No need to listen to roots-changed events....

No need to listen to roots-changed events. PyPackageManagerImpl.MySdkRootWatcher refreshes packages cache (DS-49)

python/src/com/jetbrains/python/packaging/ui/PyPackagesToolWindowTabFactory.kt

 // Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.jetbrains.python.packaging.ui
 
-import com.intellij.ProjectTopics
 import com.intellij.openapi.Disposable
 import com.intellij.openapi.fileEditor.FileEditorManager
 import com.intellij.openapi.fileEditor.FileEditorManagerEvent
@@ -9,8 +8,6 @@ import com.intellij.openapi.fileEditor.FileEditorManagerListener
 import com.intellij.openapi.module.ModuleUtilCore
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.projectRoots.Sdk
-import com.intellij.openapi.roots.ModuleRootEvent
-import com.intellij.openapi.roots.ModuleRootListener
 import com.intellij.openapi.ui.PackagesToolWindowTab
 import com.intellij.openapi.ui.PackagesToolWindowTabFactory
 import com.intellij.openapi.vfs.VirtualFile
@@ -35,7 +32,7 @@ class PyPackagesToolWindowTabFactory : PackagesToolWindowTabFactory {
 
   override fun createContent(project: Project, parentDisposable: Disposable): PackagesToolWindowTab {
     val panel = PyInstalledPackagesPanel(project, PackagesNotificationPanel())
-    updateForCurrentFile(project, panel, true)
+    updateForCurrentFile(project, panel)
 
     val connection = project.messageBus.connect(parentDisposable)
 
@@ -43,15 +40,7 @@ class PyPackagesToolWindowTabFactory : PackagesToolWindowTabFactory {
     connection.subscribe(
       FileEditorManagerListener.FILE_EDITOR_MANAGER,
       object : FileEditorManagerListener {
-        override fun selectionChanged(event: FileEditorManagerEvent) = updateForFile(project, panel, event.newFile, false)
-      }
-    )
-
-    // sdk has been possibly changed
-    connection.subscribe(
-      ProjectTopics.PROJECT_ROOTS,
-      object : ModuleRootListener {
-        override fun rootsChanged(event: ModuleRootEvent) = updateForCurrentFile(project, panel, true)
+        override fun selectionChanged(event: FileEditorManagerEvent) = updateForFile(project, panel, event.newFile)
       }
     )
 
@@ -59,30 +48,30 @@ class PyPackagesToolWindowTabFactory : PackagesToolWindowTabFactory {
     connection.subscribe(
       PyPackageManager.PACKAGE_MANAGER_TOPIC,
       PyPackageManager.Listener {
-        // skip packages that have been refreshed for another sdk
-        if (currentSdk == it) updateForSdk(project, panel, it, false)
+        updateForCurrentFile(project, panel)
       }
     )
 
     return PackagesToolWindowTab("Python", panel)
   }
 
-  private fun updateForCurrentFile(project: Project, panel: PyInstalledPackagesPanel, force: Boolean) {
-    updateForFile(project, panel, FileEditorManager.getInstance(project).selectedFiles.firstOrNull(), force)
+  private fun updateForCurrentFile(project: Project, panel: PyInstalledPackagesPanel) {
+    updateForFile(project, panel, FileEditorManager.getInstance(project).selectedFiles.firstOrNull())
   }
 
-  private fun updateForFile(project: Project, panel: PyInstalledPackagesPanel, file: VirtualFile?, force: Boolean) {
-    updateForSdk(project, panel, file?.let { PythonSdkType.findPythonSdk(ModuleUtilCore.findModuleForFile(it, project)) }, force)
+  private fun updateForFile(project: Project, panel: PyInstalledPackagesPanel, file: VirtualFile?) {
+    updateForSdk(project, panel, file?.let { PythonSdkType.findPythonSdk(ModuleUtilCore.findModuleForFile(it, project)) })
   }
 
-  private fun updateForSdk(project: Project, panel: PyInstalledPackagesPanel, sdk: Sdk?, force: Boolean) {
-    val latestPackages = sdk?.let { PyPackageManagers.getInstance().forSdk(it).packages }
+  private fun updateForSdk(project: Project, panel: PyInstalledPackagesPanel, sdk: Sdk?) {
+    val packageManagers = PyPackageManagers.getInstance()
 
-    if (force || currentSdk != sdk || currentPackages != latestPackages) {
+    val latestPackages = sdk?.let { packageManagers.forSdk(it).packages }
+    if (currentSdk != sdk || currentPackages != latestPackages) {
       currentSdk = sdk
       currentPackages = latestPackages
 
-      panel.updatePackages(sdk?.let { PyPackageManagers.getInstance().getManagementService(project, it) })
+      panel.updatePackages(sdk?.let { packageManagers.getManagementService(project, it) })
       panel.updateNotifications(sdk)
     }
   }