608 lines
13 KiB
Go
608 lines
13 KiB
Go
// Copyright (c) 2012-2020 Ugorji Nwoke. All rights reserved.
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// Use of this source code is governed by a MIT license found in the LICENSE file.
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package codec
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import (
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"bufio"
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"bytes"
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"io"
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"strings"
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)
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// decReader abstracts the reading source, allowing implementations that can
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// read from an io.Reader or directly off a byte slice with zero-copying.
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type decReader interface {
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// readx will return a view of the []byte if decoding from a []byte, OR
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// read into the implementation scratch buffer if possible i.e. n < len(scratchbuf), OR
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// create a new []byte and read into that
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readx(n uint) []byte
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readb([]byte)
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readn1() byte
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readn2() [2]byte
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readn3() [3]byte
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readn4() [4]byte
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readn8() [8]byte
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// readn1eof() (v uint8, eof bool)
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// // read up to 8 bytes at a time
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// readn(num uint8) (v [8]byte)
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numread() uint // number of bytes read
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// skip any whitespace characters, and return the first non-matching byte
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skipWhitespace() (token byte)
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// jsonReadNum will include last read byte in first element of slice,
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// and continue numeric characters until it sees a non-numeric char
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// or EOF. If it sees a non-numeric character, it will unread that.
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jsonReadNum() []byte
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// jsonReadAsisChars will read json plain characters (anything but " or \)
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// and return a slice terminated by a non-json asis character.
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jsonReadAsisChars() []byte
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// skip will skip any byte that matches, and return the first non-matching byte
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// skip(accept *bitset256) (token byte)
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// readTo will read any byte that matches, stopping once no-longer matching.
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// readTo(accept *bitset256) (out []byte)
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// readUntil will read, only stopping once it matches the 'stop' byte (which it excludes).
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readUntil(stop byte) (out []byte)
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}
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// ------------------------------------------------
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type unreadByteStatus uint8
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// unreadByteStatus goes from
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// undefined (when initialized) -- (read) --> canUnread -- (unread) --> canRead ...
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const (
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unreadByteUndefined unreadByteStatus = iota
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unreadByteCanRead
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unreadByteCanUnread
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)
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// const defBufReaderSize = 4096
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// --------------------
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// ioReaderByteScanner contains the io.Reader and io.ByteScanner interfaces
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type ioReaderByteScanner interface {
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io.Reader
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io.ByteScanner
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// ReadByte() (byte, error)
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// UnreadByte() error
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// Read(p []byte) (n int, err error)
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}
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// ioReaderByteScannerT does a simple wrapper of a io.ByteScanner
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// over a io.Reader
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type ioReaderByteScannerT struct {
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r io.Reader
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l byte // last byte
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ls unreadByteStatus // last byte status
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_ [2]byte // padding
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b [4]byte // tiny buffer for reading single bytes
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}
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func (z *ioReaderByteScannerT) ReadByte() (c byte, err error) {
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if z.ls == unreadByteCanRead {
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z.ls = unreadByteCanUnread
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c = z.l
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} else {
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_, err = z.Read(z.b[:1])
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c = z.b[0]
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}
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return
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}
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func (z *ioReaderByteScannerT) UnreadByte() (err error) {
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switch z.ls {
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case unreadByteCanUnread:
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z.ls = unreadByteCanRead
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case unreadByteCanRead:
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err = errDecUnreadByteLastByteNotRead
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case unreadByteUndefined:
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err = errDecUnreadByteNothingToRead
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default:
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err = errDecUnreadByteUnknown
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}
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return
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}
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func (z *ioReaderByteScannerT) Read(p []byte) (n int, err error) {
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if len(p) == 0 {
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return
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}
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var firstByte bool
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if z.ls == unreadByteCanRead {
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z.ls = unreadByteCanUnread
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p[0] = z.l
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if len(p) == 1 {
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n = 1
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return
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}
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firstByte = true
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p = p[1:]
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}
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n, err = z.r.Read(p)
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if n > 0 {
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if err == io.EOF && n == len(p) {
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err = nil // read was successful, so postpone EOF (till next time)
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}
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z.l = p[n-1]
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z.ls = unreadByteCanUnread
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}
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if firstByte {
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n++
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}
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return
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}
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func (z *ioReaderByteScannerT) reset(r io.Reader) {
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z.r = r
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z.ls = unreadByteUndefined
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z.l = 0
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}
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// ioDecReader is a decReader that reads off an io.Reader.
