devela/data/id/seq.rs
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// devela::data::id::seq
//
//! Sequential unique IDs.
//
/// A macro for constructing a unique sequential identifier generator.
///
/// It generates the necessary static instances dynamically.
///
/// # Example
/// ```
/// # use devela::id_seq;
/// id_seq![AppId1, u8];
///
/// assert_eq![AppId1::generated_ids(), 0];
/// assert_eq![AppId1::remaining_ids(), u8::MAX - 1];
///
/// assert_eq![AppId1::new().unwrap().value(), 1];
/// assert_eq![AppId1::new_unchecked().value(), 2];
///
/// // generate all remaining ids.
/// for _ in 2..u8::MAX {
/// let _ = AppId1::new_fast_unchecked();
/// }
/// assert_eq![AppId1::new_fast(), None];
/// ```
///
/// See also the [id_seq][crate::_info::examples::id_seq] example.
#[macro_export]
#[cfg_attr(cargo_primary_package, doc(hidden))]
macro_rules! id_seq {
(
// $name: the name of the sequential ID generator. E.g. AppId1.
// $prim: the underlying primitive type. E.g. u64.
$name:ident,
$prim:ty
) => {
$crate::paste! {
$crate::id_seq![
$name, // the name of the ID generator.
$name, // the name of the ID generator (as a type).
[<$name:upper>], // the name of the static.
[<$prim:lower>], // the underlying primitive type.
[<Atomic $prim:camel>] // the atomic type in the static.
];
}
};
($name:ident, $tname:ty, $static:ident, $prim:ty, $atomic:ident) => {
/// A static atomic counter used to generate unique sequential identifiers of type `$prim`.
static $static: core::sync::atomic::$atomic =
core::sync::atomic::$atomic::new(<$prim>::MIN + 1);
#[doc = concat!("A unique sequential identifier `", stringify!($prim), "` generator.")]
///
#[doc = concat!("The counter starts at [`", stringify!($prim), "::MIN`]` + 1`,")]
/// and increments with each new identifier generated.
///
/// The implementation guards against wrap-around
#[doc = concat!("after [`", stringify!($prim), "::MAX`],")]
/// by returning `None` in the checked methods, or panicking in the unchecked methods.
///
/// See also the [`id_seq`] macro.
#[derive(Debug)]
#[must_use]
pub struct $name {
id: $prim,
}
impl $name {
/* generators */
#[doc = concat!("Generates some unique `", stringify!($name), "` ID.")]
///
/// Alias of [`new_balanced`][Self::new_balanced].
///
/// Returns `None` on overflow.
#[must_use]
pub fn new() -> Option<Self> {
Self::new_balanced()
}
#[doc = concat!("Generates some unique `", stringify!($name), "` ID.")]
///
/// Alias of [`new_balanced_unchecked`][Self::new_balanced_unchecked].
///
/// # Panics
/// Panics on overflow.
pub fn new_unchecked() -> Self {
Self::new_balanced_unchecked()
}
#[doc = concat!(
"Generates some unique `", stringify!($name), "` ID with [`SeqCst`] ordering.")
]
///
/// Ensures the strongest memory consistency across all threads,
/// even at the cost of performance.
///
/// Returns `None` on overflow.
///
/// [`SeqCst`]: core::sync::atomic::Ordering::SeqCst
#[must_use]
pub fn new_strong() -> Option<Self> {
Self::new_custom(core::sync::atomic::Ordering::SeqCst)
}
#[doc = concat!(
"Generates a unique `", stringify!($name), "` ID with [`SeqCst`] ordering.")
]
///
/// Ensures the strongest memory consistency across all threads,
/// even at the cost of performance.
///
/// # Panics
/// Panics on overflow.
///
/// [`SeqCst`]: core::sync::atomic::Ordering::SeqCst
pub fn new_strong_unchecked() -> Self {
Self::new_custom_unchecked(core::sync::atomic::Ordering::SeqCst)
}
#[doc = concat!(
"Generates some unique `", stringify!($name), "` ID with [`AcqRel`] ordering.")
]
///
/// Balances performance and memory safety,
/// ensuring consistent visibility across threads.
