forked from Shiloh/githaven
119 lines
2.9 KiB
Go
119 lines
2.9 KiB
Go
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// Copyright (c) 2019 Couchbase, Inc.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package zap
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import (
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"encoding/binary"
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"fmt"
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"github.com/blevesearch/bleve/index/scorch/segment"
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)
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type chunkedIntDecoder struct {
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startOffset uint64
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dataStartOffset uint64
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chunkOffsets []uint64
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curChunkBytes []byte
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data []byte
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r *segment.MemUvarintReader
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}
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// newChunkedIntDecoder expects an optional or reset chunkedIntDecoder for better reuse.
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func newChunkedIntDecoder(buf []byte, offset uint64, rv *chunkedIntDecoder) *chunkedIntDecoder {
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if rv == nil {
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rv = &chunkedIntDecoder{startOffset: offset, data: buf}
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} else {
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rv.startOffset = offset
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rv.data = buf
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}
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var n, numChunks uint64
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var read int
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if offset == termNotEncoded {
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numChunks = 0
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} else {
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numChunks, read = binary.Uvarint(buf[offset+n : offset+n+binary.MaxVarintLen64])
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}
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n += uint64(read)
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if cap(rv.chunkOffsets) >= int(numChunks) {
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rv.chunkOffsets = rv.chunkOffsets[:int(numChunks)]
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} else {
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rv.chunkOffsets = make([]uint64, int(numChunks))
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}
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for i := 0; i < int(numChunks); i++ {
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rv.chunkOffsets[i], read = binary.Uvarint(buf[offset+n : offset+n+binary.MaxVarintLen64])
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n += uint64(read)
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}
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rv.dataStartOffset = offset + n
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return rv
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}
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func (d *chunkedIntDecoder) loadChunk(chunk int) error {
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if d.startOffset == termNotEncoded {
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d.r = segment.NewMemUvarintReader([]byte(nil))
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return nil
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}
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if chunk >= len(d.chunkOffsets) {
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return fmt.Errorf("tried to load freq chunk that doesn't exist %d/(%d)",
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chunk, len(d.chunkOffsets))
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}
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end, start := d.dataStartOffset, d.dataStartOffset
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s, e := readChunkBoundary(chunk, d.chunkOffsets)
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start += s
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end += e
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d.curChunkBytes = d.data[start:end]
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if d.r == nil {
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d.r = segment.NewMemUvarintReader(d.curChunkBytes)
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} else {
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d.r.Reset(d.curChunkBytes)
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}
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return nil
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}
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func (d *chunkedIntDecoder) reset() {
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d.startOffset = 0
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d.dataStartOffset = 0
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d.chunkOffsets = d.chunkOffsets[:0]
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d.curChunkBytes = d.curChunkBytes[:0]
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d.data = d.data[:0]
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if d.r != nil {
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d.r.Reset([]byte(nil))
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}
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}
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func (d *chunkedIntDecoder) isNil() bool {
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return d.curChunkBytes == nil || len(d.curChunkBytes) == 0
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}
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func (d *chunkedIntDecoder) readUvarint() (uint64, error) {
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return d.r.ReadUvarint()
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}
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func (d *chunkedIntDecoder) SkipUvarint() {
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d.r.SkipUvarint()
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}
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func (d *chunkedIntDecoder) SkipBytes(count int) {
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d.r.SkipBytes(count)
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}
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func (d *chunkedIntDecoder) Len() int {
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return d.r.Len()
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}
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