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/bucket/bandwidth/reader.go

@@ -0,0 +1,80 @@
+// 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 bandwidth
+
+import (
+	"context"
+	"io"
+)
+
+// MonitoredReader monitors the bandwidth
+type MonitoredReader struct {
+	opts              *MonitorReaderOptions
+	bucketMeasurement *bucketMeasurement // bucket measurement object
+	reader            io.Reader          // Reader to wrap
+	throttle          *throttle          // throttle the rate at which replication occur
+	monitor           *Monitor           // Monitor reference
+	lastErr           error              // last error reported, if this non-nil all reads will fail.
+}
+
+// MonitorReaderOptions provides configurable options for monitor reader implementation.
+type MonitorReaderOptions struct {
+	Bucket               string
+	Object               string
+	HeaderSize           int
+	BandwidthBytesPerSec int64
+	ClusterBandwidth     int64
+}
+
+// NewMonitoredReader returns a io.Reader that reports bandwidth details.
+func NewMonitoredReader(ctx context.Context, monitor *Monitor, reader io.Reader, opts *MonitorReaderOptions) *MonitoredReader {
+	return &MonitoredReader{
+		opts:              opts,
+		bucketMeasurement: monitor.track(opts.Bucket, opts.Object),
+		reader:            reader,
+		throttle:          monitor.throttleBandwidth(ctx, opts.Bucket, opts.BandwidthBytesPerSec, opts.ClusterBandwidth),
+		monitor:           monitor,
+	}
+}
+
+// Read wraps the read reader
+func (m *MonitoredReader) Read(p []byte) (n int, err error) {
+	if m.lastErr != nil {
+		err = m.lastErr
+		return
+	}
+
+	p = p[:m.throttle.GetLimitForBytes(int64(len(p)))]
+
+	n, err = m.reader.Read(p)
+	if err != nil {
+		m.lastErr = err
+	}
+
+	update := n + m.opts.HeaderSize
+	unused := len(p) - update
+
+	m.bucketMeasurement.incrementBytes(uint64(update))
+	m.opts.HeaderSize = 0 // Set to 0 post first read
+
+	if unused > 0 {
+		m.throttle.ReleaseUnusedBandwidth(int64(unused))
+	}
+
+	return
+}