FIX: Fix for the event buffer growing unbounded in Editor when a controller is connected and certain options are set (#1636)

Author: peterhall-unity3d

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -13,6 +13,7 @@ however, it has to be formatted properly to pass verification tests.
 ### Fixed
 - Fixed unclosed profiler marker in `InvokeCallbacksSafe_AnyCallbackReturnsTrue` which would lead to eventually broken profiler traces in some cases like using `PlayerInput` (case ISXB-393).
 - Fixed InputAction.bindings.count not getting correctly updated after removing bindings with Erase().
+- Fixed an issue where connecting a gamepad in the editor with certain settings will cause memory and performance to degrade ([case UUM-19480](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-19480)).
 
 ## [1.5.0] - 2023-01-24
 

Packages/com.unity.inputsystem/InputSystem/InputManager.cs

@@ -2881,6 +2881,19 @@ private unsafe void OnUpdate(InputUpdateType updateType, ref InputEventBuffer ev
 #endif
                 );
 
+
+            bool dropStatusEvents = false;
+
+#if UNITY_EDITOR
+            if (!gameIsPlaying && gameShouldGetInputRegardlessOfFocus && (eventBuffer.sizeInBytes > (100 * 1024)))
+            {
+                // If the game is not playing but we're sending all input events to the game, the buffer can just grow unbounded.
+                // So, in that case, set a flag to say we'd like to drop status events, and do not early out.
+                canEarlyOut = false;
+                dropStatusEvents = true;
+            }
+#endif
+
             if (canEarlyOut)
             {
                 // Normally, we process action timeouts after first processing all events. If we have no
@@ -2952,6 +2965,19 @@ private unsafe void OnUpdate(InputUpdateType updateType, ref InputEventBuffer ev
                     var currentEventTimeInternal = currentEventReadPtr->internalTime;
                     var currentEventType = currentEventReadPtr->type;
 
+#if UNITY_EDITOR
+                    if (dropStatusEvents)
+                    {
+                        // If the type here is a status event, ask advance not to leave the event in the buffer.  Otherwise, leave it there.
+                        if (currentEventType == StateEvent.Type || currentEventType == DeltaStateEvent.Type || currentEventType == IMECompositionEvent.Type)
+                            m_InputEventStream.Advance(false);
+                        else
+                            m_InputEventStream.Advance(true);
+
+                        continue;
+                    }
+#endif
+
                     // In the editor, we discard all input events that occur in-between exiting edit mode and having
                     // entered play mode as otherwise we'll spill a bunch of UI events that have occurred while the
                     // UI was sort of neither in this mode nor in that mode. This would usually lead to the game receiving