1 files changed, 383 insertions, 0 deletions
diff --git a/vendor/github.com/philhofer/fwd/reader.go b/vendor/github.com/philhofer/fwd/reader.go
new file mode 100644
index 00000000..75be62ab
--- /dev/null
+++ b/vendor/github.com/philhofer/fwd/reader.go
@@ -0,0 +1,383 @@
+// The `fwd` package provides a buffered reader
+// and writer. Each has methods that help improve
+// the encoding/decoding performance of some binary
+// protocols.
+//
+// The `fwd.Writer` and `fwd.Reader` type provide similar
+// functionality to their counterparts in `bufio`, plus
+// a few extra utility methods that simplify read-ahead
+// and write-ahead. I wrote this package to improve serialization
+// performance for http://github.com/tinylib/msgp,
+// where it provided about a 2x speedup over `bufio` for certain
+// workloads. However, care must be taken to understand the semantics of the
+// extra methods provided by this package, as they allow
+// the user to access and manipulate the buffer memory
+// directly.
+//
+// The extra methods for `fwd.Reader` are `Peek`, `Skip`
+// and `Next`. `(*fwd.Reader).Peek`, unlike `(*bufio.Reader).Peek`,
+// will re-allocate the read buffer in order to accommodate arbitrarily
+// large read-ahead. `(*fwd.Reader).Skip` skips the next `n` bytes
+// in the stream, and uses the `io.Seeker` interface if the underlying
+// stream implements it. `(*fwd.Reader).Next` returns a slice pointing
+// to the next `n` bytes in the read buffer (like `Peek`), but also
+// increments the read position. This allows users to process streams
+// in arbitrary block sizes without having to manage appropriately-sized
+// slices. Additionally, obviating the need to copy the data from the
+// buffer to another location in memory can improve performance dramatically
+// in CPU-bound applications.
+//
+// `fwd.Writer` only has one extra method, which is `(*fwd.Writer).Next`, which
+// returns a slice pointing to the next `n` bytes of the writer, and increments
+// the write position by the length of the returned slice. This allows users
+// to write directly to the end of the buffer.
+//
+package fwd
+
+import "io"
+
+const (
+	// DefaultReaderSize is the default size of the read buffer
+	DefaultReaderSize = 2048
+
+	// minimum read buffer; straight from bufio
+	minReaderSize = 16
+)
+
+// NewReader returns a new *Reader that reads from 'r'
+func NewReader(r io.Reader) *Reader {
+	return NewReaderSize(r, DefaultReaderSize)
+}
+
+// NewReaderSize returns a new *Reader that
+// reads from 'r' and has a buffer size 'n'
+func NewReaderSize(r io.Reader, n int) *Reader {
+	rd := &Reader{
+		r:    r,
+		data: make([]byte, 0, max(minReaderSize, n)),
+	}
+	if s, ok := r.(io.Seeker); ok {
+		rd.rs = s
+	}
+	return rd
+}
+
+// Reader is a buffered look-ahead reader
+type Reader struct {
+	r io.Reader // underlying reader
+
+	// data[n:len(data)] is buffered data; data[len(data):cap(data)] is free buffer space
+	data  []byte // data
+	n     int    // read offset
+	state error  // last read error
+
+	// if the reader past to NewReader was
+	// also an io.Seeker, this is non-nil
+	rs io.Seeker
+}
+
+// Reset resets the underlying reader
+// and the read buffer.
+func (r *Reader) Reset(rd io.Reader) {
+	r.r = rd
+	r.data = r.data[0:0]
+	r.n = 0
+	r.state = nil
+	if s, ok := rd.(io.Seeker); ok {
+		r.rs = s
+	} else {
+		r.rs = nil
+	}
+}
+
+// more() does one read on the underlying reader
+func (r *Reader) more() {
+	// move data backwards so that
+	// the read offset is 0; this way
+	// we can supply the maximum number of
+	// bytes to the reader
+	if r.n != 0 {
+		if r.n < len(r.data) {
+			r.data = r.data[:copy(r.data[0:], r.data[r.n:])]
+		} else {
+			r.data = r.data[:0]
+		}
+		r.n = 0
+	}
+	var a int
+	a, r.state = r.r.Read(r.data[len(r.data):cap(r.data)])
+	if a == 0 && r.state == nil {
+		r.state = io.ErrNoProgress
+		return
+	} else if a > 0 && r.state == io.EOF {
+		// discard the io.EOF if we read more than 0 bytes.
