr) ? 0 : last_parent_chunk_ptr->child_offset;
// TODO: clean this up so I don't have to do it twice here and in get_first_non_leaf_parent
// The offset needs to be brought back because we're going to start with the prior hash, and so the chunk
// will start from there and may need 1 more to fill
CHECK_AND_ASSERT_THROW_MES(chunk_width > offset, "unexpected offset");
if (child_layer_last_hash_updated)
offset = offset > 0 ? (offset - 1) : (chunk_width - 1);
// If we're adding new children to an existing last chunk, then we need to pull the parent start idx back 1
// since we'll be updating the existing parent hash of the last chunk
if (offset > 0 || child_layer_last_hash_updated)
{
CHECK_AND_ASSERT_THROW_MES(parents_out.start_idx > 0, "parent start idx should be > 0");
--parents_out.start_idx;
}
// If we're creating a *new* root at the existing root layer, we may need to include the *existing* root when
// hashing the *existing* root layer
std::vector<typename C_PARENT::Scalar> child_scalars;
@ -418,7 +409,12 @@ private:
// Hash the chunk of children
typename C_PARENT::Point chunk_hash = chunk_start_idx == 0
? get_first_non_leaf_parent<C_PARENT>(c_parent, chunk, chunk_width, child_layer_last_hash_updated, last_parent_chunk_ptr)
? get_first_non_leaf_parent<C_PARENT>(c_parent,
chunk,
chunk_width,
child_layer_last_hash_updated,
last_parent_chunk_ptr,
offset)
: get_new_parent<C_PARENT>(c_parent, chunk);
MDEBUG("Hash chunk_start_idx " << chunk_start_idx << " result: " << c_parent.to_string(chunk_hash)
@ -451,9 +447,6 @@ private:
if (leaves.tuples.empty())
return;
// Flatten leaves [(O.x, I.x, C.x),(O.x, I.x, C.x),...] -> [scalar, scalar, scalar, scalar, scalar, scalar,...]
const std::vector<typename C2::Scalar> children = flatten_leaves(leaves.tuples);
const std::size_t max_chunk_size = m_leaf_layer_chunk_width;
const std::size_t offset = (last_chunk_ptr == nullptr) ? 0 : last_chunk_ptr->child_offset;
@ -465,6 +458,9 @@ private:
--parents_out.start_idx;
}
// Flatten leaves [(O.x, I.x, C.x),(O.x, I.x, C.x),...] -> [scalar, scalar, scalar, scalar, scalar, scalar,...]
const std::vector<typename C2::Scalar> children = flatten_leaves(leaves.tuples);
// See how many new children are needed to fill up the existing last chunk
CHECK_AND_ASSERT_THROW_MES(max_chunk_size > offset, "unexpected offset");
std::size_t chunk_size = std::min(children.size(), max_chunk_size - offset);