private void doSaveDocument(@NotNull final Document document)
      throws IOException, SaveVetoException {
    VirtualFile file = getFile(document);

    if (file == null
        || file instanceof LightVirtualFile
        || file.isValid() && !isFileModified(file)) {
      removeFromUnsaved(document);
      return;
    }

    if (file.isValid() && needsRefresh(file)) {
      file.refresh(false, false);
      if (!myUnsavedDocuments.contains(document)) return;
    }

    for (FileDocumentSynchronizationVetoer vetoer :
        Extensions.getExtensions(FileDocumentSynchronizationVetoer.EP_NAME)) {
      if (!vetoer.maySaveDocument(document)) {
        throw new SaveVetoException();
      }
    }

    final AccessToken token =
        ApplicationManager.getApplication().acquireWriteActionLock(getClass());
    try {
      doSaveDocumentInWriteAction(document, file);
    } finally {
      token.finish();
    }
  }
  @Override
  public void contentsChanged(VirtualFileEvent event) {
    if (event.isFromSave()) return;
    final VirtualFile file = event.getFile();
    final Document document = getCachedDocument(file);
    if (document == null) {
      myMultiCaster.fileWithNoDocumentChanged(file);
      return;
    }

    if (isBinaryWithDecompiler(file)) {
      myMultiCaster.fileWithNoDocumentChanged(
          file); // This will generate PSI event at FileManagerImpl
    }

    long documentStamp = document.getModificationStamp();
    long oldFileStamp = event.getOldModificationStamp();
    if (documentStamp != oldFileStamp) {
      LOG.info("reload from disk?");
      LOG.info("  documentStamp:" + documentStamp);
      LOG.info("  oldFileStamp:" + oldFileStamp);

      if (file.isValid() && askReloadFromDisk(file, document)) {
        reloadFromDisk(document);
      }
    } else {
      reloadFromDisk(document);
    }
  }
 @Override
 public boolean requestWriting(@NotNull Document document, Project project) {
   final VirtualFile file = getInstance().getFile(document);
   if (project != null && file != null && file.isValid()) {
     return !file.getFileType().isBinary()
         && ReadonlyStatusHandler.ensureFilesWritable(project, file);
   }
   if (document.isWritable()) {
     return true;
   }
   document.fireReadOnlyModificationAttempt();
   return false;
 }
  private void doSaveDocumentInWriteAction(@NotNull Document document, @NotNull VirtualFile file)
      throws IOException {
    if (!file.isValid()) {
      removeFromUnsaved(document);
      return;
    }

    if (!file.equals(getFile(document))) {
      registerDocument(document, file);
    }

    if (!isSaveNeeded(document, file)) {
      if (document instanceof DocumentEx) {
        ((DocumentEx) document).setModificationStamp(file.getModificationStamp());
      }
      removeFromUnsaved(document);
      updateModifiedProperty(file);
      return;
    }

    myMultiCaster.beforeDocumentSaving(document);

    LOG.assertTrue(file.isValid());

    String text = document.getText();
    String lineSeparator = getLineSeparator(document, file);
    if (!lineSeparator.equals("\n")) {
      text = StringUtil.convertLineSeparators(text, lineSeparator);
    }

    Project project = ProjectLocator.getInstance().guessProjectForFile(file);
    LoadTextUtil.write(project, file, this, text, document.getModificationStamp());

    myUnsavedDocuments.remove(document);
    LOG.assertTrue(!myUnsavedDocuments.contains(document));
    myTrailingSpacesStripper.clearLineModificationFlags(document);
  }