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added overlapped ring buffer impl, see the #5
An overlapped ring buffer will overwrite the existing head element in putting new elem but the ring buffer is full. The original ring buffer of ourselves is to return a wrong state and stop putting action, see the `ErrQueueFull`. The new overlapped ring buffer will be created by calling `NewOverlappedRingBuffer()`. Any issues are welcome.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,121 @@ | ||
| package mpmc | ||
|
|
||
| import ( | ||
| "runtime" | ||
| "sync/atomic" | ||
|
|
||
| "github.com/hedzr/go-ringbuf/v2/mpmc/state" | ||
| ) | ||
|
|
||
| type orbuf[T any] struct { | ||
| ringBuf[T] | ||
| } | ||
|
|
||
| func (rb *orbuf[T]) Put(item T) (err error) { return rb.Enqueue(item) } //nolint:revive | ||
|
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| func (rb *orbuf[T]) Enqueue(item T) (err error) { //nolint:revive | ||
| var tail, head, nt, nh uint32 | ||
| var holder *rbItem[T] | ||
| for { | ||
| head = atomic.LoadUint32(&rb.head) | ||
| tail = atomic.LoadUint32(&rb.tail) | ||
| nt = (tail + 1) & rb.capModMask | ||
|
|
||
| isEmpty := head == tail | ||
| if isEmpty && head == MaxUint32 { | ||
| err = ErrQueueNotReady | ||
| return | ||
| } | ||
|
|
||
| isFull := nt == head | ||
| if isFull { | ||
| nh = (head + 1) & rb.capModMask | ||
| atomic.CompareAndSwapUint32(&rb.head, head, nh) | ||
| } | ||
|
|
||
| holder = &rb.data[tail] | ||
| atomic.CompareAndSwapUint32(&rb.tail, tail, nt) | ||
| retry: | ||
| if !atomic.CompareAndSwapUint64(&holder.readWrite, 0, 2) { //nolint:gomnd | ||
| if !atomic.CompareAndSwapUint64(&holder.readWrite, 1, 2) { //nolint:gomnd | ||
| if atomic.LoadUint64(&holder.readWrite) == 0 { | ||
| goto retry // sometimes, short circuit | ||
| } | ||
| runtime.Gosched() // time to time | ||
| continue | ||
| } | ||
| } | ||
|
|
||
| if rb.initializer != nil { | ||
| rb.initializer.CloneIn(item, &holder.value) | ||
| } else { | ||
| holder.value = item | ||
| } | ||
| if !atomic.CompareAndSwapUint64(&holder.readWrite, 2, 1) { //nolint:gomnd | ||
| err = ErrRaced // runtime.Gosched() // never happens | ||
| } | ||
|
|
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| if state.VerboseEnabled { | ||
| state.Verbose("[W] enqueued", | ||
| "tail", tail, "new-tail", nt, "head", head, "value", toString(holder.value), | ||
| "value(rb.data[0])", toString(rb.data[0].value), | ||
| "value(rb.data[1])", toString(rb.data[1].value)) | ||
| } | ||
| return | ||
| } | ||
| } | ||
|
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||
| func (rb *orbuf[T]) Get() (item T, err error) { return rb.Dequeue() } //nolint:revive | ||
|
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| func (rb *orbuf[T]) Dequeue() (item T, err error) { //nolint:revive | ||
| var tail, head, nh uint32 | ||
| var holder *rbItem[T] | ||
| for { | ||
| // var quad uint64 | ||
| // quad = atomic.LoadUint64((*uint64)(unsafe.Pointer(&rb.head))) | ||
| // head = (uint32)(quad & MaxUint32_64) | ||
| // tail = (uint32)(quad >> 32) | ||
| head = atomic.LoadUint32(&rb.head) | ||
| tail = atomic.LoadUint32(&rb.tail) | ||
|
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||
| isEmpty := head == tail | ||
| if isEmpty { | ||
| if head == MaxUint32 { | ||
| err = ErrQueueNotReady | ||
| return | ||
| } | ||
| err = ErrQueueEmpty | ||
| return | ||
| } | ||
|
|
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| holder = &rb.data[head] | ||
|
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| nh = (head + 1) & rb.capModMask | ||
| atomic.CompareAndSwapUint32(&rb.head, head, nh) | ||
| retry: | ||
| if !atomic.CompareAndSwapUint64(&holder.readWrite, 1, 3) { //nolint:gomnd | ||
| if atomic.LoadUint64(&holder.readWrite) == 1 { | ||
