proxmox-backup/proxmox-rrd/src/rrd.rs

405 lines
11 KiB
Rust

//! # Proxmox RRD format version 2
//!
//! The new format uses
//! [CBOR](https://datatracker.ietf.org/doc/html/rfc8949) as storage
//! format. This way we can use the serde serialization framework,
//! which make our code more flexible, much nicer and type safe.
//!
//! ## Features
//!
//! * Well defined data format [CBOR](https://datatracker.ietf.org/doc/html/rfc8949)
//! * Plattform independent (big endian f64, hopefully a standard format?)
//! * Arbitrary number of RRAs (dynamically changeable)
use std::path::Path;
use anyhow::{bail, format_err, Error};
use serde::{Serialize, Deserialize};
use proxmox::tools::fs::{replace_file, CreateOptions};
use proxmox_schema::api;
use crate::rrd_v1;
/// Proxmox RRD v2 file magic number
// openssl::sha::sha256(b"Proxmox Round Robin Database file v2.0")[0..8];
pub const PROXMOX_RRD_MAGIC_2_0: [u8; 8] = [224, 200, 228, 27, 239, 112, 122, 159];
#[api()]
#[derive(Debug, Serialize, Deserialize, Copy, Clone, PartialEq)]
#[serde(rename_all = "kebab-case")]
/// RRD data source type
pub enum DST {
/// Gauge values are stored unmodified.
Gauge,
/// Stores the difference to the previous value.
Derive,
/// Stores the difference to the previous value (like Derive), but
/// detect counter overflow (and ignores that value)
Counter,
}
#[api()]
#[derive(Debug, Serialize, Deserialize, Copy, Clone, PartialEq)]
#[serde(rename_all = "kebab-case")]
/// Consolidation function
pub enum CF {
/// Average
Average,
/// Maximum
Maximum,
/// Minimum
Minimum,
/// Use the last value
Last,
}
#[derive(Serialize, Deserialize)]
pub struct DataSource {
/// Data source type
pub dst: DST,
/// Last update time (epoch)
pub last_update: f64,
/// Stores the last value, used to compute differential value for
/// derive/counters
pub last_value: f64,
}
impl DataSource {
pub fn new(dst: DST) -> Self {
Self {
dst,
last_update: 0.0,
last_value: f64::NAN,
}
}
fn compute_new_value(&mut self, time: f64, mut value: f64) -> Result<f64, Error> {
if time < 0.0 {
bail!("got negative time");
}
if time <= self.last_update {
bail!("time in past ({} < {})", time, self.last_update);
}
if value.is_nan() {
bail!("new value is NAN");
}
// derive counter value
let is_counter = self.dst == DST::Counter;
if is_counter || self.dst == DST::Derive {
let time_diff = time - self.last_update;
let diff = if self.last_value.is_nan() {
0.0
} else if is_counter && value < 0.0 {
bail!("got negative value for counter");
} else if is_counter && value < self.last_value {
// Note: We do not try automatic overflow corrections, but
// we update last_value anyways, so that we can compute the diff
// next time.
self.last_value = value;
bail!("conter overflow/reset detected");
} else {
value - self.last_value
};
self.last_value = value;
value = diff/time_diff;
} else {
self.last_value = value;
}
Ok(value)
}
}
#[derive(Serialize, Deserialize)]
pub struct RRA {
pub resolution: u64,
pub cf: CF,
/// Count values computed inside this update interval
pub last_count: u64,
/// The actual data
pub data: Vec<f64>,
}
impl RRA {
pub fn new(cf: CF, resolution: u64, points: usize) -> Self {
Self {
cf,
resolution,
last_count: 0,
data: vec![f64::NAN; points],
}
}
pub fn slot_end_time(&self, time: u64) -> u64 {
self.resolution * (time / self.resolution + 1)
}
pub fn slot_start_time(&self, time: u64) -> u64 {
self.resolution * (time / self.resolution)
}
pub fn slot(&self, time: u64) -> usize {
((time / self.resolution) as usize) % self.data.len()
}
// directly overwrite data slots
// the caller need to set last_update value on the DataSource manually.
