Add ServerDrivesPerfInfo() admin API (#6969)

This is part of implementation for mc admin health command. The
ServerDrivesPerfInfo() admin API returns read and write speed
information for all the drives (local and remote) in a given Minio
server deployment.

Part of minio/mc#2606

pkg/disk/disk.go

@@ -1,5 +1,5 @@
 /*
- * Minio Cloud Storage, (C) 2015 Minio, Inc.
+ * Minio Cloud Storage, (C) 2018 Minio, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,26 @@
 
 package disk
 
+import (
+	"bytes"
+	"crypto/rand"
+	"errors"
+	"os"
+	"path"
+	"strconv"
+	"time"
+
+	humanize "github.com/dustin/go-humanize"
+)
+
+// file size for performance read and write checks
+const randBufSize = 1 * humanize.KiByte
+const randParts = 1024
+const fileSize = randParts * randBufSize
+
+// Total count of read / write iteration for performance measurement
+const iterations = 10
+
 // Info stat fs struct is container which holds following values
 // Total - total size of the volume / disk
 // Free - free size of the volume / disk
@@ -32,3 +52,87 @@ type Info struct {
 	// Usage is calculated per tenant.
 	Usage uint64
 }
+
+// Performance holds informantion about read and write speed of a disk
+type Performance struct {
+	Path       string  `json:"path"`
+	Error      string  `json:"error,omitempty"`
+	WriteSpeed float64 `json:"writeSpeed"`
+	ReadSpeed  float64 `json:"readSpeed"`
+}
+
+// GetPerformance returns given disk's read and write performance
+func GetPerformance(path string) Performance {
+	perf := Performance{}
+	write, read, err := doPerfMeasure(path)
+	if err != nil {
+		perf.Error = err.Error()
+		return perf
+	}
+	perf.WriteSpeed = write
+	perf.ReadSpeed = read
+	return perf
+}
+
+// Calculate the write and read performance - write and read 10 tmp (1 MiB)
+// files and find the average time taken (Bytes / Sec)
+func doPerfMeasure(fsPath string) (write, read float64, err error) {
+	var count int
+	var totalWriteElapsed time.Duration
+	var totalReadElapsed time.Duration
+
+	defer os.RemoveAll(fsPath)
+
+	randBuf := make([]byte, randBufSize)
+	rand.Read(randBuf)
+	buf := bytes.Repeat(randBuf, randParts)
+
+	// create the enclosing directory
+	err = os.MkdirAll(fsPath, 0777)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	for count = 1; count <= iterations; count++ {
+		fsTempObjPath := path.Join(fsPath, strconv.Itoa(count))
+
+		// Write performance calculation
+		writeStart := time.Now()
+		n, err := writeFile(fsTempObjPath, buf)
+
+		if err != nil {
+			return 0, 0, err
+		}
+		if n != fileSize {
+			return 0, 0, errors.New("Could not write temporary data to disk")
+		}
+
+		writeElapsed := time.Since(writeStart)
+		totalWriteElapsed += writeElapsed
+
+		// Read performance calculation
+		readStart := time.Now()
+		n, err = readFile(fsTempObjPath, buf)
+
+		if err != nil {
+			return 0, 0, err
+		}
+		if n != fileSize {
+			return 0, 0, errors.New("Could not read temporary data from disk")
+		}
+
+		readElapsed := time.Since(readStart)
+		totalReadElapsed += readElapsed
+	}
+	// Average time spent = total time elapsed / number of writes
+	avgWriteTime := totalWriteElapsed.Seconds() / float64(count)
+	// Write perf = fileSize (in Bytes) / average time spent writing (in seconds)
+	write = fileSize / avgWriteTime
+
+	// Average time spent = total time elapsed / number of writes
+	avgReadTime := totalReadElapsed.Seconds() / float64(count)
+	// read perf = fileSize (in Bytes) / average time spent reading (in seconds)
+	read = fileSize / avgReadTime
+
+	return write, read, nil
+}

pkg/disk/helpers.go

@@ -0,0 +1,52 @@
+/*
+ * Minio Cloud Storage, (C) 2018 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 disk
+
+import (
+	"os"
+)
+
+func readFile(path string, buf []byte) (int, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	n, err := f.Read(buf)
+	if err != nil {
+		return 0, err
+	}
+
+	return n, nil
+}
+
+func writeFile(path string, data []byte) (int, error) {
+	f, err := os.Create(path)
+	if err != nil {
+		return 0, err
+	}
+	defer f.Close()
+
+	n, err := f.Write(data)
+	if err != nil {
+		return 0, err
+	}
+
+	f.Sync()
+	return n, nil
+}