///
/// Returns `None` on overflow.
///
/// [`AcqRel`]: core::sync::atomic::Ordering::AcqRel
#[must_use]
pub fn new_balanced() -> Option<Self> {
Self::new_custom(core::sync::atomic::Ordering::AcqRel)
}
#[doc = concat!(
"Generates a unique `", stringify!($name), "` ID with [`AcqRel`] ordering.")
]
///
/// Balances performance and memory safety,
/// ensuring consistent visibility across threads.
///
/// # Panics
/// Panics on overflow.
///
/// [`AcqRel`]: core::sync::atomic::Ordering::AcqRel
pub fn new_balanced_unchecked() -> Self {
Self::new_custom_unchecked(core::sync::atomic::Ordering::AcqRel)
}
#[doc = concat!(
"Generates some unique `", stringify!($name), "` ID with [`Relaxed`] ordering.")
]
///
/// Offers maximum performance in low-contention scenarios
/// where memory ordering is not a concern.
///
/// Returns `None` on overflow.
///
/// [`Relaxed`]: core::sync::atomic::Ordering::Relaxed
#[must_use]
pub fn new_fast() -> Option<Self> {
Self::new_custom(core::sync::atomic::Ordering::Relaxed)
}
#[doc = concat!(
"Generates a unique `", stringify!($name), "` ID with [`Relaxed`] ordering.")
]
///
/// Offers maximum performance in low-contention scenarios
/// where memory ordering is not a concern.
///
/// # Panics
/// Panics on overflow.
///
/// [`Relaxed`]: core::sync::atomic::Ordering::Relaxed
pub fn new_fast_unchecked() -> Self {
Self::new_custom_unchecked(core::sync::atomic::Ordering::Relaxed)
}
/* iterators */
/// Iterator over generated IDs with `SeqCst` ordering.
///
/// Ensures the strongest memory consistency across all threads,
/// even at the cost of performance.
///
/// [`SeqCst`]: core::sync::atomic::Ordering::SeqCst
pub fn iter_strong() -> impl Iterator<Item = $name> {
core::iter::from_fn(|| Self::new_strong())
}
/// Iterator over generated IDs with `SeqCst` ordering.
///
/// Ensures the strongest memory consistency across all threads,
/// even at the cost of performance.
///
/// # Panics
/// Panics on overflow.
///
/// [`SeqCst`]: core::sync::atomic::Ordering::SeqCst
pub fn iter_strong_unchecked() -> impl Iterator<Item = $name> {
core::iter::from_fn(|| Some(Self::new_strong_unchecked()))
}
/// Iterator over generated IDs with `AcqRel` ordering.
///
/// Balances performance and memory safety,
/// ensuring consistent visibility across threads.
///
/// [`AcqRel`]: core::sync::atomic::Ordering::AcqRel
pub fn iter_balanced() -> impl Iterator<Item = $name> {
core::iter::from_fn(|| Self::new_balanced())
}
/// Iterator over generated IDs with `AcqRel` ordering.
///
/// Balances performance and memory safety,
/// ensuring consistent visibility across threads.
///
/// # Panics
/// Panics on overflow.
///
/// [`AcqRel`]: core::sync::atomic::Ordering::AcqRel
pub fn iter_balanced_unchecked() -> impl Iterator<Item = $name> {
core::iter::from_fn(|| Some(Self::new_balanced_unchecked()))
}
/// Iterator over generated IDs with `Relaxed` ordering.
///
/// Offers maximum performance in low-contention scenarios
/// where memory ordering is not a concern.
///
/// [`Relaxed`]: core::sync::atomic::Ordering::Relaxed
pub fn iter_fast() -> impl Iterator<Item = $name> {
core::iter::from_fn(|| Self::new_fast())
}
/// Iterator over generated IDs with `Relaxed` ordering.
///
/// Offers maximum performance in low-contention scenarios
/// where memory ordering is not a concern.
///
/// # Panics
/// Panics on overflow.
///
/// [`Relaxed`]: core::sync::atomic::Ordering::Relaxed
pub fn iter_fast_unchecked() -> impl Iterator<Item = $name> {
core::iter::from_fn(|| Some(Self::new_fast_unchecked()))
}
/* queries */
/// Returns the underlying unique ID value
#[doc = concat!("as a `", stringify!($prim), "`.")]
