perf: Budget less memory for Replay Checkpoints (#28052) (#5145)

* perf: Replays use less memory for checkpoints (#28052)

- Simple change of the CVars and some stats
- Based on a Lizard replay, checkpoints move from on average every 70 ticks to every 350.

* Set a minimum number of ticks that must pass between checkpoints

* Fix stat collection, split _checkpointMinInterval, more CheckpointState

* update release notes

RELEASE-NOTES.md

@@ -39,7 +39,7 @@ END TEMPLATE-->
 
 ### New features
 
-*None yet*
+* A new `replay.checkpoint_min_interval` cvar has been added. It can be used to limit the frequency at which checkpoints are generated when loading a replay.
 
 ### Bugfixes
 
@@ -47,7 +47,7 @@ END TEMPLATE-->
 
 ### Other
 
-*None yet*
+* The default values of various replay related cvars have been changed to try and reduce memory usage.
 
 ### Internal
 

Robust.Client/Replays/Loading/ReplayLoadManager.Checkpoints.cs

@@ -133,6 +133,11 @@ public sealed partial class ReplayLoadManager
         var spawnedTracker = 0;
         var stateTracker = 0;
         var curState = state0;
+
+        var stats_due_ticks = 0;
+        var stats_due_spawned = 0;
+        var stats_due_state = 0;
+
         for (var i = 1; i < states.Count; i++)
         {
             if (i % 10 == 0)
@@ -150,11 +155,28 @@ public sealed partial class ReplayLoadManager
             serverTime[i] = GetTime(curState.ToSequence) - initialTime;
             ticksSinceLastCheckpoint++;
 
+            // Don't create checkpoints too frequently no matter the circumstance
+            if (ticksSinceLastCheckpoint < _checkpointMinInterval)
+                continue;
+
+            // Check if enough time, spawned entities or changed states have occurred.
             if (ticksSinceLastCheckpoint < _checkpointInterval
                 && spawnedTracker < _checkpointEntitySpawnThreshold
                 && stateTracker < _checkpointEntityStateThreshold)
-            {
                 continue;
+
+            // Track and update statistics about why checkpoints are getting created:
+            if (ticksSinceLastCheckpoint >= _checkpointInterval)
+            {
+                stats_due_ticks += 1;
+            }
+            else if (spawnedTracker >= _checkpointEntitySpawnThreshold)
+            {
+                stats_due_spawned += 1;
+            }
+            else if (stateTracker >= _checkpointEntityStateThreshold)
+            {
+                stats_due_state += 1;
             }
 
             ticksSinceLastCheckpoint = 0;
@@ -169,7 +191,8 @@ public sealed partial class ReplayLoadManager
             checkPoints.Add(new CheckpointState(newState, timeBase, cvars, i, detached));
         }
 
-        _sawmill.Info($"Finished generating checkpoints. Elapsed time: {st.Elapsed}");
+        _sawmill.Info($"Finished generating {checkPoints.Count} checkpoints. Elapsed time: {st.Elapsed}. Checkpoint every {(float)states.Count / checkPoints.Count} ticks on average");
+        _sawmill.Info($"Checkpoint stats - Spawning: {stats_due_spawned} StateChanges: {stats_due_state} Ticks: {stats_due_ticks}. ");
         await callback(states.Count, states.Count, LoadingState.ProcessingFiles, false);
         return (checkPoints.ToArray(), serverTime);
     }

Robust.Client/Replays/Loading/ReplayLoadManager.cs

@@ -34,6 +34,7 @@ public sealed partial class ReplayLoadManager : IReplayLoadManager
     private ushort _metaId;
     private bool _initialized;
     private int _checkpointInterval;
+    private int _checkpointMinInterval;
     private int _checkpointEntitySpawnThreshold;
     private int _checkpointEntityStateThreshold;
     private ISawmill _sawmill = default!;
@@ -45,6 +46,7 @@ public sealed partial class ReplayLoadManager : IReplayLoadManager
 
