MemoryMetrics

数据结构

字节索引	类型	字段含义
0-3	float32	物理内存使用率 [%]
4-5	uint16	已用物理内存 [MiB]
6-7	uint16	实际可用物理内存 [MiB]，包含可回收缓存/Buffer
8-9	uint16	已用交换空间 Swap [MiB]
10-11	uint16	已用共享内存 tmpfs/shm [MiB]
12-15	uint32	累计硬缺页中断次数
16	uint8	是否触发过 OOM Killer，0 为否，1 为是
17-19	uint8	保留字段，必须为 0

MemoryMetrics 固定为 20 字节

示例

C++ 示例

struct MemoryMetrics {
  float usage;
  uint16_t used;
  uint16_t available;
  uint16_t swap_used;
  uint16_t shm_used;
  uint32_t major_page_faults;
  uint8_t has_oom_event;
  uint8_t reserved[3];
};

Rust 示例

#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct MemoryMetrics {
    pub usage: f32,
    pub used: u16,
    pub available: u16,
    pub swap_used: u16,
    pub shm_used: u16,
    pub major_page_faults: u32,
    pub has_oom_event: u8,
    pub reserved: [u8; 3],
}

const _: () = {
    assert!(core::mem::size_of::<MemoryMetrics>() == 20);
    assert!(core::mem::align_of::<MemoryMetrics>() == 4);
};

Dart 示例

import 'dart:typed_data';

final class MemoryMetricsView {
  static const int byteLength = 20;

  final ByteData data;

  MemoryMetricsView(ByteBuffer buffer, [int offsetInBytes = 0])
      : data = ByteData.view(buffer, offsetInBytes, byteLength);

  double get usage => data.getFloat32(0, Endian.little);
  int get used => data.getUint16(4, Endian.little);
  int get available => data.getUint16(6, Endian.little);
  int get swapUsed => data.getUint16(8, Endian.little);
  int get shmUsed => data.getUint16(10, Endian.little);
  int get majorPageFaults => data.getUint32(12, Endian.little);
  bool get hasOomEvent => data.getUint8(16) != 0;
}

Java 示例

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

public final class MemoryMetricsView {
  public static final int BYTE_LENGTH = 20;

  private final ByteBuffer buffer;
  private final int offset;

  public MemoryMetricsView(ByteBuffer buffer, int offset) {
    if (offset < 0 || offset + BYTE_LENGTH > buffer.capacity()) {
      throw new IndexOutOfBoundsException("MemoryMetrics payload requires 20 bytes");
    }
    this.buffer = buffer.order(ByteOrder.LITTLE_ENDIAN);
    this.offset = offset;
  }

  public float usage() { return buffer.getFloat(offset); }
  public int used() { return Short.toUnsignedInt(buffer.getShort(offset + 4)); }
  public int available() { return Short.toUnsignedInt(buffer.getShort(offset + 6)); }
  public int swapUsed() { return Short.toUnsignedInt(buffer.getShort(offset + 8)); }
  public int shmUsed() { return Short.toUnsignedInt(buffer.getShort(offset + 10)); }
  public long majorPageFaults() { return Integer.toUnsignedLong(buffer.getInt(offset + 12)); }
  public boolean hasOomEvent() { return buffer.get(offset + 16) != 0; }
}