Merging upstream version 1.2.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 182 insertions, 0 deletions

diff --git a/dependencies/pkg/mod/github.com/go-sql-driver/mysql@v1.8.1/buffer.go b/dependencies/pkg/mod/github.com/go-sql-driver/mysql@v1.8.1/buffer.go
new file mode 100644
index 0000000..0774c5c
--- /dev/null
+++ b/dependencies/pkg/mod/github.com/go-sql-driver/mysql@v1.8.1/buffer.go
@@ -0,0 +1,182 @@
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2013 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package mysql
+
+import (
+	"io"
+	"net"
+	"time"
+)
+
+const defaultBufSize = 4096
+const maxCachedBufSize = 256 * 1024
+
+// A buffer which is used for both reading and writing.
+// This is possible since communication on each connection is synchronous.
+// In other words, we can't write and read simultaneously on the same connection.
+// The buffer is similar to bufio.Reader / Writer but zero-copy-ish
+// Also highly optimized for this particular use case.
+// This buffer is backed by two byte slices in a double-buffering scheme
+type buffer struct {
+	buf     []byte // buf is a byte buffer who's length and capacity are equal.
+	nc      net.Conn
+	idx     int
+	length  int
+	timeout time.Duration
+	dbuf    [2][]byte // dbuf is an array with the two byte slices that back this buffer
+	flipcnt uint      // flipccnt is the current buffer counter for double-buffering
+}
+
+// newBuffer allocates and returns a new buffer.
+func newBuffer(nc net.Conn) buffer {
+	fg := make([]byte, defaultBufSize)
+	return buffer{
+		buf:  fg,
+		nc:   nc,
+		dbuf: [2][]byte{fg, nil},
+	}
+}
+
+// flip replaces the active buffer with the background buffer
+// this is a delayed flip that simply increases the buffer counter;
+// the actual flip will be performed the next time we call `buffer.fill`
+func (b *buffer) flip() {
+	b.flipcnt += 1
+}
+
+// fill reads into the buffer until at least _need_ bytes are in it
+func (b *buffer) fill(need int) error {
+	n := b.length
+	// fill data into its double-buffering target: if we've called
+	// flip on this buffer, we'll be copying to the background buffer,
+	// and then filling it with network data; otherwise we'll just move
+	// the contents of the current buffer to the front before filling it
+	dest := b.dbuf[b.flipcnt&1]
+
+	// grow buffer if necessary to fit the whole packet.
+	if need > len(dest) {
+		// Round up to the next multiple of the default size
+		dest = make([]byte, ((need/defaultBufSize)+1)*defaultBufSize)
+
+		// if the allocated buffer is not too large, move it to backing storage
+		// to prevent extra allocations on applications that perform large reads
+		if len(dest) <= maxCachedBufSize {
+			b.dbuf[b.flipcnt&1] = dest
+		}
+	}
+
+	// if we're filling the fg buffer, move the existing data to the start of it.
+	// if we're filling the bg buffer, copy over the data
+	if n > 0 {
+		copy(dest[:n], b.buf[b.idx:])
+	}
+
+	b.buf = dest
+	b.idx = 0
+
+	for {
+		if b.timeout > 0 {
+			if err := b.nc.SetReadDeadline(time.Now().Add(b.timeout)); err != nil {
+				return err
+			}
+		}
+
+		nn, err := b.nc.Read(b.buf[n:])
+		n += nn
+
+		switch err {
+		case nil:
+			if n < need {
+				continue
+			}
+			b.length = n
+			return nil
+
+		case io.EOF:
+			if n >= need {
+				b.length = n
+				return nil
+			}
+			return io.ErrUnexpectedEOF
+
+		default:
+			return err
+		}
+	}
+}
+
+// returns next N bytes from buffer.
+// The returned slice is only guaranteed to be valid until the next read
+func (b *buffer) readNext(need int) ([]byte, error) {
+	if b.length < need {
+		// refill
+		if err := b.fill(need); err != nil {
+			return nil, err
+		}
+	}
+
+	offset := b.idx
+	b.idx += need
+	b.length -= need
+	return b.buf[offset:b.idx], nil
+}
+
+// takeBuffer returns a buffer with the requested size.
+// If possible, a slice from the existing buffer is returned.
+// Otherwise a bigger buffer is made.
+// Only one buffer (total) can be used at a time.
+func (b *buffer) takeBuffer(length int) ([]byte, error) {
+	if b.length > 0 {
+		return nil, ErrBusyBuffer
+	}
+
+	// test (cheap) general case first
+	if length <= cap(b.buf) {
+		return b.buf[:length], nil
+	}
+
+	if length < maxPacketSize {
+		b.buf = make([]byte, length)
+		return b.buf, nil
+	}
+
+	// buffer is larger than we want to store.
+	return make([]byte, length), nil
+}
+
+// takeSmallBuffer is shortcut which can be used if length is
+// known to be smaller than defaultBufSize.
+// Only one buffer (total) can be used at a time.
+func (b *buffer) takeSmallBuffer(length int) ([]byte, error) {
+	if b.length > 0 {
+		return nil, ErrBusyBuffer
+	}
+	return b.buf[:length], nil
+}
+
+// takeCompleteBuffer returns the complete existing buffer.
+// This can be used if the necessary buffer size is unknown.
+// cap and len of the returned buffer will be equal.
+// Only one buffer (total) can be used at a time.
+func (b *buffer) takeCompleteBuffer() ([]byte, error) {
+	if b.length > 0 {
+		return nil, ErrBusyBuffer
+	}
+	return b.buf, nil
+}
+
+// store stores buf, an updated buffer, if its suitable to do so.
+func (b *buffer) store(buf []byte) error {
+	if b.length > 0 {
+		return ErrBusyBuffer
+	} else if cap(buf) <= maxPacketSize && cap(buf) > cap(b.buf) {
+		b.buf = buf[:cap(buf)]
+	}
+	return nil
+}