[CWS] improve speed of btfhub archive constant builder script (#11467)

* [CWS] run multiple tar/btf extractions in parallel

* [CWS] increase concurrent goroutines

pkg/security/probe/constantfetch/btfhub/main.go

@@ -11,6 +11,7 @@ package main
 import (
 	"archive/tar"
 	"bytes"
+	"context"
 	"encoding/json"
 	"flag"
 	"fmt"
@@ -20,37 +21,37 @@ import (
 	"path"
 	"path/filepath"
 	"reflect"
+	"runtime"
+	"sort"
 	"strings"
+	"sync"
 
 	"github.com/DataDog/datadog-agent/pkg/security/ebpf/kernel"
+	"github.com/DataDog/datadog-agent/pkg/security/log"
 	"github.com/DataDog/datadog-agent/pkg/security/probe"
 	"github.com/DataDog/datadog-agent/pkg/security/probe/constantfetch"
 	utilKernel "github.com/DataDog/datadog-agent/pkg/util/kernel"
 	"github.com/smira/go-xz"
+	"golang.org/x/sync/semaphore"
 )
 
 func main() {
 	var archiveRootPath string
 	var constantOutputPath string
-	var sampling int
 
 	flag.StringVar(&archiveRootPath, "archive-root", "", "Root path of BTFHub archive")
 	flag.StringVar(&constantOutputPath, "output", "", "Output path for JSON constants")
-	flag.IntVar(&sampling, "sampling", 1, "Sampling rate, take 1 over n elements")
 	flag.Parse()
 
-	twCollector := newTreeWalkCollector(sampling)
+	twCollector := newTreeWalkCollector()
 
 	if err := filepath.WalkDir(archiveRootPath, twCollector.treeWalkerBuilder(archiveRootPath)); err != nil {
 		panic(err)
 	}
-	fmt.Printf("%d kernels\n", len(twCollector.kernels))
-	fmt.Printf("%d unique constants\n", len(twCollector.constants))
 
-	export := constantfetch.BTFHubConstants{
-		Constants: twCollector.constants,
-		Kernels:   twCollector.kernels,
-	}
+	export := twCollector.finish()
+	fmt.Printf("%d kernels\n", len(export.Kernels))
+	fmt.Printf("%d unique constants\n", len(export.Constants))
 
 	output, err := json.MarshalIndent(export, "", "\t")
 	if err != nil {
@@ -63,52 +64,59 @@ func main() {
 }
 
 type treeWalkCollector struct {
-	constants []map[string]uint64
-	kernels   []constantfetch.BTFHubKernel
 	counter   int
-	sampling  int
+	wg        sync.WaitGroup
+	sem       *semaphore.Weighted
+	resultsMu sync.Mutex
+	results   []extractionResult
 }
 
-func newTreeWalkCollector(sampling int) *treeWalkCollector {
+func newTreeWalkCollector() *treeWalkCollector {
 	return &treeWalkCollector{
-		constants: make([]map[string]uint64, 0),
-		kernels:   make([]constantfetch.BTFHubKernel, 0),
-		counter:   0,
-		sampling:  sampling,
+		counter: 0,
+		sem:     semaphore.NewWeighted(int64(runtime.NumCPU() * 2)),
 	}
 }
 
-func (c *treeWalkCollector) appendConstants(distrib, version, arch, unameRelease string, constants map[string]uint64) {
-	index := -1
-	for i, other := range c.constants {
-		if reflect.DeepEqual(other, constants) {
-			index = i
-			break
+func (c *treeWalkCollector) finish() constantfetch.BTFHubConstants {
+	c.wg.Wait()
+
+	sort.Slice(c.results, func(i, j int) bool { return c.results[i].index < c.results[j].index })
+
+	constants := make([]map[string]uint64, 0)
+	kernels := make([]constantfetch.BTFHubKernel, 0)
+
+	for _, res := range c.results {
+		index := -1
+		for i, other := range constants {
+			if reflect.DeepEqual(other, res.constants) {
+				index = i
+				break
+			}
+		}
+
+		if index == -1 {
+			index = len(constants)
+			constants = append(constants, res.constants)
 		}
-	}
 
-	if index == -1 {
-		index = len(c.constants)
-		c.constants = append(c.constants, constants)
+		kernels = append(kernels, constantfetch.BTFHubKernel{
+			Distribution:   res.distribution,
+			DistribVersion: res.distribVersion,
+			Arch:           res.arch,
+			UnameRelease:   res.unameRelease,
+			ConstantsIndex: index,
+		})
 	}
 
-	c.kernels = append(c.kernels, constantfetch.BTFHubKernel{
-		Distribution:   distrib,
-		DistribVersion: version,
-		Arch:           arch,
-		UnameRelease:   unameRelease,
-		ConstantsIndex: index,
-	})
+	return constantfetch.BTFHubConstants{
+		Constants: constants,
+		Kernels:   kernels,
+	}
 }
 
 func (c *treeWalkCollector) treeWalkerBuilder(prefix string) fs.WalkDirFunc {
 	return func(path string, d fs.DirEntry, err error) error {
-		c.counter++
-		if c.counter != c.sampling {
-			return nil
-		}
-		c.counter = 0
-
 		if err != nil {
 			return err
 		}
@@ -120,6 +128,9 @@ func (c *treeWalkCollector) treeWalkerBuilder(prefix string) fs.WalkDirFunc {
 			return nil
 		}
 
+		btfRunIndex := c.counter
+		c.counter++
+
 		pathSuffix := strings.TrimPrefix(path, prefix)
 
 		btfParts := strings.Split(pathSuffix, "/")
@@ -132,18 +143,52 @@ func (c *treeWalkCollector) treeWalkerBuilder(prefix string) fs.WalkDirFunc {
 		arch := btfParts[len(btfParts)-2]
 		unameRelease := strings.TrimSuffix(btfParts[len(btfParts)-1], ".btf.tar.xz")
 
-		fmt.Println(path)
-
-		constants, err := extractConstantsFromBTF(path, distribution, distribVersion)
-		if err != nil {
-			return err
+		c.wg.Add(1)
+		if err := c.sem.Acquire(context.TODO(), 1); err != nil {
+			return fmt.Errorf("failed to acquire sem token: %w", err)
 		}
 
-		c.appendConstants(distribution, distribVersion, arch, unameRelease, constants)
+		go func() {
+			defer func() {
+				c.wg.Done()
+				c.sem.Release(1)
+			}()
+
+			fmt.Println(btfRunIndex, path)
+
+			constants, err := extractConstantsFromBTF(path, distribution, distribVersion)
+			if err != nil {
+				log.Errorf("failed to extract constants from `%s`: %v", path, err)
+				return
+			}
+
+			res := extractionResult{
+				index:          btfRunIndex,
+				distribution:   distribution,
+				distribVersion: distribVersion,
+				arch:           arch,
+				unameRelease:   unameRelease,
+				constants:      constants,
+			}
+
+			c.resultsMu.Lock()
+			c.results = append(c.results, res)
+			c.resultsMu.Unlock()
+		}()
+
 		return nil
 	}
 }
 
+type extractionResult struct {
+	index          int
+	distribution   string
+	distribVersion string
+	arch           string
+	unameRelease   string
+	constants      map[string]uint64
+}
+
 func extractConstantsFromBTF(archivePath, distribution, distribVersion string) (map[string]uint64, error) {
 	btfReader, err := createBTFReaderFromTarball(archivePath)
 	if err != nil {