From a57ab19ff5f0879cd46836b3047c476ae7b9cf3a Mon Sep 17 00:00:00 2001
From: Aleksey Pivovarov <AMPivovarov@gmail.com>
Date: Fri, 10 Mar 2023 15:57:41 +0100
Subject: [PATCH] vcs: introduce async trees

GitOrigin-RevId: 6e293bb87a4f22ae85c4a3b4e6340299a9b29352
---
 .../vcs/changes/ui/AsyncChangesTree.kt        | 132 ++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ui/AsyncChangesTree.kt

diff --git a/platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ui/AsyncChangesTree.kt b/platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ui/AsyncChangesTree.kt
new file mode 100644
index 000000000000..5525a8007f24
--- /dev/null
+++ b/platform/vcs-impl/src/com/intellij/openapi/vcs/changes/ui/AsyncChangesTree.kt
@@ -0,0 +1,132 @@
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.openapi.vcs.changes.ui
+
+import com.intellij.openapi.application.EDT
+import com.intellij.openapi.application.ModalityState
+import com.intellij.openapi.application.asContextElement
+import com.intellij.openapi.progress.coroutineToIndicator
+import com.intellij.openapi.project.Project
+import com.intellij.util.concurrency.annotations.RequiresEdt
+import kotlinx.coroutines.*
+import kotlinx.coroutines.flow.*
+import javax.swing.tree.DefaultTreeModel
+
+/**
+ * Call [shutdown] when the tree is no longer needed.
+ */
+abstract class AsyncChangesTree : ChangesTree {
+  protected abstract val changesTreeModel: AsyncChangesTreeModel
+
+  val scope = CoroutineScope(SupervisorJob())
+
+  private val _requests = MutableSharedFlow<Request>()
+  private val _model = MutableStateFlow(Model(TreeModelBuilder.buildEmpty(), null))
+
+  private val _busy = MutableStateFlow(false)
+  val busy: Flow<Boolean> = _busy.asStateFlow()
+
+
+  constructor(project: Project,
+              showCheckboxes: Boolean,
+              highlightProblems: Boolean)
+    : this(project, showCheckboxes, highlightProblems, true)
+
+  constructor(project: Project,
+              showCheckboxes: Boolean,
+              highlightProblems: Boolean,
+              withSpeedSearch: Boolean)
+    : super(project, showCheckboxes, highlightProblems, withSpeedSearch) {
+    start()
+  }
+
+  fun shutdown() {
+    scope.cancel()
+  }
+
+
+  override fun shouldShowBusyIconIfNeeded(): Boolean = true
+
+  override fun rebuildTree() {
+    requestRefresh()
+  }
+
+  override fun rebuildTree(treeStateStrategy: TreeStateStrategy<*>) {
+    requestRefresh(treeStateStrategy)
+  }
+
+
+  fun requestRefresh() {
+    requestRefreshImpl(treeStateStrategy = null)
+  }
+
+  fun requestRefresh(treeStateStrategy: TreeStateStrategy<*>) {
+    requestRefreshImpl(treeStateStrategy = treeStateStrategy)
+  }
+
+  private fun requestRefreshImpl(treeStateStrategy: TreeStateStrategy<*>?) {
+    val refreshGrouping = grouping
+    scope.launch {
+      _requests.emit(Request(refreshGrouping, treeStateStrategy))
+    }
+  }
+
+
+  private fun start() {
+    scope.launch {
+      _requests.collectLatest { request ->
+        handleRequest(request)
+      }
+    }
+
+    val edtContext = Dispatchers.EDT + ModalityState.any().asContextElement()
+    scope.launch(edtContext) {
+      _busy.collectLatest {
+        setPaintBusy(it)
+      }
+    }
+    scope.launch(edtContext) {
+      _model.collectLatest { model ->
+        updateTreeModel(model)
+      }
+    }
+  }
+
+  private suspend fun handleRequest(request: Request) {
+    _busy.value = true
+    try {
+      val treeModel = changesTreeModel.buildTreeModel(request.grouping)
+      val model = Model(treeModel, request.treeStateStrategy)
+      _model.value = model
+    }
+    finally {
+      _busy.value = false
+    }
+  }
+
+  @RequiresEdt
+  private suspend fun updateTreeModel(model: Model) {
+    coroutineToIndicator {
+      val strategy = model.treeStateStrategy
+      if (strategy != null) {
+        updateTreeModel(model.treeModel, strategy)
+      }
+      else {
+        updateTreeModel(model.treeModel)
+      }
+    }
+  }
+
+  private class Request(
+    val grouping: ChangesGroupingPolicyFactory,
+    val treeStateStrategy: TreeStateStrategy<*>?
+  )
+
+  private class Model(
+    val treeModel: DefaultTreeModel,
+    val treeStateStrategy: TreeStateStrategy<*>?
+  )
+}
+
+interface AsyncChangesTreeModel {
+  suspend fun buildTreeModel(grouping: ChangesGroupingPolicyFactory): DefaultTreeModel
+}