Migrate Differential comments to ApplicationTransactions

Summary:
Ref T2222. This is the big one.

This migrates each `DifferentialComment` to one or more ApplicationTransactions (action, cc, reviewers, update, comment, inlines), and makes `DifferentialComment` a double-reader for ApplicationTransactions.

The migration is pretty straightforward:

  - If a comment took an action not otherwise covered, it gets an "action" transaction. This is something like "epriestley abandoned this revision.".
  - If a comment updated the diff, it gets an "updated diff" transaction. Very old transactions of this type may not have a diff ID (probably only at Facebook).
  - If a comment added or removed reviewers, it gets a "changed reviewers" transaction.
  - If a comment added CCs, it gets a "subscribers" transaction.
  - If a comment added comment text, it gets a "comment" transaction.
  - For each inline attached to a comment, we generate an "inline" transaction.

Most comments generate a small number of transactions, but a few generate a significant number.

At HEAD, the code is basically already doing this, so comments in the last day or two already obey these rules, roughly, and will all generate only one transaction (except inlines).

Because we've already preallocated PHIDs in the comment text table, we only need to write to the transaction table.

NOTE: This significantly degrades Differential, making inline comments pretty much useless (they each get their own transaction, and don't show line numbers or files). The data is all fine, but the UI is garbage now. This needs to be fixed before we can deploy this to users, but it's easily separable since it's all just display code.

Specifically, they look like this:

{F112270}

Test Plan:
I've migrated locally and put things through their paces, but it's hard to catch sketchy stuff locally because most of my test data is nonsense and bad migrations wouldn't necessarily look out of place.
IMPORTANT: I'm planning to push this to a branch and then shift production over to the branch, and run it for a day or two before bringing it to master.

I generally feel good about this change: it's not that big since we were able to separate a lot of pieces out of it, and it's pretty straightforward. That said, it's still one of the most scary/dangerous changes we've ever made.

