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Posted to reviews@yunikorn.apache.org by "wilfred-s (via GitHub)" <gi...@apache.org> on 2023/06/22 13:17:07 UTC
[GitHub] [yunikorn-core] wilfred-s commented on a diff in pull request #562: [YUNIKORN-1799] Create basic ringbuffer implementation
wilfred-s commented on code in PR #562:
URL: https://github.com/apache/yunikorn-core/pull/562#discussion_r1238429702
##########
pkg/events/event_ringbuffer.go:
##########
@@ -0,0 +1,213 @@
+/*
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements. See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership. The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package events
+
+import (
+ "sync"
+
+ "github.com/apache/yunikorn-scheduler-interface/lib/go/si"
+)
+
+type resultState int
+
+const (
+ resultOK resultState = iota
+ bufferEmpty
+ idNotFound
+)
+
+type eventRange struct {
+ start uint64
+ end uint64
+}
+
+// eventRingBuffer A specialized circular buffer to store event objects.
+//
+// Unlike to regular circular buffers, existing entries are never directly removed and new entries can be added if the buffer is full.
+// In this case, the oldest entry is overwritten and can be collected by the GC.
+//
+// Retrieving the records can be achieved with GetEventsFromID and GetRecentEntries.
+type eventRingBuffer struct {
+ events []*si.EventRecord
+ capacity uint64
+ idx uint64
+ full bool
+
+ id uint64 // increasing unique id
+ startId uint64 // id of the message at index 0
+ lowestId uint64 // the lowest available id in the buffer (e.idx when it becomes full)
+
+ sync.RWMutex
+}
+
+// Add adds an event to the ring buffer. If the buffer is full, the oldest element is overwritten.
+// This method never fails.
+// Each event has an ID, however, this mapping is not stored directly. Instead, we store the starting ID at
+// index 0 and the lowest available ID.
+func (e *eventRingBuffer) Add(event *si.EventRecord) {
+ e.Lock()
+ defer e.Unlock()
+
+ e.events[e.idx] = event
+ if e.idx == 0 {
+ e.startId = e.id
+ }
+ if e.idx == e.capacity-1 {
+ e.full = true
+ }
+ e.idx = (e.idx + 1) % e.capacity
+ if e.full {
+ // once the buffer becomes full, we keep incrementing this value
+ // this is the id of the element which is about to be overwritten at the next Add() call
+ e.lowestId++
+ }
+
+ e.id++
+}
+
+func (e *eventRingBuffer) GetEventsFromID(id uint64) ([]*si.EventRecord, resultState) {
+ e.RLock()
+ defer e.RUnlock()
+
+ storedId, state := e.id2pos(id)
+ if state != resultOK {
+ return nil, state
+ }
+
+ if e.full {
+ r1 := eventRange{
+ start: storedId,
+ end: e.capacity,
+ }
+ r2 := eventRange{
+ start: 0,
+ end: e.idx,
+ }
+ return e.getEntriesFromRanges(r1, r2), resultOK
+ }
+
+ return e.getEntriesFromRanges(eventRange{
+ start: storedId,
+ end: e.idx,
+ }), resultOK
+}
+
+func (e *eventRingBuffer) GetRecentEntries(count uint64) ([]*si.EventRecord, uint64, resultState) {
+ e.RLock()
+ defer e.RUnlock()
+
+ if !e.full && e.idx == 0 {
+ return nil, 0, bufferEmpty
+ }
+
+ if e.full {
+ if count > e.capacity {
+ count = e.capacity
+ }
+ if count > e.idx {
+ startPos := e.capacity - count + e.idx
+ r1 := eventRange{
+ start: startPos,
+ end: e.capacity,
+ }
+ r2 := eventRange{
+ start: 0,
+ end: e.idx,
+ }
+
+ return e.getEntriesFromRanges(r1, r2), e.pos2id(startPos), resultOK
+ }
+
+ startIdx := e.idx - count
+ return e.getEntriesFromRanges(eventRange{
+ start: startIdx,
+ end: e.idx,
+ }), e.pos2id(startIdx), resultOK
+ }
+
+ if count > e.idx {
+ count = e.idx
+ }
+ startIdx := e.idx - count
+ return e.getEntriesFromRanges(eventRange{
+ start: startIdx,
+ end: e.idx,
+ }), startIdx, resultOK
+}
+
+func (e *eventRingBuffer) getEntriesFromRanges(ranges ...eventRange) []*si.EventRecord {
+ total := uint64(0)
+ for _, r := range ranges {
+ total += r.end - r.start
+ }
+
+ src := make([]*si.EventRecord, 0)
Review Comment:
Please pre-allocate the slice for a better performance, the append might otherwise reallocate causing extra overhead.
