Make pipe buffer implementation standard.

A follow-up change will convert the networking code to use this standard
pipe implementation.

PiperOrigin-RevId: 297903206

1 files changed, 67 insertions, 0 deletions

diff --git a/pkg/buffer/buffer.go b/pkg/buffer/buffer.go
new file mode 100644
index 000000000..d5f64609b
--- /dev/null
+++ b/pkg/buffer/buffer.go
@@ -0,0 +1,67 @@
+// Copyright 2020 The gVisor 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 buffer provides the implementation of a buffer view.
+package buffer
+
+import (
+	"sync"
+)
+
+const bufferSize = 8144 // See below.
+
+// Buffer encapsulates a queueable byte buffer.
+//
+// Note that the total size is slightly less than two pages. This is done
+// intentionally to ensure that the buffer object aligns with runtime
+// internals. We have no hard size or alignment requirements. This two page
+// size will effectively minimize internal fragmentation, but still have a
+// large enough chunk to limit excessive segmentation.
+//
+// +stateify savable
+type Buffer struct {
+	data  [bufferSize]byte
+	read  int
+	write int
+	bufferEntry
+}
+
+// Reset resets internal data.
+//
+// This must be called before use.
+func (b *Buffer) Reset() {
+	b.read = 0
+	b.write = 0
+}
+
+// Empty indicates the buffer is empty.
+//
+// This indicates there is no data left to read.
+func (b *Buffer) Empty() bool {
+	return b.read == b.write
+}
+
+// Full indicates the buffer is full.
+//
+// This indicates there is no capacity left to write.
+func (b *Buffer) Full() bool {
+	return b.write == len(b.data)
+}
+
+// bufferPool is a pool for buffers.
+var bufferPool = sync.Pool{
+	New: func() interface{} {
+		return new(Buffer)
+	},
+}