/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at
http://mozilla.org/MPL/2.0/. */
use std::time::{Duration, SystemTime, UNIX_EPOCH};
/// The maximum number of whole milliseconds that can be represented in
/// an `f64` without loss of precision.
const MAX_FLOAT_MILLISECONDS: f64 = ((1u64 << f64::MANTISSA_DIGITS) - 1) as f64;
/// Typesafe way to manage server timestamps without accidentally mixing them up with
/// local ones.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Default)]
pub struct ServerTimestamp(pub i64);
impl ServerTimestamp {
pub fn from_float_seconds(ts: f64) -> Self {
let rf = (ts * 1000.0).round();
if !(0.0..=MAX_FLOAT_MILLISECONDS).contains(&rf) {
error_support::report_error!("sync15-illegal-timestamp", "Illegal timestamp: {}", ts
);
ServerTimestamp(0)
} else {
ServerTimestamp(rf as i64)
}
}
pub fn from_millis(ts: i64) -> Self {
// Catch it in tests, but just complain and replace with 0 otherwise.
debug_assert!(ts >= 0, "Bad timestamp: {}", ts);
if ts >= 0 {
Self(ts)
} else {
error_support::report_error!(
"sync15-illegal-timestamp",
"Illegal timestamp, substituting 0: {}",
ts
);
Self(0)
}
}
}
// This lets us use these in hyper header! blocks.
impl std::str::FromStr for ServerTimestamp {
type Err = std::num::ParseFloatError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let val = f64::from_str(s)?;
Ok(Self::from_float_seconds(val))
}
}
impl std::fmt::Display for ServerTimestamp {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", self.0 as f64 / 1000.0)
}
}
impl ServerTimestamp {
pub const EPOCH: ServerTimestamp = ServerTimestamp(0);
/// Returns None if `other` is later than `self` (Duration may not represent
/// negative timespans in rust).
#[inline]
pub fn duration_since(self, other: ServerTimestamp) -> Option<Duration> {
let delta = self.0 - other.0;
if delta < 0 {
None
} else {
Some(Duration::from_millis(delta as u64))
}
}
/// Get the milliseconds for the timestamp.
#[inline]
pub fn as_millis(self) -> i64 {
self.0
}
}
impl serde::ser::Serialize for ServerTimestamp {
fn serialize<S: serde::ser::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
serializer.serialize_f64(self.0 as f64 / 1000.0)
}
}
impl<'de> serde::de::Deserialize<'de> for ServerTimestamp {
fn deserialize<D: serde::de::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
f64::deserialize(d).map(Self::from_float_seconds)
}
}
/// Exposed only for tests that need to create a server timestamp from the system time
/// Please be cautious when constructing the timestamp directly, as constructing the server
/// timestamp from system time is almost certainly not what you'd want to do for non-test code
impl TryFrom<SystemTime> for ServerTimestamp {
type Error = std::time::SystemTimeError;
fn try_from(value: SystemTime) -> Result<Self, Self::Error> {
Ok(Self(value.duration_since(UNIX_EPOCH)?.as_millis() as i64))
}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_server_timestamp() {
let t0 = ServerTimestamp(10_300_150);
let t1 = ServerTimestamp(10_100_050);
assert!(t1.duration_since(t0).is_none());
assert!(t0.duration_since(t1).is_some());
let dur = t0.duration_since(t1).unwrap();
assert_eq!(dur.as_secs(), 200);
assert_eq!(dur.subsec_nanos(), 100_000_000);
}
#[test]
fn test_serde() {
let ts = ServerTimestamp(123_456);
// test serialize
let ser = serde_json::to_string(&ts).unwrap();
assert_eq!("123.456".to_string(), ser);
// test deserialize of float
let ts: ServerTimestamp = serde_json::from_str(&ser).unwrap();
assert_eq!(ServerTimestamp(123_456), ts);
// test deserialize of whole number
let ts: ServerTimestamp = serde_json::from_str("123").unwrap();
assert_eq!(ServerTimestamp(123_000), ts);
// test deserialize of negative number
let ts: ServerTimestamp = serde_json::from_str("-123").unwrap();
assert_eq!(ServerTimestamp(0), ts);
}
}
