proof_gen_and_tree_build.go

// MIT License
//
// Copyright (c) 2023 Tommy TIAN
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package merkletree

import "sync"

func (m *MerkleTree) proofGenAndTreeBuild() error {
	if err := m.treeBuild(); err != nil {
		return err
	}

	m.computeAllProofsFromTree()

	return nil
}

func (m *MerkleTree) proofGenAndTreeBuildParallel() error {
	if err := m.treeBuildParallel(); err != nil {
		return err
	}

	m.computeAllProofsFromTreeParallel()

	return nil
}

func (m *MerkleTree) computeAllProofsFromTree() {
	m.initProofs()

	for step := 0; step < len(m.nodes); step++ {
		var (
			batch    = 1 << step
			nodeSize = len(m.nodes[step])
		)

		for nodeIdx := 0; nodeIdx < nodeSize; nodeIdx += 2 {
			updateProofInTwoBatchesFromTree(m.Proofs, m.nodes[step], nodeIdx, batch, step)
		}
	}
}

func (m *MerkleTree) computeAllProofsFromTreeParallel() {
	m.initProofs()

	for step := 0; step < len(m.nodes); step++ {
		var (
			batch    = 1 << step
			nodeSize = len(m.nodes[step])
			wg       = new(sync.WaitGroup)
		)
		// Limit the number of workers to the previous level length.
		numRoutines := min(m.NumRoutines, nodeSize)
		wg.Add(numRoutines)

		for startIdx := 0; startIdx < numRoutines; startIdx++ {
			go func(startIdx int) {
				defer wg.Done()

				for nodeIdx := startIdx; nodeIdx < nodeSize; nodeIdx += numRoutines << 1 {
					updateProofInTwoBatchesFromTree(m.Proofs, m.nodes[step], nodeIdx, batch, step)
				}
			}(startIdx << 1)
		}
		wg.Wait()
	}
}

func updateProofInTwoBatchesFromTree(proofs []*Proof, buffer [][]byte, idx, batch, step int) {
	start := idx * batch
	end := min(start+batch, len(proofs))

	for i := start; i < end; i++ {
		proofs[i].Path += 1 << step
		proofs[i].Siblings = append(proofs[i].Siblings, buffer[idx+1])
	}

	start += batch
	end = min(start+batch, len(proofs))

	for i := start; i < end; i++ {
		proofs[i].Siblings = append(proofs[i].Siblings, buffer[idx])
	}
}