mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
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141 lines
3.1 KiB
Go
141 lines
3.1 KiB
Go
package bytesutil
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import (
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"fmt"
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"io"
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"sync"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
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)
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var (
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// Verify ByteBuffer implements the given interfaces.
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_ io.Writer = &ByteBuffer{}
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_ fs.MustReadAtCloser = &ByteBuffer{}
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_ io.ReaderFrom = &ByteBuffer{}
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// Verify reader implement filestream.ReadCloser interface.
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_ filestream.ReadCloser = &reader{}
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)
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// ByteBuffer implements a simple byte buffer.
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type ByteBuffer struct {
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// B is the underlying byte slice.
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B []byte
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}
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// Path returns an unique id for bb.
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func (bb *ByteBuffer) Path() string {
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return fmt.Sprintf("ByteBuffer/%p/mem", bb)
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}
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// Reset resets bb.
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func (bb *ByteBuffer) Reset() {
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bb.B = bb.B[:0]
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}
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// Write appends p to bb.
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func (bb *ByteBuffer) Write(p []byte) (int, error) {
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bb.B = append(bb.B, p...)
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return len(p), nil
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}
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// MustReadAt reads len(p) bytes starting from the given offset.
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func (bb *ByteBuffer) MustReadAt(p []byte, offset int64) {
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if offset < 0 {
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logger.Panicf("BUG: cannot read at negative offset=%d", offset)
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}
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if offset > int64(len(bb.B)) {
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logger.Panicf("BUG: too big offset=%d; cannot exceed len(bb.B)=%d", offset, len(bb.B))
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}
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if n := copy(p, bb.B[offset:]); n < len(p) {
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logger.Panicf("BUG: EOF occurred after reading %d bytes out of %d bytes at offset %d", n, len(p), offset)
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}
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}
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// ReadFrom reads all the data from r to bb until EOF.
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func (bb *ByteBuffer) ReadFrom(r io.Reader) (int64, error) {
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b := bb.B
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bLen := len(b)
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b = ResizeWithCopyMayOverallocate(b, 4*1024)
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b = b[:cap(b)]
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offset := bLen
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for {
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if free := len(b) - offset; free < offset {
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n := len(b)
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b = append(b, make([]byte, n)...)
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}
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n, err := r.Read(b[offset:])
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offset += n
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if err != nil {
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bb.B = b[:offset]
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if err == io.EOF {
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err = nil
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}
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return int64(offset - bLen), err
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}
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}
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}
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// MustClose closes bb for subsequent re-use.
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func (bb *ByteBuffer) MustClose() {
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// Do nothing, since certain code rely on bb reading after MustClose call.
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}
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// NewReader returns new reader for the given bb.
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func (bb *ByteBuffer) NewReader() filestream.ReadCloser {
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return &reader{
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bb: bb,
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}
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}
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type reader struct {
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bb *ByteBuffer
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// readOffset is the offset in bb.B for read.
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readOffset int
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}
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// Path returns an unique id for the underlying ByteBuffer.
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func (r *reader) Path() string {
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return r.bb.Path()
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}
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// Read reads up to len(p) bytes from bb.
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func (r *reader) Read(p []byte) (int, error) {
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var err error
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n := copy(p, r.bb.B[r.readOffset:])
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if n < len(p) {
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err = io.EOF
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}
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r.readOffset += n
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return n, err
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}
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// MustClose closes bb for subsequent re-use.
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func (r *reader) MustClose() {
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r.bb = nil
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r.readOffset = 0
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}
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// ByteBufferPool is a pool of ByteBuffers.
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type ByteBufferPool struct {
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p sync.Pool
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}
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// Get obtains a ByteBuffer from bbp.
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func (bbp *ByteBufferPool) Get() *ByteBuffer {
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bbv := bbp.p.Get()
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if bbv == nil {
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return &ByteBuffer{}
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}
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return bbv.(*ByteBuffer)
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}
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// Put puts bb into bbp.
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func (bbp *ByteBufferPool) Put(bb *ByteBuffer) {
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bb.Reset()
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bbp.p.Put(bb)
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}
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