You have just calculated the total above.
##########
pkg/events/event_ringbuffer.go:
##########
@@ -0,0 +1,213 @@
+/*
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements. See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership. The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package events
+
+import (
+ "sync"
+
+ "github.com/apache/yunikorn-scheduler-interface/lib/go/si"
+)
+
+type resultState int
+
+const (
+ resultOK resultState = iota
+ bufferEmpty
+ idNotFound
+)
+
+type eventRange struct {
+ start uint64
+ end uint64
+}
+
+// eventRingBuffer A specialized circular buffer to store event objects.
+//
+// Unlike to regular circular buffers, existing entries are never directly removed and new entries can be added if the buffer is full.
+// In this case, the oldest entry is overwritten and can be collected by the GC.
+//
+// Retrieving the records can be achieved with GetEventsFromID and GetRecentEntries.
+type eventRingBuffer struct {
+ events []*si.EventRecord
+ capacity uint64
+ idx uint64
+ full bool
+
+ id uint64 // increasing unique id
+ startId uint64 // id of the message at index 0
+ lowestId uint64 // the lowest available id in the buffer (e.idx when it becomes full)
+
+ sync.RWMutex
+}
+
+// Add adds an event to the ring buffer. If the buffer is full, the oldest element is overwritten.
+// This method never fails.
+// Each event has an ID, however, this mapping is not stored directly. Instead, we store the starting ID at
+// index 0 and the lowest available ID.
+func (e *eventRingBuffer) Add(event *si.EventRecord) {
+ e.Lock()
+ defer e.Unlock()
+
+ e.events[e.idx] = event
+ if e.idx == 0 {
+ e.startId = e.id
+ }
+ if e.idx == e.capacity-1 {
+ e.full = true
+ }
+ e.idx = (e.idx + 1) % e.capacity
+ if e.full {
+ // once the buffer becomes full, we keep incrementing this value
+ // this is the id of the element which is about to be overwritten at the next Add() call
+ e.lowestId++
+ }
+
+ e.id++
+}
+
+func (e *eventRingBuffer) GetEventsFromID(id uint64) ([]*si.EventRecord, resultState) {
+ e.RLock()
+ defer e.RUnlock()
+
+ storedId, state := e.id2pos(id)
+ if state != resultOK {
+ return nil, state
+ }
+
+ if e.full {
+ r1 := eventRange{
+ start: storedId,
+ end: e.capacity,
+ }
+ r2 := eventRange{
+ start: 0,
+ end: e.idx,
+ }
+ return e.getEntriesFromRanges(r1, r2), resultOK
+ }
+
+ return e.getEntriesFromRanges(eventRange{
+ start: storedId,
+ end: e.idx,
+ }), resultOK
+}
+
+func (e *eventRingBuffer) GetRecentEntries(count uint64) ([]*si.EventRecord, uint64, resultState) {
+ e.RLock()
+ defer e.RUnlock()
+
+ if !e.full && e.idx == 0 {
+ return nil, 0, bufferEmpty
+ }
+
+ if e.full {
+ if count > e.capacity {
+ count = e.capacity
+ }
+ if count > e.idx {
+ startPos := e.capacity - count + e.idx
+ r1 := eventRange{
+ start: startPos,
+ end: e.capacity,
+ }
+ r2 := eventRange{
+ start: 0,
+ end: e.idx,
+ }
+
+ return e.getEntriesFromRanges(r1, r2), e.pos2id(startPos), resultOK
+ }
+
+ startIdx := e.idx - count
+ return e.getEntriesFromRanges(eventRange{
+ start: startIdx,
+ end: e.idx,
+ }), e.pos2id(startIdx), resultOK
+ }
+
+ if count > e.idx {
+ count = e.idx
+ }
+ startIdx := e.idx - count
+ return e.getEntriesFromRanges(eventRange{
+ start: startIdx,
+ end: e.idx,
+ }), startIdx, resultOK
+}
+
+func (e *eventRingBuffer) getEntriesFromRanges(ranges ...eventRange) []*si.EventRecord {
+ total := uint64(0)
Review Comment:
simple var declaration for total is easier to read
##########
pkg/events/event_ringbuffer.go:
##########
@@ -0,0 +1,213 @@
+/*
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements. See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership. The ASF licenses this file
+ to you under the Apache License, Version 2.0 (the
+ "License"); you may not use this file except in compliance
+ with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+package events
+
+import (
+ "sync"
+
+ "github.com/apache/yunikorn-scheduler-interface/lib/go/si"
+)
+
+type resultState int
+
+const (
+ resultOK resultState = iota
+ bufferEmpty
+ idNotFound
+)
+
+type eventRange struct {
+ start uint64
+ end uint64
+}
+
+// eventRingBuffer A specialized circular buffer to store event objects.
