Add CgroupSummary to parse /proc/cgroups (prometheus#424)

* add CgroupSummary to parse /proc/cgroups

Signed-off-by: bielu <[email protected]>

* update copyright

Signed-off-by: bielu <[email protected]>

proc_cgroups.go

@@ -0,0 +1,98 @@
+// Copyright 2021 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 (
+	"bufio"
+	"bytes"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/prometheus/procfs/internal/util"
+)
+
+// CgroupSummary models one line from /proc/cgroups.
+// This file contains information about the controllers that are compiled into the kernel.
+//
+// Also see http://man7.org/linux/man-pages/man7/cgroups.7.html
+type CgroupSummary struct {
+	// The name of the controller. controller is also known as subsystem.
+	SubsysName string
+	// The unique ID of the cgroup hierarchy on which this controller is mounted.
+	Hierarchy int
+	// The number of control groups in this hierarchy using this controller.
+	Cgroups int
+	// This field contains the value 1 if this controller is enabled, or 0 if it has been disabled
+	Enabled int
+}
+
+// parseCgroupSummary parses each line of the /proc/cgroup file
+// Line format is `subsys_name	hierarchy	num_cgroups	enabled`.
+func parseCgroupSummaryString(CgroupSummaryStr string) (*CgroupSummary, error) {
+	var err error
+
+	fields := strings.Fields(CgroupSummaryStr)
+	// require at least 4 fields
+	if len(fields) < 4 {
+		return nil, fmt.Errorf("at least 4 fields required, found %d fields in cgroup info string: %s", len(fields), CgroupSummaryStr)
+	}
+
+	CgroupSummary := &CgroupSummary{
+		SubsysName: fields[0],
+	}
+	CgroupSummary.Hierarchy, err = strconv.Atoi(fields[1])
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse hierarchy ID")
+	}
+	CgroupSummary.Cgroups, err = strconv.Atoi(fields[2])
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse Cgroup Num")
+	}
+	CgroupSummary.Enabled, err = strconv.Atoi(fields[3])
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse Enabled")
+	}
+	return CgroupSummary, nil
+}
+
+// parseCgroupSummary reads each line of the /proc/cgroup file.
+func parseCgroupSummary(data []byte) ([]CgroupSummary, error) {
+	var CgroupSummarys []CgroupSummary
+	scanner := bufio.NewScanner(bytes.NewReader(data))
+	for scanner.Scan() {
+		CgroupSummaryString := scanner.Text()
+		// ignore comment lines
+		if strings.HasPrefix(CgroupSummaryString, "#") {
+			continue
+		}
+		CgroupSummary, err := parseCgroupSummaryString(CgroupSummaryString)
+		if err != nil {
+			return nil, err
+		}
+		CgroupSummarys = append(CgroupSummarys, *CgroupSummary)
+	}
+
+	err := scanner.Err()
+	return CgroupSummarys, err
+}
+
+// CgroupSummarys returns information about current /proc/cgroups.
+func (fs FS) CgroupSummarys() ([]CgroupSummary, error) {
+	data, err := util.ReadFileNoStat(fs.proc.Path("cgroups"))
+	if err != nil {
+		return nil, err
+	}
+	return parseCgroupSummary(data)
+}

proc_cgroups_test.go

@@ -0,0 +1,64 @@
+// Copyright 2021 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 (
+	"reflect"
+	"testing"
+)
+
+func TestParseCgroupSummaryString(t *testing.T) {
+	tests := []struct {
+		name          string
+		s             string
+		shouldErr     bool
+		CgroupSummary *CgroupSummary
+	}{
+		{
+			name: "cpuset simple line",
+			s: "cpuset	7	148	1",
+			shouldErr: false,
+			CgroupSummary: &CgroupSummary{
+				SubsysName: "cpuset",
+				Hierarchy:  7,
+				Cgroups:    148,
+				Enabled:    1,
+			},
+		},
+		{
+			name: "memory cgroup number mis format",
+			s: "memory	9	##	1",
+			shouldErr:     true,
+			CgroupSummary: nil,
+		},
+	}
+
+	for i, test := range tests {
+		t.Logf("[%02d] test %q", i, test.name)
+
+		CgroupSummary, err := parseCgroupSummaryString(test.s)
+
+		if test.shouldErr && err == nil {
+			t.Errorf("%s: expected an error, but none occurred", test.name)
+		}
+		if !test.shouldErr && err != nil {
+			t.Errorf("%s: unexpected error: %v", test.name, err)
+		}
+
+		if want, have := test.CgroupSummary, CgroupSummary; !reflect.DeepEqual(want, have) {
+			t.Errorf("cgroup:\nwant:\n%+v\nhave:\n%+v", want, have)
+		}
+	}
+
+}