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type ioDecReader struct {
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rr ioReaderByteScannerT // the reader passed in, wrapped into a reader+bytescanner
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n uint // num read
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blist *bytesFreelist
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bufr []byte // buffer for readTo/readUntil
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br ioReaderByteScanner // main reader used for Read|ReadByte|UnreadByte
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bb *bufio.Reader // created internally, and reused on reset if needed
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x [64 + 40]byte // for: get struct field name, swallow valueTypeBytes, etc
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}
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func (z *ioDecReader) reset(r io.Reader, bufsize int, blist *bytesFreelist) {
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z.blist = blist
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z.n = 0
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z.bufr = z.blist.check(z.bufr, 256)
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z.br = nil
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var ok bool
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if bufsize <= 0 {
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z.br, ok = r.(ioReaderByteScanner)
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if !ok {
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z.rr.reset(r)
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z.br = &z.rr
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}
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return
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}
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// bufsize > 0 ...
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// if bytes.[Buffer|Reader], no value in adding extra buffer
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// if bufio.Reader, no value in extra buffer unless size changes
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switch bb := r.(type) {
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case *strings.Reader:
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z.br = bb
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case *bytes.Buffer:
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z.br = bb
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case *bytes.Reader:
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z.br = bb
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case *bufio.Reader:
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if bb.Size() == bufsize {
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z.br = bb
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}
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}
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if z.br == nil {
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if z.bb != nil && z.bb.Size() == bufsize {
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z.bb.Reset(r)
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} else {
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z.bb = bufio.NewReaderSize(r, bufsize)
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}
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z.br = z.bb
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}
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}
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func (z *ioDecReader) numread() uint {
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return z.n
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}
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func (z *ioDecReader) readn1() (b uint8) {
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b, err := z.br.ReadByte()
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halt.onerror(err)
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z.n++
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return
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}
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func (z *ioDecReader) readn2() (bs [2]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readn3() (bs [3]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readn4() (bs [4]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readn8() (bs [8]byte) {
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z.readb(bs[:])
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return
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}
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func (z *ioDecReader) readx(n uint) (bs []byte) {
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if n == 0 {
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return zeroByteSlice
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}
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if n < uint(len(z.x)) {
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bs = z.x[:n]
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} else {
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bs = make([]byte, n)
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}
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nn, err := readFull(z.br, bs)
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z.n += nn
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halt.onerror(err)
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return
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}
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func (z *ioDecReader) readb(bs []byte) {
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if len(bs) == 0 {
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return
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}
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nn, err := readFull(z.br, bs)
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z.n += nn
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halt.onerror(err)
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}
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// func (z *ioDecReader) readn1eof() (b uint8, eof bool) {
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// b, err := z.br.ReadByte()
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// if err == nil {
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// z.n++
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// } else if err == io.EOF {
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// eof = true
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// } else {
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// halt.onerror(err)
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// }
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// return
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// }
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func (z *ioDecReader) jsonReadNum() (bs []byte) {
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z.unreadn1()
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z.bufr = z.bufr[:0]
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LOOP:
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// i, eof := z.readn1eof()
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i, err := z.br.ReadByte()
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if err == io.EOF {
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return z.bufr
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}
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if err != nil {
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halt.onerror(err)
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}
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z.n++
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if isNumberChar(i) {
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z.bufr = append(z.bufr, i)
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goto LOOP
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}
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z.unreadn1()
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return z.bufr
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}
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func (z *ioDecReader) jsonReadAsisChars() (bs []byte) {
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z.bufr = z.bufr[:0]
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LOOP:
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i := z.readn1()
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z.bufr = append(z.bufr, i)
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if i == '"' || i == '\\' {
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return z.bufr
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}
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goto LOOP
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}
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func (z *ioDecReader) skipWhitespace() (token byte) {
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LOOP:
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token = z.readn1()
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if isWhitespaceChar(token) {
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goto LOOP
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}
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return
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}
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// func (z *ioDecReader) readUntil(stop byte) []byte {
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// z.bufr = z.bufr[:0]
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// LOOP:
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// token := z.readn1()
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// z.bufr = append(z.bufr, token)
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// if token == stop {
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// return z.bufr[:len(z.bufr)-1]
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// }
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// goto LOOP
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// }
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func (z *ioDecReader) readUntil(stop byte) []byte {
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z.bufr = z.bufr[:0]
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LOOP:
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token := z.readn1()
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if token == stop {
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return z.bufr
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}
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z.bufr = append(z.bufr, token)
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goto LOOP
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}
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func (z *ioDecReader) unreadn1() {
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err := z.br.UnreadByte()
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halt.onerror(err)
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z.n--
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}
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// ------------------------------------
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// bytesDecReader is a decReader that reads off a byte slice with zero copying
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//
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// Note: we do not try to convert index'ing out of bounds to an io.EOF.
