providers/linux: optimize parseKeyValue (#186)

This optimizes `parseKeyValue()` function in the linux provider. It reduces the CPU cost and completely eliminates memory allocations. ``` │ before.txt │ after.txt │ │ sec/op │ sec/op vs base │ ParseKeyValue-10 3540.0n ± ∞ ¹ 972.6n ± ∞ ¹ -72.53% (p=0.008 n=5) │ B/op │ B/op vs base │ ParseKeyValue-10 6.672Ki ± ∞ ¹ 0.000Ki ± ∞ ¹ -100.00% (p=0.008 n=5) │ allocs/op │ allocs/op vs base │ ParseKeyValue-10 58.00 ± ∞ ¹ 0.00 ± ∞ ¹ -100.00% (p=0.008 n=5) ``` --------- Co-authored-by: Andrew Kroh <andrew.kroh@elastic.co> Co-authored-by: Dan Kortschak <90160302+efd6@users.noreply.github.com>
elastic · Aug 16, 2023 · 865a715 · 865a715
1 parent e4ac65c
commit 865a715
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Showing 8 changed files with 186 additions and 13 deletions.
diff --git a/.changelog/186.txt b/.changelog/186.txt
@@ -0,0 +1,3 @@
+```release-note:enhancement
+linux: optimize linux key value parsing (ie: /proc files)
+```
diff --git a/providers/linux/capabilities_linux.go b/providers/linux/capabilities_linux.go
@@ -86,7 +86,7 @@ func capabilityName(num int) string {
 func readCapabilities(content []byte) (*types.CapabilityInfo, error) {
 	var cap types.CapabilityInfo
 
-	err := parseKeyValue(content, ":", func(key, value []byte) error {
+	err := parseKeyValue(content, ':', func(key, value []byte) error {
 		var err error
 		switch string(key) {
 		case "CapInh":

diff --git a/providers/linux/memory_linux.go b/providers/linux/memory_linux.go
@@ -29,7 +29,7 @@ func parseMemInfo(content []byte) (*types.HostMemoryInfo, error) {
 	}
 
 	hasAvailable := false
-	err := parseKeyValue(content, ":", func(key, value []byte) error {
+	err := parseKeyValue(content, ':', func(key, value []byte) error {
 		num, err := parseBytesOrNumber(value)
 		if err != nil {
 			return fmt.Errorf("failed to parse %v value of %v: %w", string(key), string(value), err)

diff --git a/providers/linux/process_linux.go b/providers/linux/process_linux.go
@@ -229,7 +229,7 @@ func (p *process) User() (types.UserInfo, error) {
 	}
 
 	var user types.UserInfo
-	err = parseKeyValue(content, ":", func(key, value []byte) error {
+	err = parseKeyValue(content, ':', func(key, value []byte) error {
 		// See proc(5) for the format of /proc/[pid]/status
 		switch string(key) {
 		case "Uid":

diff --git a/providers/linux/seccomp_linux.go b/providers/linux/seccomp_linux.go
@@ -47,7 +47,7 @@ func (m SeccompMode) String() string {
 func readSeccompFields(content []byte) (*types.SeccompInfo, error) {
 	var seccomp types.SeccompInfo
 
-	err := parseKeyValue(content, ":", func(key, value []byte) error {
+	err := parseKeyValue(content, ':', func(key, value []byte) error {
 		switch string(key) {
 		case "Seccomp":
 			mode, err := strconv.ParseUint(string(value), 10, 8)

diff --git a/providers/linux/util.go b/providers/linux/util.go
@@ -26,20 +26,28 @@ import (
 	"strconv"
 )
 
-func parseKeyValue(content []byte, separator string, callback func(key, value []byte) error) error {
-	sc := bufio.NewScanner(bytes.NewReader(content))
-	for sc.Scan() {
-		parts := bytes.SplitN(sc.Bytes(), []byte(separator), 2)
-		if len(parts) != 2 {
+// parseKeyValue parses key/val pairs separated by the provided separator from
+// each line in content and invokes the callback. White-space is trimmed from
+// val. Empty lines are ignored. All non-empty lines must contain the separator
+// otherwise an error is returned.
+func parseKeyValue(content []byte, separator byte, callback func(key, value []byte) error) error {
+	var line []byte
+
+	for len(content) > 0 {
+		line, content, _ = bytes.Cut(content, []byte{'\n'})
+		if len(line) == 0 {
 			continue
 		}
 
-		if err := callback(parts[0], bytes.TrimSpace(parts[1])); err != nil {
-			return err
+		key, value, ok := bytes.Cut(line, []byte{separator})
+		if !ok {
+			return fmt.Errorf("separator %q not found", separator)
 		}
+
+		callback(key, bytes.TrimSpace(value))
 	}
 