+//
+// Unlike to regular circular buffers, existing entries are never directly removed and new entries can be added if the buffer is full.
+// In this case, the oldest entry is overwritten and can be collected by the GC.
+//
+// Retrieving the records can be achieved with GetEventsFromID and GetRecentEntries.
+type eventRingBuffer struct {
+ events []*si.EventRecord
+ capacity uint64
+ idx uint64
+ full bool
+
+ id uint64 // increasing unique id
+ startId uint64 // id of the message at index 0
+ lowestId uint64 // the lowest available id in the buffer (e.idx when it becomes full)
+
+ sync.RWMutex
+}
+
+// Add adds an event to the ring buffer. If the buffer is full, the oldest element is overwritten.
+// This method never fails.
+// Each event has an ID, however, this mapping is not stored directly. Instead, we store the starting ID at
+// index 0 and the lowest available ID.
+func (e *eventRingBuffer) Add(event *si.EventRecord) {
+ e.Lock()
+ defer e.Unlock()
+
+ e.events[e.idx] = event
+ if e.idx == 0 {
+ e.startId = e.id
+ }
+ if e.idx == e.capacity-1 {
+ e.full = true
+ }
+ e.idx = (e.idx + 1) % e.capacity
+ if e.full {
+ // once the buffer becomes full, we keep incrementing this value
+ // this is the id of the element which is about to be overwritten at the next Add() call
+ e.lowestId++
+ }
+
+ e.id++
+}
+
+func (e *eventRingBuffer) GetEventsFromID(id uint64) ([]*si.EventRecord, resultState) {
+ e.RLock()
+ defer e.RUnlock()
+
+ storedId, state := e.id2pos(id)
+ if state != resultOK {
+ return nil, state
+ }
+
+ if e.full {
+ r1 := eventRange{
+ start: storedId,
+ end: e.capacity,
+ }
+ r2 := eventRange{
+ start: 0,
+ end: e.idx,
+ }
+ return e.getEntriesFromRanges(r1, r2), resultOK
+ }
+
+ return e.getEntriesFromRanges(eventRange{
+ start: storedId,
+ end: e.idx,
+ }), resultOK
+}
+
+func (e *eventRingBuffer) GetRecentEntries(count uint64) ([]*si.EventRecord, uint64, resultState) {
+ e.RLock()
+ defer e.RUnlock()
+
+ if !e.full && e.idx == 0 {
+ return nil, 0, bufferEmpty
+ }
+
+ if e.full {
+ if count > e.capacity {
+ count = e.capacity
+ }
+ if count > e.idx {
+ startPos := e.capacity - count + e.idx
+ r1 := eventRange{
+ start: startPos,
+ end: e.capacity,
+ }
+ r2 := eventRange{
+ start: 0,
+ end: e.idx,
+ }
+
+ return e.getEntriesFromRanges(r1, r2), e.pos2id(startPos), resultOK
+ }
+
+ startIdx := e.idx - count
+ return e.getEntriesFromRanges(eventRange{
+ start: startIdx,
+ end: e.idx,
+ }), e.pos2id(startIdx), resultOK
+ }
+
+ if count > e.idx {
+ count = e.idx
+ }
+ startIdx := e.idx - count
+ return e.getEntriesFromRanges(eventRange{
+ start: startIdx,
+ end: e.idx,
+ }), startIdx, resultOK
+}
+
+func (e *eventRingBuffer) getEntriesFromRanges(ranges ...eventRange) []*si.EventRecord {
+ total := uint64(0)
+ for _, r := range ranges {
+ total += r.end - r.start
+ }
+
+ src := make([]*si.EventRecord, 0)
+ for _, r := range ranges {
+ events := e.events[r.start:r.end]
+ src = append(src, events...)
+ }
Review Comment:
Can we use copy to speed up this process?
```
dest := make([]*si.EventRecord, total)
copy(dest, src[r1.start:])
copyFInish := r1.end - r1.start
copy(dest[copyFInish:], src[r2.start:])
```
The second copy is only needed if there are two ranges otherwise the first copy will do it all
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