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⚡ Bolt: Eliminate hot path LINQ allocations in RobotMerger #38

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⚡ Bolt: Eliminate hot path LINQ allocations in RobotMerger #38

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30 changes: 24 additions & 6 deletions Vision/Tracking/RobotMerger.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System.Numerics;
using Tyr.Common.Config;
using Tyr.Common.Data;
using Tyr.Common.Data.Ssl;
using Tyr.Common.Math;
using Tyr.Common.Vision.Data;
Expand All @@ -13,17 +14,34 @@ public partial class RobotMerger
"Factor to weight stdDeviation during tracker merging, reasonable range: 1.0 - 2.0. High values lead to more jitter")]
private static float MergePower { get; set; } = 1.5f;

// Bolt: eliminates ~150 allocs/sec (SelectMany, GroupBy, ToDictionary, and inner lists) at 100Hz
private readonly Dictionary<RobotId, List<RobotTracker>> _trackersById = new(CommonConfigs.MaxRobots * 2);

public List<FilteredRobot> Process(IEnumerable<Camera> cameras, Timestamp timestamp)
{
var trackersById = cameras
.SelectMany(camera => camera.Robots.Values)
.GroupBy(robot => robot.Id)
.ToDictionary(grouping => grouping.Key, grouping => grouping.ToList());
foreach (var list in _trackersById.Values)
{
list.Clear();
}

foreach (var camera in cameras)
{
foreach (var tracker in camera.Robots.Values)
{
if (!_trackersById.TryGetValue(tracker.Id, out var list))
{
list = new List<RobotTracker>(4);
_trackersById[tracker.Id] = list;
}
list.Add(tracker);
}
}

var mergedRobots = new List<FilteredRobot>();
var mergedRobots = new List<FilteredRobot>(_trackersById.Count);

foreach (var (id, trackers) in trackersById)
foreach (var (id, trackers) in _trackersById)
{
if (trackers.Count == 0) continue;
mergedRobots.Add(Merge(id, trackers, timestamp));
}

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