lbcd/blockchain/indexers/txindex.go
Olaoluwa Osuntokun a26e2634fa
blockchain/indexers: update indexing to use stxos instead of utxo view for blocks
In this commit, we update all the indexers to use the stxo set for a
particular block rather than the utxo view for the block. We do this as
we can eliminate a large number of random reads for each block, and can
instead deserialize a single instance of all the outputs spent in that
block and feed in the prev input scripts to each indexer.
2018-05-30 20:47:40 -07:00

483 lines
16 KiB
Go

// Copyright (c) 2016 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package indexers
import (
"errors"
"fmt"
"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/database"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
)
const (
// txIndexName is the human-readable name for the index.
txIndexName = "transaction index"
)
var (
// txIndexKey is the key of the transaction index and the db bucket used
// to house it.
txIndexKey = []byte("txbyhashidx")
// idByHashIndexBucketName is the name of the db bucket used to house
// the block id -> block hash index.
idByHashIndexBucketName = []byte("idbyhashidx")
// hashByIDIndexBucketName is the name of the db bucket used to house
// the block hash -> block id index.
hashByIDIndexBucketName = []byte("hashbyididx")
// errNoBlockIDEntry is an error that indicates a requested entry does
// not exist in the block ID index.
errNoBlockIDEntry = errors.New("no entry in the block ID index")
)
// -----------------------------------------------------------------------------
// The transaction index consists of an entry for every transaction in the main
// chain. In order to significantly optimize the space requirements a separate
// index which provides an internal mapping between each block that has been
// indexed and a unique ID for use within the hash to location mappings. The ID
// is simply a sequentially incremented uint32. This is useful because it is
// only 4 bytes versus 32 bytes hashes and thus saves a ton of space in the
// index.
//
// There are three buckets used in total. The first bucket maps the hash of
// each transaction to the specific block location. The second bucket maps the
// hash of each block to the unique ID and the third maps that ID back to the
// block hash.
//
// NOTE: Although it is technically possible for multiple transactions to have
// the same hash as long as the previous transaction with the same hash is fully
// spent, this code only stores the most recent one because doing otherwise
// would add a non-trivial amount of space and overhead for something that will
// realistically never happen per the probability and even if it did, the old
// one must be fully spent and so the most likely transaction a caller would
// want for a given hash is the most recent one anyways.
//
// The serialized format for keys and values in the block hash to ID bucket is:
// <hash> = <ID>
//
// Field Type Size
// hash chainhash.Hash 32 bytes
// ID uint32 4 bytes
// -----
// Total: 36 bytes
//
// The serialized format for keys and values in the ID to block hash bucket is:
// <ID> = <hash>
//
// Field Type Size
// ID uint32 4 bytes
// hash chainhash.Hash 32 bytes
// -----
// Total: 36 bytes
//
// The serialized format for the keys and values in the tx index bucket is:
//
// <txhash> = <block id><start offset><tx length>
//
// Field Type Size
// txhash chainhash.Hash 32 bytes
// block id uint32 4 bytes
// start offset uint32 4 bytes
// tx length uint32 4 bytes
// -----
// Total: 44 bytes
// -----------------------------------------------------------------------------
// dbPutBlockIDIndexEntry uses an existing database transaction to update or add
// the index entries for the hash to id and id to hash mappings for the provided
// values.
func dbPutBlockIDIndexEntry(dbTx database.Tx, hash *chainhash.Hash, id uint32) error {
// Serialize the height for use in the index entries.
var serializedID [4]byte
byteOrder.PutUint32(serializedID[:], id)
// Add the block hash to ID mapping to the index.
meta := dbTx.Metadata()
hashIndex := meta.Bucket(idByHashIndexBucketName)
if err := hashIndex.Put(hash[:], serializedID[:]); err != nil {
return err
}
// Add the block ID to hash mapping to the index.
idIndex := meta.Bucket(hashByIDIndexBucketName)
return idIndex.Put(serializedID[:], hash[:])
}
// dbRemoveBlockIDIndexEntry uses an existing database transaction remove index
// entries from the hash to id and id to hash mappings for the provided hash.