Reviewers: btrahan

CC: chad, aran

Maniphest Tasks: T2222

Differential Revision: https://secure.phabricator.com/D8210

resources/sql/autopatches/20140212.dx.1.armageddon.php

@@ -0,0 +1,222 @@
+<?php
+
+$conn_w = id(new DifferentialRevision())->establishConnection('w');
+$rows = new LiskRawMigrationIterator($conn_w, 'differential_comment');
+
+$content_source = PhabricatorContentSource::newForSource(
+  PhabricatorContentSource::SOURCE_LEGACY,
+  array())->serialize();
+
+echo "Migrating Differential comments to modern storage...\n";
+foreach ($rows as $row) {
+  $id = $row['id'];
+  echo "Migrating comment {$id}...\n";
+
+  $revision = id(new DifferentialRevision())->load($row['revisionID']);
+  if (!$revision) {
+    echo "No revision, continuing.\n";
+    continue;
+  }
+
+  $revision_phid = $revision->getPHID();
+
+  $comments = queryfx_all(
+    $conn_w,
+    'SELECT * FROM %T WHERE legacyCommentID = %d',
+    'differential_transaction_comment',
+    $id);
+
+  $main_comments = array();
+  $inline_comments = array();
+
+  foreach ($comments as $comment) {
+    if ($comment['changesetID']) {
+      $inline_comments[] = $comment;
+    } else {
+      $main_comments[] = $comment;
+    }
+  }
+
+  $metadata = json_decode($row['metadata'], true);
+  if (!is_array($metadata)) {
+    $metadata = array();
+  }
+
+  $key_cc = DifferentialComment::METADATA_ADDED_CCS;
+  $key_add_rev = DifferentialComment::METADATA_ADDED_REVIEWERS;
+  $key_rem_rev = DifferentialComment::METADATA_REMOVED_REVIEWERS;
+  $key_diff_id = DifferentialComment::METADATA_DIFF_ID;
+
+  $xactions = array();
+
+  // Build the main action transaction.
+  switch ($row['action']) {
+    case DifferentialAction::ACTION_COMMENT:
+    case DifferentialAction::ACTION_ADDREVIEWERS:
+    case DifferentialAction::ACTION_ADDCCS:
+    case DifferentialAction::ACTION_UPDATE:
+    case DifferentialTransaction::TYPE_INLINE:
+      // These actions will have their transactions created by other rules.
+      break;
+    default:
+      // Otherwise, this is a normal action (like an accept or reject).
+      $xactions[] = array(
+        'type' => DifferentialTransaction::TYPE_ACTION,
+        'old' => null,
+        'new' => $row['action'],
+      );
+      break;
+  }
+
+  // Build the diff update transaction, if one exists.
+  $diff_id = idx($metadata, $key_diff_id);
+  if (!is_scalar($diff_id)) {
+    $diff_id = null;
+  }
+
+  if ($diff_id || $row['action'] == DifferentialAction::ACTION_UPDATE) {
+    $xactions[] = array(
+      'type' => DifferentialTransaction::TYPE_UPDATE,
+      'old' => null,
+      'new' => $diff_id,
+    );
+  }
+
+  // Build the add/remove reviewers transaction, if one exists.
+  $add_rev = idx($metadata, $key_add_rev, array());
+  if (!is_array($add_rev)) {
+    $add_rev = array();
+  }
+  $rem_rev = idx($metadata, $key_rem_rev, array());
+  if (!is_array($rem_rev)) {
+    $rem_rev = array();
+  }
+
+  if ($add_rev || $rem_rev) {
+    $old = array();
+    foreach ($rem_rev as $phid) {
+      if (!is_scalar($phid)) {
+        continue;
+      }
+      $old[$phid] = array(
+        'src' => $revision_phid,
+        'type' => PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER,
+        'dst' => $phid,
+      );
+    }
+
+    $new = array();
+    foreach ($add_rev as $phid) {
+      if (!is_scalar($phid)) {
+        continue;
+      }
+      $new[$phid] = array(
+        'src' => $revision_phid,
+        'type' => PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER,
+        'dst' => $phid,
+      );
+    }
+
+    $xactions[] = array(
+      'type' => PhabricatorTransactions::TYPE_EDGE,
+      'old' => $old,
+      'new' => $new,
+      'meta' => array(
+        'edge:type' => PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER,
+      ),
+    );
+  }
+
+  // Build the CC transaction, if one exists.
+  $add_cc = idx($metadata, $key_cc, array());
+  if (!is_array($add_cc)) {
+    $add_cc = array();
+  }
+
+  if ($add_cc) {
+    $xactions[] = array(
+      'type' => PhabricatorTransactions::TYPE_SUBSCRIBERS,
+      'old' => array(),
+      'new' => array_fuse($add_cc),
+    );
+  }
+
+
+  // Build the main comment transaction.
+  foreach ($main_comments as $main) {
+    $xactions[] = array(
+      'type' => PhabricatorTransactions::TYPE_COMMENT,
+      'old' => null,
+      'new' => null,
+      'phid' => $main['transactionPHID'],
+      'comment' => $main,
+    );
+  }
+
+  // Build inline comment transactions.
+  foreach ($inline_comments as $inline) {
+    $xactions[] = array(
+      'type' => DifferentialTransaction::TYPE_INLINE,
+      'old' => null,
+      'new' => null,
+      'phid' => $inline['transactionPHID'],
+      'comment' => $inline,
+    );
+  }
+
+  foreach ($xactions as $xaction) {
+    // Generate a new PHID, if we don't already have one from the comment
+    // table. We pregenerated into the comment table to make this a little
+    // easier, so we only need to write to one table.
+    $xaction_phid = idx($xaction, 'phid');
+    if (!$xaction_phid) {
+      $xaction_phid = PhabricatorPHID::generateNewPHID(
+        PhabricatorApplicationTransactionPHIDTypeTransaction::TYPECONST,
+        DifferentialPHIDTypeRevision::TYPECONST);
+    }
+    unset($xaction['phid']);
+
+    $comment_phid = null;
+    $comment_version = 0;
+    if (idx($xaction, 'comment')) {
+      $comment_phid = $xaction['comment']['phid'];
+      $comment_version = 1;
+    }
+
+    $old = idx($xaction, 'old');
+    $new = idx($xaction, 'new');
+    $meta = idx($xaction, 'meta', array());
+
+    queryfx(
+      $conn_w,
+      'INSERT INTO %T (phid, authorPHID, objectPHID, viewPolicy, editPolicy,
+          commentPHID, commentVersion, transactionType, oldValue, newValue,
+          contentSource, metadata, dateCreated, dateModified)
+        VALUES (%s, %s, %s, %s, %s, %ns, %d, %s, %ns, %ns, %s, %s, %d, %d)',
+      'differential_transaction',
+
+      // PHID, authorPHID, objectPHID
+      $xaction_phid,
+      (string)$row['authorPHID'],
+      $revision_phid,
+
+      // viewPolicy, editPolicy, commentPHID, commentVersion
+      'public',
+      (string)$row['authorPHID'],
+      $comment_phid,
+      $comment_version,
+
+      // transactionType, oldValue, newValue, contentSource, metadata
+      $xaction['type'],
+      json_encode($old),
+      json_encode($new),
+      $content_source,
+      json_encode($meta),
+
+      // dates
+      $row['dateCreated'],
+      $row['dateModified']);
+  }
+
+}
+echo "Done.\n";

