Go语言中实现内存感知型LRU缓存的系统级淘汰策略

package main

import (
    "fmt"
    "syscall"
)

// MemStats 结构体用于存储系统内存统计信息
type MemStats struct {
    Total uint64 // 总物理内存
    Free  uint64 // 空闲物理内存
    Used  uint64 // 已用物理内存
}

// ReadSysMemStats 函数读取Linux系统的内存统计
func ReadSysMemStats(s *MemStats) error {
    if s == nil {
        return fmt.Errorf("MemStats pointer cannot be nil")
    }

    var info syscall.Sysinfo_t
    err := syscall.Sysinfo(&info)
    if err != nil {
        return fmt.Errorf("failed to get system info: %w", err)
    }

    // Sysinfo_t 中的内存单位是字节
    s.Total = info.Totalram
    s.Free = info.Freeram
    s.Used = s.Total - s.Free // 简单计算已用内存

    return nil
}

func main() {
    var stats MemStats
    err := ReadSysMemStats(&stats)
    if err != nil {
        fmt.Printf("Error reading system memory stats: %v\n", err)
        return
    }
    fmt.Printf("Linux System Memory Stats:\n")
    fmt.Printf("  Total: %d bytes (%.2f GB)\n", stats.Total, float64(stats.Total)/1024/1024/1024)
    fmt.Printf("  Free:  %d bytes (%.2f GB)\n", stats.Free, float64(stats.Free)/1024/1024/1024)
    fmt.Printf("  Used:  %d bytes (%.2f GB)\n", stats.Used, float64(stats.Used)/1024/1024/1024)
}

package main

/*
#include <mach/mach.h>
#include <mach/mach_host.h>
*/
import "C"

import (
    "fmt"
    "unsafe"
)

// SysMemStats 结构体用于存储系统内存统计信息
type SysMemStats struct {
    Total uint64 // 总物理内存
    Free  uint64 // 空闲物理内存
    Used  uint64 // 已用物理内存
}

// readSysMemStats 函数读取macOS系统的内存统计
func readSysMemStats(s *SysMemStats) error {
    if s == nil {
        return fmt.Errorf("SysMemStats pointer cannot be nil")
    }

    var vm_pagesize C.vm_size_t
    var vm_stat C.vm_statistics_data_t
    var count C.mach_msg_type_number_t = C.HOST_VM_INFO_COUNT

    host_port := C.host_t(C.mach_host_self())

    // 获取页大小
    C.host_page_size(host_port, &vm_pagesize)

    // 获取VM统计信息
    status := C.host_statistics(
        host_port,
        C.HOST_VM_INFO,
        C.host_info_t(unsafe.Pointer(&vm_stat)),
        &count)

    if status != C.KERN_SUCCESS {
        return fmt.Errorf("could not get vm statistics: %d", status)
    }

    // 统计数据以页为单位，需要乘以页大小转换为字节
    free := uint64(vm_stat.free_count)
    active := uint64(vm_stat.active_count)
    inactive := uint64(vm_stat.inactive_count)
    wired := uint64(vm_stat.wire_count)
    pagesize := uint64(vm_pagesize)

    s.Used = (active + inactive + wired) * pagesize
    s.Free = free * pagesize
    s.Total = s.Used + s.Free // 总内存 = 已用 + 空闲

    return nil
}

func main() {
    var stats SysMemStats
    err := readSysMemStats(&stats)
    if err != nil {
        fmt.Printf("Error reading system memory stats: %v\n", err)
        return
    }
    fmt.Printf("macOS System Memory Stats:\n")
    fmt.Printf("  Total: %d bytes (%.2f GB)\n", stats.Total, float64(stats.Total)/1024/1024/1024)
    fmt.Printf("  Free:  %d bytes (%.2f GB)\n", stats.Free, float64(stats.Free)/1024/1024/1024)
    fmt.Printf("  Used:  %d bytes (%.2f GB)\n", stats.Used, float64(stats.Used)/1024/1024/1024)
}

// 伪代码示例
type LRUCache struct {
    // ... LRU 缓存的内部实现 ...
    currentSize int
    maxSize     int
}

func (c *LRUCache) Evict() {
    // 淘汰最久未使用的项，直到达到某个目标大小或内存阈值
    // ...
}

type CacheManager struct {
    cache       *LRUCache
    minFreeMem  uint64 // 最小空闲内存阈值（字节）
    pollInterval time.Duration
    stopChan    chan struct{}
}

func NewCacheManager(cache *LRUCache, minFreeMem uint64, interval time.Duration) *CacheManager {
    return &CacheManager{
        cache:       cache,
        minFreeMem:  minFreeMem,
        pollInterval: interval,
        stopChan:    make(chan struct{}),
    }
}

func (cm *CacheManager) StartMonitoring() {
    ticker := time.NewTicker(cm.pollInterval)
    defer ticker.Stop()

    for {
        select {
        case <-ticker.C:
            var stats SysMemStats // 或 MemStats for Linux
            err := readSysMemStats(&stats) // 或 ReadSysMemStats for Linux
            if err != nil {
                fmt.Printf("Error getting system memory: %v\n", err)
                continue
            }

            if stats.Free < cm.minFreeMem {
                fmt.Printf("System free memory (%d) below threshold (%d), triggering cache eviction.\n", stats.Free, cm.minFreeMem)
                cm.cache.Evict() // 调用LRU缓存的淘汰方法
            }
        case <-cm.stopChan:
            fmt.Println("Cache memory monitoring stopped.")
            return
        }
    }
}

func (cm *CacheManager) StopMonitoring() {
    close(cm.stopChan)
}