Build basic infrastructure for an activity feed

Summary: This defines an extremely basic version of an activity feed, like
Facebook's news feed. It doesn't do much of interest yet.
Test Plan: Published some feed stories:
https://secure.phabricator.com/file/view/PHID-FILE-5061aa72105bbdc05b21/
Reviewed By: tuomaspelkonen
Reviewers: jungejason, tuomaspelkonen, aran
Commenters: codeblock, jungejason
CC: aran, epriestley, codeblock, tuomaspelkonen, jungejason
Differential Revision: 593

src/applications/feed/query/PhabricatorFeedQuery.php

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+<?php
+
+/*
+ * Copyright 2011 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+final class PhabricatorFeedQuery {
+
+  private $filterPHIDs;
+  private $limit = 100;
+  private $after;
+
+  public function setFilterPHIDs(array $phids) {
+    $this->filterPHIDs = $phids;
+    return $this;
+  }
+
+  public function setLimit($limit) {
+    $this->limit = $limit;
+    return $this;
+  }
+
+  public function setAfter($after) {
+    $this->after = $after;
+    return $this;
+  }
+
+  public function execute() {
+
+    $ref_table = new PhabricatorFeedStoryReference();
+    $story_table = new PhabricatorFeedStoryData();
+
+    $conn = $story_table->establishConnection('r');
+
+    $where = array();
+    if ($this->filterPHIDs) {
+      $where[] = qsprintf(
+        $conn,
+        'ref.objectPHID IN (%Ls)',
+        $this->filterPHIDs);
+    }
+
+    if ($where) {
+      $where = 'WHERE ('.implode(') AND (', $where).')';
+    } else {
+      $where = '';
+    }
+
+    $data = queryfx_all(
+      $conn,
+      'SELECT story.* FROM %T ref
+        JOIN %T story ON ref.chronologicalKey = story.chronologicalKey
+        %Q
+        GROUP BY story.chronologicalKey
+        ORDER BY story.chronologicalKey DESC
+        LIMIT %d',
+      $ref_table->getTableName(),
+      $story_table->getTableName(),
+      $where,
+      $this->limit);
+    $data = $story_table->loadAllFromArray($data);
+
+    $stories = array();
+    foreach ($data as $story_data) {
+      $class = $story_data->getStoryType();
+
+      try {
+        if (!class_exists($class) ||
+            !is_subclass_of($class, 'PhabricatorFeedStory')) {
+          $class = 'PhabricatorFeedStoryUnknown';
+        }
+      } catch (PhutilMissingSymbolException $ex) {
+        // If the class can't be loaded, libphutil will throw an exception.
+        // Render the story using the unknown story view.
+        $class = 'PhabricatorFeedStoryUnknown';
+      }
+
+      $stories[] = newv($class, array($story_data));
+    }
+
+    return $stories;
+  }
+}

src/applications/feed/query/__init__.php

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+<?php
+/**
+ * This file is automatically generated. Lint this module to rebuild it.
+ * @generated
+ */
+
+
+
+phutil_require_module('phabricator', 'applications/feed/storage/story');
+phutil_require_module('phabricator', 'applications/feed/storage/storyreference');
+phutil_require_module('phabricator', 'storage/qsprintf');
+phutil_require_module('phabricator', 'storage/queryfx');
+
+phutil_require_module('phutil', 'utils');
+
+
+phutil_require_source('PhabricatorFeedQuery.php');