func dbRemoveBlockIDIndexEntry(dbTx database.Tx, hash *chainhash.Hash) error {
// Remove the block hash to ID mapping.
meta := dbTx.Metadata()
hashIndex := meta.Bucket(idByHashIndexBucketName)
serializedID := hashIndex.Get(hash[:])
if serializedID == nil {
return nil
}
if err := hashIndex.Delete(hash[:]); err != nil {
return err
}
// Remove the block ID to hash mapping.
idIndex := meta.Bucket(hashByIDIndexBucketName)
return idIndex.Delete(serializedID)
}
// dbFetchBlockIDByHash uses an existing database transaction to retrieve the
// block id for the provided hash from the index.
func dbFetchBlockIDByHash(dbTx database.Tx, hash *chainhash.Hash) (uint32, error) {
hashIndex := dbTx.Metadata().Bucket(idByHashIndexBucketName)
serializedID := hashIndex.Get(hash[:])
if serializedID == nil {
return 0, errNoBlockIDEntry
}
return byteOrder.Uint32(serializedID), nil
}
// dbFetchBlockHashBySerializedID uses an existing database transaction to
// retrieve the hash for the provided serialized block id from the index.
func dbFetchBlockHashBySerializedID(dbTx database.Tx, serializedID []byte) (*chainhash.Hash, error) {
idIndex := dbTx.Metadata().Bucket(hashByIDIndexBucketName)
hashBytes := idIndex.Get(serializedID)
if hashBytes == nil {
return nil, errNoBlockIDEntry
}
var hash chainhash.Hash
copy(hash[:], hashBytes)
return &hash, nil
}
// dbFetchBlockHashByID uses an existing database transaction to retrieve the
// hash for the provided block id from the index.
func dbFetchBlockHashByID(dbTx database.Tx, id uint32) (*chainhash.Hash, error) {
var serializedID [4]byte
byteOrder.PutUint32(serializedID[:], id)
return dbFetchBlockHashBySerializedID(dbTx, serializedID[:])
}
// putTxIndexEntry serializes the provided values according to the format
// described about for a transaction index entry. The target byte slice must
// be at least large enough to handle the number of bytes defined by the
// txEntrySize constant or it will panic.
func putTxIndexEntry(target []byte, blockID uint32, txLoc wire.TxLoc) {
byteOrder.PutUint32(target, blockID)
byteOrder.PutUint32(target[4:], uint32(txLoc.TxStart))
byteOrder.PutUint32(target[8:], uint32(txLoc.TxLen))
}
// dbPutTxIndexEntry uses an existing database transaction to update the
// transaction index given the provided serialized data that is expected to have
// been serialized putTxIndexEntry.
func dbPutTxIndexEntry(dbTx database.Tx, txHash *chainhash.Hash, serializedData []byte) error {
txIndex := dbTx.Metadata().Bucket(txIndexKey)
return txIndex.Put(txHash[:], serializedData)
}
// dbFetchTxIndexEntry uses an existing database transaction to fetch the block
// region for the provided transaction hash from the transaction index. When
// there is no entry for the provided hash, nil will be returned for the both
// the region and the error.
func dbFetchTxIndexEntry(dbTx database.Tx, txHash *chainhash.Hash) (*database.BlockRegion, error) {
// Load the record from the database and return now if it doesn't exist.
txIndex := dbTx.Metadata().Bucket(txIndexKey)
serializedData := txIndex.Get(txHash[:])
if len(serializedData) == 0 {
return nil, nil
}
// Ensure the serialized data has enough bytes to properly deserialize.
if len(serializedData) < 12 {
return nil, database.Error{
ErrorCode: database.ErrCorruption,
Description: fmt.Sprintf("corrupt transaction index "+
"entry for %s", txHash),
}
}
// Load the block hash associated with the block ID.
hash, err := dbFetchBlockHashBySerializedID(dbTx, serializedData[0:4])
if err != nil {
return nil, database.Error{
ErrorCode: database.ErrCorruption,
Description: fmt.Sprintf("corrupt transaction index "+
"entry for %s: %v", txHash, err),
}
}
// Deserialize the final entry.
