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WIP: impl for getpage, test passes, other smgr services aren't covere…
…d, measure overhead first
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Original file line number | Diff line number | Diff line change |
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use std::{ | ||
sync::atomic::{AtomicU32, Ordering}, | ||
time::Duration, | ||
}; | ||
|
||
#[derive(Debug)] | ||
pub struct CounterU32 { | ||
inner: AtomicU32, | ||
} | ||
impl Default for CounterU32 { | ||
fn default() -> Self { | ||
Self { | ||
inner: AtomicU32::new(u32::MAX), | ||
} | ||
} | ||
} | ||
impl CounterU32 { | ||
pub fn open(&self) -> Result<(), &'static str> { | ||
match self | ||
.inner | ||
.compare_exchange(u32::MAX, 0, Ordering::Relaxed, Ordering::Relaxed) | ||
{ | ||
Ok(_) => Ok(()), | ||
Err(_) => Err("open() called on clsoed state"), | ||
} | ||
} | ||
pub fn close(&self) -> Result<u32, &'static str> { | ||
match self.inner.swap(u32::MAX, Ordering::Relaxed) { | ||
u32::MAX => Err("close() called on closed state"), | ||
x => Ok(x), | ||
} | ||
} | ||
|
||
pub fn add(&self, count: u32) -> Result<(), &'static str> { | ||
if count == 0 { | ||
return Ok(()); | ||
} | ||
let mut had_err = None; | ||
self.inner | ||
.fetch_update(Ordering::Relaxed, Ordering::Relaxed, |cur| match cur { | ||
u32::MAX => { | ||
had_err = Some("add() called on closed state"); | ||
None | ||
} | ||
x => { | ||
let (new, overflowed) = x.overflowing_add(count); | ||
if new == u32::MAX || overflowed { | ||
had_err = Some("add() overflowed the counter"); | ||
None | ||
} else { | ||
Some(new) | ||
} | ||
} | ||
}) | ||
.map_err(|_| had_err.expect("we set it whenever the function returns None")) | ||
.map(|_| ()) | ||
} | ||
} | ||
|
||
#[derive(Default, Debug)] | ||
pub struct MicroSecondsCounterU32 { | ||
inner: CounterU32, | ||
} | ||
|
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impl MicroSecondsCounterU32 { | ||
pub fn open(&self) -> Result<(), &'static str> { | ||
self.inner.open() | ||
} | ||
pub fn add(&self, duration: Duration) -> Result<(), &'static str> { | ||
match duration.as_micros().try_into() { | ||
Ok(x) => self.inner.add(x), | ||
Err(_) => Err("add(): duration conversion error"), | ||
} | ||
} | ||
pub fn close_and_checked_sub_from(&self, from: Duration) -> Result<Duration, &'static str> { | ||
let val = self.inner.close()?; | ||
let val = Duration::from_micros(val as u64); | ||
let subbed = match from.checked_sub(val) { | ||
Some(v) => v, | ||
None => return Err("Duration::checked_sub"), | ||
}; | ||
Ok(subbed) | ||
} | ||
} | ||
|
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#[cfg(test)] | ||
mod tests { | ||
|
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use super::*; | ||
|
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#[test] | ||
fn test_basic() { | ||
let counter = MicroSecondsCounterU32::default(); | ||
counter.open().unwrap(); | ||
counter.add(Duration::from_micros(23)).unwrap(); | ||
let res = counter | ||
.close_and_checked_sub_from(Duration::from_micros(42)) | ||
.unwrap(); | ||
assert_eq!(res, Duration::from_micros(42 - 23)); | ||
} | ||
} |
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