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// instead, we let it bubble up to the exported Encode/Decode method
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// and recover it as an io.EOF.
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//
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// Every function here MUST defensively check bounds either explicitly
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// or via a bounds check.
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//
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// see panicValToErr(...) function in helper.go.
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type bytesDecReader struct {
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b []byte // data
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c uint // cursor
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}
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func (z *bytesDecReader) reset(in []byte) {
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z.b = in[:len(in):len(in)] // reslicing must not go past capacity
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z.c = 0
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}
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func (z *bytesDecReader) numread() uint {
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return z.c
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}
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// Note: slicing from a non-constant start position is more expensive,
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// as more computation is required to decipher the pointer start position.
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// However, we do it only once, and it's better than reslicing both z.b and return value.
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func (z *bytesDecReader) readx(n uint) (bs []byte) {
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// x := z.c + n
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// bs = z.b[z.c:x]
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// z.c = x
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bs = z.b[z.c : z.c+n]
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z.c += n
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return
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}
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func (z *bytesDecReader) readb(bs []byte) {
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copy(bs, z.readx(uint(len(bs))))
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}
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// MARKER: do not use this - as it calls into memmove (as the size of data to move is unknown)
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// func (z *bytesDecReader) readnn(bs []byte, n uint) {
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// x := z.c
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// copy(bs, z.b[x:x+n])
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// z.c += n
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// }
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// func (z *bytesDecReader) readn(num uint8) (bs [8]byte) {
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// x := z.c + uint(num)
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// copy(bs[:], z.b[z.c:x]) // slice z.b completely, so we get bounds error if past
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// z.c = x
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// return
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// }
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// func (z *bytesDecReader) readn1() uint8 {
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// z.c++
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// return z.b[z.c-1]
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// }
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// MARKER: readn{1,2,3,4,8} should throw an out of bounds error if past length.
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// MARKER: readn1: explicitly ensure bounds check is done
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// MARKER: readn{2,3,4,8}: ensure you slice z.b completely so we get bounds error if past end.
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func (z *bytesDecReader) readn1() (v uint8) {
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v = z.b[z.c]
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z.c++
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return
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}
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func (z *bytesDecReader) readn2() (bs [2]byte) {
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// copy(bs[:], z.b[z.c:z.c+2])
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// bs[1] = z.b[z.c+1]
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// bs[0] = z.b[z.c]
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bs = okBytes2(z.b[z.c : z.c+2])
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z.c += 2
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return
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}
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func (z *bytesDecReader) readn3() (bs [3]byte) {
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// copy(bs[1:], z.b[z.c:z.c+3])
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bs = okBytes3(z.b[z.c : z.c+3])
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z.c += 3
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return
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}
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func (z *bytesDecReader) readn4() (bs [4]byte) {
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// copy(bs[:], z.b[z.c:z.c+4])
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bs = okBytes4(z.b[z.c : z.c+4])
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z.c += 4
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return
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}
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func (z *bytesDecReader) readn8() (bs [8]byte) {
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// copy(bs[:], z.b[z.c:z.c+8])
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bs = okBytes8(z.b[z.c : z.c+8])
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z.c += 8
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return
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}
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func (z *bytesDecReader) jsonReadNum() []byte {
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z.c-- // unread
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i := z.c
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LOOP:
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// gracefully handle end of slice, as end of stream is meaningful here
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if i < uint(len(z.b)) && isNumberChar(z.b[i]) {
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i++
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goto LOOP
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}
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z.c, i = i, z.c
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// MARKER: 20230103: byteSliceOf here prevents inlining of jsonReadNum
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// return byteSliceOf(z.b, i, z.c)
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return z.b[i:z.c]
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}
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func (z *bytesDecReader) jsonReadAsisChars() []byte {
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i := z.c
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LOOP:
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token := z.b[i]
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i++
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if token == '"' || token == '\\' {
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z.c, i = i, z.c
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return byteSliceOf(z.b, i, z.c)
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// return z.b[i:z.c]
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}
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goto LOOP
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}
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func (z *bytesDecReader) skipWhitespace() (token byte) {
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i := z.c
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LOOP:
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token = z.b[i]
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if isWhitespaceChar(token) {
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i++
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goto LOOP
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}
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z.c = i + 1
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return
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}
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func (z *bytesDecReader) readUntil(stop byte) (out []byte) {
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i := z.c
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LOOP:
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if z.b[i] == stop {
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out = byteSliceOf(z.b, z.c, i)
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// out = z.b[z.c:i]
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z.c = i + 1
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return
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}
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i++
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goto LOOP
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}
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// --------------
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type decRd struct {
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rb bytesDecReader
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ri *ioDecReader
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decReader
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bytes bool // is bytes reader
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// MARKER: these fields below should belong directly in Encoder.