src/__phutil_library_map__.php

@@ -464,6 +464,7 @@ phutil_register_library_map(array(
     'DifferentialTitleFieldSpecification' => 'applications/differential/field/specification/DifferentialTitleFieldSpecification.php',
     'DifferentialTransaction' => 'applications/differential/storage/DifferentialTransaction.php',
     'DifferentialTransactionComment' => 'applications/differential/storage/DifferentialTransactionComment.php',
+    'DifferentialTransactionQuery' => 'applications/differential/query/DifferentialTransactionQuery.php',
     'DifferentialUnitFieldSpecification' => 'applications/differential/field/specification/DifferentialUnitFieldSpecification.php',
     'DifferentialUnitStatus' => 'applications/differential/constants/DifferentialUnitStatus.php',
     'DifferentialUnitTestResult' => 'applications/differential/constants/DifferentialUnitTestResult.php',
@@ -2856,11 +2857,7 @@ phutil_register_library_map(array(
     'DifferentialChangesetTwoUpRenderer' => 'DifferentialChangesetHTMLRenderer',
     'DifferentialChangesetTwoUpTestRenderer' => 'DifferentialChangesetTestRenderer',
     'DifferentialChangesetViewController' => 'DifferentialController',
-    'DifferentialComment' =>
+    'DifferentialComment' => 'PhabricatorMarkupInterface',
-    array(
-      0 => 'DifferentialDAO',
-      1 => 'PhabricatorMarkupInterface',
-    ),
     'DifferentialCommentEditor' => 'PhabricatorEditor',
     'DifferentialCommentMail' => 'DifferentialMail',
     'DifferentialCommentPreviewController' => 'DifferentialController',
@@ -2981,6 +2978,7 @@ phutil_register_library_map(array(
     'DifferentialTitleFieldSpecification' => 'DifferentialFreeformFieldSpecification',
     'DifferentialTransaction' => 'PhabricatorApplicationTransaction',
     'DifferentialTransactionComment' => 'PhabricatorApplicationTransactionComment',
+    'DifferentialTransactionQuery' => 'PhabricatorApplicationTransactionQuery',
     'DifferentialUnitFieldSpecification' => 'DifferentialFieldSpecification',
     'DifferentialViewPolicyFieldSpecification' => 'DifferentialFieldSpecification',
     'DiffusionBranchTableController' => 'DiffusionController',

src/applications/differential/conduit/ConduitAPI_differential_getrevisioncomments_Method.php

@@ -1,11 +1,16 @@
 <?php
 
-/**
- * @group conduit
- */
 final class ConduitAPI_differential_getrevisioncomments_Method
   extends ConduitAPI_differential_Method {
 
+  public function getMethodStatus() {
+    return self::METHOD_STATUS_DEPRECATED;
+  }
+
+  public function getMethodStatusDescription() {
+    return pht('Obsolete and doomed, see T2222.');
+  }
+
   public function getMethodDescription() {
     return "Retrieve Differential Revision Comments.";
   }
@@ -13,7 +18,7 @@ final class ConduitAPI_differential_getrevisioncomments_Method
   public function defineParamTypes() {
     return array(
       'ids' => 'required list<int>',
-      'inlines' => 'optional bool',
+      'inlines' => 'optional bool (deprecated)',
     );
   }
 
@@ -34,47 +39,36 @@ final class ConduitAPI_differential_getrevisioncomments_Method
       return $results;
     }
 
-    $comments = id(new DifferentialCommentQuery())
+    $revisions = id(new DifferentialRevisionQuery())
-      ->withRevisionIDs($revision_ids)
+      ->setViewer($request->getUser())
+      ->withIDs($revision_ids)
       ->execute();
 
-    $with_inlines = $request->getValue('inlines');
+    if (!$revisions) {
-    if ($with_inlines) {
+      return $results;
-      $inlines = id(new DifferentialInlineCommentQuery())
-        ->withRevisionIDs($revision_ids)
-        ->execute();
-      $changesets = array();
-      if ($inlines) {
-        $changesets = id(new DifferentialChangeset())->loadAllWhere(
-          'id IN (%Ld)',
-          array_unique(mpull($inlines, 'getChangesetID')));
-        $inlines = mgroup($inlines, 'getCommentID');
-      }
     }
 
+    $comments = id(new DifferentialCommentQuery())
+      ->withRevisionPHIDs(mpull($revisions, 'getPHID'))
+      ->execute();
+
+    $revisions = mpull($revisions, null, 'getPHID');
+
     foreach ($comments as $comment) {
-      // TODO: Sort this out in the ID -> PHID change.
+      $revision = idx($revisions, $comment->getRevisionPHID());
-      $revision_id = $comment->getRevisionID();
+      if (!$revision) {
+        continue;
+      }
+
       $result = array(
-        'revisionID'  => $revision_id,
+        'revisionID'  => $revision->getID(),
         'action'      => $comment->getAction(),
         'authorPHID'  => $comment->getAuthorPHID(),
         'dateCreated' => $comment->getDateCreated(),
         'content'     => $comment->getContent(),
       );
 
