refactor: replace deprecated ioutil calls (#101)

This PR replace deprecated ioutil calls, deprecated in go 1.16: https://go.dev/doc/go1.16#ioutil Main reason for this is to use the more efficient replacement for `ReadDir`: https://pkg.go.dev/io/ioutil#ReadDir While benchmarking APM Server locally (remote es + local apm-server) I noticed ~32% of cpu time was spent retrieving the metrics from the debugs var handler. The methods are from this library and I think there are a few quick/easy performance improvements.
elastic · Oct 26, 2023 · 3bc3ccc · 3bc3ccc
1 parent 8630a5d
commit 3bc3ccc
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Showing 9 changed files with 20 additions and 29 deletions.
diff --git a/metric/memory/memory_helpers.go b/metric/memory/memory_helpers.go
@@ -22,7 +22,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
+	"os"
 	"strconv"
 	"strings"
 
@@ -58,7 +58,7 @@ func ParseMeminfo(rootfs resolve.Resolver) (map[string]uint64, error) {
 }
 
 func readFile(file string, handler func(string) bool) error {
-	contents, err := ioutil.ReadFile(file)
+	contents, err := os.ReadFile(file)
 	if err != nil {
 		return fmt.Errorf("error reading file %s: %w", file, err)
 	}

diff --git a/metric/system/cgroup/cgcommon/util.go b/metric/system/cgroup/cgcommon/util.go
@@ -21,7 +21,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -36,7 +35,7 @@ var (
 
 // ParseUintFromFile reads a single uint value from a file.
 func ParseUintFromFile(path ...string) (uint64, error) {
-	value, err := ioutil.ReadFile(filepath.Join(path...))
+	value, err := os.ReadFile(filepath.Join(path...))
 	if err != nil {
 		// Not all features are implemented/enabled by each OS.
 		if os.IsNotExist(err) {

diff --git a/metric/system/cgroup/cgv1/cpuacct.go b/metric/system/cgroup/cgv1/cpuacct.go
@@ -21,7 +21,6 @@ import (
 	"bufio"
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"time"
@@ -106,7 +105,7 @@ func cpuacctUsage(path string, cpuacct *CPUAccountingSubsystem) error {
 }
 
 func cpuacctUsagePerCPU(path string, cpuacct *CPUAccountingSubsystem) error {
-	contents, err := ioutil.ReadFile(filepath.Join(path, "cpuacct.usage_percpu"))
+	contents, err := os.ReadFile(filepath.Join(path, "cpuacct.usage_percpu"))
 	if err != nil {
 		if os.IsNotExist(err) {
 			return nil

diff --git a/metric/system/cgroup/cgv2/memory.go b/metric/system/cgroup/cgv2/memory.go
@@ -22,7 +22,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -249,7 +248,7 @@ func fetchEventsFile(path, file string) (Events, error) {
 // Some values, such as mem.max and mem.high, can be set to "max," which disables the metric.
 func maxOrValue(path, file string) (opt.Uint, error) {
 	var finalMetric opt.Uint
-	highRaw, err := ioutil.ReadFile(filepath.Join(path, file))
+	highRaw, err := os.ReadFile(filepath.Join(path, file))
 	if err != nil {
 		return finalMetric, fmt.Errorf("error reading %s.high file: %w", path, err)
 	}
@@ -272,7 +271,7 @@ func maxOrValue(path, file string) (opt.Uint, error) {
 // Note that this assumes all the values in the struct are either `uint64`, `opt.Bytes` or `opt.BytesOpt`
 func fillStatStruct(path string) (MemoryStat, error) {
 	statPath := filepath.Join(path, "memory.stat")
-	raw, err := ioutil.ReadFile(statPath)
+	raw, err := os.ReadFile(statPath)
 	if err != nil {
 		return MemoryStat{}, fmt.Errorf("error reading memory.stat: %w", err)
 	}

diff --git a/metric/system/cgroup/reader.go b/metric/system/cgroup/reader.go
@@ -19,7 +19,7 @@ package cgroup
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -142,7 +142,7 @@ func NewReaderOptions(opts ReaderOptions) (*Reader, error) {
 func (r *Reader) CgroupsVersion(pid int) (CgroupsVersion, error) {
 	cgPath := filepath.Join("/proc/", strconv.Itoa(pid), "cgroup")
 	cgPath = r.rootfsMountpoint.ResolveHostFS(cgPath)
-	cgraw, err := ioutil.ReadFile(cgPath)
+	cgraw, err := os.ReadFile(cgPath)
 	if err != nil {
 		return CgroupsV1, fmt.Errorf("error reading %s: %w", cgPath, err)
 	}
@@ -358,7 +358,7 @@ func readControllerList(cgroupsFile string, v2path string) ([]string, error) {
 		return []string{}, nil
 	}
 	file := filepath.Join(v2path, cgpath, "cgroup.controllers")
-	controllersRaw, err := ioutil.ReadFile(file)
+	controllersRaw, err := os.ReadFile(file)
 	if err != nil {
 		return nil, fmt.Errorf("error reading %s: %w", file, err)
 	}

diff --git a/metric/system/cgroup/util.go b/metric/system/cgroup/util.go
@@ -21,7 +21,6 @@ import (
 	"bufio"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -276,7 +275,7 @@ the container as /sys/fs/cgroup/unified and start the system module with the hos
 				controllerPath = r.rootfsMountpoint.ResolveHostFS(filepath.Join("/sys/fs/cgroup/unified", path))
 			}
 
