ebpf_exporter

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package cgroup
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import (
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	"io/fs"
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	"log"
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	"path/filepath"
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)
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type walkerMonitor struct {
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	path    string
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	mapping map[int]string
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}
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func newWalkerMonitor(path string) (*walkerMonitor, error) {
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	mapping, err := walk(path)
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	if err != nil {
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		return nil, err
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	}
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	return &walkerMonitor{path: path, mapping: mapping}, nil
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}
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func (m *walkerMonitor) Resolve(id int) string {
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	// Try to resolve in cache first
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	if existing, ok := m.mapping[id]; ok {
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		return existing
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	}
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	// Refresh mapping to see if we a new cgroup appeared since last time
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	if mapping, err := walk(m.path); err != nil {
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		log.Printf("Error refreshing mapping: %v", err)
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	} else {
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		for id, name := range mapping {
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			m.mapping[id] = name
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		}
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	}
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	// If no new cgroup appeared, cache negative resolution to prevent constant refreshes
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	if _, ok := m.mapping[id]; !ok {
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		m.mapping[id] = ""
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	}
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	// Return whatever we have now (either newly resolved or cached negative value)
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	return m.mapping[id]
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}
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func walk(dir string) (map[int]string, error) {
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	mapping := map[int]string{}
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	err := filepath.WalkDir(dir, func(path string, entry fs.DirEntry, err error) error {
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		if err != nil {
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			return err
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		}
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		if !entry.IsDir() {
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			return nil
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		}
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		inode, err := inode(path)
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		if err != nil {
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			log.Printf("Error resolving inode for %q: %v", path, err)
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			return nil
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		}
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		mapping[inode] = path
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		return nil
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	})
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	return mapping, err
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}
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