         _initialized = true;
         _confMan.OnValueChanged(CVars.CheckpointInterval, value => _checkpointInterval = value, true);
+        _confMan.OnValueChanged(CVars.CheckpointMinInterval, value => _checkpointMinInterval = value, true);
         _confMan.OnValueChanged(CVars.CheckpointEntitySpawnThreshold, value => _checkpointEntitySpawnThreshold = value,
             true);
         _confMan.OnValueChanged(CVars.CheckpointEntityStateThreshold, value => _checkpointEntityStateThreshold = value,

Robust.Client/Replays/Playback/ReplayPlaybackManager.Time.cs

@@ -41,12 +41,12 @@ internal sealed partial class ReplayPlaybackManager
             skipEffectEvents = true;
             ResetToNearestCheckpoint(value, false);
         }
-        else if (value > Replay.CurrentIndex + _checkpointInterval)
+        else if (value > Replay.CurrentIndex + _checkpointMinInterval)
         {
             // If we are skipping many ticks into the future, we try to skip directly to a checkpoint instead of
             // applying every tick.
             var nextCheckpoint = GetNextCheckpoint(Replay, Replay.CurrentIndex);
-            if (nextCheckpoint.Index < value)
+            if (nextCheckpoint.Index < value && nextCheckpoint.Index > Replay.CurrentIndex)
                 ResetToNearestCheckpoint(value, false);
         }
 

Robust.Client/Replays/Playback/ReplayPlaybackManager.cs

@@ -51,7 +51,7 @@ internal sealed partial class ReplayPlaybackManager : IReplayPlaybackManager
 
     public ReplayData? Replay { get; private set; }
     public NetUserId? Recorder => Replay?.Recorder;
-    private int _checkpointInterval;
+    private int _checkpointMinInterval;
     private int _visualEventThreshold;
     public uint? AutoPauseCountdown { get; set; }
     public int? ScrubbingTarget { get; set; }
@@ -93,7 +93,7 @@ internal sealed partial class ReplayPlaybackManager : IReplayPlaybackManager
         _initialized = true;
         _sawmill = _logMan.GetSawmill("replay");
         _metaId = _factory.GetRegistration(typeof(MetaDataComponent)).NetID!.Value;
-        _confMan.OnValueChanged(CVars.CheckpointInterval, (value) => _checkpointInterval = value, true);
+        _confMan.OnValueChanged(CVars.CheckpointMinInterval, (value) => _checkpointMinInterval = value, true);
         _confMan.OnValueChanged(CVars.ReplaySkipThreshold, (value) => _visualEventThreshold = value, true);
         _client.RunLevelChanged += OnRunLevelChanged;
     }

Robust.Shared/CVars.cs

@@ -1647,15 +1647,20 @@ namespace Robust.Shared
         /// </summary>
         public static readonly CVarDef<int> ReplaySkipThreshold = CVarDef.Create("replay.skip_threshold", 30);
 
+        /// <summary>
+        /// Minimum number of ticks before a new checkpoint tick is generated (overrides SpawnThreshold and StateThreshold)
+        /// </summary>
+        public static readonly CVarDef<int> CheckpointMinInterval = CVarDef.Create("replay.checkpoint_min_interval", 60);
+
         /// <summary>
         /// Maximum number of ticks before a new checkpoint tick is generated.
         /// </summary>
-        public static readonly CVarDef<int> CheckpointInterval = CVarDef.Create("replay.checkpoint_interval", 200);
+        public static readonly CVarDef<int> CheckpointInterval = CVarDef.Create("replay.checkpoint_interval", 500);
 
         /// <summary>
         /// Maximum number of entities that can be spawned before a new checkpoint tick is generated.
         /// </summary>
-        public static readonly CVarDef<int> CheckpointEntitySpawnThreshold = CVarDef.Create("replay.checkpoint_entity_spawn_threshold", 100);
+        public static readonly CVarDef<int> CheckpointEntitySpawnThreshold = CVarDef.Create("replay.checkpoint_entity_spawn_threshold", 1000);
 
         /// <summary>
         /// Maximum number of entity states that can be applied before a new checkpoint tick is generated.