[FileManager] Do drive search incrementally

chrome/browser/resources/file_manager/js/directory_contents.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Type of a root directory.
  * @enum
  */
 var RootType = {
   DOWNLOADS: 'downloads',
@@ skipping 510 matching lines @@
 DirectoryContentsBasic.prototype.createDirectory = function(
     name, successCallback, errorCallback) {
   var onSuccess = function(newEntry) {
     this.prefetchMetadata([newEntry], function() {successCallback(newEntry);});
   }
 
   this.entry_.getDirectory(name, {create: true, exclusive: true},
                            onSuccess.bind(this), errorCallback);
 };
 
+/**
+ * Delay to be used for gdata search scan.
+ * The goal is to reduce the number of server requests when user is typing the
+ * query.
+ */
+DirectoryContentsGDataSearch.SCAN_DELAY = 200;
+
+/**
+ * Number of results at which we stop the search.
+ * Note that max number of shown results is MAX_RESULTS + search feed size.
+ */
+DirectoryContentsGDataSearch.MAX_RESULTS = 999;
 
 /**
  * @constructor
  * @extends {DirectoryContents}
  * @param {FileListContext} context File list context.
  * @param {DirectoryEntry} dirEntry Current directory.
  * @param {string} query Search query.
  */
 function DirectoryContentsGDataSearch(context, dirEntry, query) {
   DirectoryContents.call(this, context);
   this.query_ = query;
   this.directoryEntry_ = dirEntry;
+  this.nextFeed_ = '';
+  this.done_ = false;
+  this.fetchedResultsNum_ = 0;
 }
 
 /**
  * Extends DirectoryContents.
  */
 DirectoryContentsGDataSearch.prototype.__proto__ = DirectoryContents.prototype;
 
 /**
  * Create the copy of the object, but without scan started.
  * @return {DirectoryContentsBasic} Object copy.
@@ skipping 21 matching lines @@
  * @return {string} The path.
  */
 DirectoryContentsGDataSearch.prototype.getPath = function() {
   return this.directoryEntry_.fullPath;
 };
 
 /**
  * Start directory scan.
  */
 DirectoryContentsGDataSearch.prototype.scan = function() {
-  chrome.fileBrowserPrivate.searchGData(this.query_,
-                                        this.onNewEntries.bind(this));
+  // Let's give another search a chance to cancel us before we begin.
+  setTimeout(this.readNextChunk.bind(this),
+             DirectoryContentsGDataSearch.SCAN_DELAY);
 };
 
 /**
  * All the results are read in one chunk, so when we try to read second chunk,
  * it means we're done.
  */
 DirectoryContentsGDataSearch.prototype.readNextChunk = function() {
-  this.onCompleted();
+  if (this.scanCancelled_)
+    return;
+
+  if (this.done_) {
+    this.onCompleted();
+    return;
+  }
+
+  var searchCallback = (function(entries, nextFeed) {
+    // TODO(tbarzic): Improve error handling.
+    if (!entries) {
+      console.log('Drive search encountered an error');
+      this.onCompleted();
+      return;
+    }
+    this.nextFeed_ = nextFeed;
+    this.fetchedResultsNum_ += entries.length;
+    if (this.fetchedResultsNum_ >= DirectoryContentsGDataSearch.MAX_RESULTS)
+      this.nextFeed_ = '';
+
+    this.done_ = (this.nextFeed_ == '');
+    this.onNewEntries(entries);
+  }).bind(this);
+
+  chrome.fileBrowserPrivate.searchGData(this.query_,
+                                        this.nextFeed_,
+                                        searchCallback);
 };
 
 
 /**
  * @constructor
  * @extends {DirectoryContents}
  * @param {FileListContext} context File list context.
  * @param {DirectoryEntry} dirEntry Current directory.
  * @param {string} query Search query.
  */
@@ skipping 101 matching lines @@
 
   getNextChunk();
 };
 
 /**
  * Empty.
  */
 DirectoryContentsLocalSearch.prototype.readNextChunk = function() {
   this.onCompleted();
 };