Resolve relationship edit conflicts more naturally

Summary:
Ref T11179. Ref T4768. Currently, on `master`, if two users open "Edit Revisions" at the same time, then add revisions A and B, only the last state wins (just "B").

Instead, apply these as "add A" and "add B" so they merge in a natural way.

Test Plan:
  - Opened edit dialog in two windows.
  - Added "A" in one, "B" in the other.
  - Saved both.
  - Saw "Added A" and "Added B" transactions, instead of "Added A" and "Removed A, added B".

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4768, T11179

Differential Revision: https://secure.phabricator.com/D16164

resources/celerity/map.php

@@ -11,7 +11,7 @@ return array(
     'core.pkg.js' => 'f2139810',
     'darkconsole.pkg.js' => 'e7393ebb',
     'differential.pkg.css' => 'b3eea3f5',
-    'differential.pkg.js' => '4b7d8f19',
+    'differential.pkg.js' => '01a010d6',
     'diffusion.pkg.css' => '91c5d3a6',
     'diffusion.pkg.js' => '3a9a8bfa',
     'maniphest.pkg.css' => '4845691a',
@@ -495,7 +495,7 @@ return array(
     'rsrc/js/core/behavior-lightbox-attachments.js' => 'f8ba29d7',
     'rsrc/js/core/behavior-line-linker.js' => '1499a8cb',
     'rsrc/js/core/behavior-more.js' => 'a80d0378',
-    'rsrc/js/core/behavior-object-selector.js' => '49b73b36',
+    'rsrc/js/core/behavior-object-selector.js' => '9030ebef',
     'rsrc/js/core/behavior-oncopy.js' => '2926fff2',
     'rsrc/js/core/behavior-phabricator-nav.js' => '56a1ca03',
     'rsrc/js/core/behavior-phabricator-remarkup-assist.js' => '116cf19b',
@@ -658,7 +658,7 @@ return array(
     'javelin-behavior-phabricator-line-linker' => '1499a8cb',
     'javelin-behavior-phabricator-nav' => '56a1ca03',
     'javelin-behavior-phabricator-notification-example' => '8ce821c5',
-    'javelin-behavior-phabricator-object-selector' => '49b73b36',
+    'javelin-behavior-phabricator-object-selector' => '9030ebef',
     'javelin-behavior-phabricator-oncopy' => '2926fff2',
     'javelin-behavior-phabricator-remarkup-assist' => '116cf19b',
     'javelin-behavior-phabricator-reveal-content' => '60821bc7',
@@ -1214,12 +1214,6 @@ return array(
       'javelin-uri',
       'phabricator-notification',
     ),
-    '49b73b36' => array(
-      'javelin-behavior',
-      'javelin-dom',
-      'javelin-request',
-      'javelin-util',
-    ),
     '4b700e9e' => array(
       'javelin-behavior',
       'javelin-dom',
@@ -1608,6 +1602,12 @@ return array(
       'javelin-dom',
       'javelin-request',
     ),
+    '9030ebef' => array(
+      'javelin-behavior',
+      'javelin-dom',
+      'javelin-request',
+      'javelin-util',
+    ),
     '9196fb06' => array(
       'javelin-install',
       'javelin-dom',

src/applications/search/controller/PhabricatorSearchRelationshipController.php

@@ -44,18 +44,20 @@ final class PhabricatorSearchRelationshipController
     $src_handle = $handles[$src_phid];
 
     $done_uri = $src_handle->getURI();
+    $initial_phids = $dst_phids;
 
     if ($request->isFormPost()) {
       $phids = explode(';', $request->getStr('phids'));
       $phids = array_filter($phids);
       $phids = array_values($phids);
 
-      // TODO: Embed these in the form instead, to gracefully resolve
-      // concurrent edits like we do for subscribers and projects.
-      $old_phids = $dst_phids;
+      $initial_phids = $request->getStrList('initialPHIDs');
 
-      $add_phids = $phids;
-      $rem_phids = array_diff($old_phids, $add_phids);
+      // Apply the changes as adds and removes relative to the original state
+      // of the object when the dialog was rendered so that two users adding
+      // relationships at the same time don't race and overwrite one another.
+      $add_phids = array_diff($phids, $initial_phids);
+      $rem_phids = array_diff($initial_phids, $phids);
 
       if ($add_phids) {
         $dst_objects = id(new PhabricatorObjectQuery())
@@ -149,6 +151,7 @@ final class PhabricatorSearchRelationshipController
 
     return id(new PhabricatorObjectSelectorDialog())
       ->setUser($viewer)
+      ->setInitialPHIDs($initial_phids)
       ->setHandles($handles)
       ->setFilters($filters)
       ->setSelectedFilter('created')

src/view/control/PhabricatorObjectSelectorDialog.php

@@ -10,6 +10,7 @@ final class PhabricatorObjectSelectorDialog extends Phobject {
   private $searchURI;
   private $selectedFilter;
   private $excluded;
+  private $initialPHIDs;
 
   private $title;
   private $header;
@@ -77,6 +78,15 @@ final class PhabricatorObjectSelectorDialog extends Phobject {
     return $this;
   }
 
+  public function setInitialPHIDs(array $initial_phids) {
+    $this->initialPHIDs = $initial_phids;
+    return $this;
+  }
+
+  public function getInitialPHIDs() {
+    return $this->initialPHIDs;
+  }
+
   public function buildDialog() {
     $user = $this->user;
 
@@ -171,8 +181,14 @@ final class PhabricatorObjectSelectorDialog extends Phobject {
       $view = new PhabricatorHandleObjectSelectorDataView($handle);
       $handle_views[$phid] = $view->renderData();
     }
+
     $dialog->addHiddenInput('phids', implode(';', array_keys($this->handles)));
 
+    $initial_phids = $this->getInitialPHIDs();
+    if ($initial_phids) {
+      $initial_phids = implode(', ', $initial_phids);
+      $dialog->addHiddenInput('initialPHIDs', $initial_phids);
+    }
 
     Javelin::initBehavior(
       'phabricator-object-selector',

webroot/rsrc/js/core/behavior-object-selector.js

@@ -18,10 +18,21 @@ JX.behavior('phabricator-object-selector', function(config) {
   var query_timer = null;
   var query_delay = 50;
 
-  var phid_input = JX.DOM.find(
+  // TODO: This is fairly grotesque, but the dialog has two different forms
+  // inside it and there's no way to sigil the inputs in the "real" form right
+  // now. Clean this up when the dialog as a whole gets cleaned up.
+
+  var inputs = JX.DOM.scry(
     JX.$(config.form),
     'input',
     'aphront-dialog-application-input');
+  var phid_input;
+  for (var ii = 0; ii < inputs.length; ii++) {
+    if (inputs[ii].name == 'phids') {
+      phid_input = inputs[ii];
+      break;
+    }
+  }
 
   var last_value = JX.$(config.query).value;