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trieDB

triedb is a library that acts as a layer over a key-value database, formatting those data into a radix-16 trie compatible with polkadot spec.
It offers functionalities for writing and reading operations and uses lazy loading to fetch data from the database, as well as a caching system to optimize searches.

Main features

  • Writes: Basic functions to manipulate data in the trie.
  • Reads: Basic functions to get data from the trie.
  • Lazy Loading: Load data on demand.
  • Caching: Enhances search performance.
  • Compatibility: Works with any database implementing the hashdb.HashDB interface and any cache implementing the TrieCache interface.
  • Merkle proofs: Create and verify merkle proofs.
  • Iterator: Traverse the trie keys in order.

Usage

Create a Trie

To create an empty trie:

trie := triedb.NewEmptyTrieDB(db)

Insert Data

To insert a key and its associated value:

err := trie.Set([]byte("key"), []byte("value"))

Get Data

To get the value associated with a key:

value := trie.Get([]byte("key"))

Note: value will be empty []byte() if there is no value for that key in the DB

Remove Data

To delete a key and its associated value:

trie.Delete([]byte("key"))

Commit Data

All modifications happen in memory until a commit is applied to the database. The commit is automatically applied whenever the root hash of the trie is calculated using:

rootHash, err := trie.Hash()
if err != nil {
    // handle error
}

or

rootHash := trie.MustHash()

Create a merkle proof

To create a merkle proof you will need a db previously created using a trie, the trieVersion (v0, v1), the rootHash for the trie in that db and an slice of keys for which the proof will be created.

merkleProof, err := proof.NewMerkleProof(db, trieVersion, rootHash, keys)

Verify merkle proofs

In order to verify a merkle proof you can execute the Verify method over a previously created proof specifying the trieVersion, rootHash and the items you want to check, doing the following:

err = merkleProof.Verify(trieVersion, rootHash, items)
if err != nil {
    fmt.Println("Invalid proof")
}

Note: items is a slice of proofItem structure.

Iterator

There are two ways to use the key iterator. Iterating by keys

trieIterator := triedb.NewTrieDBIterator(trie)

for key := iter.NextKey(); key != nil; key = iter.NextKey() {
    fmt.Printf("key: %s", key)
}

Iterating by entries

trieIterator := triedb.NewTrieDBIterator(trie)

for entry := iter.NextEntry(); entry != nil; entry = iter.NextEntry() {
    fmt.Printf("key: %s, value: %s", entry.Key, entry.Value)
}