chore: make deps, go mod vendor

vendor/google.golang.org/grpc/mem/buffer_slice.go

@@ -0,0 +1,226 @@
+/*
+ *
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package mem
+
+import (
+	"io"
+)
+
+// BufferSlice offers a means to represent data that spans one or more Buffer
+// instances. A BufferSlice is meant to be immutable after creation, and methods
+// like Ref create and return copies of the slice. This is why all methods have
+// value receivers rather than pointer receivers.
+//
+// Note that any of the methods that read the underlying buffers such as Ref,
+// Len or CopyTo etc., will panic if any underlying buffers have already been
+// freed. It is recommended to not directly interact with any of the underlying
+// buffers directly, rather such interactions should be mediated through the
+// various methods on this type.
+//
+// By convention, any APIs that return (mem.BufferSlice, error) should reduce
+// the burden on the caller by never returning a mem.BufferSlice that needs to
+// be freed if the error is non-nil, unless explicitly stated.
+type BufferSlice []Buffer
+
+// Len returns the sum of the length of all the Buffers in this slice.
+//
+// # Warning
+//
+// Invoking the built-in len on a BufferSlice will return the number of buffers
+// in the slice, and *not* the value returned by this function.
+func (s BufferSlice) Len() int {
+	var length int
+	for _, b := range s {
+		length += b.Len()
+	}
+	return length
+}
+
+// Ref invokes Ref on each buffer in the slice.
+func (s BufferSlice) Ref() {
+	for _, b := range s {
+		b.Ref()
+	}
+}
+
+// Free invokes Buffer.Free() on each Buffer in the slice.
+func (s BufferSlice) Free() {
+	for _, b := range s {
+		b.Free()
+	}
+}
+
+// CopyTo copies each of the underlying Buffer's data into the given buffer,
+// returning the number of bytes copied. Has the same semantics as the copy
+// builtin in that it will copy as many bytes as it can, stopping when either dst
+// is full or s runs out of data, returning the minimum of s.Len() and len(dst).
+func (s BufferSlice) CopyTo(dst []byte) int {
+	off := 0
+	for _, b := range s {
+		off += copy(dst[off:], b.ReadOnlyData())
+	}
+	return off
+}
+
+// Materialize concatenates all the underlying Buffer's data into a single
+// contiguous buffer using CopyTo.
+func (s BufferSlice) Materialize() []byte {
+	l := s.Len()
+	if l == 0 {
+		return nil
+	}
+	out := make([]byte, l)
+	s.CopyTo(out)
+	return out
+}
+
+// MaterializeToBuffer functions like Materialize except that it writes the data
+// to a single Buffer pulled from the given BufferPool.
+//
+// As a special case, if the input BufferSlice only actually has one Buffer, this
+// function simply increases the refcount before returning said Buffer. Freeing this
+// buffer won't release it until the BufferSlice is itself released.
+func (s BufferSlice) MaterializeToBuffer(pool BufferPool) Buffer {
+	if len(s) == 1 {
+		s[0].Ref()
+		return s[0]
+	}
+	sLen := s.Len()
+	if sLen == 0 {
+		return emptyBuffer{}
+	}
+	buf := pool.Get(sLen)
+	s.CopyTo(*buf)
+	return NewBuffer(buf, pool)
+}
+
+// Reader returns a new Reader for the input slice after taking references to
+// each underlying buffer.
+func (s BufferSlice) Reader() Reader {
+	s.Ref()
+	return &sliceReader{
+		data: s,
+		len:  s.Len(),
+	}
+}
+
+// Reader exposes a BufferSlice's data as an io.Reader, allowing it to interface
+// with other parts systems. It also provides an additional convenience method
+// Remaining(), which returns the number of unread bytes remaining in the slice.
+// Buffers will be freed as they are read.
+type Reader interface {
+	io.Reader
+	io.ByteReader
+	// Close frees the underlying BufferSlice and never returns an error. Subsequent
+	// calls to Read will return (0, io.EOF).
+	Close() error
+	// Remaining returns the number of unread bytes remaining in the slice.
+	Remaining() int
+}
+
+type sliceReader struct {
+	data BufferSlice
+	len  int
+	// The index into data[0].ReadOnlyData().
+	bufferIdx int
+}
+
+func (r *sliceReader) Remaining() int {
+	return r.len
+}
+
+func (r *sliceReader) Close() error {
+	r.data.Free()
+	r.data = nil
+	r.len = 0
+	return nil
+}
+
+func (r *sliceReader) freeFirstBufferIfEmpty() bool {
+	if len(r.data) == 0 || r.bufferIdx != len(r.data[0].ReadOnlyData()) {
+		return false
+	}
+
+	r.data[0].Free()
+	r.data = r.data[1:]
+	r.bufferIdx = 0
+	return true
+}
+
+func (r *sliceReader) Read(buf []byte) (n int, _ error) {
+	if r.len == 0 {
+		return 0, io.EOF
+	}
+
+	for len(buf) != 0 && r.len != 0 {
+		// Copy as much as possible from the first Buffer in the slice into the
+		// given byte slice.
+		data := r.data[0].ReadOnlyData()
+		copied := copy(buf, data[r.bufferIdx:])
+		r.len -= copied       // Reduce len by the number of bytes copied.
+		r.bufferIdx += copied // Increment the buffer index.
+		n += copied           // Increment the total number of bytes read.
+		buf = buf[copied:]    // Shrink the given byte slice.
+
+		// If we have copied all the data from the first Buffer, free it and advance to
+		// the next in the slice.
+		r.freeFirstBufferIfEmpty()
+	}
+
+	return n, nil
+}
+
+func (r *sliceReader) ReadByte() (byte, error) {
+	if r.len == 0 {
+		return 0, io.EOF
+	}
+
+	// There may be any number of empty buffers in the slice, clear them all until a
+	// non-empty buffer is reached. This is guaranteed to exit since r.len is not 0.
+	for r.freeFirstBufferIfEmpty() {
+	}
+
+	b := r.data[0].ReadOnlyData()[r.bufferIdx]
+	r.len--
+	r.bufferIdx++
+	// Free the first buffer in the slice if the last byte was read
+	r.freeFirstBufferIfEmpty()
+	return b, nil
+}
+
+var _ io.Writer = (*writer)(nil)
+
+type writer struct {
+	buffers *BufferSlice
+	pool    BufferPool
+}
+
+func (w *writer) Write(p []byte) (n int, err error) {
+	b := Copy(p, w.pool)
+	*w.buffers = append(*w.buffers, b)
+	return b.Len(), nil
+}
+
+// NewWriter wraps the given BufferSlice and BufferPool to implement the
+// io.Writer interface. Every call to Write copies the contents of the given
+// buffer into a new Buffer pulled from the given pool and the Buffer is added to
+// the given BufferSlice.
+func NewWriter(buffers *BufferSlice, pool BufferPool) io.Writer {
+	return &writer{buffers: buffers, pool: pool}
+}