A multithreaded and single threaded string interner that allows strings to be cached with a minimal memory footprint,
associating them with a unique key that can be used to retrieve them at any time. A Rodeo
allows O(1)
internment and resolution and can be turned into a RodeoReader
to allow for contention-free resolutions
with both key to str and str to key operations. It can also be turned into a RodeoResolver
with only
key to str operations for the lowest possible memory usage.
Which interner do I use?
For single-threaded workloads Rodeo
is encouraged, while multi-threaded applications should use ThreadedRodeo
.
Both of these are the only way to intern strings, but most applications will hit a stage where they are done interning
strings, and at that point is where the choice between RodeoReader
and RodeoResolver
. If the user needs to get
keys for strings still, then they must use the RodeoReader
(although they can still transfer into a RodeoResolver
)
at this point. For users who just need key to string resolution, the RodeoResolver
gives contention-free access at the
minimum possible memory usage. Note that to gain access to ThreadedRodeo
the multi-threaded
feature is required.
Cargo Features
By default lasso
has one dependency, hashbrown
, and only Rodeo
is exposed. Hashbrown is used since the raw_entry
api is currently unstable in the standard library's hashmap.
The raw hashmap API is used for custom hashing within the hashmaps, which works to dramatically reduce memory usage
To make use of ThreadedRodeo
, you must enable the multi-threaded
feature.
multi-threaded
- Enables ThreadedRodeo
, the interner for multi-threaded tasks
ahasher
- Use ahash
's RandomState
as the default hasher
no-std
- Enables no_std
+ alloc
support for Rodeo
and ThreadedRodeo
- Automatically enables the following required features:
ahasher
- no_std
hashing function
serialize
- Implements Serialize
and Deserialize
for all Spur
types and all interners
inline-more
- Annotate external apis with #[inline]
Example: Using Rodeo
use lasso::Rodeo;
let mut rodeo = Rodeo::default();
let key = rodeo.get_or_intern("Hello, world!");
// Easily retrieve the value of a key and find the key for values
assert_eq!("Hello, world!", rodeo.resolve(&key));
assert_eq!(Some(key), rodeo.get("Hello, world!"));
// Interning the same string again will yield the same key
let key2 = rodeo.get_or_intern("Hello, world!");
assert_eq!(key, key2);
Example: Using ThreadedRodeo
use lasso::ThreadedRodeo;
use std::{thread, sync::Arc};
let rodeo = Arc::new(ThreadedRodeo::default());
let key = rodeo.get_or_intern("Hello, world!");
// Easily retrieve the value of a key and find the key for values
assert_eq!("Hello, world!", rodeo.resolve(&key));
assert_eq!(Some(key), rodeo.get("Hello, world!"));
// Interning the same string again will yield the same key
let key2 = rodeo.get_or_intern("Hello, world!");
assert_eq!(key, key2);
// ThreadedRodeo can be shared across threads
let moved = Arc::clone(&rodeo);
let hello = thread::spawn(move || {
assert_eq!("Hello, world!", moved.resolve(&key));
moved.get_or_intern("Hello from the thread!")
})
.join()
.unwrap();
assert_eq!("Hello, world!", rodeo.resolve(&key));
assert_eq!("Hello from the thread!", rodeo.resolve(&hello));
Example: Creating a RodeoReader
use lasso::Rodeo;
// Rodeo and ThreadedRodeo are interchangeable here
let mut rodeo = Rodeo::default();
let key = rodeo.get_or_intern("Hello, world!");
assert_eq!("Hello, world!", rodeo.resolve(&key));
let reader = rodeo.into_reader();
// Reader keeps all the strings from the parent
assert_eq!("Hello, world!", reader.resolve(&key));
assert_eq!(Some(key), reader.get("Hello, world!"));
// The Reader can now be shared across threads, no matter what kind of Rodeo created it
Example: Creating a RodeoResolver
use lasso::Rodeo;
// Rodeo and ThreadedRodeo are interchangeable here
let mut rodeo = Rodeo::default();
let key = rodeo.get_or_intern("Hello, world!");
assert_eq!("Hello, world!", rodeo.resolve(&key));
let resolver = rodeo.into_resolver();
// Resolver keeps all the strings from the parent
assert_eq!("Hello, world!", resolver.resolve(&key));
// The Resolver can now be shared across threads, no matter what kind of Rodeo created it
Example: Making a custom-ranged key
Sometimes you want your keys to only inhabit (or not inhabit) a certain range of values so that you can have custom niches.