+		// the next call to Read should return io.EOF again.
+		r.state = nil
+	}
+	r.data = r.data[:len(r.data)+a]
+}
+
+// pop error
+func (r *Reader) err() (e error) {
+	e, r.state = r.state, nil
+	return
+}
+
+// pop error; EOF -> io.ErrUnexpectedEOF
+func (r *Reader) noEOF() (e error) {
+	e, r.state = r.state, nil
+	if e == io.EOF {
+		e = io.ErrUnexpectedEOF
+	}
+	return
+}
+
+// buffered bytes
+func (r *Reader) buffered() int { return len(r.data) - r.n }
+
+// Buffered returns the number of bytes currently in the buffer
+func (r *Reader) Buffered() int { return len(r.data) - r.n }
+
+// BufferSize returns the total size of the buffer
+func (r *Reader) BufferSize() int { return cap(r.data) }
+
+// Peek returns the next 'n' buffered bytes,
+// reading from the underlying reader if necessary.
+// It will only return a slice shorter than 'n' bytes
+// if it also returns an error. Peek does not advance
+// the reader. EOF errors are *not* returned as
+// io.ErrUnexpectedEOF.
+func (r *Reader) Peek(n int) ([]byte, error) {
+	// in the degenerate case,
+	// we may need to realloc
+	// (the caller asked for more
+	// bytes than the size of the buffer)
+	if cap(r.data) < n {
+		old := r.data[r.n:]
+		r.data = make([]byte, n+r.buffered())
+		r.data = r.data[:copy(r.data, old)]
+		r.n = 0
+	}
+
+	// keep filling until
+	// we hit an error or
+	// read enough bytes
+	for r.buffered() < n && r.state == nil {
+		r.more()
+	}
+
+	// we must have hit an error
+	if r.buffered() < n {
+		return r.data[r.n:], r.err()
+	}
+
+	return r.data[r.n : r.n+n], nil
+}
+
+// Skip moves the reader forward 'n' bytes.
+// Returns the number of bytes skipped and any
+// errors encountered. It is analogous to Seek(n, 1).
+// If the underlying reader implements io.Seeker, then
+// that method will be used to skip forward.
+//
+// If the reader encounters
+// an EOF before skipping 'n' bytes, it
+// returns io.ErrUnexpectedEOF. If the
+// underlying reader implements io.Seeker, then
+// those rules apply instead. (Many implementations
+// will not return `io.EOF` until the next call
+// to Read.)
+func (r *Reader) Skip(n int) (int, error) {
+
+	// fast path
+	if r.buffered() >= n {
+		r.n += n
+		return n, nil
+	}
+
+	// use seeker implementation
+	// if we can
+	if r.rs != nil {
+		return r.skipSeek(n)
+	}
+
+	// loop on filling
+	// and then erasing
+	o := n
+	for r.buffered() < n && r.state == nil {
+		r.more()
+		// we can skip forward
+		// up to r.buffered() bytes
+		step := min(r.buffered(), n)
+		r.n += step
+		n -= step
+	}
+	// at this point, n should be
+	// 0 if everything went smoothly
+	return o - n, r.noEOF()
+}
+
+// Next returns the next 'n' bytes in the stream.
+// Unlike Peek, Next advances the reader position.
+// The returned bytes point to the same
+// data as the buffer, so the slice is
+// only valid until the next reader method call.
+// An EOF is considered an unexpected error.
+// If an the returned slice is less than the
+// length asked for, an error will be returned,
+// and the reader position will not be incremented.
