trie

package
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 Go to latest Published: Jan 12, 2022 License: MIT Imports: 16 Imported by: 0

Documentation

Overview

Package trie implements Merkle Patricia Tries.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func CopyBytes 

func CopyBytes(b []byte) (copiedBytes []byte)

CopyBytes returns an exact copy of the provided bytes.

func VerifyProof 

func VerifyProof(rootHash types.Hash32, key []byte, proofDb DatabaseReader) (value []byte, nodes int, err error)

VerifyProof checks merkle proofs. The given proof must contain the value for key in a trie with the given root hash. VerifyProof returns an error if the proof contains invalid trie nodes or the wrong value.

Types

type Database 

type Database struct {
	// contains filtered or unexported fields
}

Database is an intermediate write layer between the trie data structures and the disk database. The aim is to accumulate trie writes in-memory and only periodically flush a couple tries to disk, garbage collecting the remainder.

func NewDatabase 

func NewDatabase(diskdb database.Database) *Database

NewDatabase creates a new trie database to store ephemeral trie content before its written out to disk or garbage collected.

func (*Database) Cap 

func (db *Database) Cap(limit types.StorageSize) error

Cap iteratively flushes old but still referenced trie nodes until the total memory usage goes below the given threshold.

func (*Database) Commit 

func (db *Database) Commit(node types.Hash32, report bool) error

Commit iterates over all the children of a particular node, writes them out to disk, forcefully tearing down all references in both directions.

As a side effect, all pre-images accumulated up to this point are also written.

func (*Database) Dereference 

func (db *Database) Dereference(root types.Hash32)

Dereference removes an existing reference from a root node.

func (*Database) DiskDB 

func (db *Database) DiskDB() DatabaseReader

DiskDB retrieves the persistent storage backing the trie database.

func (*Database) InsertBlob 

func (db *Database) InsertBlob(hash types.Hash32, blob []byte)

InsertBlob writes a new reference tracked blob to the memory database if it's yet unknown. This method should only be used for non-trie nodes that require reference counting, since trie nodes are garbage collected directly through their embedded children.

func (*Database) Node 

func (db *Database) Node(hash types.Hash32) ([]byte, error)

Node retrieves an encoded cached trie node from memory. If it cannot be found cached, the method queries the persistent database for the content.

func (*Database) Nodes 

func (db *Database) Nodes() []types.Hash32

Nodes retrieves the hashes of all the nodes cached within the memory database. This method is extremely expensive and should only be used to validate internal states in test code.

func (*Database) Reference 

func (db *Database) Reference(child types.Hash32, parent types.Hash32)

Reference adds a new reference from a parent node to a child node.

func (*Database) Size 

func (db *Database) Size() (types.StorageSize, types.StorageSize)

Size returns the current storage size of the memory cache in front of the persistent database layer.

type DatabaseReader 

type DatabaseReader interface {
	// Get retrieves the value associated with key from the database.
	Get(key []byte) (value []byte, err error)

	// Has retrieves whether a key is present in the database.
	Has(key []byte) (bool, error)
}

DatabaseReader wraps the Get and Has method of a backing store for the trie.

type Iterator 

type Iterator struct {
	Key   []byte // Current data key on which the iterator is positioned on
	Value []byte // Current data value on which the iterator is positioned on
	Err   error
	// contains filtered or unexported fields
}

Iterator is a key-value trie iterator that traverses a Trie.

func NewIterator 

func NewIterator(it NodeIterator) *Iterator

NewIterator creates a new key-value iterator from a node iterator.

func (*Iterator) Next 

func (it *Iterator) Next() bool

Next moves the iterator forward one key-value entry.

func (*Iterator) Prove 

func (it *Iterator) Prove() [][]byte

Prove generates the Merkle proof for the leaf node the iterator is currently positioned on.

type LeafCallback 

type LeafCallback func(leaf []byte, parent types.Hash32) error

LeafCallback is a callback type invoked when a trie operation reaches a leaf node. It's used by state sync and commit to allow handling external references between account and storage tries.

type MissingNodeError 

type MissingNodeError struct {
	NodeHash types.Hash32 // hash of the missing node
	Path     []byte       // hex-encoded path to the missing node
}

MissingNodeError is returned by the trie functions (TryGet, TryUpdate, TryDelete) in the case where a trie node is not present in the local database. It contains information necessary for retrieving the missing node.

func (*MissingNodeError) Error 

func (err *MissingNodeError) Error() string

type NodeIterator 

type NodeIterator interface {
	// Next moves the iterator to the next node. If the parameter is false, any child
	// nodes will be skipped.
	Next(bool) bool