This allows you to pack more data into what would otherwise be unused space, which can be critical for memory-sensitive applications.
use lasso::{Key, Rodeo};
// First make our key type, this will be what we use as handles into our interner
#[derive(Copy, Clone, PartialEq, Eq)]
struct NicheKey(u32);
// This will reserve the upper 255 values for us to use as niches
const NICHE: usize = 0xFF000000;
// Implementing `Key` is unsafe and requires that anything given to `try_from_usize` must produce the
// same `usize` when `into_usize` is later called
unsafe impl Key for NicheKey {
fn into_usize(self) -> usize {
self.0 as usize
}
fn try_from_usize(int: usize) -> Option<Self> {
if int < NICHE {
// The value isn't in our niche range, so we're good to go
Some(Self(int as u32))
} else {
// The value interferes with our niche, so we return `None`
None
}
}
}
// To make sure we're upholding `Key`'s safety contract, let's make two small tests
#[test]
fn value_in_range() {
let key = NicheKey::try_from_usize(0).unwrap();
assert_eq!(key.into_usize(), 0);
let key = NicheKey::try_from_usize(NICHE - 1).unwrap();
assert_eq!(key.into_usize(), NICHE - 1);
}
#[test]
fn value_out_of_range() {
let key = NicheKey::try_from_usize(NICHE);
assert!(key.is_none());
let key = NicheKey::try_from_usize(u32::max_value() as usize);
assert!(key.is_none());
}
// And now we're done and can make `Rodeo`s or `ThreadedRodeo`s that use our custom key!
let mut rodeo: Rodeo<NicheKey> = Rodeo::new();
let key = rodeo.get_or_intern("It works!");
assert_eq!(rodeo.resolve(&key), "It works!");
Example: Creation using FromIterator
use lasso::Rodeo;
use core::iter::FromIterator;
// Works for both `Rodeo` and `ThreadedRodeo`
let rodeo = Rodeo::from_iter(vec![
"one string",
"two string",
"red string",
"blue string",
]);
assert!(rodeo.contains("one string"));
assert!(rodeo.contains("two string"));
assert!(rodeo.contains("red string"));
assert!(rodeo.contains("blue string"));
use lasso::Rodeo;
use core::iter::FromIterator;
// Works for both `Rodeo` and `ThreadedRodeo`
let rodeo: Rodeo = vec!["one string", "two string", "red string", "blue string"]
.into_iter()
.collect();
assert!(rodeo.contains("one string"));
assert!(rodeo.contains("two string"));
assert!(rodeo.contains("red string"));
assert!(rodeo.contains("blue string"));
Benchmarks
Benchmarks were gathered with Criterion.rs
OS: Windows 10
CPU: Ryzen 9 3900X at 3800Mhz
RAM: 3200Mhz
Rustc: Stable 1.44.1
Rodeo
STD RandomState
Method |
Time |
Throughput |
resolve |
1.9251 μs |
13.285 GiB/s |
try_resolve |
1.9214 μs |
13.311 GiB/s |
resolve_unchecked |
1.4356 μs |
17.816 GiB/s |
get_or_intern (empty) |
60.350 μs |
433.96 MiB/s |
get_or_intern (filled) |
57.415 μs |
456.15 MiB/s |
try_get_or_intern (empty) |
58.978 μs |
444.06 MiB/s |
try_get_or_intern (filled) |
57.421 μs |
456.10 MiB/s |
get (empty) |
37.288 μs |
702.37 MiB/s |
get (filled) |
55.095 μs |
475.36 MiB/s |
AHash
Method |
Time |
Throughput |
try_resolve |
1.9282 μs |
13.264 GiB/s |
resolve |
1.9404 μs |
13.181 GiB/s |
resolve_unchecked |
1.4328 μs |
17.851 GiB/s |
get_or_intern (empty) |
38.029 μs |
688.68 MiB/s |
get_or_intern (filled) |
33.650 μs |
778.30 MiB/s |
try_get_or_intern (empty) |
39.392 μs |
664.84 MiB/s |
try_get_or_intern (filled) |
33.435 μs |
783.31 MiB/s |
get (empty) |
12.565 μs |
2.0356 GiB/s |
get (filled) |
26.545 μs |
986.61 MiB/s |
FXHash
Method |
Time |
Throughput |
resolve |
1.9014 μs |
13.451 GiB/s |
try_resolve |
1.9278 μs |
13.267 GiB/s |
resolve_unchecked |
1.4449 μs |
17.701 GiB/s |
get_or_intern (empty) |
32.523 μs |
805.27 MiB/s |
