rename all remaining packages to internal/ (#12418)

This is to ensure that there are no projects
that try to import `minio/minio/pkg` into
their own repo. Any such common packages should
go to `https://github.com/minio/pkg`

internal/bpool/bpool.go

@@ -0,0 +1,72 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package bpool
+
+// BytePoolCap implements a leaky pool of []byte in the form of a bounded channel.
+type BytePoolCap struct {
+	c    chan []byte
+	w    int
+	wcap int
+}
+
+// NewBytePoolCap creates a new BytePool bounded to the given maxSize, with new
+// byte arrays sized based on width.
+func NewBytePoolCap(maxSize int, width int, capwidth int) (bp *BytePoolCap) {
+	return &BytePoolCap{
+		c:    make(chan []byte, maxSize),
+		w:    width,
+		wcap: capwidth,
+	}
+}
+
+// Get gets a []byte from the BytePool, or creates a new one if none are
+// available in the pool.
+func (bp *BytePoolCap) Get() (b []byte) {
+	select {
+	case b = <-bp.c:
+	// reuse existing buffer
+	default:
+		// create new buffer
+		if bp.wcap > 0 {
+			b = make([]byte, bp.w, bp.wcap)
+		} else {
+			b = make([]byte, bp.w)
+		}
+	}
+	return
+}
+
+// Put returns the given Buffer to the BytePool.
+func (bp *BytePoolCap) Put(b []byte) {
+	select {
+	case bp.c <- b:
+		// buffer went back into pool
+	default:
+		// buffer didn't go back into pool, just discard
+	}
+}
+
+// Width returns the width of the byte arrays in this pool.
+func (bp *BytePoolCap) Width() (n int) {
+	return bp.w
+}
+
+// WidthCap returns the cap width of the byte arrays in this pool.
+func (bp *BytePoolCap) WidthCap() (n int) {
+	return bp.wcap
+}