///
/// The value is guaranteed to be a valid sequential identifier, from
#[doc = concat!("`", stringify!($prim) ,"::MIN` to `", stringify!($prim), "::MAX`.")]
pub fn value(&self) -> $prim {
self.id
}
/// Returns the number of IDs generated so far.
///
/// Alias of [`generated_ids_balanced`][Self::generated_ids_balanced].
#[must_use]
pub fn generated_ids() -> $prim {
Self::generated_ids_balanced()
}
/// Returns the number of IDs generated so far with [`SeqCst`] ordering.
///
/// Ensures the strongest memory consistency across all threads,
/// even at the cost of performance.
///
/// [`SeqCst`]: core::sync::atomic::Ordering::SeqCst
#[must_use]
pub fn generated_ids_strong() -> $prim {
let current_id = $static.load(core::sync::atomic::Ordering::SeqCst);
current_id - 1
}
/// Returns the number of IDs generated so far with [`Acquire`] ordering.
///
/// Balances performance and memory safety,
/// ensuring consistent visibility across threads.
///
/// [`Acquire`]: core::sync::atomic::Ordering::Acquire
#[must_use]
pub fn generated_ids_balanced() -> $prim {
let current_id = $static.load(core::sync::atomic::Ordering::Acquire);
current_id - 1
}
/// Returns the number of IDs generated so far with [`Relaxed`] ordering.
///
/// Offers maximum performance in low-contention scenarios
/// where memory ordering is not a concern.
///
/// [`Relaxed`]: core::sync::atomic::Ordering::Relaxed
#[must_use]
pub fn generated_ids_fast() -> $prim {
let current_id = $static.load(core::sync::atomic::Ordering::Relaxed);
current_id - 1
}
/// Returns the number of remaining IDs.
///
/// Alias of [`remaining_ids_balanced`][Self::remaining_ids_balanced].
#[must_use]
pub fn remaining_ids() -> $prim {
Self::remaining_ids_balanced()
}
/// Returns the number of remaining IDs with [`SeqCst`] ordering.
///
/// Ensures the strongest memory consistency across all threads,
/// even at the cost of performance.
///
/// [`SeqCst`]: core::sync::atomic::Ordering::SeqCst
#[must_use]
pub fn remaining_ids_strong() -> $prim {
let current_id = $static.load(core::sync::atomic::Ordering::SeqCst);
<$prim>::MAX - current_id
}
/// Returns the number of remaining IDs with [`Acquire`] ordering.
///
/// Balances performance and memory safety,
/// ensuring consistent visibility across threads.
///
/// [`Acquire`]: core::sync::atomic::Ordering::Acquire
#[must_use]
pub fn remaining_ids_balanced() -> $prim {
let current_id = $static.load(core::sync::atomic::Ordering::Acquire);
<$prim>::MAX - current_id
}
/// Returns the number of remaining IDs with [`Relaxed`] ordering.
///
/// Offers maximum performance in low-contention scenarios
/// where memory ordering is not a concern.