region := database.BlockRegion{Hash: &chainhash.Hash{}}
copy(region.Hash[:], hash[:])
region.Offset = byteOrder.Uint32(serializedData[4:8])
region.Len = byteOrder.Uint32(serializedData[8:12])
return &region, nil
}
// dbAddTxIndexEntries uses an existing database transaction to add a
// transaction index entry for every transaction in the passed block.
func dbAddTxIndexEntries(dbTx database.Tx, block *btcutil.Block, blockID uint32) error {
// The offset and length of the transactions within the serialized
// block.
txLocs, err := block.TxLoc()
if err != nil {
return err
}
// As an optimization, allocate a single slice big enough to hold all
// of the serialized transaction index entries for the block and
// serialize them directly into the slice. Then, pass the appropriate
// subslice to the database to be written. This approach significantly
// cuts down on the number of required allocations.
offset := 0
serializedValues := make([]byte, len(block.Transactions())*txEntrySize)
for i, tx := range block.Transactions() {
putTxIndexEntry(serializedValues[offset:], blockID, txLocs[i])
endOffset := offset + txEntrySize
err := dbPutTxIndexEntry(dbTx, tx.Hash(),
serializedValues[offset:endOffset:endOffset])
if err != nil {
return err
}
offset += txEntrySize
}
return nil
}
// dbRemoveTxIndexEntry uses an existing database transaction to remove the most
// recent transaction index entry for the given hash.
func dbRemoveTxIndexEntry(dbTx database.Tx, txHash *chainhash.Hash) error {
txIndex := dbTx.Metadata().Bucket(txIndexKey)
serializedData := txIndex.Get(txHash[:])
if len(serializedData) == 0 {
return fmt.Errorf("can't remove non-existent transaction %s "+
"from the transaction index", txHash)
}
return txIndex.Delete(txHash[:])
}
// dbRemoveTxIndexEntries uses an existing database transaction to remove the
// latest transaction entry for every transaction in the passed block.
func dbRemoveTxIndexEntries(dbTx database.Tx, block *btcutil.Block) error {
for _, tx := range block.Transactions() {
err := dbRemoveTxIndexEntry(dbTx, tx.Hash())
if err != nil {
return err
}
}
return nil
}
// TxIndex implements a transaction by hash index. That is to say, it supports
// querying all transactions by their hash.
type TxIndex struct {
db database.DB
curBlockID uint32
}
// Ensure the TxIndex type implements the Indexer interface.
var _ Indexer = (*TxIndex)(nil)
// Init initializes the hash-based transaction index. In particular, it finds
// the highest used block ID and stores it for later use when connecting or
// disconnecting blocks.
//
// This is part of the Indexer interface.
func (idx *TxIndex) Init() error {
// Find the latest known block id field for the internal block id
// index and initialize it. This is done because it's a lot more
// efficient to do a single search at initialize time than it is to
// write another value to the database on every update.
err := idx.db.View(func(dbTx database.Tx) error {
// Scan forward in large gaps to find a block id that doesn't
// exist yet to serve as an upper bound for the binary search
// below.
var highestKnown, nextUnknown uint32
testBlockID := uint32(1)
increment := uint32(100000)
for {
_, err := dbFetchBlockHashByID(dbTx, testBlockID)
if err != nil {
nextUnknown = testBlockID
break
}
highestKnown = testBlockID
testBlockID += increment
}
log.Tracef("Forward scan (highest known %d, next unknown %d)",
highestKnown, nextUnknown)
// No used block IDs due to new database.
if nextUnknown == 1 {
return nil
}
// Use a binary search to find the final highest used block id.
// This will take at most ceil(log_2(increment)) attempts.
for {
testBlockID = (highestKnown + nextUnknown) / 2
_, err := dbFetchBlockHashByID(dbTx, testBlockID)
if err != nil {
nextUnknown = testBlockID
} else {
highestKnown = testBlockID
}
log.Tracef("Binary scan (highest known %d, next "+
"unknown %d)", highestKnown, nextUnknown)
if highestKnown+1 == nextUnknown {
break
}
}
idx.curBlockID = highestKnown
return nil
})
if err != nil {
return err
}
log.Debugf("Current internal block ID: %d", idx.curBlockID)
return nil
}
// Key returns the database key to use for the index as a byte slice.
