Detect removed files and reflect the state in chrome://downloads and the download shelf

chrome/browser/resources/downloads.js

 // Copyright (c) 2011 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.
 
 ///////////////////////////////////////////////////////////////////////////////
 // Helper functions
 function $(o) {return document.getElementById(o);}
 
 /**
  * Sets the display style of a node.
@@ skipping 274 matching lines @@
 }
 
 /**
  * The states a download can be in. These correspond to states defined in
  * DownloadsDOMHandler::CreateDownloadItemValue
  */
 Download.States = {
   IN_PROGRESS : "IN_PROGRESS",
   CANCELLED : "CANCELLED",
   COMPLETE : "COMPLETE",
+  REMOVED : "REMOVED",

[hendrickson_a, 2011/06/07 15:38:52]

I don't like this mismatch between the states in DownloadItem and in JavaScript.

[Randy Smith (Not in Mondays), 2011/06/07 18:51:10]

I'm sorry if this was covered earlier and the state's not in my brain anymore,
but why include the REMOVED status?  I'd rather not do that; a) it's not really
a state of a download, and b) what an C++ observer seeing "REMOVED" should do is
immediately stop observing the download item and remove it from any lists it
contains.   Extending that to an asynchronous renderer interaction seems like
asking for trouble.   

[haraken1, 2011/06/08 05:11:49]

I got it. I removed REMOVED state from Download.States. Instead, I introduced
this.fileExternallyRemoved_, which corresponds to
DownloadItem::file_externally_removed_ in C++. 


On 2011/06/07 18:51:10, rdsmith wrote:

   PAUSED : "PAUSED",
   DANGEROUS : "DANGEROUS",
   INTERRUPTED : "INTERRUPTED",
 }
 
 /**
  * Explains why a download is in DANGEROUS state.
  */
 Download.DangerType = {
   NOT_DANGEROUS: "NOT_DANGEROUS",
@@ skipping 136 matching lines @@
 
 /**
  * @return {String} User-visible status update text.
  */
 Download.prototype.getStatusText_ = function() {
   switch (this.state_) {
     case Download.States.IN_PROGRESS:
       return this.progressStatusText_;
     case Download.States.CANCELLED:
       return localStrings.getString('status_cancelled');
+    case Download.States.REMOVED:
+      return localStrings.getString('status_removed');
     case Download.States.PAUSED:
       return localStrings.getString('status_paused');
     case Download.States.DANGEROUS:
       var desc = this.dangerType_ == Download.DangerType.DANGEROUS_FILE ?
           'danger_file_desc' : 'danger_url_desc';
       return localStrings.getString(desc);
     case Download.States.INTERRUPTED:
       return localStrings.getString('status_interrupted');
     case Download.States.COMPLETE:
       return '';
@@ skipping 64 matching lines @@
  */
 Download.prototype.cancel_ = function() {
   chrome.send('cancel', [this.id_.toString()]);
   return false;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Page:
 var downloads, localStrings, resultsTimeout;
 
+/**
+ * The FIFO array that stores updates of download files to be appeared
+ * on the download page. It is guaranteed that the updates in this array
+ * are reflected to the download page in a FIFO order.
+*/
+var fifo_results;
+
 function load() {
+  fifo_results = new Array();
   localStrings = new LocalStrings();
   downloads = new Downloads();
   $('term').focus();
   setSearch('');
 }
 
 function setSearch(searchText) {
+  fifo_results.length = 0;
   downloads.clear();
   downloads.setSearchText(searchText);
   chrome.send('getDownloads', [searchText.toString()]);
 }
 
 function clearAll() {
+  fifo_results.length = 0;
   downloads.clear();
   downloads.setSearchText('');
   chrome.send('clearAll', []);
   return false;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // Chrome callbacks:
 /**
  * Our history system calls this function with results from searches or when
  * downloads are added or removed.
  */
 function downloadsList(results) {
   if (resultsTimeout)
     clearTimeout(resultsTimeout);
   window.console.log('results');
+  fifo_results.length = 0;
   downloads.clear();
   downloadUpdated(results);
   downloads.updateSummary();
 }
 
 /**
  * When a download is updated (progress, state change), this is called.
  */
 function downloadUpdated(results) {
   // Sometimes this can get called too early.
   if (!downloads)
     return;
 
+  fifo_results = fifo_results.concat(results);
+  tryDownloadUpdatedPeriodically();
+}
+
+/**
+ * Try to reflect as much updates as possible within 50ms.
+ * This function is scheduled again and again until all updates are reflected.
+ */
+function tryDownloadUpdatedPeriodically() {
   var start = Date.now();
-  for (var i = 0; i < results.length; i++) {
-    downloads.updated(results[i]);
+  while (fifo_results.length) {
+    var result = fifo_results.shift();
+    downloads.updated(result);
     // Do as much as we can in 50ms.
     if (Date.now() - start > 50) {
       clearTimeout(resultsTimeout);
-      resultsTimeout = setTimeout(downloadUpdated, 5, results.slice(i + 1));
+      resultsTimeout = setTimeout(tryDownloadUpdatedPeriodically, 5);
       break;
     }
   }
 }
 
 // Add handlers to HTML elements.
 document.body.onload = load;
 $('clear-all').onclick = function () { clearAll(''); };
 $('search-link').onclick = function () {
   setSearch('');
   return false;
 };
 $('search-form').onsubmit = function () {
   setSearch(this.term.value);
   return false;
 };