scalalang2 / golang-fifo

Modern efficient cache design with simple FIFO queue only in Golang
MIT License
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cache go golang library s3-fifo sieve

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golang-fifo

This is a modern cache implementation, inspired by the following papers, provides high efficiency.

This offers state-of-the-art efficiency and scalability compared to other LRU-based cache algorithms.

Basic Usage

import "github.com/scalalang2/golang-fifo/sieve"

size := 1e5
ttl := 0 // 0 means no expiration
cache := sieve.New[string, string](size, ttl)

// set value under hello
cache.Set("hello", "world")

// get value under hello
val, ok := cache.Get("hello")
if ok {
    fmt.Printf("value: %s", val) // => "world"
}

// set more keys
for i := 0; i < 10; i++ {
    cache.Set(fmt.Sprintf("key%d", i), fmt.Sprintf("value%d", i))
}

// get number of cache entries
fmt.Printf("len: %d", cache.Len()) // => 11

// remove value under hello
removed := cache.Remove("hello")
if removed {
    fmt.Println("hello was removed")
}

Expiry

import "github.com/scalalang2/golang-fifo/sieve"

size := 1e5
ttl := time.Second * 3600 // 1 hour
cache := sieve.New[string, string](size, ttl)

// this callback will be called when the element is expired
cahe.SetOnEvict(func(key string, value string) {
    fmt.Printf("key: %s, value: %s was evicted", key, value)
})

// set value under hello
cache.Set("hello", "world")

// remove all cache entries and stop the eviction goroutine.
cache.Close()

Benchmark Result

The benchmark result were obtained using go-cache-benchmark

itemSize=500000, workloads=7500000, cacheSize=0.10%, zipf's alpha=0.99, concurrency=16

      CACHE      | HITRATE |   QPS   |  HITS   | MISSES
-----------------+---------+---------+---------+----------
  sieve          | 47.66%  | 2508361 | 3574212 | 3925788
  tinylfu        | 47.37%  | 2269542 | 3552921 | 3947079
  s3-fifo        | 47.17%  | 1651619 | 3538121 | 3961879
  slru           | 46.49%  | 2201350 | 3486476 | 4013524
  s4lru          | 46.09%  | 2484266 | 3456682 | 4043318
  two-queue      | 45.49%  | 1713502 | 3411800 | 4088200
  clock          | 37.34%  | 2370417 | 2800750 | 4699250
  lru-groupcache | 36.59%  | 2206841 | 2743894 | 4756106
  lru-hashicorp  | 36.57%  | 2055358 | 2743000 | 4757000

SIEVE delivers both high hit rates and the highest QPS(queries per seconds) compared to other LRU-based caches. Additionally, It approximately improves 30% for efficiency than a simple LRU cache.

Increasing efficiency means not only reducing cache misses, but also reducing the demand for heavy operations such as backend database access, which lowers the mean latency.

While LRU promotes accessed objects to the head of the queue, requiring a potentially slow lock acquisition, SIEVE only needs to update a single bit upon a cache hit. This update can be done with a significantly faster reader lock, leading to increased performance.

The real-world traces are also evaluated at here

Appendix

Performance : golang-fifo ```shell goos: linux goarch: amd64 pkg: github.com/scalalang2/golang-fifo cpu: Intel(R) Core(TM) i5-10600KF CPU @ 4.10GHz BenchmarkCache BenchmarkCache/cache=sieve BenchmarkCache/cache=sieve/t=int32 BenchmarkCache/cache=sieve/t=int32-12 2765682 393.8 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 3037669 388.1 ns/op 149 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 3075998 395.0 ns/op 149 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 2924646 392.0 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 2632326 409.3 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 2746551 463.5 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 3004071 401.0 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 2398981 456.0 ns/op 149 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 2698939 422.9 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int32-12 2647030 392.1 ns/op 148 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64 BenchmarkCache/cache=sieve/t=int64-12 2532614 414.1 ns/op 158 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2825973 419.3 ns/op 158 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2693790 407.1 ns/op 158 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2882792 414.7 ns/op 157 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2903197 421.7 ns/op 157 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2876046 435.7 ns/op 157 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2846494 410.4 ns/op 157 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2455807 440.1 ns/op 158 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2774462 435.1 ns/op 158 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=int64-12 2833150 433.9 ns/op 157 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string BenchmarkCache/cache=sieve/t=string-12 2117859 546.9 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2079752 527.1 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2210930 530.8 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2122942 514.4 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2222488 553.6 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2260266 558.6 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2239196 567.1 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 2064308 576.8 ns/op 186 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 1882754 569.9 ns/op 185 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=string-12 1917342 574.6 ns/op 185 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite BenchmarkCache/cache=sieve/t=composite-12 1825063 707.0 ns/op 223 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1745775 660.1 ns/op 224 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1680552 678.1 ns/op 225 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1774438 690.1 ns/op 224 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1530580 731.1 ns/op 226 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1663950 761.7 ns/op 225 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1607760 678.4 ns/op 225 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1703283 784.4 ns/op 225 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1295089 864.6 ns/op 229 B/op 4 allocs/op BenchmarkCache/cache=sieve/t=composite-12 1552182 769.9 ns/op 226 B/op 4 allocs/op ```
Why LRU Cache is not good enough? - LRU is often implemented with a doubly linked list and a hash table, requiring two pointers per cache entry, which becomes large overhead when the object is small. - It promotes objects to the head of the queue upon cache hit, which performs at least six random memory accesses protected by lock, which limits the scalability.
Things to consider before adoption - Both **S3-FIFO** and **SIEVE** have a O(n) time complexity for cache eviction, which only occurs when all objects are hit the cache, which means that there is a perfect (100%) hit rate in the cache. - **SIEVE** is not designed to be scan-resistant. Therefore, it's currently recommended for web cache workloads, which typically follow a power-law distribution. - **S3-FIFO** filters out one-hit-wonders early, It bears some resemblance to designing scan-resistant cache eviction algorithms. - **SIEVE** scales well for read-intensive applications such as blogs and online shops, because it doesn't require to hold a writer lock on cache hit. - The `golang-fifo` library aims to provide a straightforward and efficient cache implementation, similar to [hashicorp-lru](https://github.com/hashicorp/golang-lru) and [groupcache](https://github.com/golang/groupcache). Its goal is not to outperform highly specialized in-memory cache libraries (e.g. [bigcache](https://github.com/allegro/bigcache), [freecache](https://github.com/coocood/freecache) and etc).
Brief overview of SIEVE & S3-FIFO Various workloads typically follows **Power law distribution (e.g. Zipf's law)** as shown in the following figure. ![zipflaw_discovered_by_realworld](./docs/zipf_law_discovered_by_realworld_traces.png) The analysis reveals that most requests are "one-hit-wonders", which means it's accessed only once. Consequently, a cache eviction strategy should quickly remove most objects after insertion. **S3-FIFO** and **SIEVE** achieves this goal with simplicity, efficiency, and scalability using simple FIFO queue only. ![s3-fifo-is-powerful-algorithm](./docs/graphs_shows_s3_fifo_is_powerful.png)

Contribution

How to run unit test

$ go test -v ./...

How to run benchmark test

$ ./bench.sh