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Refactor SessionWindowPipe to use Queue instead of LinkedList #181

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Refactor SessionWindowPipe to use Queue instead of LinkedList #181

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59 changes: 41 additions & 18 deletions Sources/Core/Microsoft.StreamProcessing/Operators/SessionWindow/SessionWindowPipe.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Runtime.Serialization;
using Microsoft.StreamProcessing.Internal;
using Microsoft.StreamProcessing.Internal.Collections;
Expand All @@ -25,7 +26,7 @@ internal sealed class SessionWindowPipe<TKey, TPayload> : UnaryPipe<TKey, TPaylo
[DataMember]
private StreamMessage<TKey, TPayload> output;

private LinkedList<TKey> orderedKeys = new LinkedList<TKey>();
private Queue<SessionThreshold> orderedKeys = new Queue<SessionThreshold>();
[DataMember]
private FastDictionary2<TKey, long> windowEndTimeDictionary = new FastDictionary2<TKey, long>();
[DataMember]
Expand Down Expand Up @@ -68,13 +69,21 @@ private void ReachTime(int pIndex, long timestamp)
}
}

var current = this.orderedKeys.First;
while (current != null)
while (this.orderedKeys.Count > 0)
{
this.lastDataTimeDictionary.Lookup(current.Value, out int cIndex);
var current = this.orderedKeys.Peek();
this.lastDataTimeDictionary.Lookup(current.Key, out int cIndex);
var threshold = this.lastDataTimeDictionary.entries[cIndex].value == long.MinValue
? this.windowEndTimeDictionary.entries[cIndex].value
: Math.Min(this.lastDataTimeDictionary.entries[cIndex].value + this.sessionTimeout, this.windowEndTimeDictionary.entries[cIndex].value);
: CalculateThreshold(this.lastDataTimeDictionary.entries[cIndex].value, cIndex);

// Skip stale threshold entries (can happen when threshold is updated and new entry is enqueued)
if (current.Threshold != threshold)
{
this.orderedKeys.Dequeue();
continue;
}

if (timestamp >= threshold)
{
var queue = this.stateDictionary.entries[cIndex].value;
Expand All @@ -95,13 +104,12 @@ private void ReachTime(int pIndex, long timestamp)
this.windowEndTimeDictionary.entries[cIndex].value = StreamEvent.MaxSyncTime;
else
{
this.windowEndTimeDictionary.Remove(current.Value);
this.lastDataTimeDictionary.Remove(current.Value);
this.stateDictionary.Remove(current.Value);
this.windowEndTimeDictionary.Remove(current.Key);
this.lastDataTimeDictionary.Remove(current.Key);
this.stateDictionary.Remove(current.Key);
}

this.orderedKeys.RemoveFirst();
current = this.orderedKeys.First;
this.orderedKeys.Dequeue();
}
else break;
}
Expand Down Expand Up @@ -142,17 +150,18 @@ public override unsafe void OnNext(StreamMessage<TKey, TPayload> batch)
if (!this.lastDataTimeDictionary.Lookup(batch.key.col[i], out keyIndex))
keyIndex = AllocatePartition(batch.key.col[i]);

var newThreshold = CalculateThreshold(vsync[i], keyIndex);

if (!this.stateDictionary.entries[keyIndex].value.Any())
this.orderedKeys.AddLast(new LinkedListNode<TKey>(batch.key.col[i]));
{
this.orderedKeys.Enqueue(new SessionThreshold { Key = batch.key.col[i], Threshold = newThreshold });
}
else
{
var oldThreshold = Math.Min(this.lastDataTimeDictionary.entries[keyIndex].value + this.sessionTimeout, this.windowEndTimeDictionary.entries[keyIndex].value);
var newThreshold = Math.Min(vsync[i] + this.sessionTimeout, this.windowEndTimeDictionary.entries[keyIndex].value);
var oldThreshold = CalculateThreshold(this.lastDataTimeDictionary.entries[keyIndex].value, keyIndex);
if (newThreshold > oldThreshold)
{
var node = this.orderedKeys.Find(batch.key.col[i]);
this.orderedKeys.Remove(node);
this.orderedKeys.AddLast(node);
this.orderedKeys.Enqueue(new SessionThreshold { Key = batch.key.col[i], Threshold = newThreshold });
}
}

Expand Down Expand Up @@ -227,10 +236,10 @@ protected override void UpdatePointers()
{
temp.Add(Tuple.Create(
this.windowEndTimeDictionary.entries[iter].key,
Math.Min(this.lastDataTimeDictionary.entries[iter].value + this.sessionTimeout, this.windowEndTimeDictionary.entries[iter].value)));
CalculateThreshold(this.lastDataTimeDictionary.entries[iter].value, iter)));
}
}
foreach (var item in temp.OrderBy(o => o.Item2)) this.orderedKeys.AddLast(new LinkedListNode<TKey>(item.Item1));
foreach (var item in temp.OrderBy(o => o.Item2)) this.orderedKeys.Enqueue(new SessionThreshold { Key = item.Item1, Threshold = item.Item2 });
base.UpdatePointers();
}

Expand All @@ -242,6 +251,10 @@ protected override void DisposeState()
this.stateDictionary.Clear();
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
private long CalculateThreshold(long lastDataTime, int keyIndex) =>
Math.Min(lastDataTime + this.sessionTimeout, this.windowEndTimeDictionary.entries[keyIndex].value);

[DataContract]
private struct ActiveEvent
{
Expand All @@ -256,5 +269,15 @@ private struct ActiveEvent

public override string ToString() => "Key='" + this.Key + "', Payload='" + this.Payload;
}

[DataContract]
private struct SessionThreshold
{
[DataMember]
public long Threshold;

[DataMember]
public TKey Key;
}
}
}