block[disk_stats]: new block

Reads disk stats from sysfs.

See: https://docs.kernel.org/admin-guide/iostats.html

src/blocks.rs

@@ -156,6 +156,7 @@ define_blocks!(
     cpu,
     custom,
     custom_dbus,
+    disk_stats,
     disk_space,
     #[deprecated(
         since = "0.33.0",

src/blocks/disk_stats.rs

@@ -0,0 +1,168 @@
+//! Disk I/O statistics
+//!
+//! # Configuration
+//!
+//! Key | Values | Default
+//! ----|--------|--------
+//! `device` | Block device name to monitor (as specified in `/dev/`) | If not set, device will be automatically selected every `interval`
+//! `format` | A string to customise the output of this block. See below for available placeholders. | `" $icon $available "`
+//! `interval` | Update interval in seconds | `2`
+//!
+//! Placeholder | Value | Type   | Unit
+//! ------------|-------|--------|-------
+//! `icon` | A static icon | Icon | -
+//! `device` | The name of device | Text | -
+//! `speed_read` | Read speed | Number | Bytes per second
+//! `speed_write` | Write speed | Number | Bytes per second
+//!
+//! # Examples
+//!
+//! ```toml
+//! [[block]]
+//! block = "disk_stats"
+//! device = "sda"
+//! format = " $icon $speed_write.eng(prefix:K) "
+//! ```
+//!
+//! # Icons Used
+//!
+//! - `disk_drive`
+
+use super::prelude::*;
+use crate::util::read_file;
+use libc::c_ulong;
+use std::ops;
+use std::path::Path;
+use std::time::Instant;
+use tokio::fs::read_dir;
+
+/// Path for block devices
+const BLOCK_DEVICES_PATH: &str = "/sys/class/block";
+
+#[derive(Deserialize, Debug, SmartDefault)]
+#[serde(deny_unknown_fields, default)]
+pub struct Config {
+    pub device: Option<String>,
+    #[default(2.into())]
+    pub interval: Seconds,
+    pub format: FormatConfig,
+    pub missing_format: FormatConfig,
+}
+
+pub async fn run(config: &Config, api: &CommonApi) -> Result<()> {
+    let format = config
+        .format
+        .with_default(" $icon $speed_read.eng(prefix:K) $speed_write.eng(prefix:K) ")?;
+    let missing_format = config.missing_format.with_default(" × ")?;
+
+    let mut timer = config.interval.timer();
+    let mut old_stats = None;
+    let mut stats_timer = Instant::now();
+
+    loop {
+        let mut device = config.device.clone();
+        if device.is_none() {
+            device = find_device().await?;
+        }
+        match device {
+            None => {
+                api.set_widget(Widget::new().with_format(missing_format.clone()))?;
+            }
+            Some(device) => {
+                let mut widget = Widget::new();
+
+                widget.set_format(format.clone());
+
+                let new_stats = read_stats(&device).await?;
+                let sector_size = read_sector_size(&device).await?;
+
+                let mut speed_read = 0.0;
+                let mut speed_write = 0.0;
+                if let Some(old_stats) = old_stats {
+                    let diff = new_stats - old_stats;
+                    let elapsed = stats_timer.elapsed().as_secs_f64();
+                    stats_timer = Instant::now();
+                    let size_read = diff.sectors_read as u64 * sector_size;
+                    let size_written = diff.sectors_written as u64 * sector_size;
+                    speed_read = size_read as f64 / elapsed;
+                    speed_write = size_written as f64 / elapsed;
+                };
+                old_stats = Some(new_stats);
+
+                widget.set_values(map! {
+                    "icon" => Value::icon("disk_drive"),
+                    "speed_read" => Value::bytes(speed_read),
+                    "speed_write" => Value::bytes(speed_write),
+                    "device" => Value::text(device),
+                });
+
+                api.set_widget(widget)?;
+            }
+        }
+
+        select! {
+            _ = timer.tick() => continue,
+            _ = api.wait_for_update_request() => continue,
+        }
+    }
+}
+
+async fn find_device() -> Result<Option<String>> {
+    let mut sysfs_dir = read_dir(BLOCK_DEVICES_PATH)
+        .await
+        .error("Failed to open /sys/class/block directory")?;
+    while let Some(dir) = sysfs_dir
+        .next_entry()
+        .await
+        .error("Failed to read /sys/class/block directory")?
+    {
+        let path = dir.path();
+        if path.join("device").exists() {
+            return Ok(Some(
+                dir.file_name()
+                    .into_string()
+                    .map_err(|_| Error::new("Invalid device filename"))?,
+            ));
+        }
+    }
+
+    Ok(None)
+}
+
+#[derive(Debug, Default, Clone, Copy)]
+struct Stats {
+    sectors_read: c_ulong,
+    sectors_written: c_ulong,
+}
+
+impl ops::Sub for Stats {
+    type Output = Self;
+
+    fn sub(mut self, rhs: Self) -> Self::Output {
+        self.sectors_read = self.sectors_read.wrapping_sub(rhs.sectors_read);
+        self.sectors_written = self.sectors_written.wrapping_sub(rhs.sectors_written);
+        self
+    }
+}
+
+async fn read_stats(device: &str) -> Result<Stats> {
+    let raw = read_file(Path::new(BLOCK_DEVICES_PATH).join(device).join("stat"))
+        .await
+        .error("Failed to read stat file")?;
+    let fields: Vec<&str> = raw.split_whitespace().collect();
+    Ok(Stats {
+        sectors_read: fields[2].parse().error("Failed to parse sectors read")?,
+        sectors_written: fields[6].parse().error("Failed to parse sectors written")?,
+    })
+}
+
+async fn read_sector_size(device: &str) -> Result<u64> {
+    let raw = read_file(
+        Path::new(BLOCK_DEVICES_PATH)
+            .join(device)
+            .join("queue/hw_sector_size"),
+    )
+    .await
+    .error("Failed to read HW sector size")?;
+    raw.parse::<u64>().error("Failed to parse HW sector size")
+}