-			cgpaths, err := ioutil.ReadDir(controllerPath)
+			cgpaths, err := os.ReadDir(controllerPath)
 			if err != nil {
 				return cPaths, fmt.Errorf("error fetching cgroupV2 controllers for cgroup location '%s' and path line '%s': %w", r.cgroupMountpoints.V2Loc, line, err)
 			}

diff --git a/metric/system/filesystem/filesystem_test.go b/metric/system/filesystem/filesystem_test.go
@@ -18,7 +18,6 @@
 package filesystem
 
 import (
-	"io/ioutil"
 	"os"
 	"runtime"
 	"testing"
@@ -56,9 +55,7 @@ func TestFileSystemListFiltering(t *testing.T) {
 		t.Skip("These cases don't need to work on Windows")
 	}
 	_ = logp.DevelopmentSetup()
-	fakeDevDir, err := ioutil.TempDir(os.TempDir(), "dir")
-	assert.Empty(t, err)
-	defer os.RemoveAll(fakeDevDir)
+	fakeDevDir := t.TempDir()
 
 	cases := []struct {
 		description   string

diff --git a/metric/system/numcpu/cpu_linux.go b/metric/system/numcpu/cpu_linux.go
@@ -20,7 +20,6 @@ package numcpu
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"strings"
 )
@@ -42,7 +41,7 @@ func getCPU() (int, bool, error) {
 		cpuPath = "/sys/devices/system/cpu/present"
 	}
 
-	rawFile, err := ioutil.ReadFile(cpuPath)
+	rawFile, err := os.ReadFile(cpuPath)
 	// if the file doesn't exist, assume it's a support issue and not a bug
 	if errors.Is(err, os.ErrNotExist) {
 		return -1, false, nil

diff --git a/metric/system/process/process_linux_common.go b/metric/system/process/process_linux_common.go
@@ -24,7 +24,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"os/user"
 	"strconv"
@@ -246,7 +245,7 @@ func getUser(hostfs resolve.Resolver, pid int) (string, error) {
 
 func getEnvData(hostfs resolve.Resolver, pid int, filter func(string) bool) (mapstr.M, error) {
 	path := hostfs.Join("proc", strconv.Itoa(pid), "environ")
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if errors.Is(err, os.ErrPermission) { // pass through permission errors
 		return nil, err
 	} else if err != nil {
@@ -277,7 +276,7 @@ func getMemData(hostfs resolve.Resolver, pid int) (ProcMemInfo, error) {
 	// Memory data
 	state := ProcMemInfo{}
 	path := hostfs.Join("proc", strconv.Itoa(pid), "statm")
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		return state, fmt.Errorf("error opening file %s: %w", path, err)
 	}
@@ -306,7 +305,7 @@ func getCPUTime(hostfs resolve.Resolver, pid int) (ProcCPUInfo, error) {
 	state := ProcCPUInfo{}
 
 	pathCPU := hostfs.Join("proc", strconv.Itoa(pid), "stat")
-	data, err := ioutil.ReadFile(pathCPU)
+	data, err := os.ReadFile(pathCPU)
 	if err != nil {
 		return state, fmt.Errorf("error opening file %s: %w", pathCPU, err)
 	}
@@ -347,7 +346,7 @@ func getCPUTime(hostfs resolve.Resolver, pid int) (ProcCPUInfo, error) {
 
 func getArgs(hostfs resolve.Resolver, pid int) ([]string, error) {
 	path := hostfs.Join("proc", strconv.Itoa(pid), "cmdline")
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		return nil, fmt.Errorf("error opening file %s: %w", path, err)
 	}
@@ -371,7 +370,7 @@ func getFDStats(hostfs resolve.Resolver, pid int) (ProcFDInfo, error) {
 	state := ProcFDInfo{}
 
 	path := hostfs.Join("proc", strconv.Itoa(pid), "limits")
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		return state, fmt.Errorf("error opening file %s: %w", path, err)
 	}
@@ -398,7 +397,7 @@ func getFDStats(hostfs resolve.Resolver, pid int) (ProcFDInfo, error) {
 	}
 
 	pathFD := hostfs.Join("proc", strconv.Itoa(pid), "fd")
-	fds, err := ioutil.ReadDir(pathFD)
+	fds, err := os.ReadDir(pathFD)
 	if errors.Is(err, os.ErrPermission) { // ignore permission errors, passthrough other data
 		return state, nil
 	} else if err != nil {
@@ -416,7 +415,7 @@ func getLinuxBootTime(hostfs resolve.Resolver) (uint64, error) {
 
 	path := hostfs.Join("proc", "stat")
 	// grab system boot time
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		return 0, fmt.Errorf("error opening file %s: %w", path, err)
 	}
@@ -440,7 +439,7 @@ func getLinuxBootTime(hostfs resolve.Resolver) (uint64, error) {
 func getProcStatus(hostfs resolve.Resolver, pid int) (map[string]string, error) {
 	status := make(map[string]string, 42)
 	path := hostfs.Join("proc", strconv.Itoa(pid), "status")
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		return nil, fmt.Errorf("error opening file %s: %w", path, err)
 	}