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    merkle-patricia-tree
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    4.2.0 • Public • Published

    merkle-patricia-tree

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    This is an implementation of the modified merkle patricia tree as specified in the Ethereum Yellow Paper:

    The modified Merkle Patricia tree (trie) provides a persistent data structure to map between arbitrary-length binary data (byte arrays). It is defined in terms of a mutable data structure to map between 256-bit binary fragments and arbitrary-length binary data. The core of the trie, and its sole requirement in terms of the protocol specification is to provide a single 32-byte value that identifies a given set of key-value pairs.

    The only backing store supported is LevelDB through the levelup module.

    INSTALL

    npm install merkle-patricia-tree

    USAGE

    There are 3 variants of the tree implemented in this library, namely: BaseTrie, CheckpointTrie and SecureTrie. CheckpointTrie adds checkpointing functionality to the BaseTrie with the methods checkpoint, commit and revert. SecureTrie extends CheckpointTrie and is the most suitable variant for Ethereum applications. It stores values under the keccak256 hash of their keys.

    By default trie nodes are not deleted from the underlying DB to not corrupt older trie states (as of v4.2.0). If you are only interested in the latest state of a trie you can switch to a delete behavior (e.g. if you want to save disk space) by using the deleteFromDB constructor option (see related release notes in the changelog for more details).

    Initialization and Basic Usage

    import level from 'level'
    import { BaseTrie as Trie } from 'merkle-patricia-tree'
    
    const db = level('./testdb')
    const trie = new Trie(db)
    
    async function test() {
      await trie.put(Buffer.from('test'), Buffer.from('one'))
      const value = await trie.get(Buffer.from('test'))
      console.log(value.toString()) // 'one'
    }
    
    test()

    Merkle Proofs

    const trie = new Trie()
    
    async function test() {
      await trie.put(Buffer.from('test'), Buffer.from('one'))
      const proof = await Trie.createProof(trie, Buffer.from('test'))
      const value = await Trie.verifyProof(trie.root, Buffer.from('test'), proof)
      console.log(value.toString()) // 'one'
    }
    
    test()

    Read stream on Geth DB

    import level from 'level'
    import { SecureTrie as Trie } from 'merkle-patricia-tree'
    
    const db = level('YOUR_PATH_TO_THE_GETH_CHAIN_DB')
    // Set stateRoot to block #222
    const stateRoot = '0xd7f8974fb5ac78d9ac099b9ad5018bedc2ce0a72dad1827a1709da30580f0544'
    // Convert the state root to a Buffer (strip the 0x prefix)
    const stateRootBuffer = Buffer.from(stateRoot.slice(2), 'hex')
    // Initialize trie
    const trie = new Trie(db, stateRootBuffer)
    
    trie
      .createReadStream()
      .on('data', console.log)
      .on('end', () => {
        console.log('End.')
      })

    Read Account State including Storage from Geth DB

    import level from 'level'
    import rlp from 'rlp'
    import { BN, bufferToHex } from 'ethereumjs-util'
    import Account from 'ethereumjs-account'
    import { SecureTrie as Trie } from 'merkle-patricia-tree'
    
    const stateRoot = 'STATE_ROOT_OF_A_BLOCK'
    
    const db = level('YOUR_PATH_TO_THE_GETH_CHAINDATA_FOLDER')
    const trie = new Trie(db, stateRoot)
    
    const address = 'AN_ETHEREUM_ACCOUNT_ADDRESS'
    
    async function test() {
      const data = await trie.get(address)
      const acc = new Account(data)
    
      console.log('-------State-------')
      console.log(`nonce: ${new BN(acc.nonce)}`)
      console.log(`balance in wei: ${new BN(acc.balance)}`)
      console.log(`storageRoot: ${bufferToHex(acc.stateRoot)}`)
      console.log(`codeHash: ${bufferToHex(acc.codeHash)}`)
    
      let storageTrie = trie.copy()
      storageTrie.root = acc.stateRoot
    
      console.log('------Storage------')
      const stream = storageTrie.createReadStream()
      stream
        .on('data', (data) => {
          console.log(`key: ${bufferToHex(data.key)}`)
          console.log(`Value: ${bufferToHex(rlp.decode(data.value))}`)
        })
        .on('end', () => {
          console.log('Finished reading storage.')
        })
    }
    
    test()

    Additional examples with detailed explanations are available here.

    API

    Documentation

    TESTING

    npm test

    BENCHMARKS

    There are two simple benchmarks in the benchmarks folder:

    • random.ts runs random PUT operations on the tree.
    • checkpointing.ts runs checkpoints and commits between PUT operations.

    A third benchmark using mainnet data to simulate real load is also under consideration.

    Benchmarks can be run with:

    npm run benchmarks

    To run a profiler on the random.ts benchmark and generate a flamegraph with 0x you can use:

    npm run profiling

    0x processes the stacks and generates a profile folder (<pid>.0x) containing flamegraph.html.

    REFERENCES

    EthereumJS

    See our organizational documentation for an introduction to EthereumJS as well as information on current standards and best practices.

    If you want to join for work or do improvements on the libraries have a look at our contribution guidelines.

    LICENSE

    MPL-2.0

    Install

    npm i merkle-patricia-tree

    DownloadsWeekly Downloads

    154,245

    Version

    4.2.0

    License

    MPL-2.0

    Unpacked Size

    300 kB

    Total Files

    75

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