trie

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 Go to latest Published: Sep 7, 2021 License: GPL-3.0 Imports: 25 Imported by: 0

Documentation

Overview

Package trie implements Merkle Patricia Tries.

Index

Constants

This section is empty.

Variables

View Source 
var ErrAlreadyProcessed = errors.New("already processed")

ErrAlreadyProcessed is returned by the trie sync when it's requested to process a node it already processed previously.

View Source 
var ErrCommitDisabled = errors.New("no database for committing")
View Source 
var ErrNotRequested = errors.New("not requested")

ErrNotRequested is returned by the trie sync when it's requested to process a node it did not request.

Functions

func VerifyProof 

func VerifyProof(rootHash common.Hash, key []byte, proofDb mpcdb.KeyValueReader) (value []byte, 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.

func VerifyRangeProof 

func VerifyRangeProof(rootHash common.Hash, firstKey []byte, lastKey []byte, keys [][]byte, values [][]byte, proof mpcdb.KeyValueReader) (error, bool)

VerifyRangeProof checks whether the given leaf nodes and edge proof can prove the given trie leaves range is matched with the specific root. Besides, the range should be consecutive(no gap inside) and monotonic increasing.

Note the given proof actually contains two edge proofs. Both of them can be non-existent proofs. For example the first proof is for a non-existent key 0x03, the last proof is for a non-existent key 0x10. The given batch leaves are [0x04, 0x05, .. 0x09]. It's still feasible to prove the given batch is valid.

The firstKey is paired with firstProof, not necessarily the same as keys[0] (unless firstProof is an existent proof). Similarly, lastKey and lastProof are paired.

Expect the normal case, this function can also be used to verify the following range proofs:

  • All elements proof. In this case the proof can be nil, but the range should be all the leaves in the trie.
  • One element proof. In this case no matter the edge proof is a non-existent proof or not, we can always verify the correctness of the proof.
  • Zero element proof. In this case a single non-existent proof is enough to prove. Besides, if there are still some other leaves available on the right side, then an error will be returned.

Except returning the error to indicate the proof is valid or not, the function will also return a flag to indicate whether there exists more accounts/slots in the trie.

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.

Note, the trie Database is **not** thread safe in its mutations, but it **is** thread safe in providing individual, independent node access. The rationale behind this split design is to provide read access to RPC handlers and sync servers even while the trie is executing expensive garbage collection.

func NewDatabase 

func NewDatabase(diskdb mpcdb.KeyValueStore) *Database

NewDatabase creates a new trie database to store ephemeral trie content before its written out to disk or garbage collected. No read cache is created, so all data retrievals will hit the underlying disk database.

func NewDatabaseWithCache 

func NewDatabaseWithCache(diskdb mpcdb.KeyValueStore, cache int, journal string) *Database

NewDatabaseWithCache creates a new trie database to store ephemeral trie content before its written out to disk or garbage collected. It also acts as a read cache for nodes loaded from disk.

func (*Database) Cap 

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

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

Note, this method is a non-synchronized mutator. It is unsafe to call this concurrently with other mutators.

func (*Database) Commit 

func (db *Database) Commit(node common.Hash, report bool, callback func(common.Hash)) 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.

Note, this method is a non-synchronized mutator. It is unsafe to call this concurrently with other mutators.

func (*Database) Dereference 

func (db *Database) Dereference(root common.Hash)

Dereference removes an existing reference from a root node.

func (*Database) DiskDB 

func (db *Database) DiskDB() mpcdb.KeyValueStore

DiskDB retrieves the persistent storage backing the trie database.

func (*Database) Node 

func (db *Database) Node(hash common.Hash) ([]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() []common.Hash

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 common.Hash, parent common.Hash)

Reference adds a new reference from a parent node to a child node. This function is used to add reference between internal trie node and external node(e.g. storage trie root), all internal trie nodes are referenced together by database itself.

func (*Database) SaveCache 

func (db *Database) SaveCache(dir string) error

SaveCache atomically saves fast cache data to the given dir using all available CPU cores.

func (*Database) SaveCachePeriodically 

func (db *Database) SaveCachePeriodically(dir string, interval time.Duration, stopCh <-chan struct{})

SaveCachePeriodically atomically saves fast cache data to the given dir with the specified interval. All dump operation will only use a single CPU core.

func (*Database) Size 

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

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

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. Note that the value returned by the iterator is raw. If the content is encoded (e.g. storage value is RLP-encoded), it's caller's duty to decode it.

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(path []byte, leaf []byte, parent common.Hash) 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 common.Hash // 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() common.Hash

	// 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() common.Hash

	// 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 common.Hash, db *Database) (*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 common.Hash, 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() common.Hash

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 mpcdb.KeyValueWriter) 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) 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) TryGetNode 

func (t *SecureTrie) TryGetNode(path []byte) ([]byte, int, error)

TryGetNode attempts to retrieve a trie node by compact-encoded path. It is not possible to use keybyte-encoding as the path might contain odd nibbles.

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 StackTrie 

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

StackTrie is a trie implementation that expects keys to be inserted in order. Once it determines that a subtree will no longer be inserted into, it will hash it and free up the memory it uses.

func NewStackTrie 

func NewStackTrie(db mpcdb.KeyValueStore) *StackTrie

NewStackTrie allocates and initializes an empty trie.

func (*StackTrie) Commit 

func (st *StackTrie) Commit() (common.Hash, error)

Commit will firstly hash the entrie trie if it's still not hashed and then commit all nodes to the associated database. Actually most of the trie nodes MAY have been committed already. The main purpose here is to commit the root node.