	// Error returns the error status of the iterator.
	Error() error

	// Hash returns the hash of the current node.
	Hash() types.Hash32

	// Parent returns the hash of the parent of the current node. The hash may be the one
	// grandparent if the immediate parent is an internal node with no hash.
	Parent() types.Hash32

	// Path returns the hex-encoded path to the current node.
	// Callers must not retain references to the return value after calling Next.
	// For leaf nodes, the last element of the path is the 'terminator symbol' 0x10.
	Path() []byte

	// Leaf returns true iff the current node is a leaf node.
	Leaf() bool

	// LeafKey returns the key of the leaf. The method panics if the iterator is not
	// positioned at a leaf. Callers must not retain references to the value after
	// calling Next.
	LeafKey() []byte

	// LeafBlob returns the content of the leaf. The method panics if the iterator
	// is not positioned at a leaf. Callers must not retain references to the value
	// after calling Next.
	LeafBlob() []byte

	// LeafProof returns the Merkle proof of the leaf. The method panics if the
	// iterator is not positioned at a leaf. Callers must not retain references
	// to the value after calling Next.
	LeafProof() [][]byte
}

NodeIterator is an iterator to traverse the trie pre-order.

func NewDifferenceIterator 

func NewDifferenceIterator(a, b NodeIterator) (NodeIterator, *int)

NewDifferenceIterator constructs a NodeIterator that iterates over elements in b that are not in a. Returns the iterator, and a pointer to an integer recording the number of nodes seen.

func NewUnionIterator 

func NewUnionIterator(iters []NodeIterator) (NodeIterator, *int)

NewUnionIterator constructs a NodeIterator that iterates over elements in the union of the provided NodeIterators. Returns the iterator, and a pointer to an integer recording the number of nodes visited.

type SecureTrie 

type SecureTrie struct {
	// contains filtered or unexported fields
}

SecureTrie wraps a trie with key hashing. In a secure trie, all access operations hash the key using keccak256. This prevents calling code from creating long chains of nodes that increase the access time.

Contrary to a regular trie, a SecureTrie can only be created with New and must have an attached database. The database also stores the preimage of each key.

SecureTrie is not safe for concurrent use.

func NewSecure 

func NewSecure(root types.Hash32, db *Database, cachelimit uint16) (*SecureTrie, error)

NewSecure creates a trie with an existing root node from a backing database and optional intermediate in-memory node pool.

If root is the zero hash or the sha3 hash of an empty string, the trie is initially empty. Otherwise, New will panic if db is nil and returns MissingNodeError if the root node cannot be found.

Accessing the trie loads nodes from the database or node pool on demand. Loaded nodes are kept around until their 'cache generation' expires. A new cache generation is created by each call to Commit. cachelimit sets the number of past cache generations to keep.

func (*SecureTrie) Commit 

func (t *SecureTrie) Commit(onleaf LeafCallback) (root types.Hash32, err error)

Commit writes all nodes and the secure hash pre-images to the trie's database. Nodes are stored with their sha3 hash as the key.

Committing flushes nodes from memory. Subsequent Get calls will load nodes from the database.

func (*SecureTrie) Copy 

func (t *SecureTrie) Copy() *SecureTrie

Copy returns a copy of SecureTrie.

func (*SecureTrie) Delete 

func (t *SecureTrie) Delete(key []byte)

Delete removes any existing value for key from the trie.

func (*SecureTrie) Get 

func (t *SecureTrie) Get(key []byte) []byte

Get returns the value for key stored in the trie. The value bytes must not be modified by the caller.

func (*SecureTrie) GetKey 

func (t *SecureTrie) GetKey(shaKey []byte) []byte

GetKey returns the sha3 preimage of a hashed key that was previously used to store a value.

func (*SecureTrie) Hash 

func (t *SecureTrie) Hash() types.Hash32

Hash returns the root hash of SecureTrie. It does not write to the database and can be used even if the trie doesn't have one.

func (*SecureTrie) NodeIterator 

func (t *SecureTrie) NodeIterator(start []byte) NodeIterator

NodeIterator returns an iterator that returns nodes of the underlying trie. Iteration starts at the key after the given start key.

func (*SecureTrie) Prove 

func (t *SecureTrie) Prove(key []byte, fromLevel uint, proofDb database.Putter) error

Prove constructs a merkle proof for key. The result contains all encoded nodes on the path to the value at key. The value itself is also included in the last node and can be retrieved by verifying the proof.