pub fn insert_data(
&mut self,
start: u64,
resolution: u64,
data: Vec<Option<f64>>,
) -> Result<(), Error> {
if resolution != self.resolution {
bail!("inser_data failed: got wrong resolution");
}
let mut index = self.slot(start);
for i in 0..data.len() {
if let Some(v) = data[i] {
self.data[index] = v;
}
index += 1; if index >= self.data.len() { index = 0; }
}
Ok(())
}
fn delete_old_slots(&mut self, time: f64, last_update: f64) {
let epoch = time as u64;
let last_update = last_update as u64;
let reso = self.resolution;
let num_entries = self.data.len() as u64;
let min_time = epoch - num_entries*reso;
let min_time = (min_time/reso + 1)*reso;
let mut t = last_update.saturating_sub(num_entries*reso);
let mut index = self.slot(t);
for _ in 0..num_entries {
t += reso;
index += 1; if index >= self.data.len() { index = 0; }
if t < min_time {
self.data[index] = f64::NAN;
} else {
break;
}
}
}
fn compute_new_value(&mut self, time: f64, last_update: f64, value: f64) {
let epoch = time as u64;
let last_update = last_update as u64;
let reso = self.resolution;
let index = self.slot(epoch);
let last_index = self.slot(last_update);
if (epoch - last_update) > reso || index != last_index {
self.last_count = 0;
}
let last_value = self.data[index];
if last_value.is_nan() {
self.last_count = 0;
}
let new_count = if self.last_count < u64::MAX {
self.last_count + 1
} else {
u64::MAX // should never happen
};
if self.last_count == 0 {
self.data[index] = value;
self.last_count = 1;
} else {
let new_value = match self.cf {
CF::Maximum => if last_value > value { last_value } else { value },
CF::Minimum => if last_value < value { last_value } else { value },
CF::Last => value,
CF::Average => {
(last_value*(self.last_count as f64))/(new_count as f64)
+ value/(new_count as f64)
}
};
self.data[index] = new_value;
self.last_count = new_count;
}
}
pub fn extract_data(
&self,
start: u64,
end: u64,
last_update: f64,
) -> (u64, u64, Vec<Option<f64>>) {
let last_update = last_update as u64;
let reso = self.resolution;
let num_entries = self.data.len() as u64;
let mut list = Vec::new();
let rrd_end = self.slot_end_time(last_update);
let rrd_start = rrd_end.saturating_sub(reso*num_entries);
let mut t = start;
let mut index = self.slot(t);
for _ in 0..num_entries {
if t > end { break; };
if t < rrd_start || t > rrd_end {
list.push(None);
} else {
let value = self.data[index];
if value.is_nan() {
list.push(None);
} else {
list.push(Some(value));
}
}
t += reso;
index += 1; if index >= self.data.len() { index = 0; }
}
(start, reso, list)
}
}
#[derive(Serialize, Deserialize)]
pub struct RRD {
pub source: DataSource,
pub rra_list: Vec<RRA>,
}
impl RRD {
pub fn new(dst: DST, rra_list: Vec<RRA>) -> RRD {
let source = DataSource::new(dst);
RRD {
source,
rra_list,
}
}
fn from_raw(raw: &[u8]) -> Result<Self, Error> {
if raw.len() < 8 {
bail!("not an rrd file - file is too small ({})", raw.len());
}
let rrd = if raw[0..8] == rrd_v1::PROXMOX_RRD_MAGIC_1_0 {
let v1 = rrd_v1::RRDv1::from_raw(&raw)?;
v1.to_rrd_v2()
.map_err(|err| format_err!("unable to convert from old V1 format - {}", err))?
} else if raw[0..8] == PROXMOX_RRD_MAGIC_2_0 {
serde_cbor::from_slice(&raw[8..])
.map_err(|err| format_err!("unable to decode RRD file - {}", err))?
} else {
bail!("not an rrd file - unknown magic number");
};
if rrd.source.last_update < 0.0 {
bail!("rrd file has negative last_update time");
}
Ok(rrd)
}
/// Load data from a file
pub fn load(path: &Path) -> Result<Self, std::io::Error> {
let raw = std::fs::read(path)?;
match Self::from_raw(&raw) {
Ok(rrd) => Ok(rrd),
Err(err) => Err(std::io::Error::new(std::io::ErrorKind::Other, err.to_string())),
}
}
/// Store data into a file (atomic replace file)
pub fn save(&self, filename: &Path, options: CreateOptions) -> Result<(), Error> {
let mut data: Vec<u8> = Vec::new();
data.extend(&PROXMOX_RRD_MAGIC_2_0);
serde_cbor::to_writer(&mut data, self)?;
replace_file(filename, &data, options)
}
pub fn last_update(&self) -> f64 {
self.source.last_update
}
/// Update the value (in memory)
///
/// Note: This does not call [Self::save].
pub fn update(&mut self, time: f64, value: f64) {
let value = match self.source.compute_new_value(time, value) {
Ok(value) => value,
Err(err) => {
log::error!("rrd update failed: {}", err);
return;
}
};
let last_update = self.source.last_update;
self.source.last_update = time;
for rra in self.rra_list.iter_mut() {
rra.delete_old_slots(time, last_update);
rra.compute_new_value(time, last_update, value);
}
}
/// Extract data from the archive
///
/// This selects the RRA with specified [CF] and (minimum)
/// resolution, and extract data from `start` to `end`.
///
/// `start`: Start time. If not sepecified, we simply extract 10 data points.
/// `end`: End time. Default is to use the current time.
pub fn extract_data(
&self,
cf: CF,
resolution: u64,
start: Option<u64>,
end: Option<u64>,
) -> Result<(u64, u64, Vec<Option<f64>>), Error> {
let mut rra: Option<&RRA> = None;
for item in self.rra_list.iter() {
if item.cf != cf { continue; }
if item.resolution > resolution { continue; }
if let Some(current) = rra {
if item.resolution > current.resolution {
rra = Some(item);
}
} else {
rra = Some(item);
}
}
match rra {
Some(rra) => {
let end = end.unwrap_or_else(|| proxmox_time::epoch_f64() as u64);
let start = start.unwrap_or(end - 10*rra.resolution);
Ok(rra.extract_data(start, end, self.source.last_update))
}
None => bail!("unable to find RRA suitable ({:?}:{})", cf, resolution),
}
}
}