feat: enhance storage stats and cluster health reporting

- Introduced new data structures for bucket and storage statistics, including BucketSummary, StorageStats, and ClusterHealth.
- Implemented runtime statistics tracking for buckets, including object count and total size.
- Added methods to retrieve storage stats and bucket summaries in the FileStore.
- Enhanced the SmartStorage interface to expose storage stats and cluster health.
- Implemented tests for runtime stats, cluster health, and credential management.
- Added support for runtime-managed credentials with atomic replacement.
- Improved filesystem usage reporting for storage locations.

rust/src/cluster/drive_manager.rs

@@ -1,9 +1,9 @@
+use super::config::DriveConfig;
 use anyhow::Result;
 use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use std::path::{Path, PathBuf};
 use tokio::fs;
-use super::config::DriveConfig;
 
 // ============================
 // Drive format (on-disk metadata)
@@ -33,6 +33,7 @@ pub enum DriveStatus {
 #[derive(Debug, Clone)]
 pub struct DriveStats {
     pub total_bytes: u64,
+    pub available_bytes: u64,
     pub used_bytes: u64,
     pub avg_write_latency_us: u64,
     pub avg_read_latency_us: u64,
@@ -45,6 +46,7 @@ impl Default for DriveStats {
     fn default() -> Self {
         Self {
             total_bytes: 0,
+            available_bytes: 0,
             used_bytes: 0,
             avg_write_latency_us: 0,
             avg_read_latency_us: 0,
@@ -55,7 +57,7 @@ impl Default for DriveStats {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct DriveState {
     pub path: PathBuf,
     pub format: Option<DriveFormat>,
@@ -74,10 +76,15 @@ pub struct DriveManager {
 impl DriveManager {
     /// Initialize drive manager with configured drive paths.
     pub async fn new(config: &DriveConfig) -> Result<Self> {
-        let mut drives = Vec::with_capacity(config.paths.len());
+        let paths: Vec<PathBuf> = config.paths.iter().map(PathBuf::from).collect();
+        Self::from_paths(&paths).await
+    }
 
-        for path_str in &config.paths {
-            let path = PathBuf::from(path_str);
+    /// Initialize drive manager from an explicit list of resolved paths.
+    pub async fn from_paths(paths: &[PathBuf]) -> Result<Self> {
+        let mut drives = Vec::with_capacity(paths.len());
+
+        for path in paths {
             let storage_dir = path.join(".smartstorage");
 
             // Ensure the drive directory exists
@@ -92,7 +99,7 @@ impl DriveManager {
             };
 
             drives.push(DriveState {
-                path,
+                path: path.clone(),
                 format,
                 status,
                 stats: DriveStats::default(),
@@ -154,6 +161,11 @@ impl DriveManager {
         &self.drives
     }
 
+    /// Get a cloneable snapshot of current drive states.
+    pub fn snapshot(&self) -> Vec<DriveState> {
+        self.drives.clone()
+    }
+
     /// Get drives that are online.
     pub fn online_drives(&self) -> Vec<usize> {
         self.drives
@@ -203,6 +215,11 @@ impl DriveManager {
         let _ = fs::remove_file(&probe_path).await;
 
         let latency = start.elapsed();
+        if let Some((total_bytes, available_bytes, used_bytes)) = filesystem_usage(&drive.path) {
+            drive.stats.total_bytes = total_bytes;
+            drive.stats.available_bytes = available_bytes;
+            drive.stats.used_bytes = used_bytes;
+        }
         drive.stats.avg_write_latency_us = latency.as_micros() as u64;
         drive.stats.last_check = Utc::now();
 
@@ -240,3 +257,30 @@ impl DriveManager {
         serde_json::from_str(&content).ok()
     }
 }
+
+#[cfg(unix)]
+fn filesystem_usage(path: &Path) -> Option<(u64, u64, u64)> {
+    use std::ffi::CString;
+    use std::os::unix::ffi::OsStrExt;
+
+    let path_bytes = path.as_os_str().as_bytes();
+    let c_path = CString::new(path_bytes).ok()?;
+    let mut stat: libc::statvfs = unsafe { std::mem::zeroed() };
+
+    if unsafe { libc::statvfs(c_path.as_ptr(), &mut stat) } != 0 {
+        return None;
+    }
+
+    let block_size = stat.f_frsize as u64;
+    let total_bytes = stat.f_blocks as u64 * block_size;
+    let available_bytes = stat.f_bavail as u64 * block_size;
+    let free_bytes = stat.f_bfree as u64 * block_size;
+    let used_bytes = total_bytes.saturating_sub(free_bytes);
+
+    Some((total_bytes, available_bytes, used_bytes))
+}
+
+#[cfg(not(unix))]
+fn filesystem_usage(_path: &Path) -> Option<(u64, u64, u64)> {
+    None
+}