add simple rrd implementation

src/rrd/cache.rs

@@ -0,0 +1,82 @@
+use std::time::{SystemTime, UNIX_EPOCH};
+use std::path::PathBuf;
+use std::collections::HashMap;
+use std::sync::{RwLock};
+
+use anyhow::{format_err, Error};
+use lazy_static::lazy_static;
+use serde_json::Value;
+
+use proxmox::tools::fs::{create_path, CreateOptions};
+
+use super::*;
+
+const PBS_RRD_BASEDIR: &str = "/var/lib/proxmox-backup/rrdb";
+
+lazy_static!{
+    static ref RRD_CACHE: RwLock<HashMap<String, RRD>> = {
+        RwLock::new(HashMap::new())
+    };
+}
+
+/// Create rrdd stat dir with correct permission
+pub fn create_rrdb_dir() -> Result<(), Error> {
+
+    let backup_user = crate::backup::backup_user()?;
+    let opts = CreateOptions::new()
+        .owner(backup_user.uid)
+        .group(backup_user.gid);
+
+    create_path(PBS_RRD_BASEDIR, None, Some(opts))
+        .map_err(|err: Error| format_err!("unable to create rrdb stat dir - {}", err))?;
+
+    Ok(())
+}
+
+fn now() -> Result<u64, Error> {
+    let epoch = SystemTime::now().duration_since(UNIX_EPOCH)?;
+    Ok(epoch.as_secs())
+}
+
+pub fn update_value(rel_path: &str, value: f64) -> Result<(), Error> {
+
+    let mut path = PathBuf::from(PBS_RRD_BASEDIR);
+    path.push(rel_path);
+
+    std::fs::create_dir_all(path.parent().unwrap())?;
+
+    let mut map = RRD_CACHE.write().unwrap();
+    let now = now()?;
+    
+    if let Some(rrd) = map.get_mut(rel_path) {
+        rrd.update(now, value);
+        rrd.save(&path)?;
+    } else {
+        let mut rrd = match RRD::load(&path) {
+            Ok(rrd) => rrd,
+            Err(_) => RRD::new(),
+        };
+        rrd.update(now, value);
+        rrd.save(&path)?;
+        map.insert(rel_path.into(), rrd);
+    }
+   
+    Ok(())
+}
+
+pub fn extract_data(
+    rel_path: &str,
+    timeframe: RRDTimeFrameResolution,
+    mode: RRDMode,
+) -> Result<Value, Error> {
+
+    let now = now()?;
+
+    let map = RRD_CACHE.read().unwrap();
+    
+    if let Some(rrd) = map.get(rel_path) {
+        Ok(rrd.extract_data(now, timeframe, mode))
+    } else {
+        Ok(RRD::new().extract_data(now, timeframe, mode))
+    }
+}