-      if ($with_inlines) {
+      $results[$revision->getID()][] = $result;
-        $result['inlines'] = array();
-        foreach (idx($inlines, $comment->getID(), array()) as $inline) {
-          $changeset = idx($changesets, $inline->getChangesetID());
-          $result['inlines'][] = $this->buildInlineInfoDictionary(
-            $inline,
-            $changeset);
-        }
-        // TODO: Put synthetic inlines without an attached comment somewhere.
-      }
-
-      $results[$revision_id][] = $result;
     }
 
     return $results;

src/applications/differential/constants/DifferentialAction.php

@@ -90,6 +90,11 @@ final class DifferentialAction {
           $title = pht('%s reopened this revision.',
             $author_name);
         break;
+        case DifferentialTransaction::TYPE_INLINE:
+          $title = pht(
+            '%s added an inline comment.',
+            $author_name);
+          break;
         default:
           $title = pht('Ghosts happened to this revision.');
         break;

src/applications/differential/editor/DifferentialCommentEditor.php

@@ -624,7 +624,7 @@ final class DifferentialCommentEditor extends PhabricatorEditor {
 
     // If this edit has comments or inline comments, save a transaction for
     // the comment content.
-    if (strlen($this->message) || $inline_comments) {
+    if (strlen($this->message)) {
       $comments[] = id(clone $template)
         ->setAction(DifferentialAction::ACTION_COMMENT)
         ->setContent((string)$this->message);
@@ -634,8 +634,6 @@ final class DifferentialCommentEditor extends PhabricatorEditor {
       $comment->save();
     }
 
-    $last_comment = last($comments);
-
     $changesets = array();
     if ($inline_comments) {
       $load_ids = mpull($inline_comments, 'getChangesetID');
@@ -646,12 +644,13 @@ final class DifferentialCommentEditor extends PhabricatorEditor {
           $load_ids);
       }
       foreach ($inline_comments as $inline) {
-        // For now, attach inlines to the last comment. We'll eventually give
+        $inline_xaction_comment = $inline->getTransactionCommentForSave();
-        // them their own transactions, but this would be fairly gross during
+        $inline_xaction_comment->setRevisionPHID($revision->getPHID());
-        // the storage transition and we'll have to do special thing with these
+
-        // during migration anyway.
+        $comments[] = id(clone $template)
-        $inline->setCommentID($last_comment->getID());
+          ->setAction(DifferentialTransaction::TYPE_INLINE)
-        $inline->save();
+          ->setProxyComment($inline_xaction_comment)
+          ->save();
       }
     }
 
@@ -702,7 +701,7 @@ final class DifferentialCommentEditor extends PhabricatorEditor {
 
       // NOTE: Don't use this, it will be removed after ApplicationTransactions.
       // For now, it powers inline comment rendering over the Asana brdige.
-      'temporaryCommentID'   => $last_comment->getID(),
+      'temporaryTransactionPHIDs' => mpull($comments, 'getPHID'),
     );
 
     id(new PhabricatorFeedStoryPublisher())

src/applications/differential/query/DifferentialCommentQuery.php

@@ -6,67 +6,29 @@
 final class DifferentialCommentQuery
   extends PhabricatorOffsetPagedQuery {
 
-  private $revisionIDs;
+  private $revisionPHIDs;
 
-  public function withRevisionIDs(array $ids) {
+  public function withRevisionPHIDs(array $phids) {
-    $this->revisionIDs = $ids;
+    $this->revisionPHIDs = $phids;
     return $this;
   }
 
   public function execute() {
-    $table = new DifferentialComment();
+    // TODO: We're getting rid of this, it is the bads.
-    $conn_r = $table->establishConnection('r');
+    $viewer = PhabricatorUser::getOmnipotentUser();
 
-    $data = queryfx_all(
+    $xactions = id(new DifferentialTransactionQuery())
-      $conn_r,
+      ->setViewer($viewer)
-      'SELECT * FROM %T %Q %Q',
+      ->withObjectPHIDs($this->revisionPHIDs)
-      $table->getTableName(),
+      ->needComments(true)
-      $this->buildWhereClause($conn_r),
+      ->execute();
-      $this->buildLimitClause($conn_r));
 
