[VOL-3255] enhancement to support device metrics

Change-Id: Ic26c2db30a58943a4eef6276ae1cf40350d51702
diff --git a/vendor/github.com/prometheus/procfs/mdstat.go b/vendor/github.com/prometheus/procfs/mdstat.go
new file mode 100644
index 0000000..2af3ada
--- /dev/null
+++ b/vendor/github.com/prometheus/procfs/mdstat.go
@@ -0,0 +1,194 @@
+// Copyright 2018 The Prometheus Authors
+// 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 procfs
+
+import (
+	"fmt"
+	"io/ioutil"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	statusLineRE   = regexp.MustCompile(`(\d+) blocks .*\[(\d+)/(\d+)\] \[[U_]+\]`)
+	recoveryLineRE = regexp.MustCompile(`\((\d+)/\d+\)`)
+)
+
+// MDStat holds info parsed from /proc/mdstat.
+type MDStat struct {
+	// Name of the device.
+	Name string
+	// activity-state of the device.
+	ActivityState string
+	// Number of active disks.
+	DisksActive int64
+	// Total number of disks the device requires.
+	DisksTotal int64
+	// Number of failed disks.
+	DisksFailed int64
+	// Spare disks in the device.
+	DisksSpare int64
+	// Number of blocks the device holds.
+	BlocksTotal int64
+	// Number of blocks on the device that are in sync.
+	BlocksSynced int64
+}
+
+// MDStat parses an mdstat-file (/proc/mdstat) and returns a slice of
+// structs containing the relevant info.  More information available here:
+// https://raid.wiki.kernel.org/index.php/Mdstat
+func (fs FS) MDStat() ([]MDStat, error) {
+	data, err := ioutil.ReadFile(fs.proc.Path("mdstat"))
+	if err != nil {
+		return nil, fmt.Errorf("error parsing mdstat %s: %s", fs.proc.Path("mdstat"), err)
+	}
+	mdstat, err := parseMDStat(data)
+	if err != nil {
+		return nil, fmt.Errorf("error parsing mdstat %s: %s", fs.proc.Path("mdstat"), err)
+	}
+	return mdstat, nil
+}
+
+// parseMDStat parses data from mdstat file (/proc/mdstat) and returns a slice of
+// structs containing the relevant info.
+func parseMDStat(mdStatData []byte) ([]MDStat, error) {
+	mdStats := []MDStat{}
+	lines := strings.Split(string(mdStatData), "\n")
+
+	for i, line := range lines {
+		if strings.TrimSpace(line) == "" || line[0] == ' ' ||
+			strings.HasPrefix(line, "Personalities") ||
+			strings.HasPrefix(line, "unused") {
+			continue
+		}
+
+		deviceFields := strings.Fields(line)
+		if len(deviceFields) < 3 {
+			return nil, fmt.Errorf("not enough fields in mdline (expected at least 3): %s", line)
+		}
+		mdName := deviceFields[0] // mdx
+		state := deviceFields[2]  // active or inactive
+
+		if len(lines) <= i+3 {
+			return nil, fmt.Errorf(
+				"error parsing %s: too few lines for md device",
+				mdName,
+			)
+		}
+
+		// Failed disks have the suffix (F) & Spare disks have the suffix (S).
+		fail := int64(strings.Count(line, "(F)"))
+		spare := int64(strings.Count(line, "(S)"))
+		active, total, size, err := evalStatusLine(lines[i], lines[i+1])
+
+		if err != nil {
+			return nil, fmt.Errorf("error parsing md device lines: %s", err)
+		}
+
+		syncLineIdx := i + 2
+		if strings.Contains(lines[i+2], "bitmap") { // skip bitmap line
+			syncLineIdx++
+		}
+
+		// If device is syncing at the moment, get the number of currently
+		// synced bytes, otherwise that number equals the size of the device.
+		syncedBlocks := size
+		recovering := strings.Contains(lines[syncLineIdx], "recovery")
+		resyncing := strings.Contains(lines[syncLineIdx], "resync")
+
+		// Append recovery and resyncing state info.
+		if recovering || resyncing {
+			if recovering {
+				state = "recovering"
+			} else {
+				state = "resyncing"
+			}
+
+			// Handle case when resync=PENDING or resync=DELAYED.
+			if strings.Contains(lines[syncLineIdx], "PENDING") ||
+				strings.Contains(lines[syncLineIdx], "DELAYED") {
+				syncedBlocks = 0
+			} else {
+				syncedBlocks, err = evalRecoveryLine(lines[syncLineIdx])
+				if err != nil {
+					return nil, fmt.Errorf("error parsing sync line in md device %s: %s", mdName, err)
+				}
+			}
+		}
+
+		mdStats = append(mdStats, MDStat{
+			Name:          mdName,
+			ActivityState: state,
+			DisksActive:   active,
+			DisksFailed:   fail,
+			DisksSpare:    spare,
+			DisksTotal:    total,
+			BlocksTotal:   size,
+			BlocksSynced:  syncedBlocks,
+		})
+	}
+
+	return mdStats, nil
+}
+
+func evalStatusLine(deviceLine, statusLine string) (active, total, size int64, err error) {
+
+	sizeStr := strings.Fields(statusLine)[0]
+	size, err = strconv.ParseInt(sizeStr, 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unexpected statusLine %s: %s", statusLine, err)
+	}
+
+	if strings.Contains(deviceLine, "raid0") || strings.Contains(deviceLine, "linear") {
+		// In the device deviceLine, only disks have a number associated with them in [].
+		total = int64(strings.Count(deviceLine, "["))
+		return total, total, size, nil
+	}
+
+	if strings.Contains(deviceLine, "inactive") {
+		return 0, 0, size, nil
+	}
+
+	matches := statusLineRE.FindStringSubmatch(statusLine)
+	if len(matches) != 4 {
+		return 0, 0, 0, fmt.Errorf("couldn't find all the substring matches: %s", statusLine)
+	}
+
+	total, err = strconv.ParseInt(matches[2], 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unexpected statusLine %s: %s", statusLine, err)
+	}
+
+	active, err = strconv.ParseInt(matches[3], 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("unexpected statusLine %s: %s", statusLine, err)
+	}
+
+	return active, total, size, nil
+}
+
+func evalRecoveryLine(recoveryLine string) (syncedBlocks int64, err error) {
+	matches := recoveryLineRE.FindStringSubmatch(recoveryLine)
+	if len(matches) != 2 {
+		return 0, fmt.Errorf("unexpected recoveryLine: %s", recoveryLine)
+	}
+
+	syncedBlocks, err = strconv.ParseInt(matches[1], 10, 64)
+	if err != nil {
+		return 0, fmt.Errorf("%s in recoveryLine: %s", err, recoveryLine)
+	}
+
+	return syncedBlocks, nil
+}