| goto retry // sometimes, short circuit | ||
| } | ||
| runtime.Gosched() // time to time | ||
| continue | ||
| } | ||
|
|
||
| if rb.initializer != nil { | ||
| item = rb.initializer.CloneOut(&holder.value) | ||
| } else { | ||
| item = holder.value | ||
| // holder.value = zero | ||
| } | ||
| if !atomic.CompareAndSwapUint64(&holder.readWrite, 3, 0) { //nolint:gomnd | ||
| err = ErrRaced // runtime.Gosched() // never happens | ||
| } | ||
|
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| if state.VerboseEnabled { | ||
| state.Verbose("[ringbuf][GET] states are:", | ||
| "cap", rb.Cap(), "qty", rb.qty(head, tail), "tail", tail, "head", head, "new-head", nh, "item", toString(item)) | ||
| } | ||
|
|
||
| return | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,79 @@ | ||
| package mpmc | ||
|
|
||
| import ( | ||
| "errors" | ||
| "fmt" | ||
| "testing" | ||
| ) | ||
|
|
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| func TestOverlappedRingBuf_Put_OneByOne(t *testing.T) { //nolint:revive | ||
| var err error | ||
| rb := NewOverlappedRingBuffer(NLtd, WithDebugMode[uint32](true)) | ||
| size := rb.Cap() - 1 | ||
| // t.Logf("Ring Buffer created, capacity = %v, real size: %v", size+1, size) | ||
| defer rb.Close() | ||
|
|
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| for i := uint32(0); i < size; i++ { | ||
| err = rb.Enqueue(i) | ||
| if err != nil { | ||
| t.Fatalf("faild on i=%v. err: %+v", i, err) | ||
| // } else { | ||
| // t.Logf("%5d. '%v' put, quantity = %v.", i, i, fast.Quantity()) | ||
| } | ||
| t.Logf(" %3d. ringbuf elements -> %v", i, rb) | ||
| } | ||
|
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| for i := size; i < size+size; i++ { | ||
| err = rb.Put(i) | ||
| if errors.Is(err, ErrQueueFull) { | ||
| t.Fatalf("> %3d. expect ErrQueueFull but no error raised. err: %+v", i, err) | ||
| } | ||
| t.Logf(" %3d. ringbuf elements -> %v", i, rb) | ||
| } | ||
|
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| var it any | ||
| it, err = rb.Dequeue() | ||
| _, _ = it, err | ||
| t.Logf(" %3d. ringbuf elements -> %v", -1, rb) | ||
| it, err = rb.Dequeue() | ||
| _, _ = it, err | ||
| t.Logf(" %3d. ringbuf elements -> %v", -1, rb) | ||
| if fmt.Sprintf("%v", rb) != "[17,18,19,20,21,22,23,24,25,26,27,28,29,]/13" { | ||
| t.Fatalf("faild: expecting elements are: [17,18,19,20,21,22,23,24,25,26,27,28,29,]/13") | ||
| } | ||
|
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| for i := size * 2; i < size*3+2; i++ { | ||
| err = rb.Put(i) | ||
| if errors.Is(err, ErrQueueFull) { | ||
| t.Fatalf("> %3d. expect ErrQueueFull but no error raised. err: %+v", i, err) | ||
| } | ||
| t.Logf(" %3d. ringbuf elements -> %v", i, rb) | ||
| } | ||
| if fmt.Sprintf("%v", rb) != "[32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,]/15" { | ||
| t.Fatalf("faild: expecting elements are: [32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,]/15") | ||
| } | ||
|
|
||
| for i := 0; ; i++ { | ||
| it, err = rb.Dequeue() | ||
| if err != nil { | ||
| if errors.Is(err, ErrQueueEmpty) { | ||
| break | ||
| } | ||
| t.Fatalf("faild on i=%v. err: %+v. item: %v", i, err, it) | ||
| // } else { | ||
| // t.Logf("< %3d. '%v' GOT, quantity = %v.", i, it, fast.Quantity()) | ||
| } | ||
| if rb.Size() == 0 { | ||
| // t.Log("empty ring buffer elements") | ||
| if fmt.Sprintf("%v", rb) != "[]/0" { | ||
| t.Fatalf("faild: expecting elements are: []/0") | ||
| } | ||
| } | ||
| t.Logf(" %3d. ringbuf elements -> %v", i, rb) | ||
| } | ||
|
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| it, err = rb.Dequeue() | ||
| if err == nil { | ||
| t.Fatalf("faild: Dequeue on an empty ringbuf should return an ErrQueueEmpty object.") | ||
| } | ||
| } |
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