-    $comments = $table->loadAllFromArray($data);
+    $results = array();
-
+    foreach ($xactions as $xaction) {
-    // We've moved the actual text storage into DifferentialTransactionComment,
+      $results[] = DifferentialComment::newFromModernTransaction($xaction);
-    // so load the relevant pieces of text we need.
-    if ($comments) {
-      $this->loadCommentText($comments);
     }
 
-    return $comments;
+    return $results;
   }
 
-  private function buildWhereClause(AphrontDatabaseConnection $conn_r) {
-    $where = array();
-
-    if ($this->revisionIDs) {
-      $where[] = qsprintf(
-        $conn_r,
-        'revisionID IN (%Ld)',
-        $this->revisionIDs);
-    }
-
-    return $this->formatWhereClause($where);
-  }
-
-  private function loadCommentText(array $comments) {
-    $table = new DifferentialTransactionComment();
-    $conn_r = $table->establishConnection('r');
-
-    $data = queryfx_all(
-      $conn_r,
-      'SELECT * FROM %T WHERE legacyCommentID IN (%Ld) AND changesetID IS NULL',
-      $table->getTableName(),
-      mpull($comments, 'getID'));
-    $texts = $table->loadAllFromArray($data);
-    $texts = mpull($texts, null, 'getLegacyCommentID');
-
-    foreach ($comments as $comment) {
-      $text = idx($texts, $comment->getID());
-      if ($text) {
-        $comment->setProxyComment($text);
-      }
-    }
-  }
-
-
 }

src/applications/differential/query/DifferentialTransactionQuery.php

@@ -0,0 +1,10 @@
+<?php
+
+final class DifferentialTransactionQuery
+  extends PhabricatorApplicationTransactionQuery {
+
+  public function getTemplateApplicationTransaction() {
+    return new DifferentialTransaction();
+  }
+
+}

src/applications/differential/search/DifferentialSearchIndexer.php

@@ -53,7 +53,7 @@ final class DifferentialSearchIndexer
       time());
 
     $comments = id(new DifferentialCommentQuery())
-      ->withRevisionIDs(array($rev->getID()))
+      ->withRevisionPHIDs(array($rev->getPHID()))
       ->execute();
 
     $inlines = id(new DifferentialInlineCommentQuery())

src/applications/differential/storage/DifferentialComment.php

@@ -1,6 +1,9 @@
 <?php
 
-final class DifferentialComment extends DifferentialDAO
+/**
+ * Temporary proxy shell around ApplicationTransactions.
+ */
+final class DifferentialComment
   implements PhabricatorMarkupInterface {
 
   const METADATA_ADDED_REVIEWERS   = 'added-reviewers';
@@ -10,36 +13,244 @@ final class DifferentialComment extends DifferentialDAO
 
   const MARKUP_FIELD_BODY          = 'markup:body';
 
-  protected $authorPHID;
-  protected $revisionID;
-  protected $action;
-  protected $content = '';
-  protected $cache;
-  protected $metadata = array();
-  protected $contentSource;
-
   private $arbitraryDiffForFacebook;
   private $proxyComment;
+  private $proxy;
+
+  public function __construct() {
+    $this->proxy = new DifferentialTransaction();
+  }
 
   public function __clone() {
+    $this->proxy = clone $this->proxy;
     if ($this->proxyComment) {
       $this->proxyComment = clone $this->proxyComment;
     }
   }
 
+  public static function newFromModernTransaction(
+    DifferentialTransaction $xaction) {
+
+    $obj = new DifferentialComment();
+    $obj->proxy = $xaction;
+
+    if ($xaction->hasComment()) {
+      $obj->proxyComment = $xaction->getComment();
+    }
+
+    return $obj;
+  }
+
+  public function getPHID() {
+    return $this->proxy->getPHID();
+  }
+
   public function getContent() {
     return $this->getProxyComment()->getContent();
   }
 
   public function setContent($content) {
-    // NOTE: We no longer read this field, but there's no cost to continuing
-    // to write it in case something goes horribly wrong, since it makes it
-    // far easier to back out of this.
-    $this->content = $content;
     $this->getProxyComment()->setContent($content);
     return $this;
   }
 