//
// This is part of the Indexer interface.
func (idx *TxIndex) Key() []byte {
return txIndexKey
}
// Name returns the human-readable name of the index.
//
// This is part of the Indexer interface.
func (idx *TxIndex) Name() string {
return txIndexName
}
// Create is invoked when the indexer manager determines the index needs
// to be created for the first time. It creates the buckets for the hash-based
// transaction index and the internal block ID indexes.
//
// This is part of the Indexer interface.
func (idx *TxIndex) Create(dbTx database.Tx) error {
meta := dbTx.Metadata()
if _, err := meta.CreateBucket(idByHashIndexBucketName); err != nil {
return err
}
if _, err := meta.CreateBucket(hashByIDIndexBucketName); err != nil {
return err
}
_, err := meta.CreateBucket(txIndexKey)
return err
}
// ConnectBlock is invoked by the index manager when a new block has been
// connected to the main chain. This indexer adds a hash-to-transaction mapping
// for every transaction in the passed block.
//
// This is part of the Indexer interface.
func (idx *TxIndex) ConnectBlock(dbTx database.Tx, block *btcutil.Block,
stxos []blockchain.SpentTxOut) error {
// Increment the internal block ID to use for the block being connected
// and add all of the transactions in the block to the index.
newBlockID := idx.curBlockID + 1
if err := dbAddTxIndexEntries(dbTx, block, newBlockID); err != nil {
return err
}
// Add the new block ID index entry for the block being connected and
// update the current internal block ID accordingly.
err := dbPutBlockIDIndexEntry(dbTx, block.Hash(), newBlockID)
if err != nil {
return err
}
idx.curBlockID = newBlockID
return nil
}
// DisconnectBlock is invoked by the index manager when a block has been
// disconnected from the main chain. This indexer removes the
// hash-to-transaction mapping for every transaction in the block.
//
// This is part of the Indexer interface.
func (idx *TxIndex) DisconnectBlock(dbTx database.Tx, block *btcutil.Block,
stxos []blockchain.SpentTxOut) error {
// Remove all of the transactions in the block from the index.
if err := dbRemoveTxIndexEntries(dbTx, block); err != nil {
return err
}
// Remove the block ID index entry for the block being disconnected and
// decrement the current internal block ID to account for it.
if err := dbRemoveBlockIDIndexEntry(dbTx, block.Hash()); err != nil {
return err
}
idx.curBlockID--
return nil
}
// TxBlockRegion returns the block region for the provided transaction hash
// from the transaction index. The block region can in turn be used to load the
// raw transaction bytes. When there is no entry for the provided hash, nil
// will be returned for the both the entry and the error.
//
// This function is safe for concurrent access.
func (idx *TxIndex) TxBlockRegion(hash *chainhash.Hash) (*database.BlockRegion, error) {
var region *database.BlockRegion
err := idx.db.View(func(dbTx database.Tx) error {
var err error
region, err = dbFetchTxIndexEntry(dbTx, hash)
return err
})
return region, err
}
// NewTxIndex returns a new instance of an indexer that is used to create a
// mapping of the hashes of all transactions in the blockchain to the respective
// block, location within the block, and size of the transaction.
//
// It implements the Indexer interface which plugs into the IndexManager that in
// turn is used by the blockchain package. This allows the index to be
// seamlessly maintained along with the chain.
func NewTxIndex(db database.DB) *TxIndex {
return &TxIndex{db: db}
}
// dropBlockIDIndex drops the internal block id index.
func dropBlockIDIndex(db database.DB) error {
return db.Update(func(dbTx database.Tx) error {
meta := dbTx.Metadata()
err := meta.DeleteBucket(idByHashIndexBucketName)
if err != nil {
return err
}
return meta.DeleteBucket(hashByIDIndexBucketName)
})
}
// DropTxIndex drops the transaction index from the provided database if it
// exists. Since the address index relies on it, the address index will also be
// dropped when it exists.
func DropTxIndex(db database.DB, interrupt <-chan struct{}) error {
err := dropIndex(db, addrIndexKey, addrIndexName, interrupt)
if err != nil {
return err
}
return dropIndex(db, txIndexKey, txIndexName, interrupt)
}