reliably save persistent index stamp between IDE sessions (IDEA-194315)

In particular use saved persistent index stamp when invalidate caches was requested and vfs survives the invalidation

platform/lang-impl/src/com/intellij/util/indexing/FileBasedIndexImpl.java

@@ -502,6 +502,8 @@ public class FileBasedIndexImpl extends FileBasedIndex implements BaseComponent,
     finally {
       LOG.info("START INDEX SHUTDOWN");
       try {
+        PersistentIndicesConfiguration.saveConfiguration();
+        
         for(VirtualFile file:myChangedFilesCollector.getAllFilesToUpdate()) {
           if (!file.isValid()) {
             removeDataFromIndicesForFile(Math.abs(getIdMaskingNonIdBasedFile(file)), file);
@@ -2381,6 +2383,9 @@ public class FileBasedIndexImpl extends FileBasedIndex implements BaseComponent,
     protected void prepare() {
       mySerializationManagerEx = SerializationManagerEx.getInstanceEx();
       File indexRoot = PathManager.getIndexRoot();
+
+      PersistentIndicesConfiguration.loadConfiguration();
+      
       final File corruptionMarker = new File(indexRoot, CORRUPTION_MARKER_NAME);
       currentVersionCorrupted = IndexInfrastructure.hasIndices() && corruptionMarker.exists();
       if (currentVersionCorrupted) {
@@ -2389,6 +2394,7 @@ public class FileBasedIndexImpl extends FileBasedIndex implements BaseComponent,
         // serialization manager is initialized before and use removed index root so we need to reinitialize it
         mySerializationManagerEx.reinitializeNameStorage();
         ID.reinitializeDiskStorage();
+        PersistentIndicesConfiguration.saveConfiguration();
         FileUtil.delete(corruptionMarker);
       }
     }

platform/lang-impl/src/com/intellij/util/indexing/IndexingStamp.java

@@ -63,6 +63,14 @@ public class IndexingStamp {
 
   private IndexingStamp() {}
 
+  public static void initPersistentIndexStamp(DataInput in) throws IOException {
+    IndexVersion.advanceIndexStamp(DataInputOutputUtil.readTIME(in));
+  }
+
+  public static void savePersistentIndexStamp(DataOutput out) throws IOException {
+    DataInputOutputUtil.writeTIME(out, IndexVersion.ourLastStamp);
+  }
+
   static class IndexVersion {
     private static volatile long ourLastStamp; // ensure any file index stamp increases
     final long myModificationCount;
@@ -73,12 +81,16 @@ public class IndexingStamp {
 
     private IndexVersion(long modificationCount) {
       myModificationCount = modificationCount;
+      advanceIndexStamp(modificationCount);
+    }
+
+    private static void advanceIndexStamp(long modificationCount) {
       ourLastStamp = Math.max(modificationCount, ourLastStamp);
     }
 
     public IndexVersion(DataInput in) throws IOException {
       myModificationCount = DataInputOutputUtil.readTIME(in);
-      ourLastStamp = Math.max(ourLastStamp, myModificationCount);
+      advanceIndexStamp(myModificationCount);
     }
 
     public void write(DataOutput os) throws IOException {

platform/lang-impl/src/com/intellij/util/indexing/PersistentIndicesConfiguration.java

@@ -0,0 +1,34 @@
+// Copyright 2000-2018 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.intellij.util.indexing;
+
+import com.intellij.openapi.application.PathManager;
+import com.intellij.util.io.DataInputOutputUtil;
+
+import java.io.*;
+
+class PersistentIndicesConfiguration {
+  private static final int INDICES_CONFIGURATION_VERSION = 1;
+
+  static void saveConfiguration() {
+    try (DataOutputStream out = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(indicesConfigurationFile())))) {
+      DataInputOutputUtil.writeINT(out, INDICES_CONFIGURATION_VERSION);
+      IndexingStamp.savePersistentIndexStamp(out);
+    }
+    catch (IOException ignored) {
+    }
+  }
+
+  static void loadConfiguration() {
+    try (DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream(indicesConfigurationFile())))) {
+      if (DataInputOutputUtil.readINT(in) == INDICES_CONFIGURATION_VERSION) {
+        IndexingStamp.initPersistentIndexStamp(in);
+      }
+    }
+    catch (IOException ignored) {
+    }
+  }
+
+  private static File indicesConfigurationFile() {
+    return new File(PathManager.getIndexRoot(), "indices.config");
+  }
+}