+  public function getAuthorPHID() {
+    return $this->proxy->getAuthorPHID();
+  }
+
+  public function setAuthorPHID($author_phid) {
+    $this->proxy->setAuthorPHID($author_phid);
+    return $this;
+  }
+
+  public function setContentSource($content_source) {
+    $this->proxy->setContentSource($content_source);
+    $this->proxyComment->setContentSource($content_source);
+    return $this;
+  }
+
+  public function setAction($action) {
+    $meta = array();
+    switch ($action) {
+      case DifferentialAction::ACTION_COMMENT:
+        $type = PhabricatorTransactions::TYPE_COMMENT;
+        $old = null;
+        $new = null;
+        break;
+      case DifferentialAction::ACTION_ADDREVIEWERS:
+        $type = PhabricatorTransactions::TYPE_EDGE;
+        $old = array();
+        $new = array();
+        $meta = array(
+          'edge:type' => PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER,
+        );
+        break;
+      case DifferentialAction::ACTION_ADDCCS:
+        $type = PhabricatorTransactions::TYPE_SUBSCRIBERS;
+        $old = array();
+        $new = array();
+        break;
+      case DifferentialAction::ACTION_UPDATE:
+        $type = DifferentialTransaction::TYPE_UPDATE;
+        $old = null;
+        $new = null;
+        break;
+      case DifferentialTransaction::TYPE_INLINE:
+        $type = $action;
+        $old = null;
+        $new = null;
+        break;
+      default:
+        $type = DifferentialTransaction::TYPE_ACTION;
+        $old = null;
+        $new = $action;
+        break;
+    }
+
+    $xaction = $this->proxy;
+
+    $xaction
+      ->setTransactionType($type)
+      ->setOldValue($old)
+      ->setNewValue($new);
+
+    if ($meta) {
+      foreach ($meta as $key => $value) {
+        $xaction->setMetadataValue($key, $value);
+      }
+    }
+
+    return $this;
+  }
+
+  public function getAction() {
+    switch ($this->proxy->getTransactionType()) {
+      case PhabricatorTransactions::TYPE_SUBSCRIBERS:
+        return DifferentialAction::ACTION_ADDCCS;
+      case DifferentialTransaction::TYPE_UPDATE:
+        return DifferentialAction::ACTION_UPDATE;
+      case PhabricatorTransactions::TYPE_EDGE:
+        return DifferentialAction::ACTION_ADDREVIEWERS;
+      case PhabricatorTransactions::TYPE_COMMENT:
+        return DifferentialAction::ACTION_COMMENT;
+      case DifferentialTransaction::TYPE_INLINE:
+        return DifferentialTransaction::TYPE_INLINE;
+      default:
+        return $this->proxy->getNewValue();
+    }
+  }
+
+  public function setMetadata(array $metadata) {
+    if (!$this->proxy->getTransactionType()) {
+      throw new Exception(pht('Call setAction() before setMetadata()!'));
+    }
+
+    $key_cc = self::METADATA_ADDED_CCS;
+    $key_add_rev = self::METADATA_ADDED_REVIEWERS;
+    $key_rem_rev = self::METADATA_REMOVED_REVIEWERS;
+    $key_diff_id = self::METADATA_DIFF_ID;
+
+    switch ($this->proxy->getTransactionType()) {
+      case DifferentialTransaction::TYPE_UPDATE:
+        $id = idx($metadata, $key_diff_id);
+        $this->proxy->setNewValue($id);
+        break;
+      case PhabricatorTransactions::TYPE_EDGE:
+        $rem = idx($metadata, $key_rem_rev, array());
+        $old = array();
+        foreach ($rem as $phid) {
+          $old[$phid] = array(
+            'src' => $this->proxy->getObjectPHID(),
+            'type' => PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER,
+            'dst' => $phid,
+          );
+        }
+        $this->proxy->setOldValue($old);
+
+        $add = idx($metadata, $key_add_rev, array());
+        $new = array();
+        foreach ($add as $phid) {
+          $new[$phid] = array(
+            'src' => $this->proxy->getObjectPHID(),
+            'type' => PhabricatorEdgeConfig::TYPE_DREV_HAS_REVIEWER,
+            'dst' => $phid,
+          );
+        }
+        $this->proxy->setNewValue($new);
+        break;
+      case PhabricatorTransactions::TYPE_SUBSCRIBERS:
+        $phids = idx($metadata, $key_cc, array());
+        $new = array();
+        foreach ($phids as $phid) {
+          $new[$phid] = $phid;
+        }
+        $this->proxy->setNewValue($new);
+        break;
+      default:
+        break;
+    }
+
+    return $this;
+  }
+
+  public function getMetadata() {
+    if (!$this->proxy->getTransactionType()) {
+      throw new Exception(pht('Call setAction() before getMetadata()!'));
+    }
+
+    $key_cc = self::METADATA_ADDED_CCS;
+    $key_add_rev = self::METADATA_ADDED_REVIEWERS;
+    $key_rem_rev = self::METADATA_REMOVED_REVIEWERS;
+    $key_diff_id = self::METADATA_DIFF_ID;
+
+    $type = $this->proxy->getTransactionType();
+
+    switch ($type) {
+      case PhabricatorTransactions::TYPE_SUBSCRIBERS:
+        $value = $this->proxy->getNewValue();
+        if (!$value) {
+          $value = array();
+        }
+        return array(
+          $key_cc => $value,
+        );
+      case DifferentialTransaction::TYPE_UPDATE:
+        return array(
+          $key_diff_id => $this->proxy->getNewValue(),
+        );
+      case PhabricatorTransactions::TYPE_EDGE:
+      case PhabricatorTransactions::TYPE_SUBSCRIBERS:
+        $old = $this->proxy->getOldValue();
+        if (!$old) {
+          $old = array();
+        }
+        $new = $this->proxy->getNewValue();
+        if (!$new) {
+          $new = array();
+        }
+
+        $rem = array_diff_key($old, $new);
+        $add = array_diff_key($new, $old);
+
+        if ($type == PhabricatorTransactions::TYPE_EDGE) {
+          return array(
+            $key_add_rev => array_keys($add),
+            $key_rem_rev => array_keys($rem),
+          );
+        } else {
+          return array(
+            $key_cc => array_keys($add),
+          );
+        }
+      default:
+        return array();
+    }
+  }
+
+  public function getContentSource() {
+    return $this->proxy->getContentSource();
+  }
+
   private function getProxyComment() {
     if (!$this->proxyComment) {
       $this->proxyComment = new DifferentialTransactionComment();
@@ -48,16 +259,14 @@ final class DifferentialComment extends DifferentialDAO
   }
 
