From 16f96599bc1743d3d5fd42a78bec98ba884ae994 Mon Sep 17 00:00:00 2001
From: "Egor.Ushakov" <egor.ushakov@jetbrains.com>
Date: Wed, 13 Jan 2016 14:42:47 +0300
Subject: [PATCH] vcs annotations preloader (IDEA-CR-7773): - do not schedule
 preloading for the same file more than once if not completed yet - schedule
 preloading on file select not open - do not enable in power save mode - do
 not preload if file is already closed - do not preload if annotation provider
 is not cacheable

---
 .../vcs/annotate/AnnotationsPreloader.java    | 55 +++++++++++++------
 1 file changed, 37 insertions(+), 18 deletions(-)

diff --git a/platform/vcs-impl/src/com/intellij/openapi/vcs/annotate/AnnotationsPreloader.java b/platform/vcs-impl/src/com/intellij/openapi/vcs/annotate/AnnotationsPreloader.java
index 59d692752cce..bbc61acbd545 100644
--- a/platform/vcs-impl/src/com/intellij/openapi/vcs/annotate/AnnotationsPreloader.java
+++ b/platform/vcs-impl/src/com/intellij/openapi/vcs/annotate/AnnotationsPreloader.java
@@ -15,8 +15,10 @@
  */
 package com.intellij.openapi.vcs.annotate;
 
+import com.intellij.ide.PowerSaveMode;
 import com.intellij.openapi.fileEditor.FileEditorManager;
 import com.intellij.openapi.fileEditor.FileEditorManagerAdapter;
+import com.intellij.openapi.fileEditor.FileEditorManagerEvent;
 import com.intellij.openapi.fileEditor.FileEditorManagerListener;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.registry.Registry;
@@ -24,38 +26,55 @@ import com.intellij.openapi.vcs.AbstractVcs;
 import com.intellij.openapi.vcs.ProjectLevelVcsManager;
 import com.intellij.openapi.vcs.VcsException;
 import com.intellij.openapi.vfs.VirtualFile;
-import com.intellij.util.Alarm;
+import com.intellij.util.ui.update.MergingUpdateQueue;
+import com.intellij.util.ui.update.Update;
 import org.jetbrains.annotations.NotNull;
 
 /**
  * @author egor
  */
 public class AnnotationsPreloader {
-  private final Alarm myAlarm;
+  private final MergingUpdateQueue myUpdateQueue;
+  private final Project myProject;
 
   public AnnotationsPreloader(final Project project) {
-    myAlarm = new Alarm(Alarm.ThreadToUse.POOLED_THREAD, project);
+    myProject = project;
+    myUpdateQueue = new MergingUpdateQueue("Annotations preloader queue", 1000, true, null, project, null, false);
 
     project.getMessageBus().connect(project).subscribe(FileEditorManagerListener.FILE_EDITOR_MANAGER, new FileEditorManagerAdapter() {
       @Override
-      public void fileOpened(@NotNull FileEditorManager source, @NotNull final VirtualFile file) {
-        if (!Registry.is("vcs.annotations.preload")) return;
+      public void selectionChanged(@NotNull FileEditorManagerEvent event) {
+        if (!isEnabled()) return;
+        VirtualFile file = event.getNewFile();
+        if (file != null) {
+          schedulePreloading(file);
+        }
+      }
+    });
+  }
 
-        AbstractVcs vcs = ProjectLevelVcsManager.getInstance(project).getVcsFor(file);
-        if (vcs == null) return;
-        final AnnotationProvider annotationProvider = vcs.getCachingAnnotationProvider();
-        assert annotationProvider != null;
+  private static boolean isEnabled() {
+    // TODO: check cores number?
+    return Registry.is("vcs.annotations.preload") && !PowerSaveMode.isEnabled();
+  }
 
-        myAlarm.addRequest(new Runnable() {
-          @Override
-          public void run() {
-            try {
-              annotationProvider.annotate(file);
-            }
-            catch (VcsException ignore) {
-            }
+  private void schedulePreloading(@NotNull final VirtualFile file) {
+    AbstractVcs vcs = ProjectLevelVcsManager.getInstance(myProject).getVcsFor(file);
+    if (vcs == null || !(vcs.getAnnotationProvider() instanceof VcsCacheableAnnotationProvider)) return;
+
+    final AnnotationProvider annotationProvider = vcs.getCachingAnnotationProvider();
+    assert annotationProvider != null;
+
+    myUpdateQueue.queue(new Update(file) {
+      @Override
+      public void run() {
+        try {
+          if (FileEditorManager.getInstance(myProject).isFileOpen(file)) {
+            annotationProvider.annotate(file);
           }
-        }, 0);
+        }
+        catch (VcsException ignore) {
+        }
       }
     });
   }