get_or_intern (filled) |
30.281 μs |
864.88 MiB/s |
try_get_or_intern (empty) |
31.630 μs |
828.00 MiB/s |
try_get_or_intern (filled) |
31.002 μs |
844.78 MiB/s |
get (empty) |
12.699 μs |
2.0141 GiB/s |
get (filled) |
29.220 μs |
896.28 MiB/s |
ThreadedRodeo
STD RandomState
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
resolve |
54.336 μs |
482.00 MiB/s |
364.27 μs |
71.897 MiB/s |
try_resolve |
54.582 μs |
479.82 MiB/s |
352.67 μs |
74.261 MiB/s |
get_or_intern (empty) |
266.03 μs |
98.447 MiB/s |
N\A |
N\A |
get_or_intern (filled) |
103.04 μs |
254.17 MiB/s |
441.42 μs |
59.331 MiB/s |
try_get_or_intern (empty) |
261.80 μs |
100.04 MiB/s |
N\A |
N\A |
try_get_or_intern (filled) |
102.61 μs |
255.25 MiB/s |
447.42 μs |
58.535 MiB/s |
get (empty) |
80.346 μs |
325.96 MiB/s |
N\A |
N\A |
get (filled) |
92.669 μs |
282.62 MiB/s |
439.24 μs |
59.626 MiB/s |
AHash
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
resolve |
22.261 μs |
1.1489 GiB/s |
265.46 μs |
98.658 MiB/s |
try_resolve |
22.378 μs |
1.1429 GiB/s |
268.58 μs |
97.513 MiB/s |
get_or_intern (empty) |
157.86 μs |
165.91 MiB/s |
N\A |
N\A |
get_or_intern (filled) |
56.320 μs |
465.02 MiB/s |
357.13 μs |
73.335 MiB/s |
try_get_or_intern (empty) |
161.46 μs |
162.21 MiB/s |
N\A |
N\A |
try_get_or_intern (filled) |
55.874 μs |
468.73 MiB/s |
360.25 μs |
72.698 MiB/s |
get (empty) |
43.520 μs |
601.79 MiB/s |
N\A |
N\A |
get (filled) |
53.720 μs |
487.52 MiB/s |
360.66 μs |
72.616 MiB/s |
FXHash
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
try_resolve |
17.289 μs |
1.4794 GiB/s |
238.29 μs |
109.91 MiB/s |
resolve |
19.833 μs |
1.2896 GiB/s |
237.05 μs |
110.48 MiB/s |
get_or_intern (empty) |
130.97 μs |
199.97 MiB/s |
N\A |
N\A |
get_or_intern (filled) |
42.630 μs |
614.35 MiB/s |
301.60 μs |
86.837 MiB/s |
try_get_or_intern (empty) |
129.30 μs |
202.55 MiB/s |
N\A |
N\A |
try_get_or_intern (filled) |
42.508 μs |
616.12 MiB/s |
337.29 μs |
77.648 MiB/s |
get (empty) |
28.001 μs |
935.30 MiB/s |
N\A |
N\A |
get (filled) |
37.700 μs |
694.68 MiB/s |
292.15 μs |
89.645 MiB/s |
RodeoReader
STD RandomState
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
resolve |
1.9398 μs |
13.185 GiB/s |
4.3153 μs |
5.9269 GiB/s |
try_resolve |
1.9315 μs |
13.242 GiB/s |
4.1956 μs |
6.0959 GiB/s |
resolve_unchecked |
1.4416 μs |
17.741 GiB/s |
3.1204 μs |
8.1964 GiB/s |
get (empty) |
38.886 μs |
673.50 MiB/s |
N\A |
N\A |
get (filled) |
56.271 μs |
465.42 MiB/s |
105.12 μs |
249.14 MiB/s |
AHash
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
resolve |
1.9404 μs |
13.181 GiB/s |
4.1881 μs |
6.1069 GiB/s |
try_resolve |
1.8932 μs |
13.509 GiB/s |
4.2410 μs |
6.0306 GiB/s |
resolve_unchecked |
1.4128 μs |
18.103 GiB/s |
3.1691 μs |
8.0703 GiB/s |
get (empty) |
11.952 μs |
2.1399 GiB/s |
N\A |
N\A |
get (filled) |
27.093 μs |
966.65 MiB/s |
56.269 μs |
465.44 MiB/s |
FXHash
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
resolve |
1.8987 μs |
13.471 GiB/s |
4.2117 μs |
6.0727 GiB/s |
try_resolve |
1.9103 μs |
13.389 GiB/s |
4.2254 μs |
6.0529 GiB/s |
resolve_unchecked |
1.4469 μs |
17.677 GiB/s |
3.0923 μs |
8.2709 GiB/s |
get (empty) |
12.994 μs |
1.9682 GiB/s |
N\A |
N\A |
get (filled) |
29.745 μs |
880.49 MiB/s |
52.387 μs |
499.93 MiB/s |
RodeoResolver
Method |
Time (1 Thread) |
Throughput (1 Thread) |
Time (24 Threads) |
Throughput (24 Threads) |
resolve |
1.9416 μs |
13.172 GiB/s |
3.9114 μs |
6.5387 GiB/s |
try_resolve |
1.9264 μs |
13.277 GiB/s |
3.9289 μs |
6.5097 GiB/s |
resolve_unchecked |
1.6638 μs |
15.372 GiB/s |
3.1741 μs |
8.0578 GiB/s |