   public function setProxyComment(DifferentialTransactionComment $proxy) {
-    if ($this->proxyComment) {
-      throw new Exception(pht('You can not overwrite a proxy comment.'));
-    }
     $this->proxyComment = $proxy;
     return $this;
   }
 
   public function setRevision(DifferentialRevision $revision) {
     $this->getProxyComment()->setRevisionPHID($revision->getPHID());
-    return $this->setRevisionID($revision->getID());
+    $this->proxy->setObjectPHID($revision->getPHID());
+    return $this;
   }
 
   public function giveFacebookSomeArbitraryDiff(DifferentialDiff $diff) {
@@ -66,48 +275,19 @@ final class DifferentialComment extends DifferentialDAO
   }
 
   public function getRequiredHandlePHIDs() {
-    $phids = array();
+    switch ($this->proxy->getTransactionType()) {
-
+      case PhabricatorTransactions::TYPE_SUBSCRIBERS:
-    $metadata = $this->getMetadata();
+      case PhabricatorTransactions::TYPE_EDGE:
-    $added_reviewers = idx(
+        return array_merge(
-      $metadata,
+          array_keys($this->proxy->getOldValue()),
-      self::METADATA_ADDED_REVIEWERS);
+          array_keys($this->proxy->getNewValue()));
-    if ($added_reviewers) {
-      foreach ($added_reviewers as $phid) {
-        $phids[] = $phid;
-      }
-    }
-    $added_ccs = idx(
-      $metadata,
-      self::METADATA_ADDED_CCS);
-    if ($added_ccs) {
-      foreach ($added_ccs as $phid) {
-        $phids[] = $phid;
-      }
     }
 
-    return $phids;
+    return array();
-  }
-
-  public function getConfiguration() {
-    return array(
-      self::CONFIG_SERIALIZATION => array(
-        'metadata' => self::SERIALIZATION_JSON,
-      ),
-    ) + parent::getConfiguration();
-  }
-
-  public function setContentSource(PhabricatorContentSource $content_source) {
-    $this->contentSource = $content_source->serialize();
-    return $this;
-  }
-
-  public function getContentSource() {
-    return PhabricatorContentSource::newFromSerialized($this->contentSource);
   }
 
   public function getMarkupFieldKey($field) {
-    return 'DC:'.$this->getID();
+    return 'DC:'.$this->getPHID();
   }
 
   public function newMarkupEngine($field) {
@@ -126,37 +306,49 @@ final class DifferentialComment extends DifferentialDAO
   }
 
   public function shouldUseMarkupCache($field) {
-    return (bool)$this->getID();
+    return (bool)$this->getPHID();
+  }
+
+  public function getDateCreated() {
+    return $this->proxy->getDateCreated();
+  }
+
+  public function getRevisionPHID() {
+    return $this->proxy->getObjectPHID();
   }
 
   public function save() {
-    $this->openTransaction();
+    $this->proxy->openTransaction();
-      $result = parent::save();
+      $this->proxy
+        ->setViewPolicy('public')
+        ->setEditPolicy($this->getAuthorPHID())
+        ->save();
 
-      if ($this->getContent() !== null) {
+      if ($this->getContent() !== null ||
-        $content_source = PhabricatorContentSource::newForSource(
+          $this->getProxyComment()->getChangesetID()) {
-          PhabricatorContentSource::SOURCE_LEGACY,
-          array());
 
