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Add Len() to common interface #44

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merged 4 commits into from
Apr 13, 2024
Merged

Add Len() to common interface #44

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e6e2171
Add Len() to common interface
Jun 9, 2023
9c6b76a
Change common interface to use Keys() in Len() method
Jun 12, 2023
f08595a
Add benchmark tests for Len() in simple policy
Aug 6, 2023
3621c33
Change cache interface to use internal Len method
Aug 7, 2023
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9 changes: 9 additions & 0 deletions cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@ type Interface[K comparable, V any] interface {
Keys() []K
// Delete deletes the item with provided key from the cache.
Delete(key K)
// Len returns the number of items in the cache.
Len() int
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Should add method of the Cache struct because this is breaking change.

I think good like below:

Len() int { return len(c.Keys()) }

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Do you mean that this my change below:

func (c *Cache[K, V]) Len() int {
	c.mu.Lock()
	defer c.mu.Unlock()
	return c.cache.Len()
}

should be changed to:

func (c *Cache[K, V]) Len() int {
	return len(c.Keys())
}

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@norri Yes!

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I think performance for c.cache.Len() is better than len(c.Keys()) because of for example sorting is not needed and all policies support Len(). However I can make the change if you think that it's better.

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@Code-Hex Code-Hex Jun 12, 2023 •
edited
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Could you measure the performance?
And also please implement all cache policies not just simple 🙏

I think this discussion is required all cache policies results.

I think performance for c.cache.Len() is better than len(c.Keys())

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I can try to test the performance. All other policies implement already Len() so no changes needed for those.

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I added benchmark test for both implementations and using just Len() is quite match faster:

$ go test -benchmem -bench BenchmarkLenWithKeys ./policy/simple
goos: darwin
goarch: amd64
pkg: github.com/Code-Hex/go-generics-cache/policy/simple
cpu: Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz
BenchmarkLenWithKeys-8           3777514               310.7 ns/op           104 B/op          3 allocs/op
PASS
ok      github.com/Code-Hex/go-generics-cache/policy/simple     1.640s

$ go test -benchmem -bench BenchmarkJustLen ./policy/simple
goos: darwin
goarch: amd64
pkg: github.com/Code-Hex/go-generics-cache/policy/simple
cpu: Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz
BenchmarkJustLen-8      1000000000               0.3075 ns/op          0 B/op          0 allocs/op
PASS

}

var (
Expand Down Expand Up @@ -253,6 +255,13 @@ func (c *Cache[K, V]) Delete(key K) {
c.cache.Delete(key)
}

// Len returns the number of items in the cache.
func (c *Cache[K, V]) Len() int {
c.mu.Lock()
defer c.mu.Unlock()
return c.cache.Len()
}

// Contains reports whether key is within cache.
func (c *Cache[K, V]) Contains(key K) bool {
c.mu.Lock()
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10 changes: 10 additions & 0 deletions example_test.go
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Expand Up @@ -123,6 +123,16 @@ func ExampleCache_Keys() {
// [a b c]
}

func ExampleCache_Len() {
c := cache.New(cache.AsLFU[string, int]())
c.Set("a", 1)
c.Set("b", 1)
c.Set("c", 1)
fmt.Println(c.Len())
// Output:
// 3
}

func ExampleCache_Contains() {
c := cache.New(cache.AsLRU[string, int]())
c.Set("a", 1)
Expand Down
5 changes: 5 additions & 0 deletions policy/simple/simple.go
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Original file line number Diff line number Diff line change
Expand Up @@ -59,3 +59,8 @@ func (c *Cache[K, _]) Keys() []K {
func (c *Cache[K, V]) Delete(key K) {
delete(c.items, key)
}

// Len returns the number of items in the cache.
func (c *Cache[K, V]) Len() int {
return len(c.items)
}