vmstat: implement --slabs

src/uu/slabtop/src/parse.rs

@@ -3,25 +3,35 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-use std::{
-    cmp::Ordering,
-    fs,
-    io::{Error, ErrorKind},
-};
+use std::io::Error;
+use std::{cmp::Ordering, fs, io::ErrorKind};
+use uucore::error::{UError, UResult, USimpleError};
 
 #[derive(Debug, Default)]
-pub(crate) struct SlabInfo {
-    pub(crate) meta: Vec<String>,
-    pub(crate) data: Vec<(String, Vec<u64>)>,
+pub struct SlabInfo {
+    pub meta: Vec<String>,
+    pub data: Vec<(String, Vec<u64>)>,
 }
 
 impl SlabInfo {
     // parse slabinfo from /proc/slabinfo
     // need root permission
-    pub fn new() -> Result<SlabInfo, Error> {
-        let content = fs::read_to_string("/proc/slabinfo")?;
+    pub fn new() -> UResult<SlabInfo> {
+        let error_wrapper = |e: Error| {
+            USimpleError::new(
+                1,
+                format!(
+                    "Unable to create slabinfo structure: {}",
+                    Box::<dyn UError>::from(e) // We need Display impl of UError
+                ),
+            )
+        };
+
+        let content = fs::read_to_string("/proc/slabinfo").map_err(error_wrapper)?;
 
-        Self::parse(&content).ok_or(ErrorKind::Unsupported.into())
+        Self::parse(&content)
+            .ok_or(ErrorKind::Unsupported.into())
+            .map_err(error_wrapper)
     }
 
     pub fn parse(content: &str) -> Option<SlabInfo> {

src/uu/slabtop/src/slabtop.rs

@@ -3,7 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-use crate::parse::SlabInfo;
+pub use crate::parse::SlabInfo;
 use clap::{arg, crate_version, ArgAction, Command};
 use uucore::{error::UResult, format_usage, help_about, help_section, help_usage};
 
@@ -25,6 +25,8 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 
     let slabinfo = SlabInfo::new()?.sort(*sort_flag, false);
 
+    println!("{slabinfo:?}");
+
     if matches.get_flag("once") {
         output_header(&slabinfo);
         println!();

src/uu/vmstat/Cargo.toml

@@ -17,6 +17,8 @@ clap = { workspace = true }
 terminal_size = { workspace = true }
 uucore = { workspace = true, features = ["custom-tz-fmt"] }
 
+uu_slabtop = {path = "../slabtop"}
+
 [lib]
 path = "src/vmstat.rs"
 

src/uu/vmstat/src/vmstat.rs

@@ -38,6 +38,13 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
 
         let one_header = matches.get_flag("one-header");
         let no_first = matches.get_flag("no-first");
+        let term_height = terminal_size::terminal_size()
+            .map(|size| size.1 .0)
+            .unwrap_or(0);
+
+        if matches.get_flag("slabs") {
+            return print_slabs(one_header, term_height);
+        }
 
         let delay = matches.get_one::<u64>("delay");
         let count = matches.get_one::<u64>("count");
@@ -57,14 +64,10 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
             line_count += 1;
         }
 
-        let term_height = terminal_size::terminal_size()
-            .map(|size| size.1 .0)
-            .unwrap_or(0);
-
         while count.is_none() || line_count < count.unwrap() {
             std::thread::sleep(std::time::Duration::from_secs(delay));
             let proc_data_now = ProcData::new();
-            if !one_header && term_height > 0 && ((line_count + 3) % term_height as u64 == 0) {
+            if needs_header(one_header, term_height, line_count) {
                 print_header(&pickers);
             }
             print_data(&pickers, &proc_data_now, Some(&proc_data), &matches);
@@ -76,6 +79,41 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     Ok(())
 }
 
+#[cfg(target_os = "linux")]
+fn print_slabs(one_header: bool, term_height: u16) -> UResult<()> {
+    let mut slab_data = uu_slabtop::SlabInfo::new()?.data;
+
+    slab_data.sort_by_key(|k| k.0.to_lowercase());
+
+    print_slab_header();
+
+    for (line_count, slab_item) in slab_data.into_iter().enumerate() {
+        if needs_header(one_header, term_height, line_count as u64) {
+            print_slab_header();
+        }
+
+        println!(
+            "{:<24} {:>6} {:>6} {:>6} {:>6}",
+            slab_item.0, slab_item.1[0], slab_item.1[1], slab_item.1[2], slab_item.1[3]
+        );
+    }
+
+    Ok(())
+}
+
+#[cfg(target_os = "linux")]
+fn needs_header(one_header: bool, term_height: u16, line_count: u64) -> bool {
+    !one_header && term_height > 0 && ((line_count + 3) % term_height as u64 == 0)
+}
+
+#[cfg(target_os = "linux")]
+fn print_slab_header() {
+    println!(
+        "{:<24} {:>6} {:>6} {:>6} {:>6}",
+        "Cache", "Num", "Total", "Size", "Pages"
+    );
+}
+
 #[cfg(target_os = "linux")]
 fn print_header(pickers: &[Picker]) {
     let mut section: Vec<&str> = vec![];
@@ -126,7 +164,7 @@ pub fn uu_app() -> Command {
                 .value_parser(value_parser!(u64)),
             arg!(-a --active "Display active and inactive memory"),
             // arg!(-f --forks "switch displays the number of forks since boot"),
-            // arg!(-m --slabs "Display slabinfo"),
+            arg!(-m --slabs "Display slabinfo"),
             arg!(-n --"one-header" "Display the header only once rather than periodically"),
             // arg!(-s --stats "Displays a table of various event counters and memory statistics"),
             // arg!(-d --disk "Report disk statistics"),