Function get_memory_usage

crates/lib/src/system.rs:191–268

()

/// Returns an error if `/proc/meminfo` cannot be read.
#[cfg_attr(feature = "hotpath", hotpath::measure)]
pub fn get_memory_usage() -> Result<String, Error> {
  #[cfg_attr(feature = "hotpath", hotpath::measure)]
  fn parse_memory_info() -> Result<(f64, f64), Error> {
    let mut total_memory_kb = 0u64;
    let mut available_memory_kb = 0u64;
    let mut buffer = [0u8; 1024];

    // Use fast syscall-based file reading
    let bytes_read = read_file_fast("/proc/meminfo", &mut buffer)
      .map_err(Error::from_raw_os_error)?;
    let meminfo = &buffer[..bytes_read];

    // Fast scanning for MemTotal and MemAvailable
    let mut offset = 0;
    let mut found_total = false;
    let mut found_available = false;

    while offset < meminfo.len() && (!found_total || !found_available) {
      let remaining = &meminfo[offset..];

      // Find newline or end
      let line_end = remaining
        .iter()
        .position(|&b| b == b'\n')
        .unwrap_or(remaining.len());
      let line = &remaining[..line_end];

      if line.starts_with(b"MemTotal:") {
        // Skip "MemTotal:" and whitespace
        let mut pos = 9;
        while pos < line.len() && line[pos].is_ascii_whitespace() {
          pos += 1;
        }
        total_memory_kb = parse_u64_fast(&line[pos..]);
        found_total = true;
      } else if line.starts_with(b"MemAvailable:") {
        // Skip "MemAvailable:" and whitespace
        let mut pos = 13;
        while pos < line.len() && line[pos].is_ascii_whitespace() {
          pos += 1;
        }
        available_memory_kb = parse_u64_fast(&line[pos..]);
        found_available = true;
      }

      offset += line_end + 1;
    }

    #[allow(clippy::cast_precision_loss)]
    let total_gb = total_memory_kb as f64 / 1024.0 / 1024.0;
    #[allow(clippy::cast_precision_loss)]
    let available_gb = available_memory_kb as f64 / 1024.0 / 1024.0;
    let used_memory_gb = total_gb - available_gb;

    Ok((used_memory_gb, total_gb))
  }

  let (used_memory, total_memory) = parse_memory_info()?;