Add basic bandwidth monitoring for replication. (#10501)

This change tracks bandwidth for a bucket and object

- [x] Add Admin API
- [x] Add Peer API
- [x] Add BW throttling
- [x] Admin APIs to set replication limit
- [x] Admin APIs for fetch bandwidth

pkg/bucket/bandwidth/monitor.go

@@ -0,0 +1,175 @@
+/*
+ * MinIO Cloud Storage, (C) 2020 MinIO, Inc.
+ *
+ * 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 bandwidth
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"github.com/minio/minio/pkg/bandwidth"
+	"github.com/minio/minio/pkg/pubsub"
+)
+
+// throttleBandwidth gets the throttle for bucket with the configured value
+func (m *Monitor) throttleBandwidth(ctx context.Context, bucket string, bandwidthBytesPerSecond int64) *throttle {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	throttle, ok := m.bucketThrottle[bucket]
+	if !ok {
+		throttle = newThrottle(ctx, bandwidthBytesPerSecond)
+		m.bucketThrottle[bucket] = throttle
+		return throttle
+	}
+	throttle.SetBandwidth(bandwidthBytesPerSecond)
+	return throttle
+}
+
+// SubscribeToBuckets subscribes to buckets. Empty array for monitoring all buckets.
+func (m *Monitor) SubscribeToBuckets(subCh chan interface{}, doneCh <-chan struct{}, buckets []string) {
+	m.pubsub.Subscribe(subCh, doneCh, func(f interface{}) bool {
+		if buckets != nil || len(buckets) == 0 {
+			return true
+		}
+		report, ok := f.(*bandwidth.Report)
+		if !ok {
+			return false
+		}
+		for _, b := range buckets {
+			_, ok := report.BucketStats[b]
+			if ok {
+				return true
+			}
+		}
+		return false
+	})
+}
+
+// Monitor implements the monitoring for bandwidth measurements.
+type Monitor struct {
+	lock sync.Mutex // lock for all updates
+
+	activeBuckets map[string]*bucketMeasurement // Buckets with objects in flight
+
+	bucketMovingAvgTicker *time.Ticker // Ticker for calculating moving averages
+
+	pubsub *pubsub.PubSub // PubSub for reporting bandwidths.
+
+	bucketThrottle map[string]*throttle
+
+	startProcessing sync.Once
+
+	doneCh <-chan struct{}
+}
+
+// NewMonitor returns a monitor with defaults.
+func NewMonitor(doneCh <-chan struct{}) *Monitor {
+	m := &Monitor{
+		activeBuckets:         make(map[string]*bucketMeasurement),
+		bucketMovingAvgTicker: time.NewTicker(1 * time.Second),
+		pubsub:                pubsub.New(),
+		bucketThrottle:        make(map[string]*throttle),
+		doneCh:                doneCh,
+	}
+	return m
+}
+
+// SelectionFunction for buckets
+type SelectionFunction func(bucket string) bool
+
+// SelectAllBuckets will select all buckets
+func SelectAllBuckets() SelectionFunction {
+	return func(bucket string) bool {
+		return true
+	}
+}
+
+// SelectBuckets will select all the buckets passed in.
+func SelectBuckets(buckets ...string) SelectionFunction {
+	return func(bucket string) bool {
+		for _, b := range buckets {
+			if b != "" && b == bucket {
+				return true
+			}
+		}
+		return false
+	}
+}
+
+// GetReport gets the report for all bucket bandwidth details.
+func (m *Monitor) GetReport(selectBucket SelectionFunction) *bandwidth.Report {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	return m.getReport(selectBucket)
+}
+
+func (m *Monitor) getReport(selectBucket SelectionFunction) *bandwidth.Report {
+	report := &bandwidth.Report{
+		BucketStats: make(map[string]bandwidth.Details),
+	}
+	for bucket, bucketMeasurement := range m.activeBuckets {
+		if !selectBucket(bucket) {
+			continue
+		}
+		report.BucketStats[bucket] = bandwidth.Details{
+			LimitInBytesPerSecond:            m.bucketThrottle[bucket].bytesPerSecond,
+			CurrentBandwidthInBytesPerSecond: bucketMeasurement.getExpMovingAvgBytesPerSecond(),
+		}
+	}
+	return report
+}
+
+func (m *Monitor) process(doneCh <-chan struct{}) {
+	for {
+		select {
+		case <-m.bucketMovingAvgTicker.C:
+			m.processAvg()
+		case <-doneCh:
+			return
+		default:
+		}
+	}
+}
+
+func (m *Monitor) getBucketMeasurement(bucket string, initTime time.Time) *bucketMeasurement {
+	bucketTracker, ok := m.activeBuckets[bucket]
+	if !ok {
+		bucketTracker = newBucketMeasurement(initTime)
+		m.activeBuckets[bucket] = bucketTracker
+	}
+	return bucketTracker
+}
+
+func (m *Monitor) processAvg() {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	for _, bucketMeasurement := range m.activeBuckets {
+		bucketMeasurement.updateExponentialMovingAverage(time.Now())
+	}
+	m.pubsub.Publish(m.getReport(SelectAllBuckets()))
+}
+
+// track returns the measurement object for bucket and object
+func (m *Monitor) track(bucket string, object string, timeNow time.Time) *bucketMeasurement {
+	m.lock.Lock()
+	defer m.lock.Unlock()
+	m.startProcessing.Do(func() {
+		go m.process(m.doneCh)
+	})
+	b := m.getBucketMeasurement(bucket, timeNow)
+	return b
+}