If the trie does not contain a value for key, the returned proof contains all nodes of the longest existing prefix of the key (at least the root node), ending with the node that proves the absence of the key.

func (*SecureTrie) Root 

func (t *SecureTrie) Root() []byte

Root returns the root hash of SecureTrie. Deprecated: use Hash instead.

func (*SecureTrie) TryDelete 

func (t *SecureTrie) TryDelete(key []byte) error

TryDelete removes any existing value for key from the trie. If a node was not found in the database, a MissingNodeError is returned.

func (*SecureTrie) TryGet 

func (t *SecureTrie) TryGet(key []byte) ([]byte, error)

TryGet returns the value for key stored in the trie. The value bytes must not be modified by the caller. If a node was not found in the database, a MissingNodeError is returned.

func (*SecureTrie) TryUpdate 

func (t *SecureTrie) TryUpdate(key, value []byte) error

TryUpdate associates key with value in the trie. Subsequent calls to Get will return value. If value has length zero, any existing value is deleted from the trie and calls to Get will return nil.

The value bytes must not be modified by the caller while they are stored in the trie.

If a node was not found in the database, a MissingNodeError is returned.

func (*SecureTrie) Update 

func (t *SecureTrie) Update(key, value []byte)

Update associates key with value in the trie. Subsequent calls to Get will return value. If value has length zero, any existing value is deleted from the trie and calls to Get will return nil.

The value bytes must not be modified by the caller while they are stored in the trie.

type Trie 

type Trie struct {
	// contains filtered or unexported fields
}

Trie is a Merkle Patricia Trie. The zero value is an empty trie with no database. Use New to create a trie that sits on top of a database.

Trie is not safe for concurrent use.

func New 

func New(root types.Hash32, db *Database) (*Trie, error)

New creates a trie with an existing root node from db.

If root is the zero hash or the sha3 hash of an empty string, the trie is initially empty and does not require a database. Otherwise, New will panic if db is nil and returns a MissingNodeError if root does not exist in the database. Accessing the trie loads nodes from db on demand.

func (*Trie) Commit 

func (t *Trie) Commit(onleaf LeafCallback) (root types.Hash32, err error)

Commit writes all nodes to the trie's memory database, tracking the internal and external (for account tries) references.

func (*Trie) Delete 

func (t *Trie) Delete(key []byte)

Delete removes any existing value for key from the trie.

func (*Trie) Get 

func (t *Trie) Get(key []byte) []byte

Get returns the value for key stored in the trie. The value bytes must not be modified by the caller.

func (*Trie) Hash 

func (t *Trie) Hash() types.Hash32

Hash returns the root hash of the trie. It does not write to the database and can be used even if the trie doesn't have one.

func (*Trie) NodeIterator 

func (t *Trie) NodeIterator(start []byte) NodeIterator

NodeIterator returns an iterator that returns nodes of the trie. Iteration starts at the key after the given start key.

func (*Trie) Prove 

func (t *Trie) Prove(key []byte, fromLevel uint, proofDb database.Putter) error

Prove constructs a merkle proof for key. The result contains all encoded nodes on the path to the value at key. The value itself is also included in the last node and can be retrieved by verifying the proof.

If the trie does not contain a value for key, the returned proof contains all nodes of the longest existing prefix of the key (at least the root node), ending with the node that proves the absence of the key.

func (*Trie) Root 

func (t *Trie) Root() []byte

Root returns the root hash of the trie. Deprecated: use Hash instead.

func (*Trie) SetCacheLimit 

func (t *Trie) SetCacheLimit(l uint16)

SetCacheLimit sets the number of 'cache generations' to keep. A cache generation is created by a call to Commit.

func (*Trie) TryDelete 

func (t *Trie) TryDelete(key []byte) error

TryDelete removes any existing value for key from the trie. If a node was not found in the database, a MissingNodeError is returned.

func (*Trie) TryGet 

func (t *Trie) TryGet(key []byte) ([]byte, error)

TryGet returns the value for key stored in the trie. The value bytes must not be modified by the caller. If a node was not found in the database, a MissingNodeError is returned.

func (*Trie) TryUpdate 

func (t *Trie) TryUpdate(key, value []byte) error

TryUpdate associates key with value in the trie. Subsequent calls to Get will return value. If value has length zero, any existing value is deleted from the trie and calls to Get will return nil.

The value bytes must not be modified by the caller while they are stored in the trie.

If a node was not found in the database, a MissingNodeError is returned.

func (*Trie) Update 

func (t *Trie) Update(key, value []byte)

Update associates key with value in the trie. Subsequent calls to Get will return value. If value has length zero, any existing value is deleted from the trie and calls to Get will return nil.

The value bytes must not be modified by the caller while they are stored in the trie.

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