///
/// [`Relaxed`]: core::sync::atomic::Ordering::Relaxed
#[must_use]
pub fn remaining_ids_fast() -> $prim {
let current_id = $static.load(core::sync::atomic::Ordering::Relaxed);
<$prim>::MAX - current_id
}
/* private helpers */
fn new_custom(ordering: core::sync::atomic::Ordering) -> Option<Self> {
let id = $static.fetch_add(1, ordering);
if id == <$prim>::MIN {
Self::none_on_overflow()
} else {
Some(Self { id })
}
}
#[cold] #[rustfmt::skip]
fn none_on_overflow() -> Option<Self> { None }
fn new_custom_unchecked(ordering: core::sync::atomic::Ordering) -> Self {
let id = $static.fetch_add(1, ordering);
if id == <$prim>::MIN {
Self::panic_on_overflow();
}
Self { id }
}
#[cold] #[rustfmt::skip]
fn panic_on_overflow() -> ! { panic!("ID counter overflowed"); }
}
/* trait impls */
impl From<$name> for $prim {
fn from(from: $name) -> $prim {
from.value()
}
}
impl core::hash::Hash for $name {
fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
self.id.hash(state);
}
}
impl PartialEq for $name {
fn eq(&self, other: &Self) -> bool {
self.id == other.id
}
}
impl Eq for $name {}
impl PartialOrd for $name {
fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
Some(self.id.cmp(&other.id))
}
}
impl Ord for $name {
fn cmp(&self, other: &Self) -> core::cmp::Ordering {
self.id.cmp(&other.id)
}
}
};
}
#[doc(inline)]
pub use id_seq;
mod test {
#[allow(unused_imports)] // BUG:compiler doesn't detect use of ExtAny::type_of
use crate::{assert_eq_all, id_seq, ExtAny};
#[test]
fn id_seq_start_uniqueness_end() {
id_seq![TestIdSeqU8a, u8];
id_seq![TestIdSeqU8b, u8];
id_seq![TestIdSeqI8, i8];
// unsigned starts at 1 (MIN+1)
let u8a_id1 = TestIdSeqU8a::new().unwrap();
let u8b_id1 = TestIdSeqU8b::new().unwrap();
// types are different, values can be the same
assert_ne![u8a_id1.type_of(), u8b_id1.type_of()];
assert_eq_all![1, u8a_id1.value(), u8b_id1.value()];
let u8a_id2 = TestIdSeqU8a::new().unwrap();
assert_eq![2, u8a_id2.value()];
// signed starts at MIN+1
let i8_id1 = TestIdSeqI8::new().unwrap();
let i8_id2 = TestIdSeqI8::new().unwrap();
assert_eq![i8::MIN + 1, i8_id1.value()];
assert_eq![i8::MIN + 2, i8_id2.value()];
// generate all remaining ids
for _ in 2..u8::MAX {
let _ = TestIdSeqU8a::new_fast_unchecked();
let _ = TestIdSeqI8::new_fast_unchecked();
}
// check wrapping prevention
assert_eq![TestIdSeqU8a::new_fast(), None];
assert_eq![TestIdSeqI8::new_fast(), None];
}
#[test]
#[cfg(feature = "alloc")]
fn id_seq_iter() {
use crate::Vec;
id_seq![TestIdSeqU8Iter, u8];
let ids: Vec<_> = TestIdSeqU8Iter::iter_fast().take(10).collect();
// First 10 IDs should start at 1 and end at 10
let expected_ids: Vec<u8> = (1..=10).collect();
assert_eq!(ids.iter().map(|id| id.value()).collect::<Vec<_>>(), expected_ids);
let ids: Vec<_> = TestIdSeqU8Iter::iter_balanced().take(10).collect();
// next 10 IDs should start at 11 and end at 20
let expected_ids: Vec<u8> = (11..=20).collect();
assert_eq!(ids.iter().map(|id| id.value()).collect::<Vec<_>>(), expected_ids);
}
#[test]
#[cfg(feature = "alloc")]
fn id_seq_iter_stops_at_max() {
use crate::Vec;
id_seq![TestIdSeqU8IterStops, u8];
type IdGen = TestIdSeqU8IterStops;
// move the id counter close to the maximum value
let _: Vec<_> = IdGen::iter_fast().take(252).collect();
// take the rest of the ids
let ids: Vec<_> = IdGen::iter_fast().collect();
let expected_ids = Vec::from([253, 254, 255]);
assert_eq!(ids.iter().map(|id| id.value()).collect::<Vec<_>>(), expected_ids);
}
#[test]
#[cfg(feature = "std")]
fn id_seq_iter_panics_on_overflow() {
use std::panic::catch_unwind;
id_seq![TestIdSeqU8IterPanics, u8];
type IdGen = TestIdSeqU8IterPanics;
// move the id counter to the maximum value
let _: Vec<_> = IdGen::iter_fast_unchecked().take(255).collect();
// Expect a panic on overflow
let result = catch_unwind(|| {
let _ids: Vec<_> = IdGen::iter_fast_unchecked().take(1).collect();
});
assert!(result.is_err(), "Expected panic due to overflow, but no panic occurred");
}
}