mirror of
https://gitlab.com/pulsechaincom/erigon-pulse.git
synced 2024-12-29 07:07:16 +00:00
239 lines
7.3 KiB
Go
239 lines
7.3 KiB
Go
/*
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Copyright 2021 Erigon contributors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package recsplit
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import (
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"encoding/binary"
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"math"
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"os"
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"unsafe"
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"github.com/ledgerwatch/erigon-lib/mmap"
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"github.com/ledgerwatch/erigon-lib/recsplit/eliasfano16"
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"github.com/ledgerwatch/erigon-lib/recsplit/eliasfano32"
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)
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// Index implements index lookup from the file created by the RecSplit
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type Index struct {
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indexFile string
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f *os.File
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mmapHandle1 []byte // mmap handle for unix (this is used to close mmap)
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mmapHandle2 *[mmap.MaxMapSize]byte // mmap handle for windows (this is used to close mmap)
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data []byte // slice of correct size for the index to work with
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keyCount uint64
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bytesPerRec int
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recMask uint64
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grData []uint64
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ef eliasfano16.DoubleEliasFano
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enums bool
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offsetEf *eliasfano32.EliasFano
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baseDataID uint64
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bucketCount uint64 // Number of buckets
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bucketSize int
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leafSize uint16 // Leaf size for recursive split algorithms
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primaryAggrBound uint16 // The lower bound for primary key aggregation (computed from leafSize)
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secondaryAggrBound uint16 // The lower bound for secondary key aggregation (computed from leadSize)
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salt uint32
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startSeed []uint64
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golombRice []uint32
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}
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func MustOpen(indexFile string) *Index {
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idx, err := OpenIndex(indexFile)
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if err != nil {
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panic(err)
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}
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return idx
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}
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func OpenIndex(indexFile string) (*Index, error) {
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idx := &Index{
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indexFile: indexFile,
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}
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var err error
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idx.f, err = os.Open(indexFile)
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if err != nil {
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return nil, err
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}
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var stat os.FileInfo
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if stat, err = idx.f.Stat(); err != nil {
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return nil, err
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}
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size := int(stat.Size())
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if idx.mmapHandle1, idx.mmapHandle2, err = mmap.Mmap(idx.f, size); err != nil {
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return nil, err
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}
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idx.data = idx.mmapHandle1[:size]
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// Read number of keys and bytes per record
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idx.baseDataID = binary.BigEndian.Uint64(idx.data[:8])
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idx.keyCount = binary.BigEndian.Uint64(idx.data[8:16])
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idx.bytesPerRec = int(idx.data[16])
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idx.recMask = (uint64(1) << (8 * idx.bytesPerRec)) - 1
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offset := 16 + 1 + int(idx.keyCount)*idx.bytesPerRec
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// Bucket count, bucketSize, leafSize
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idx.bucketCount = binary.BigEndian.Uint64(idx.data[offset:])
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offset += 8
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idx.bucketSize = int(binary.BigEndian.Uint16(idx.data[offset:]))
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offset += 2
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idx.leafSize = binary.BigEndian.Uint16(idx.data[offset:])
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offset += 2
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idx.primaryAggrBound = idx.leafSize * uint16(math.Max(2, math.Ceil(0.35*float64(idx.leafSize)+1./2.)))
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if idx.leafSize < 7 {
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idx.secondaryAggrBound = idx.primaryAggrBound * 2
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} else {
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idx.secondaryAggrBound = idx.primaryAggrBound * uint16(math.Ceil(0.21*float64(idx.leafSize)+9./10.))
