feat: Phase 6 Agent 系统信息+进程监控采集器

- 新增 collector/system.go: SystemCollector(OS/内核/ulimit) + ProcessCollector(Top 5 CPU/内存)
- 模型新增 SystemStat + ProcessStat + ProcessInfo
- Report 结构新增 System + Processes 字段
- Agent 启动时采集系统信息，每周期采集进程列表

agent/collector/system.go

@@ -0,0 +1,217 @@
+// Package collector 提供系统信息及进程列表采集。
+// 系统信息：OS 名称、内核版本、架构、ulimit。
+// 进程列表：按 CPU/内存排序的 Top 5 进程。
+//
+// 署名 Logan.Li
+package collector
+
+import (
+	"fmt"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"ezops/agent/model"
+)
+
+// SystemCollector 系统信息采集器
+type SystemCollector struct{}
+
+// NewSystemCollector 创建系统信息采集器
+func NewSystemCollector() *SystemCollector {
+	return &SystemCollector{}
+}
+
+// Collect 采集系统信息（OS、内核、架构、ulimit）
+func (s *SystemCollector) Collect() (model.SystemStat, error) {
+	return model.SystemStat{
+		OS:         readFirstLine("/etc/os-release", "PRETTY_NAME="),
+		Kernel:     readProcVersion(),
+		Arch:       readArch(),
+		Hostname:   readHostname(),
+		UlimitNofile: readUlimitNofile(),
+		UlimitNproc:  readUlimitNproc(),
+	}, nil
+}
+
+func readFirstLine(path, prefix string) string {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	for _, line := range strings.Split(string(data), "\n") {
+		line = strings.TrimSpace(line)
+		if strings.HasPrefix(line, prefix) {
+			val := strings.TrimPrefix(line, prefix)
+			return strings.Trim(val, `"`)
+		}
+	}
+	return ""
+}
+
+func readProcVersion() string {
+	data, err := os.ReadFile("/proc/version")
+	if err != nil {
+		return ""
+	}
+	// Linux version 6.8.0-90-generic ... (buildd@...) (gcc ...) #...
+	parts := strings.Fields(string(data))
+	if len(parts) >= 3 {
+		return strings.Join(parts[:3], " ")
+	}
+	return strings.TrimSpace(string(data))
+}
+
+func readArch() string {
+	data, err := os.ReadFile("/proc/cpuinfo")
+	if err != nil {
+		return ""
+	}
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, "flags") || strings.HasPrefix(line, "Features") {
+			return "x86_64"
+		}
+	}
+	return "unknown"
+}
+
+func readHostname() string {
+	h, _ := os.Hostname()
+	return h
+}
+
+func readUlimitNofile() int64 {
+	var rlim syscall.Rlimit
+	if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &rlim); err == nil {
+		return int64(rlim.Cur)
+	}
+	return 0
+}
+
+func readUlimitNproc() int64 {
+	var rlim syscall.Rlimit
+	if err := syscall.Getrlimit(syscall.RLIMIT_NPROC, &rlim); err == nil {
+		return int64(rlim.Cur)
+	}
+	return 0
+}
+
+// ==================== Process Collector ====================
+
+// ProcessCollector 进程列表采集器 — Top N 按 CPU/内存
+type ProcessCollector struct{}
+
+// NewProcessCollector 创建进程采集器
+func NewProcessCollector() *ProcessCollector {
+	return &ProcessCollector{}
+}
+
+// Collect 采集 Top 5 CPU 和 Top 5 内存进程
+func (p *ProcessCollector) Collect() (model.ProcessStat, error) {
+	procs := readProcStatAll()
+	if len(procs) == 0 {
+		return model.ProcessStat{}, nil
+	}
+
+	// Top 5 by CPU
+	sort.Slice(procs, func(i, j int) bool { return procs[i].CPUPercent > procs[j].CPUPercent })
+	topCPU := procs
+	if len(topCPU) > 5 {
+		topCPU = topCPU[:5]
+	}
+
+	// Top 5 by RSS
+	sort.Slice(procs, func(i, j int) bool { return procs[i].RSSKB > procs[j].RSSKB })
+	topMem := procs
+	if len(topMem) > 5 {
+		topMem = topMem[:5]
+	}
+
+	return model.ProcessStat{
+		TopCPU: topCPU,
+		TopMem: topMem,
+	}, nil
+}
+
+type procInfo struct {
+	PID        int
+	Name       string
+	CPUPercent float64
+	RSSKB      int64
+}
+
+func readProcStatAll() []procInfo {
+	entries, err := os.ReadDir("/proc")
+	if err != nil {
+		return nil
+	}
+
+	var procs []procInfo
+	for _, entry := range entries {
+		if !entry.IsDir() {
+			continue
+		}
+		pid, err := strconv.Atoi(entry.Name())
+		if err != nil {
+			continue
+		}
+
+		statData, err := os.ReadFile(fmt.Sprintf("/proc/%d/stat", pid))
+		if err != nil {
+			continue
+		}
+		stat := string(statData)
+
+		// /proc/PID/stat: PID (comm) state ppid ...
+		// comm 在括号中，可能含空格
+		closeParen := strings.LastIndex(stat, ")")
+		if closeParen < 0 {
+			continue
+		}
+		openParen := strings.Index(stat, "(")
+		if openParen < 0 {
+			continue
+		}
+		name := stat[openParen+1 : closeParen]
+
+		fields := strings.Fields(stat[closeParen+2:])
+		if len(fields) < 20 {
+			continue
+		}
+
+		// utime=fields[11], stime=fields[12], rss=fields[21]
+		utime, _ := strconv.ParseInt(fields[11], 10, 64)
+		stime, _ := strconv.ParseInt(fields[12], 10, 64)
+		rss, _ := strconv.ParseInt(fields[21], 10, 64)
+
+		// RSS pages * 4KB = RSS in KB
+		rssKB := rss * 4
+
+		// Simple CPU%: total ticks as fraction of uptime (approximate)
+		totalTicks := utime + stime
+		uptimeData, _ := os.ReadFile("/proc/uptime")
+		uptime := 0.0
+		if uptimeData != nil {
+			uptime, _ = strconv.ParseFloat(strings.Fields(string(uptimeData))[0], 64)
+		}
+		hertz := float64(syscall.Getpagesize()) * 25
+		if hertz == 0 {
+			hertz = 100
+		}
+		// CLK_TCK is typically 100 on Linux
+		cpuPercent := 0.0
+		if uptime > 0 {
+			cpuPercent = float64(totalTicks) / 100.0 / uptime * 100
+		}
+
+		procs = append(procs, procInfo{
+			PID:        pid,
+			Name:       name,
+			CPUPercent: cpuPercent,
+			RSSKB:      rssKB,
+		})
+	}
+	return procs
+}