-	return sc.Err()
+	return nil
 }
 
 func findValue(filename, separator, key string) (string, error) {

diff --git a/providers/linux/util_test.go b/providers/linux/util_test.go
@@ -0,0 +1,162 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you 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 linux
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestParseKeyValueNoEOL(t *testing.T) {
+	vals := [][2]string{}
+	err := parseKeyValue([]byte(
+		"Name:	zsh\nUmask:	0022\nState:	S (sleeping)\nUid:	1000	1000	1000	1000",
+	), ':', func(key, value []byte) error {
+		vals = append(vals, [2]string{string(key), string(value)})
+		return nil
+	})
+	assert.NoError(t, err)
+
+	assert.Equal(t, [][2]string{
+		{"Name", "zsh"},
+		{"Umask", "0022"},
+		{"State", "S (sleeping)"},
+		{"Uid", "1000\t1000\t1000\t1000"},
+	}, vals)
+}
+
+func TestParseKeyValueEmptyLine(t *testing.T) {
+	vals := [][2]string{}
+	err := parseKeyValue([]byte(
+		"Name:	zsh\nUmask:	0022\nState:	S (sleeping)\n\nUid:	1000	1000	1000	1000",
+	), ':', func(key, value []byte) error {
+		vals = append(vals, [2]string{string(key), string(value)})
+		return nil
+	})
+	assert.NoError(t, err)
+
+	assert.Equal(t, [][2]string{
+		{"Name", "zsh"},
+		{"Umask", "0022"},
+		{"State", "S (sleeping)"},
+		{"Uid", "1000\t1000\t1000\t1000"},
+	}, vals)
+}
+
+func TestParseKeyValueEOL(t *testing.T) {
+	vals := [][2]string{}
+	err := parseKeyValue([]byte(
+		"Name:	zsh\nUmask:	0022\nState:	S (sleeping)\nUid:	1000	1000	1000	1000\n",
+	), ':', func(key, value []byte) error {
+		vals = append(vals, [2]string{string(key), string(value)})
+		return nil
+	})
+	assert.NoError(t, err)
+
+	assert.Equal(t, [][2]string{
+		{"Name", "zsh"},
+		{"Umask", "0022"},
+		{"State", "S (sleeping)"},
+		{"Uid", "1000\t1000\t1000\t1000"},
+	}, vals)
+}
+
+// from cat /proc/$$/status
+var testProcStatus = []byte(`Name:	zsh
+Umask:	0022
+State:	S (sleeping)
+Tgid:	4023363
+Ngid:	0
+Pid:	4023363
+PPid:	4023357
+TracerPid:	0
+Uid:	1000	1000	1000	1000
+Gid:	1000	1000	1000	1000
+FDSize:	64
+Groups:	24 25 27 29 30 44 46 102 109 112 116 119 131 998 1000
+NStgid:	4023363
+NSpid:	4023363
+NSpgid:	4023363
+NSsid:	4023363
+VmPeak:	   15596 kB
+VmSize:	   15144 kB
+VmLck:	       0 kB
+VmPin:	       0 kB
+VmHWM:	    9060 kB
+VmRSS:	    8716 kB
+RssAnon:	    3828 kB
+RssFile:	    4888 kB
+RssShmem:	       0 kB
+VmData:	    3500 kB
+VmStk:	     328 kB
+VmExe:	     600 kB
+VmLib:	    2676 kB
+VmPTE:	      68 kB
+VmSwap:	       0 kB
+HugetlbPages:	       0 kB
+CoreDumping:	0
+THP_enabled:	1
+Threads:	1
+SigQ:	0/126683
+SigPnd:	0000000000000000
+ShdPnd:	0000000000000000
+SigBlk:	0000000000000002
+SigIgn:	0000000000384000
+SigCgt:	0000000008013003
+CapInh:	0000000000000000
+CapPrm:	0000000000000000
+CapEff:	0000000000000000
+CapBnd:	000001ffffffffff
+CapAmb:	0000000000000000
+NoNewPrivs:	0
+Seccomp:	0
+Seccomp_filters:	0
+Speculation_Store_Bypass:	thread vulnerable
+Cpus_allowed:	fff
+Cpus_allowed_list:	0-11
+Mems_allowed:	00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
+Mems_allowed_list:	0
+voluntary_ctxt_switches:	223
+nonvoluntary_ctxt_switches:	25
+`)
+
+func BenchmarkParseKeyValue(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		_ = parseKeyValue(testProcStatus, ':', func(key, value []byte) error {
+			return nil
+		})
+	}
+}
+
+func FuzzParseKeyValue(f *testing.F) {
+	testcases := []string{
+		"no_separator",
+		"no_value:",
+		"empty_value: ",
+		"normal:	223",
+	}
+	for _, tc := range testcases {
+		f.Add(tc)
+	}
+	f.Fuzz(func(t *testing.T, orig string) {
+		_ = parseKeyValue([]byte(orig), ':', func(key, value []byte) error {
+			return nil
+		})
+	})
+}
diff --git a/providers/linux/vmstat.go b/providers/linux/vmstat.go
@@ -45,7 +45,7 @@ func parseVMStat(content []byte) (*types.VMStatInfo, error) {
 	var vmStat types.VMStatInfo
 	refValues := reflect.ValueOf(&vmStat).Elem()
 
-	err := parseKeyValue(content, " ", func(key, value []byte) error {
+	err := parseKeyValue(content, ' ', func(key, value []byte) error {
 		// turn our []byte value into an int
 		val, err := parseBytesOrNumber(value)
 		if err != nil {