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}
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// Salt
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idx.salt = binary.BigEndian.Uint32(idx.data[offset:])
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offset += 4
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// Start seed
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startSeedLen := int(idx.data[offset])
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offset++
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idx.startSeed = make([]uint64, startSeedLen)
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for i := 0; i < startSeedLen; i++ {
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idx.startSeed[i] = binary.BigEndian.Uint64(idx.data[offset:])
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offset += 8
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}
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idx.enums = idx.data[offset] != 0
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offset++
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if idx.enums {
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var size int
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idx.offsetEf, size = eliasfano32.ReadEliasFano(idx.data[offset:])
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offset += size
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}
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// Size of golomb rice params
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golombParamSize := binary.BigEndian.Uint16(idx.data[offset:])
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offset += 4
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idx.golombRice = make([]uint32, golombParamSize)
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for i := uint16(0); i < golombParamSize; i++ {
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if i == 0 {
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idx.golombRice[i] = (bijMemo[i] << 27) | bijMemo[i]
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} else if i <= idx.leafSize {
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idx.golombRice[i] = (bijMemo[i] << 27) | (uint32(1) << 16) | bijMemo[i]
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} else {
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computeGolombRice(i, idx.golombRice, idx.leafSize, idx.primaryAggrBound, idx.secondaryAggrBound)
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}
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}
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l := binary.BigEndian.Uint64(idx.data[offset:])
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offset += 8
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p := (*[maxDataSize / 8]uint64)(unsafe.Pointer(&idx.data[offset]))
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idx.grData = p[:l]
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offset += 8 * int(l)
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idx.ef.Read(idx.data[offset:])
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return idx, nil
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}
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func (idx *Index) BaseDataID() uint64 { return idx.baseDataID }
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func (idx *Index) Close() error {
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if err := mmap.Munmap(idx.mmapHandle1, idx.mmapHandle2); err != nil {
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return err
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}
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if err := idx.f.Close(); err != nil {
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return err
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}
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return nil
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}
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func (idx *Index) skipBits(m uint16) int {
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return int(idx.golombRice[m] & 0xffff)
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}
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func (idx *Index) skipNodes(m uint16) int {
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return int(idx.golombRice[m]>>16) & 0x7FF
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}
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// golombParam returns the optimal Golomb parameter to use for encoding
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// salt for the part of the hash function separating m elements. It is based on
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// calculations with assumptions that we draw hash functions at random
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func (idx *Index) golombParam(m uint16) int {
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return int(idx.golombRice[m] >> 27)
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}
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func (idx *Index) Empty() bool {
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return idx.keyCount == 0
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}
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// Lookup is not thread-safe because it used id.hasher
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func (idx *Index) Lookup(bucketHash, fingerprint uint64) uint64 {
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if idx.keyCount == 0 {
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panic("no Lookup should be done when keyCount==0, please use Empty function to guard")
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}
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if idx.keyCount == 1 {
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return 0
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}
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var gr GolombRiceReader
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gr.data = idx.grData
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bucket := remap(bucketHash, idx.bucketCount)
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cumKeys, cumKeysNext, bitPos := idx.ef.Get3(bucket)
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m := uint16(cumKeysNext - cumKeys) // Number of keys in this bucket
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gr.ReadReset(int(bitPos), idx.skipBits(m))
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var level int
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for m > idx.secondaryAggrBound { // fanout = 2
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d := gr.ReadNext(idx.golombParam(m))
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hmod := remap16(remix(fingerprint+idx.startSeed[level]+d), m)
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split := (((m+1)/2 + idx.secondaryAggrBound - 1) / idx.secondaryAggrBound) * idx.secondaryAggrBound
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if hmod < split {
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m = split
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} else {
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gr.SkipSubtree(idx.skipNodes(split), idx.skipBits(split))
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m -= split
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cumKeys += uint64(split)
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}
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level++
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}
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if m > idx.primaryAggrBound {
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d := gr.ReadNext(idx.golombParam(m))
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hmod := remap16(remix(fingerprint+idx.startSeed[level]+d), m)
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part := hmod / idx.primaryAggrBound
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if idx.primaryAggrBound < m-part*idx.primaryAggrBound {
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m = idx.primaryAggrBound
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} else {
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m = m - part*idx.primaryAggrBound
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}
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cumKeys += uint64(idx.primaryAggrBound * part)
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if part != 0 {
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gr.SkipSubtree(idx.skipNodes(idx.primaryAggrBound)*int(part), idx.skipBits(idx.primaryAggrBound)*int(part))
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}
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level++
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}
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if m > idx.leafSize {
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d := gr.ReadNext(idx.golombParam(m))
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hmod := remap16(remix(fingerprint+idx.startSeed[level]+d), m)
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part := hmod / idx.leafSize
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if idx.leafSize < m-part*idx.leafSize {
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m = idx.leafSize
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} else {
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m = m - part*idx.leafSize
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}
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cumKeys += uint64(idx.leafSize * part)
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if part != 0 {
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gr.SkipSubtree(int(part), idx.skipBits(idx.leafSize)*int(part))
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}
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level++
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}
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b := gr.ReadNext(idx.golombParam(m))
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rec := int(cumKeys) + int(remap16(remix(fingerprint+idx.startSeed[level]+b), m))
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return binary.BigEndian.Uint64(idx.data[1+8+idx.bytesPerRec*(rec+1):]) & idx.recMask
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}
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func (idx *Index) Lookup2(i uint64) uint64 {
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return idx.offsetEf.Get(i)
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}
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