-        $xaction_phid = PhabricatorPHID::generateNewPHID(
+        $this->getProxyComment()
-          PhabricatorApplicationTransactionPHIDTypeTransaction::TYPECONST,
-          DifferentialPHIDTypeRevision::TYPECONST);
-
-        $proxy = $this->getProxyComment();
-        $proxy
           ->setAuthorPHID($this->getAuthorPHID())
           ->setViewPolicy('public')
           ->setEditPolicy($this->getAuthorPHID())
-          ->setContentSource($content_source)
           ->setCommentVersion(1)
-          ->setLegacyCommentID($this->getID())
+          ->setTransactionPHID($this->proxy->getPHID())
-          ->setTransactionPHID($xaction_phid)
+          ->save();
+
+        $this->proxy
+          ->setCommentVersion(1)
+          ->setCommentPHID($this->getProxyComment()->getPHID())
           ->save();
       }
 
-    $this->saveTransaction();
+    $this->proxy->saveTransaction();
 
-    return $result;
+    return $this;
+  }
+
+  public function delete() {
+    $this->proxy->delete();
+    return $this;
   }
 
 }

src/applications/differential/storage/DifferentialInlineComment.php

@@ -14,7 +14,7 @@ final class DifferentialInlineComment
     $this->proxy = clone $this->proxy;
   }
 
-  public function save() {
+  public function getTransactionCommentForSave() {
     $content_source = PhabricatorContentSource::newForSource(
       PhabricatorContentSource::SOURCE_LEGACY,
       array());
@@ -23,8 +23,14 @@ final class DifferentialInlineComment
       ->setViewPolicy('public')
       ->setEditPolicy($this->getAuthorPHID())
       ->setContentSource($content_source)
-      ->setCommentVersion(1)
+      ->setCommentVersion(1);
-      ->save();
+
+    return $this->proxy;
+  }
+
+
+  public function save() {
+    $this->getTransactionCommentForSave()->save();
 
     return $this;
   }
@@ -74,7 +80,7 @@ final class DifferentialInlineComment
   }
 
   public function isDraft() {
-    return !$this->getCommentID();
+    return !$this->proxy->getTransactionPHID();
   }
 
   public function setChangesetID($id) {

src/applications/differential/storage/DifferentialRevision.php

@@ -158,7 +158,7 @@ final class DifferentialRevision extends DifferentialDAO
       return array();
     }
     return id(new DifferentialCommentQuery())
-      ->withRevisionIDs(array($this->getID()))
+      ->withRevisionPHIDs(array($this->getPHID()))
       ->execute();
   }
 
@@ -194,7 +194,7 @@ final class DifferentialRevision extends DifferentialDAO
         $this->getID());
 
       $comments = id(new DifferentialCommentQuery())
-        ->withRevisionIDs(array($this->getID()))
+        ->withRevisionPHIDs(array($this->getPHID()))
         ->execute();
       foreach ($comments as $comment) {
         $comment->delete();

src/applications/differential/storage/DifferentialTransaction.php

@@ -2,6 +2,10 @@
 
 final class DifferentialTransaction extends PhabricatorApplicationTransaction {
 
+  const TYPE_INLINE = 'differential:inline';
+  const TYPE_UPDATE = 'differential:update';
+  const TYPE_ACTION = 'differential:action';
+
   public function getApplicationName() {
     return 'differential';
   }

src/applications/differential/view/DifferentialRevisionCommentListView.php

@@ -93,7 +93,7 @@ final class DifferentialRevisionCommentListView extends AphrontView {
       $view->setUser($this->user);
       $view->setHandles($this->handles);
       $view->setMarkupEngine($engine);
-      $view->setInlineComments(idx($inlines, $comment->getID(), array()));
+//      $view->setInlineComments(idx($inlines, $comment->getID(), array()));
       $view->setChangesets($this->changesets);
       $view->setTargetDiff($this->target);
       $view->setRevision($this->getRevision());
@@ -132,7 +132,7 @@ final class DifferentialRevisionCommentListView extends AphrontView {
     $hidden = array();
     if ($last_comment !== null) {
       foreach ($objs as $position => $comment) {
-        if (!$comment->getID()) {
+        if (!$comment->getPHID()) {
           // These are synthetic comments with summary/test plan information.
           $header[] = $html[$position];
           unset($html[$position]);

src/applications/releeph/field/specification/ReleephDiffChurnFieldSpecification.php

@@ -24,7 +24,7 @@ final class ReleephDiffChurnFieldSpecification
 
     $diff_rev = $this->getReleephRequest()->loadDifferentialRevision();
     $comments = id(new DifferentialCommentQuery())
-      ->withRevisionIDs(array($diff_rev->getID()))
+      ->withRevisionPHIDs(array($diff_rev->getPHID()))
       ->execute();
 
     $counts = array();