LLM-18251: introduce adaptive debounce for cloud completion

(cherry picked from commit 730bbb63918e8fd8b82ef2cb8720f6a8a2007006)


(cherry picked from commit d71601c2661630be1024b5f9b9451e7dc678d34b)

IJ-MR-175246

GitOrigin-RevId: 95dc7c63e9de04256335f48cfb8a26f87cec5c0d

platform/platform-impl/codeinsight-inline/src/com/intellij/codeInsight/inline/completion/InlineCompletionHandler.kt

@@ -1,6 +1,7 @@
 // Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInsight.inline.completion
 
+import com.intellij.codeInsight.inline.completion.debounce.InlineCompletionAdaptiveDebounceListener
 import com.intellij.codeInsight.inline.completion.editor.InlineCompletionEditorType
 import com.intellij.codeInsight.inline.completion.elements.InlineCompletionElement
 import com.intellij.codeInsight.inline.completion.listeners.InlineSessionWiseCaretListener
@@ -84,6 +85,9 @@ abstract class InlineCompletionHandler @ApiStatus.Internal constructor(
     invalidationListeners.addListener(logsListener)
     addEventListener(UserFactorsListener())
 
+    // Adaptive debounce listener: tracks acceptance/rejection outcomes for the last 10 minutes
+    addEventListener(InlineCompletionAdaptiveDebounceListener(editor))
+
     Disposer.register(parentDisposable, /* child = */ executor)
   }
 

platform/platform-impl/codeinsight-inline/src/com/intellij/codeInsight/inline/completion/debounce/InlineCompletionAdaptiveDebounceListener.kt

@@ -0,0 +1,41 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.codeInsight.inline.completion.debounce
+
+import com.intellij.codeInsight.inline.completion.InlineCompletionEventAdapter
+import com.intellij.codeInsight.inline.completion.InlineCompletionEventType
+import com.intellij.codeInsight.inline.completion.logs.InlineCompletionUsageTracker.ShownEvents.FinishType
+import com.intellij.openapi.editor.Editor
+
+/**
+ * Listener that observes inline completion lifecycle and records
+ * accept/reject finish type into [InlineCompletionFinishedCompletionsStorage].
+ */
+internal class InlineCompletionAdaptiveDebounceListener(private val editor: Editor) : InlineCompletionEventAdapter {
+
+  private fun serviceOrNull(): InlineCompletionFinishedCompletionsStorage? = editor.project?.let { InlineCompletionFinishedCompletionsStorage.getInstance(it) }
+
+  override fun onAfterInsert(event: InlineCompletionEventType.AfterInsert) {
+    serviceOrNull()?.record(InlineCompletionFinishedCompletionsStorage.Result.ACCEPTED)
+  }
+
+  override fun onHide(event: InlineCompletionEventType.Hide) {
+    val result = when (event.finishType) {
+      FinishType.CARET_CHANGED,
+      FinishType.EDITOR_REMOVED,
+      FinishType.FOCUS_LOST,
+      FinishType.TYPED,
+      FinishType.EMPTY,
+      FinishType.ERROR,
+      FinishType.OTHER,
+      FinishType.BACKSPACE_PRESSED,
+      FinishType.KEY_PRESSED,
+      FinishType.INVALIDATED,
+      FinishType.SELECTED,
+      FinishType.MOUSE_PRESSED,
+      FinishType.DOCUMENT_CHANGED,
+        -> InlineCompletionFinishedCompletionsStorage.Result.OTHER
+      FinishType.ESCAPE_PRESSED -> InlineCompletionFinishedCompletionsStorage.Result.REJECTED
+    }
+    serviceOrNull()?.record(result)
+  }
+}

platform/platform-impl/codeinsight-inline/src/com/intellij/codeInsight/inline/completion/debounce/InlineCompletionFinishedCompletionsStorage.kt

@@ -0,0 +1,51 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.codeInsight.inline.completion.debounce
+
+import com.intellij.codeInsight.inline.completion.debounce.InlineCompletionFinishedCompletionsStorage.Companion.EXPIRATION_MS
+import com.intellij.openapi.components.Service
+import com.intellij.openapi.components.service
+import com.intellij.openapi.project.Project
+import org.jetbrains.annotations.ApiStatus
+import java.util.*
+
+/**
+ * Project-level container of recent inline-completions for adaptive debounce tuning.
+ *
+ * Retains completions for the last [EXPIRATION_MS] milliseconds (10 minutes) and discards older ones.
+ */
+@Service(Service.Level.PROJECT)
+@ApiStatus.Internal
+class InlineCompletionFinishedCompletionsStorage {
+  enum class Result { ACCEPTED, REJECTED, OTHER }
+
+  data class FinishedCompletion(val result: Result, val finishTime: Long)
+
+  private val previousCompletions = ArrayDeque<FinishedCompletion>()
+
+  @Synchronized
+  fun record(result: Result) {
+    val now = System.currentTimeMillis()
+    cleanupExpired(now)
+    previousCompletions.addLast(FinishedCompletion(result, now))
+  }
+
+  /** Returns a snapshot of recent actions with timestamps (most recent at the end). */
+  @Synchronized
+  fun getRecentCompletions(): List<FinishedCompletion> {
+    cleanupExpired(System.currentTimeMillis())
+    return ArrayList(previousCompletions)
+  }
+
+  private fun cleanupExpired(now: Long) {
+    val threshold = now - EXPIRATION_MS
+    while (true) {
+      val first = previousCompletions.peekFirst() ?: break
+      if (first.finishTime < threshold) previousCompletions.removeFirst() else break
+    }
+  }
+
+  companion object {
+    private const val EXPIRATION_MS: Long = 10 * 60 * 1000 // 10 minutes
+    fun getInstance(project: Project): InlineCompletionFinishedCompletionsStorage = project.service()
+  }
+}