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// we pack them here for space efficiency and cache-line optimization.
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mtr bool // is maptype a known type?
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str bool // is slicetype a known type?
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be bool // is binary encoding
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js bool // is json handle
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jsms bool // is json handle, and MapKeyAsString
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cbor bool // is cbor handle
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cbreak bool // is a check breaker
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}
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// From out benchmarking, we see the following impact performance:
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//
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// - functions that are too big to inline
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// - interface calls (as no inlining can occur)
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//
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// decRd is designed to embed a decReader, and then re-implement some of the decReader
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// methods using a conditional branch.
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//
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// We only override the ones where the bytes version is inlined AND the wrapper method
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// (containing the bytes version alongside a conditional branch) is also inlined.
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//
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// We use ./run.sh -z to check.
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//
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// Right now, only numread and "carefully crafted" readn1 can be inlined.
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func (z *decRd) numread() uint {
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if z.bytes {
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return z.rb.numread()
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}
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return z.ri.numread()
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}
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func (z *decRd) readn1() (v uint8) {
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if z.bytes {
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// return z.rb.readn1()
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|
// MARKER: calling z.rb.readn1() prevents decRd.readn1 from being inlined.
|
|
// copy code, to manually inline and explicitly return here.
|
|
// Keep in sync with bytesDecReader.readn1
|
|
v = z.rb.b[z.rb.c]
|
|
z.rb.c++
|
|
return
|
|
}
|
|
return z.ri.readn1()
|
|
}
|
|
|
|
// func (z *decRd) readn4() [4]byte {
|
|
// if z.bytes {
|
|
// return z.rb.readn4()
|
|
// }
|
|
// return z.ri.readn4()
|
|
// }
|
|
|
|
// func (z *decRd) readn3() [3]byte {
|
|
// if z.bytes {
|
|
// return z.rb.readn3()
|
|
// }
|
|
// return z.ri.readn3()
|
|
// }
|
|
|
|
// func (z *decRd) skipWhitespace() byte {
|
|
// if z.bytes {
|
|
// return z.rb.skipWhitespace()
|
|
// }
|
|
// return z.ri.skipWhitespace()
|
|
// }
|
|
|
|
type devNullReader struct{}
|
|
|
|
func (devNullReader) Read(p []byte) (int, error) { return 0, io.EOF }
|
|
func (devNullReader) Close() error { return nil }
|
|
|
|
func readFull(r io.Reader, bs []byte) (n uint, err error) {
|
|
var nn int
|
|
for n < uint(len(bs)) && err == nil {
|
|
nn, err = r.Read(bs[n:])
|
|
if nn > 0 {
|
|
if err == io.EOF {
|
|
// leave EOF for next time
|
|
err = nil
|
|
}
|
|
n += uint(nn)
|
|
}
|
|
}
|
|
// do not do this below - it serves no purpose
|
|
// if n != len(bs) && err == io.EOF { err = io.ErrUnexpectedEOF }
|
|
return
|
|
}
|
|
|
|
var _ decReader = (*decRd)(nil)
|