The associated database is expected, otherwise the whole commit functionality should be disabled.

func (*StackTrie) Hash 

func (st *StackTrie) Hash() (h common.Hash)

Hash returns the hash of the current node

func (*StackTrie) Reset 

func (st *StackTrie) Reset()

func (*StackTrie) TryUpdate 

func (st *StackTrie) TryUpdate(key, value []byte) error

TryUpdate inserts a (key, value) pair into the stack trie

func (*StackTrie) Update 

func (st *StackTrie) Update(key, value []byte)

type Sync 

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

Sync is the main state trie synchronisation scheduler, which provides yet unknown trie hashes to retrieve, accepts node data associated with said hashes and reconstructs the trie step by step until all is done.

func NewSync 

func NewSync(root common.Hash, database mpcdb.KeyValueReader, callback LeafCallback, bloom *SyncBloom) *Sync

NewSync creates a new trie data download scheduler.

func (*Sync) AddCodeEntry 

func (s *Sync) AddCodeEntry(hash common.Hash, path []byte, parent common.Hash)

AddCodeEntry schedules the direct retrieval of a contract code that should not be interpreted as a trie node, but rather accepted and stored into the database as is.

func (*Sync) AddSubTrie 

func (s *Sync) AddSubTrie(root common.Hash, path []byte, parent common.Hash, callback LeafCallback)

AddSubTrie registers a new trie to the sync code, rooted at the designated parent.

func (*Sync) Commit 

func (s *Sync) Commit(dbw mpcdb.Batch) error

Commit flushes the data stored in the internal membatch out to persistent storage, returning any occurred error.

func (*Sync) Missing 

func (s *Sync) Missing(max int) (nodes []common.Hash, paths []SyncPath, codes []common.Hash)

Missing retrieves the known missing nodes from the trie for retrieval. To aid both eth/6x style fast sync and snap/1x style state sync, the paths of trie nodes are returned too, as well as separate hash list for codes.

func (*Sync) Pending 

func (s *Sync) Pending() int

Pending returns the number of state entries currently pending for download.

func (*Sync) Process 

func (s *Sync) Process(result SyncResult) error

Process injects the received data for requested item. Note it can happpen that the single response commits two pending requests(e.g. there are two requests one for code and one for node but the hash is same). In this case the second response for the same hash will be treated as "non-requested" item or "already-processed" item but there is no downside.

type SyncBloom 

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

SyncBloom is a bloom filter used during fast sync to quickly decide if a trie node or contract code already exists on disk or not. It self populates from the provided disk database on creation in a background thread and will only start returning live results once that's finished.

func NewSyncBloom 

func NewSyncBloom(memory uint64, database mpcdb.Iteratee) *SyncBloom

NewSyncBloom creates a new bloom filter of the given size (in megabytes) and initializes it from the database. The bloom is hard coded to use 3 filters.

func (*SyncBloom) Add 

func (b *SyncBloom) Add(hash []byte)

Add inserts a new trie node hash into the bloom filter.

func (*SyncBloom) Close 

func (b *SyncBloom) Close() error

Close terminates any background initializer still running and releases all the memory allocated for the bloom.

func (*SyncBloom) Contains 

func (b *SyncBloom) Contains(hash []byte) bool

Contains tests if the bloom filter contains the given hash:

  • false: the bloom definitely does not contain hash
  • true: the bloom maybe contains hash

While the bloom is being initialized, any query will return true.

type SyncPath 

type SyncPath [][]byte

SyncPath is a path tuple identifying a particular trie node either in a single trie (account) or a layered trie (account -> storage).

Content wise the tuple either has 1 element if it addresses a node in a single trie or 2 elements if it addresses a node in a stacked trie.

To support aiming arbitrary trie nodes, the path needs to support odd nibble lengths. To avoid transferring expanded hex form over the network, the last part of the tuple (which needs to index into the middle of a trie) is compact encoded. In case of a 2-tuple, the first item is always 32 bytes so that is simple binary encoded.

Examples:

  • Path 0x9 -> {0x19}
  • Path 0x99 -> {0x0099}
  • Path 0x01234567890123456789012345678901012345678901234567890123456789019 -> {0x0123456789012345678901234567890101234567890123456789012345678901, 0x19}
  • Path 0x012345678901234567890123456789010123456789012345678901234567890199 -> {0x0123456789012345678901234567890101234567890123456789012345678901, 0x0099}

type SyncResult 

type SyncResult struct {
	Hash common.Hash // Hash of the originally unknown trie node
	Data []byte      // Data content of the retrieved node
}

SyncResult is a response with requested data along with it's hash.

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 common.Hash, 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 common.Hash, 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() common.Hash

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 mpcdb.KeyValueWriter) 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) Reset 

func (t *Trie) Reset()

Reset drops the referenced root node and cleans all internal state.

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) TryGetNode 

func (t *Trie) TryGetNode(path []byte) ([]byte, int, error)

TryGetNode attempts to retrieve a trie node by compact-encoded path. It is not possible to use keybyte-encoding as the path might contain odd nibbles.

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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