Add rv cache prune command

crates/rv-cache/src/lib.rs

@@ -204,6 +204,11 @@ impl Cache {
     pub fn prune(&self) -> Result<Removal, io::Error> {
         let mut summary = Removal::default();
 
+        if !&self.root.exists() {
+            debug!("No cache found at: {}", &self.root);
+            return Ok(summary);
+        }
+
         // Remove any top-level directories that are unused. These typically represent
         // outdated cache buckets (e.g., `ruby-v0`, when latest is `ruby-v0`).
         for entry in fs_err::read_dir(&self.root)? {

crates/rv/src/commands/cache.rs

@@ -18,6 +18,8 @@ pub struct CacheCommandArgs {
 pub enum CacheCommand {
     #[command(about = "Clear the cache")]
     Clean,
+    #[command(about = "Prune all unused entries from the cache")]
+    Prune,
     #[command(about = "Show the cache directory")]
     Dir,
 }
@@ -41,3 +43,14 @@ pub fn cache_clean(config: &Config) -> io::Result<()> {
     );
     Ok(())
 }
+
+pub fn cache_prune(config: &Config) -> io::Result<()> {
+    let removal = config.cache.prune()?;
+    let num_bytes_cleaned = ByteSize::b(removal.bytes).display().iec_short();
+    println!(
+        "Removed {} directories, totalling {}",
+        removal.dirs.cyan(),
+        num_bytes_cleaned.cyan()
+    );
+    Ok(())
+}

crates/rv/src/main.rs

@@ -13,7 +13,7 @@ use tracing_subscriber::{EnvFilter, layer::SubscriberExt as _, util::SubscriberI
 pub mod commands;
 pub mod config;
 
-use crate::commands::cache::{CacheCommand, CacheCommandArgs, cache_clean, cache_dir};
+use crate::commands::cache::{CacheCommand, CacheCommandArgs, cache_clean, cache_dir, cache_prune};
 use crate::commands::ruby::dir::dir as ruby_dir;
 use crate::commands::ruby::find::find as ruby_find;
 use crate::commands::ruby::install::install as ruby_install;
@@ -293,6 +293,7 @@ async fn run() -> Result<()> {
             Commands::Cache(cache) => match cache.command {
                 CacheCommand::Dir => cache_dir(&config)?,
                 CacheCommand::Clean => cache_clean(&config)?,
+                CacheCommand::Prune => cache_prune(&config)?,
             },
             Commands::Shell(shell) => match shell.command {
                 ShellCommand::Init { shell } => shell_init(&config, shell)?,