1// Copyright 2021 The go-ethereum Authors
2// This file is part of the go-ethereum library.
3//
4// The go-ethereum library is free software: you can redistribute it and/or modify
5// it under the terms of the GNU Lesser General Public License as published by
6// the Free Software Foundation, either version 3 of the License, or
7// (at your option) any later version.
8//
9// The go-ethereum library is distributed in the hope that it will be useful,
10// but WITHOUT ANY WARRANTY; without even the implied warranty of
11// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12// GNU Lesser General Public License for more details.
13//
14// You should have received a copy of the GNU Lesser General Public License
15// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
16
17package core
18
19import (
20	"context"
21	"time"
22
23	"github.com/ethereum/go-ethereum/common"
24	"github.com/ethereum/go-ethereum/common/bitutil"
25	"github.com/ethereum/go-ethereum/core/bloombits"
26	"github.com/ethereum/go-ethereum/core/rawdb"
27	"github.com/ethereum/go-ethereum/core/types"
28	"github.com/ethereum/go-ethereum/ethdb"
29)
30
31const (
32	// bloomThrottling is the time to wait between processing two consecutive index
33	// sections. It's useful during chain upgrades to prevent disk overload.
34	bloomThrottling = 100 * time.Millisecond
35)
36
37// BloomIndexer implements a core.ChainIndexer, building up a rotated bloom bits index
38// for the Ethereum header bloom filters, permitting blazing fast filtering.
39type BloomIndexer struct {
40	size    uint64               // section size to generate bloombits for
41	db      ethdb.Database       // database instance to write index data and metadata into
42	gen     *bloombits.Generator // generator to rotate the bloom bits crating the bloom index
43	section uint64               // Section is the section number being processed currently
44	head    common.Hash          // Head is the hash of the last header processed
45}
46
47// NewBloomIndexer returns a chain indexer that generates bloom bits data for the
48// canonical chain for fast logs filtering.
49func NewBloomIndexer(db ethdb.Database, size, confirms uint64) *ChainIndexer {
50	backend := &BloomIndexer{
51		db:   db,
52		size: size,
53	}
54	table := rawdb.NewTable(db, string(rawdb.BloomBitsIndexPrefix))
55
56	return NewChainIndexer(db, table, backend, size, confirms, bloomThrottling, "bloombits")
57}
58
59// Reset implements core.ChainIndexerBackend, starting a new bloombits index
60// section.
61func (b *BloomIndexer) Reset(ctx context.Context, section uint64, lastSectionHead common.Hash) error {
62	gen, err := bloombits.NewGenerator(uint(b.size))
63	b.gen, b.section, b.head = gen, section, common.Hash{}
64	return err
65}
66
67// Process implements core.ChainIndexerBackend, adding a new header's bloom into
68// the index.
69func (b *BloomIndexer) Process(ctx context.Context, header *types.Header) error {
70	b.gen.AddBloom(uint(header.Number.Uint64()-b.section*b.size), header.Bloom)
71	b.head = header.Hash()
72	return nil
73}
74
75// Commit implements core.ChainIndexerBackend, finalizing the bloom section and
76// writing it out into the database.
77func (b *BloomIndexer) Commit() error {
78	batch := b.db.NewBatch()
79	for i := 0; i < types.BloomBitLength; i++ {
80		bits, err := b.gen.Bitset(uint(i))
81		if err != nil {
82			return err
83		}
84		rawdb.WriteBloomBits(batch, uint(i), b.section, b.head, bitutil.CompressBytes(bits))
85	}
86	return batch.Write()
87}
88
89// Prune returns an empty error since we don't support pruning here.
90func (b *BloomIndexer) Prune(threshold uint64) error {
91	return nil
92}
93