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94 lines
3.1 KiB
Go
94 lines
3.1 KiB
Go
// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package bloombits
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import (
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"errors"
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"github.com/ethereum/go-ethereum/core/types"
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)
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var (
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// errSectionOutOfBounds is returned if the user tried to add more bloom filters
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// to the batch than available space, or if tries to retrieve above the capacity.
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errSectionOutOfBounds = errors.New("section out of bounds")
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// errBloomBitOutOfBounds is returned if the user tried to retrieve specified
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// bit bloom above the capacity.
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errBloomBitOutOfBounds = errors.New("bloom bit out of bounds")
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)
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// Generator takes a number of bloom filters and generates the rotated bloom bits
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// to be used for batched filtering.
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type Generator struct {
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blooms [types.BloomBitLength][]byte // Rotated blooms for per-bit matching
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sections uint // Number of sections to batch together
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nextSec uint // Next section to set when adding a bloom
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}
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// NewGenerator creates a rotated bloom generator that can iteratively fill a
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// batched bloom filter's bits.
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func NewGenerator(sections uint) (*Generator, error) {
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if sections%8 != 0 {
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return nil, errors.New("section count not multiple of 8")
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}
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b := &Generator{sections: sections}
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for i := 0; i < types.BloomBitLength; i++ {
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b.blooms[i] = make([]byte, sections/8)
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}
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return b, nil
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}
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// AddBloom takes a single bloom filter and sets the corresponding bit column
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// in memory accordingly.
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func (b *Generator) AddBloom(index uint, bloom types.Bloom) error {
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// Make sure we're not adding more bloom filters than our capacity
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if b.nextSec >= b.sections {
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return errSectionOutOfBounds
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}
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if b.nextSec != index {
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return errors.New("bloom filter with unexpected index")
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}
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// Rotate the bloom and insert into our collection
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byteIndex := b.nextSec / 8
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bitMask := byte(1) << byte(7-b.nextSec%8)
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for i := 0; i < types.BloomBitLength; i++ {
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bloomByteIndex := types.BloomByteLength - 1 - i/8
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bloomBitMask := byte(1) << byte(i%8)
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if (bloom[bloomByteIndex] & bloomBitMask) != 0 {
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b.blooms[i][byteIndex] |= bitMask
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}
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}
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b.nextSec++
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return nil
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}
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// Bitset returns the bit vector belonging to the given bit index after all
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// blooms have been added.
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func (b *Generator) Bitset(idx uint) ([]byte, error) {
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if b.nextSec != b.sections {
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return nil, errors.New("bloom not fully generated yet")
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}
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if idx >= types.BloomBitLength {
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return nil, errBloomBitOutOfBounds
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}
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return b.blooms[idx], nil
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}
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