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Use circular queue for idle connections
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,56 @@ | ||
| package circ | ||
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| type Queue[T any] struct { | ||
| arr []T | ||
| begin int | ||
| len int | ||
| } | ||
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| func NewQueue[T any](capacity int) *Queue[T] { | ||
| return &Queue[T]{ | ||
| // TODO: Do not preallocate whole capacity of Go upstream | ||
| // accepts this: https://github.com/golang/go/issues/55978 | ||
| arr: make([]T, capacity), | ||
| } | ||
| } | ||
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| func (q *Queue[T]) Cap() int { return len(q.arr) } | ||
| func (q *Queue[T]) Len() int { return q.len } | ||
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| func (q *Queue[T]) end() int { | ||
| e := q.begin + q.len | ||
| if l := len(q.arr); e >= l { | ||
| e -= l | ||
| } | ||
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| return e | ||
| } | ||
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| func (q *Queue[T]) Enqueue(elem T) { | ||
| if q.len == len(q.arr) { | ||
| panic("enqueue: queue is full") | ||
| } | ||
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| q.arr[q.end()] = elem | ||
| q.len++ | ||
| } | ||
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| func (q *Queue[T]) Dequeue() T { | ||
| if q.len < 1 { | ||
| panic("dequeue: queue is empty") | ||
| } | ||
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| elem := q.arr[q.begin] | ||
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| // Avoid memory leaks if T is pointer or contains pointers. | ||
| var zeroVal T | ||
| q.arr[q.begin] = zeroVal | ||
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| q.len-- | ||
| q.begin++ | ||
| if q.begin == len(q.arr) { | ||
| q.begin = 0 | ||
| } | ||
|
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| return elem | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,148 @@ | ||
| package circ_test | ||
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| import ( | ||
| "fmt" | ||
| "io" | ||
| "testing" | ||
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| "github.com/jackc/puddle/v2/internal/circ" | ||
| "github.com/stretchr/testify/require" | ||
| ) | ||
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| func TestQueue_EnqueueDequeue(t *testing.T) { | ||
| r := require.New(t) | ||
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| q := circ.NewQueue[int](10) | ||
| r.Equal(10, q.Cap()) | ||
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| for i := 0; i < 10; i++ { | ||
| q.Enqueue(i) | ||
| r.Equal(i+1, q.Len()) | ||
| } | ||
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| r.Panics(func() { q.Enqueue(10) }) | ||
| r.Equal(10, q.Len()) | ||
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| for i := 0; i < 10; i++ { | ||
| j := q.Dequeue() | ||
| r.Equal(i, j) | ||
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| r.Equal(10-i-1, q.Len()) | ||
| } | ||
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| r.Panics(func() { q.Dequeue() }) | ||
| r.Equal(0, q.Len()) | ||
| } | ||
|
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| func TestQueue_EnqueueDequeueOverflow(t *testing.T) { | ||
| r := require.New(t) | ||
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| q := circ.NewQueue[int](10) | ||
| r.Equal(10, q.Cap()) | ||
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| for i := 0; i < 10; i++ { | ||
| q.Enqueue(i) | ||
| r.Equal(i+1, q.Len()) | ||
| } | ||
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| r.Panics(func() { q.Enqueue(10) }) | ||
| r.Equal(10, q.Len()) | ||
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| for i := 0; i < 5; i++ { | ||
| j := q.Dequeue() | ||
| r.Equal(i, j) | ||
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| r.Equal(10-i-1, q.Len()) | ||
| } | ||
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| for i := 10; i < 15; i++ { | ||
| q.Enqueue(i) | ||
| r.Equal(i-5+1, q.Len()) | ||
| } | ||
|
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| for i := 0; i < 10; i++ { | ||
| j := q.Dequeue() | ||
| r.Equal(i+5, j) | ||
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| r.Equal(10-i-1, q.Len()) | ||
| } | ||
|
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| r.Panics(func() { q.Dequeue() }) | ||
| r.Equal(0, q.Len()) | ||
| } | ||
|
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| func BenchmarkArrayAppend(b *testing.B) { | ||
| arr := make([]int, 0, b.N) | ||
|
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| b.ResetTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| arr = append(arr, i) | ||
| } | ||
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| // Make sure that the Go compiler doesn't optimize writes above. | ||
| b.StopTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| fmt.Fprintf(io.Discard, "%d\n", arr[i]) | ||
| } | ||
| } | ||
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| func BenchmarkArrayWrite(b *testing.B) { | ||
| arr := make([]int, b.N) | ||
|
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| b.ResetTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| arr[i] = i | ||
| } | ||
|
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| // Make sure that the Go compiler doesn't optimize writes above. | ||
| b.StopTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| fmt.Fprintf(io.Discard, "%d\n", arr[i]) | ||
| } | ||
| } | ||
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| func BenchmarkEnqueue(b *testing.B) { | ||
| q := circ.NewQueue[int](b.N) | ||
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| b.ResetTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| q.Enqueue(i) | ||
| } | ||
|
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| // Make sure that the Go compiler doesn't optimize writes above. | ||
| b.StopTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| fmt.Fprintf(io.Discard, "%d\n", q.Dequeue()) | ||
| } | ||
| } | ||
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| func BenchmarkChanWrite(b *testing.B) { | ||
| // Chennels are another way how to represent a queue. | ||
| ch := make(chan int, b.N) | ||
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| b.ResetTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| ch <- i | ||
| } | ||
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| // Make sure that the Go compiler doesn't optimize writes above. | ||
| b.StopTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| fmt.Fprintf(io.Discard, "%d\n", <-ch) | ||
| } | ||
| } | ||
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| func BenchmarkDequeue(b *testing.B) { | ||
| q := circ.NewQueue[int](b.N) | ||
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| for i := 0; i < b.N; i++ { | ||
| q.Enqueue(i) | ||
| } | ||
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| out := make([]int, b.N) | ||
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| b.ResetTimer() | ||
| for i := 0; i < b.N; i++ { | ||
| out[i] = q.Dequeue() | ||
| } | ||
| } |
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