+func (r *Reader) Next(n int) ([]byte, error) {
+
+	// in case the buffer is too small
+	if cap(r.data) < n {
+		old := r.data[r.n:]
+		r.data = make([]byte, n+r.buffered())
+		r.data = r.data[:copy(r.data, old)]
+		r.n = 0
+	}
+
+	// fill at least 'n' bytes
+	for r.buffered() < n && r.state == nil {
+		r.more()
+	}
+
+	if r.buffered() < n {
+		return r.data[r.n:], r.noEOF()
+	}
+	out := r.data[r.n : r.n+n]
+	r.n += n
+	return out, nil
+}
+
+// skipSeek uses the io.Seeker to seek forward.
+// only call this function when n > r.buffered()
+func (r *Reader) skipSeek(n int) (int, error) {
+	o := r.buffered()
+	// first, clear buffer
+	n -= o
+	r.n = 0
+	r.data = r.data[:0]
+
+	// then seek forward remaning bytes
+	i, err := r.rs.Seek(int64(n), 1)
+	return int(i) + o, err
+}
+
+// Read implements `io.Reader`
+func (r *Reader) Read(b []byte) (int, error) {
+	// if we have data in the buffer, just
+	// return that.
+	if r.buffered() != 0 {
+		x := copy(b, r.data[r.n:])
+		r.n += x
+		return x, nil
+	}
+	var n int
+	// we have no buffered data; determine
+	// whether or not to buffer or call
+	// the underlying reader directly
+	if len(b) >= cap(r.data) {
+		n, r.state = r.r.Read(b)
+	} else {
+		r.more()
+		n = copy(b, r.data)
+		r.n = n
+	}
+	if n == 0 {
+		return 0, r.err()
+	}
+	return n, nil
+}
+
+// ReadFull attempts to read len(b) bytes into
+// 'b'. It returns the number of bytes read into
+// 'b', and an error if it does not return len(b).
+// EOF is considered an unexpected error.
+func (r *Reader) ReadFull(b []byte) (int, error) {
+	var n int  // read into b
+	var nn int // scratch
+	l := len(b)
+	// either read buffered data,
+	// or read directly for the underlying
+	// buffer, or fetch more buffered data.
+	for n < l && r.state == nil {
+		if r.buffered() != 0 {
+			nn = copy(b[n:], r.data[r.n:])
+			n += nn
+			r.n += nn
+		} else if l-n > cap(r.data) {
+			nn, r.state = r.r.Read(b[n:])
+			n += nn
+		} else {
+			r.more()
+		}
+	}
+	if n < l {
+		return n, r.noEOF()
+	}
+	return n, nil
+}
+
+// ReadByte implements `io.ByteReader`
+func (r *Reader) ReadByte() (byte, error) {
+	for r.buffered() < 1 && r.state == nil {
+		r.more()
+	}
+	if r.buffered() < 1 {
+		return 0, r.err()
+	}
+	b := r.data[r.n]
+	r.n++
+	return b, nil
+}
+
+// WriteTo implements `io.WriterTo`
+func (r *Reader) WriteTo(w io.Writer) (int64, error) {
+	var (
+		i   int64
+		ii  int
+		err error
+	)
+	// first, clear buffer
+	if r.buffered() > 0 {
+		ii, err = w.Write(r.data[r.n:])
+		i += int64(ii)
+		if err != nil {
+			return i, err
+		}
+		r.data = r.data[0:0]
+		r.n = 0
+	}
+	for r.state == nil {
+		// here we just do
+		// 1:1 reads and writes
+		r.more()
+		if r.buffered() > 0 {
+			ii, err = w.Write(r.data)
+			i += int64(ii)
+			if err != nil {
+				return i, err
+			}
+			r.data = r.data[0:0]
+			r.n = 0
+		}
+	}
+	if r.state != io.EOF {
+		return i, r.err()
+	}
+	return i, nil
+}
+
+func min(a int, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+func max(a int, b int) int {
+	if a < b {
+		return b
+	}
+	return a
+}