mirror of
https://codeberg.org/forgejo/forgejo
synced 2024-08-25 17:11:16 +02:00
207 lines
5.5 KiB
Go
Vendored
207 lines
5.5 KiB
Go
Vendored
// Copyright (c) 2017 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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"bytes"
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"encoding/binary"
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"io"
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)
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// We can safely use 0 to represent termNotEncoded since 0
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// could never be a valid address for term location information.
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// (stored field index is always non-empty and earlier in the
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// file)
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const termNotEncoded = 0
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type chunkedIntCoder struct {
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final []byte
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chunkSize uint64
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chunkBuf bytes.Buffer
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chunkLens []uint64
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currChunk uint64
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buf []byte
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}
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// newChunkedIntCoder returns a new chunk int coder which packs data into
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// chunks based on the provided chunkSize and supports up to the specified
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// maxDocNum
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func newChunkedIntCoder(chunkSize uint64, maxDocNum uint64) *chunkedIntCoder {
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total := maxDocNum/chunkSize + 1
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rv := &chunkedIntCoder{
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chunkSize: chunkSize,
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chunkLens: make([]uint64, total),
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final: make([]byte, 0, 64),
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}
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return rv
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}
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// Reset lets you reuse this chunked int coder. buffers are reset and reused
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// from previous use. you cannot change the chunk size or max doc num.
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func (c *chunkedIntCoder) Reset() {
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c.final = c.final[:0]
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c.chunkBuf.Reset()
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c.currChunk = 0
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for i := range c.chunkLens {
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c.chunkLens[i] = 0
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}
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}
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// SetChunkSize changes the chunk size. It is only valid to do so
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// with a new chunkedIntCoder, or immediately after calling Reset()
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func (c *chunkedIntCoder) SetChunkSize(chunkSize uint64, maxDocNum uint64) {
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total := int(maxDocNum/chunkSize + 1)
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c.chunkSize = chunkSize
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if cap(c.chunkLens) < total {
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c.chunkLens = make([]uint64, total)
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} else {
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c.chunkLens = c.chunkLens[:total]
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}
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}
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// Add encodes the provided integers into the correct chunk for the provided
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// doc num. You MUST call Add() with increasing docNums.
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func (c *chunkedIntCoder) Add(docNum uint64, vals ...uint64) error {
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chunk := docNum / c.chunkSize
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if chunk != c.currChunk {
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// starting a new chunk
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c.Close()
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c.chunkBuf.Reset()
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c.currChunk = chunk
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}
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if len(c.buf) < binary.MaxVarintLen64 {
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c.buf = make([]byte, binary.MaxVarintLen64)
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}
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for _, val := range vals {
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wb := binary.PutUvarint(c.buf, val)
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_, err := c.chunkBuf.Write(c.buf[:wb])
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if err != nil {
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return err
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}
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}
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return nil
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}
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func (c *chunkedIntCoder) AddBytes(docNum uint64, buf []byte) error {
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chunk := docNum / c.chunkSize
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if chunk != c.currChunk {
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// starting a new chunk
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c.Close()
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c.chunkBuf.Reset()
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c.currChunk = chunk
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}
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_, err := c.chunkBuf.Write(buf)
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return err
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}
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// Close indicates you are done calling Add() this allows the final chunk
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// to be encoded.
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func (c *chunkedIntCoder) Close() {
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encodingBytes := c.chunkBuf.Bytes()
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c.chunkLens[c.currChunk] = uint64(len(encodingBytes))
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c.final = append(c.final, encodingBytes...)
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c.currChunk = uint64(cap(c.chunkLens)) // sentinel to detect double close
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}
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// Write commits all the encoded chunked integers to the provided writer.
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func (c *chunkedIntCoder) Write(w io.Writer) (int, error) {
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bufNeeded := binary.MaxVarintLen64 * (1 + len(c.chunkLens))
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if len(c.buf) < bufNeeded {
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c.buf = make([]byte, bufNeeded)
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}
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buf := c.buf
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// convert the chunk lengths into chunk offsets
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chunkOffsets := modifyLengthsToEndOffsets(c.chunkLens)
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// write out the number of chunks & each chunk offsets
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n := binary.PutUvarint(buf, uint64(len(chunkOffsets)))
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for _, chunkOffset := range chunkOffsets {
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n += binary.PutUvarint(buf[n:], chunkOffset)
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}
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tw, err := w.Write(buf[:n])
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if err != nil {
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return tw, err
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}
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// write out the data
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nw, err := w.Write(c.final)
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tw += nw
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if err != nil {
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return tw, err
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}
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return tw, nil
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}
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// writeAt commits all the encoded chunked integers to the provided writer
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// and returns the starting offset, total bytes written and an error
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func (c *chunkedIntCoder) writeAt(w io.Writer) (uint64, int, error) {
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startOffset := uint64(termNotEncoded)
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if len(c.final) <= 0 {
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return startOffset, 0, nil
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}
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if chw := w.(*CountHashWriter); chw != nil {
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startOffset = uint64(chw.Count())
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}
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tw, err := c.Write(w)
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return startOffset, tw, err
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}
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func (c *chunkedIntCoder) FinalSize() int {
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return len(c.final)
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}
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// modifyLengthsToEndOffsets converts the chunk length array
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// to a chunk offset array. The readChunkBoundary
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// will figure out the start and end of every chunk from
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// these offsets. Starting offset of i'th index is stored
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// in i-1'th position except for 0'th index and ending offset
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// is stored at i'th index position.
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// For 0'th element, starting position is always zero.
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// eg:
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// Lens -> 5 5 5 5 => 5 10 15 20
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// Lens -> 0 5 0 5 => 0 5 5 10
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// Lens -> 0 0 0 5 => 0 0 0 5
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// Lens -> 5 0 0 0 => 5 5 5 5
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// Lens -> 0 5 0 0 => 0 5 5 5
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// Lens -> 0 0 5 0 => 0 0 5 5
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func modifyLengthsToEndOffsets(lengths []uint64) []uint64 {
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var runningOffset uint64
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var index, i int
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for i = 1; i <= len(lengths); i++ {
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runningOffset += lengths[i-1]
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lengths[index] = runningOffset
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index++
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}
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return lengths
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}
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func readChunkBoundary(chunk int, offsets []uint64) (uint64, uint64) {
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var start uint64
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if chunk > 0 {
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start = offsets[chunk-1]
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}
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return start, offsets[chunk]
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}
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