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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,100 @@ | ||
| /* | ||
| * MIT License | ||
| * | ||
| * Copyright (c) 2022-2024 Tochemey | ||
| * | ||
| * Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| * of this software and associated documentation files (the "Software"), to deal | ||
| * in the Software without restriction, including without limitation the rights | ||
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| * copies of the Software, and to permit persons to whom the Software is | ||
| * furnished to do so, subject to the following conditions: | ||
| * | ||
| * The above copyright notice and this permission notice shall be included in all | ||
| * copies or substantial portions of the Software. | ||
| * | ||
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | ||
| * SOFTWARE. | ||
| */ | ||
|
|
||
| package queue | ||
|
|
||
| import ( | ||
| "sync" | ||
| "sync/atomic" | ||
| "unsafe" | ||
| ) | ||
|
|
||
| // node returns the queue node | ||
| type node[T any] struct { | ||
| value T | ||
| next *node[T] | ||
| } | ||
|
|
||
| // Mpsc is a Multi-Producer-Single-Consumer Queue | ||
| // reference: https://concurrencyfreaks.blogspot.com/2014/04/multi-producer-single-consumer-queue.html | ||
| type Mpsc[T any] struct { | ||
| head *node[T] | ||
| tail *node[T] | ||
| length int64 | ||
| lock sync.Mutex | ||
| } | ||
|
|
||
| // NewMpsc create an instance of Mpsc | ||
| func NewMpsc[T any]() *Mpsc[T] { | ||
| item := new(node[T]) | ||
| return &Mpsc[T]{ | ||
| head: item, | ||
| tail: item, | ||
| length: 0, | ||
| lock: sync.Mutex{}, | ||
| } | ||
| } | ||
|
|
||
| // Push place the given value in the queue head (FIFO). Returns always true | ||
| func (q *Mpsc[T]) Push(value T) bool { | ||
| tnode := &node[T]{ | ||
| value: value, | ||
| } | ||
| previousHead := (*node[T])(atomic.SwapPointer((*unsafe.Pointer)(unsafe.Pointer(&q.head)), unsafe.Pointer(tnode))) | ||
| atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&previousHead.next)), unsafe.Pointer(tnode)) | ||
| atomic.AddInt64(&q.length, 1) | ||
| return true | ||
| } | ||
|
|
||
| // Pop takes the QueueItem from the queue tail. Returns false if the queue is empty. Can be used in a single consumer (goroutine) only. | ||
| func (q *Mpsc[T]) Pop() (T, bool) { | ||
| var tnil T | ||
| next := (*node[T])(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&q.tail.next)))) | ||
| if next == nil { | ||
| return tnil, false | ||
| } | ||
|
|
||
| q.lock.Lock() | ||
| q.tail = next | ||
| q.lock.Unlock() | ||
| value := next.value | ||
| next.value = tnil | ||
| atomic.AddInt64(&q.length, -1) | ||
| return value, true | ||
| } | ||
|
|
||
| // Len returns queue length | ||
| func (q *Mpsc[T]) Len() int64 { | ||
| return atomic.LoadInt64(&q.length) | ||
| } | ||
|
|
||
| // IsEmpty returns true when the queue is empty | ||
| // must be called from a single, consumer goroutine | ||
| func (q *Mpsc[T]) IsEmpty() bool { | ||
| q.lock.Lock() | ||
| tail := q.tail | ||
| q.lock.Unlock() | ||
| next := (*node[T])(atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&tail.next)))) | ||
| return next == nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| /* | ||
| * MIT License | ||
| * | ||
| * Copyright (c) 2022-2024 Tochemey | ||
| * | ||
| * Permission is hereby granted, free of charge, to any person obtaining a copy | ||
| * of this software and associated documentation files (the "Software"), to deal | ||
| * in the Software without restriction, including without limitation the rights | ||
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | ||
| * copies of the Software, and to permit persons to whom the Software is | ||
| * furnished to do so, subject to the following conditions: | ||
| * | ||
| * The above copyright notice and this permission notice shall be included in all | ||
| * copies or substantial portions of the Software. | ||
| * | ||
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | ||
| * SOFTWARE. | ||
| */ | ||
|
|
||
| package queue | ||
|
|
||
| import ( | ||
| "testing" | ||
|
|
||
| "github.com/stretchr/testify/assert" | ||
| "github.com/stretchr/testify/require" | ||
| ) | ||
|
|
||
| // TODO: add go routine-based tests | ||
| func TestMpscQueue(t *testing.T) { | ||
| t.Run("With Push/Pop", func(t *testing.T) { | ||
| q := NewMpsc[int]() | ||
| require.True(t, q.IsEmpty()) | ||
| for j := 0; j < 100; j++ { | ||
| if q.Len() != 0 { | ||
| t.Fatal("expected no elements") | ||
| } else if _, ok := q.Pop(); ok { | ||
| t.Fatal("expected no elements") | ||
| } | ||
|
|
||
| for i := 0; i < j; i++ { | ||
| q.Push(i) | ||
| } | ||
|
|
||
| for i := 0; i < j; i++ { | ||
| if x, ok := q.Pop(); !ok { | ||
| t.Fatal("expected an element") | ||
| } else if x != i { | ||
| t.Fatalf("expected %d got %d", i, x) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| a := 0 | ||
| r := 0 | ||
| for j := 0; j < 100; j++ { | ||
| for i := 0; i < 4; i++ { | ||
| q.Push(a) | ||
| a++ | ||
| } | ||
|
|
||
| for i := 0; i < 2; i++ { | ||
| if x, ok := q.Pop(); !ok { | ||
| t.Fatal("expected an element") | ||
| } else if x != r { | ||
| t.Fatalf("expected %d got %d", r, x) | ||
| } | ||
| r++ | ||
| } | ||
| } | ||
|
|
||
| if q.Len() != 200 { | ||
| t.Fatalf("expected 200 elements have %d", q.Len()) | ||
| } | ||
|
|
||
| assert.True(t, q.Len() > 0) | ||
| }) | ||
| } |
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