shared index: add api to notify on index version changed

GitOrigin-RevId: 12cb1d2d06dfbad1d75455ce93c39cf9fd9d29eb

platform/lang-impl/src/com/intellij/psi/stubs/StubIndexImpl.java

@@ -188,6 +188,17 @@ public final class StubIndexImpl extends StubIndexEx implements PersistentStateC
       else registrationResultSink.registerIndexAsInitiallyBuilt(indexKey);
       if (indexRootHasChildren) FileUtil.deleteWithRenaming(indexRootDir);
       IndexingStamp.rewriteVersion(indexKey, version); // todo snapshots indices
+
+      try {
+        if (needRebuild) {
+          for (FileBasedIndexInfrastructureExtension ex : FileBasedIndexInfrastructureExtension.EP_NAME.getExtensionList()) {
+            ex.onStubIndexVersionChanged(indexKey);
+          }
+        }
+      } catch (Exception e) {
+        LOG.error(e);
+      }
+
     } else {
       registrationResultSink.registerIndexAsUptoDate(indexKey);
     }

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

@@ -333,6 +333,17 @@ public final class FileBasedIndexImpl extends FileBasedIndexEx {
       File rootDir = IndexInfrastructure.getIndexRootDir(name);
       if (versionFileExisted) FileUtil.deleteWithRenaming(rootDir);
       IndexingStamp.rewriteVersion(name, version);
+
+      try {
+        if (versionFileExisted) {
+          for (FileBasedIndexInfrastructureExtension ex : FileBasedIndexInfrastructureExtension.EP_NAME.getExtensionList()) {
+            ex.onFileBasedIndexVersionChanged(name);
+          }
+        }
+      } catch (Exception e) {
+        LOG.error(e);
+      }
+
     } else {
       registrationStatusSink.registerIndexAsUptoDate(name);
     }

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

@@ -6,6 +6,7 @@ import com.intellij.openapi.progress.ProgressIndicator;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.OrderEntry;
 import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.psi.stubs.StubIndexKey;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -49,6 +50,23 @@ public interface FileBasedIndexInfrastructureExtension {
                                                         @NotNull UpdatableIndex<K, V, FileContent> baseIndex);
 
 
+  /**
+   * Notifies the extension to handle that version of existing file based index version has been changed.
+   *
+   * Actually {@link FileBasedIndex} notifies even if index composite version (extension version + implementation version)
+   * is changed {@link FileBasedIndexImpl#getIndexExtensionVersion(FileBasedIndexExtension)}.
+   *
+   * @param indexId that version is updated.
+   */
+  void onFileBasedIndexVersionChanged(@NotNull ID<?, ?> indexId);
+
+  /**
+   * Notifies the extension to handle that version of existing stub index has been changed.
+   *
+   * @param indexId that version is updated.
+   */
+  void onStubIndexVersionChanged(@NotNull StubIndexKey<?, ?> indexId);
+
   /**
    * Executed when IntelliJ is shutting down it's indexes (IDE shutdown or plugin load/unload). It is the best time
    * for the component to flush it's state to the disk and close all pending connections.