Implement oboard diagnostics admin API (#9024)

- Implement a graph algorithm to test network bandwidth from every 
  node to every other node
- Saturate any network bandwidth adaptively, accounting for slow 
  and fast network capacity
- Implement parallel drive OBD tests
- Implement a paging mechanism for OBD test to provide periodic updates to client
- Implement Sys, Process, Host, Mem OBD Infos

pkg/net/obd.go

@@ -0,0 +1,116 @@
+/*
+ * 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 net
+
+import (
+	"github.com/montanaflynn/stats"
+)
+
+// Latency holds latency information for read/write operations to the drive
+type Latency struct {
+	Avg          float64 `json:"avg_secs,omitempty"`
+	Percentile50 float64 `json:"percentile50_secs,omitempty"`
+	Percentile90 float64 `json:"percentile90_secs,omitempty"`
+	Percentile99 float64 `json:"percentile99_secs,omitempty"`
+	Min          float64 `json:"min_secs,omitempty"`
+	Max          float64 `json:"max_secs,omitempty"`
+}
+
+// Throughput holds throughput information for read/write operations to the drive
+type Throughput struct {
+	Avg          float64 `json:"avg_bytes_per_sec,omitempty"`
+	Percentile50 float64 `json:"percentile50_bytes_per_sec,omitempty"`
+	Percentile90 float64 `json:"percentile90_bytes_per_sec,omitempty"`
+	Percentile99 float64 `json:"percentile99_bytes_per_sec,omitempty"`
+	Min          float64 `json:"min_bytes_per_sec,omitempty"`
+	Max          float64 `json:"max_bytes_per_sec,omitempty"`
+}
+
+// ComputeOBDStats takes arrays of Latency & Throughput to compute Statistics
+func ComputeOBDStats(latencies, throughputs []float64) (Latency, Throughput, error) {
+	var avgLatency float64
+	var percentile50Latency float64
+	var percentile90Latency float64
+	var percentile99Latency float64
+	var minLatency float64
+	var maxLatency float64
+
+	var avgThroughput float64
+	var percentile50Throughput float64
+	var percentile90Throughput float64
+	var percentile99Throughput float64
+	var minThroughput float64
+	var maxThroughput float64
+	var err error
+
+	if avgLatency, err = stats.Mean(latencies); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if percentile50Latency, err = stats.Percentile(latencies, 50); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if percentile90Latency, err = stats.Percentile(latencies, 90); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if percentile99Latency, err = stats.Percentile(latencies, 99); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if maxLatency, err = stats.Max(latencies); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if minLatency, err = stats.Min(latencies); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	l := Latency{
+		Avg:          avgLatency,
+		Percentile50: percentile50Latency,
+		Percentile90: percentile90Latency,
+		Percentile99: percentile99Latency,
+		Min:          minLatency,
+		Max:          maxLatency,
+	}
+
+	if avgThroughput, err = stats.Mean(throughputs); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if percentile50Throughput, err = stats.Percentile(throughputs, 50); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if percentile90Throughput, err = stats.Percentile(throughputs, 90); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if percentile99Throughput, err = stats.Percentile(throughputs, 99); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if maxThroughput, err = stats.Max(throughputs); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	if minThroughput, err = stats.Min(throughputs); err != nil {
+		return Latency{}, Throughput{}, err
+	}
+	t := Throughput{
+		Avg:          avgThroughput,
+		Percentile50: percentile50Throughput,
+		Percentile90: percentile90Throughput,
+		Percentile99: percentile99Throughput,
+		Min:          minThroughput,
+		Max:          maxThroughput,
+	}
+
+	return l, t, nil
+}