[ActivityPub] Use queues for notice distribution

ActivityPubPlugin:
- Change event-based notice distribution to queues logic

ActivityPub/lib:
- Add queue handler class activitypubqueuehandler.php

Misc:
- Add documentation for the (Start/End)InitializeQueueManager events

DOCUMENTATION/DEVELOPERS/EVENTS.txt

@@ -355,6 +355,12 @@ EndAvatarSaveForm: after saving the avatar
 StartNewQueueManager: before trying to start a new queue manager; good for plugins implementing new queue manager classes
 - $qm: empty queue manager to set
 
+StartInitializeQueueManager: about to register queue handlers in the queue manager; good for plugins to register own handlers
+- $qm: queue manager
+
+EndInitializeQueueManager: after registering queue handlers in the queue manager; good for plugins to register own handlers
+- $qm: queue manager
+
 RedirectToLogin: event when we force a redirect to login (like when going to a settings page on a remembered login)
 - $action: action object being shown
 - $user: current user

plugins/ActivityPub/ActivityPubPlugin.php

@@ -32,6 +32,7 @@ require_once __DIR__ . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'disc
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'explorer.php';
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'postman.php';
 require_once __DIR__ . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'inbox_handler.php';
+require_once __DIR__ . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'activitypubqueuehandler.php';
 
 // So that this isn't hardcoded everywhere
 define('ACTIVITYPUB_BASE_ACTOR_URI', common_root_url().'index.php/user/');
@@ -218,6 +219,42 @@ class ActivityPubPlugin extends Plugin
         return true;
     }
 
+    /**
+     * Set up queue handlers for required interactions
+     *
+     * @param QueueManager $qm
+     * @return bool event hook return
+     */
+    public function onEndInitializeQueueManager(QueueManager $qm): bool
+    {
+        // Notice distribution
+        $qm->connect('activitypub', 'ActivityPubQueueHandler');
+        return true;
+    }
+
+    /**
+     * Enqueue saved notices for distribution
+     *
+     * @param Notice $notice notice to be distributed
+     * @param Array &$transports list of transports to queue for
+     * @return bool event hook return
+     */
+    public function onStartEnqueueNotice(Notice $notice, Array &$transports): bool
+    {
+        try {
+            $id = $notice->getID();
+
+            if ($id > 0) {
+                $transports[] = 'activitypub';
+                $this->log(LOG_INFO, "Notice:{$id} queued for distribution");
+            }
+        } catch (Exception $e) {
+            $this->log(LOG_ERR, "Invalid notice, not queueing for distribution");
+        }
+
+        return true;
+    }
+
     /**
      * Plugin Nodeinfo information
      *
@@ -787,102 +824,6 @@ class ActivityPubPlugin extends Plugin
         return true;
     }
 
-    /**
-     * Insert notifications for replies, mentions and repeats
-     *
-     * @param $notice
-     * @return boolean hook flag
-     * @throws EmptyPkeyValueException
-     * @throws HTTP_Request2_Exception
-     * @throws InvalidUrlException
-     * @throws ServerException
-     * @author Diogo Cordeiro <diogo@fc.up.pt>
-     */
-    public function onStartNoticeDistribute($notice)
-    {
-        assert($notice->id > 0);        // Ignore if not a valid notice
-
-        $profile = $notice->getProfile();
-
-        if (!$profile->isLocal()) {
-            return true;
-        }
-
-        // Ignore for activity/non-(post/share)-verb notices
-        if (method_exists('ActivityUtils', 'compareVerbs')) {
-            $is_valid_verb = ActivityUtils::compareVerbs($notice->verb,
-                                                         [ActivityVerb::POST,
-                                                          ActivityVerb::SHARE]);
-        } else {
-            $is_valid_verb = ($notice->verb == ActivityVerb::POST ||
-                              $notice->verb == ActivityVerb::SHARE);
-        }
-
-        if ($notice->source == 'activity' || !$is_valid_verb) {
-            common_log(LOG_DEBUG, "Ignoring distribution of notice with id {$notice->id} due to invalid Verb");
-            return true;
-        }
-
-        $other = Activitypub_profile::from_profile_collection(
-            $notice->getAttentionProfiles()
-        );
-
-        // Is a reply?
-        if ($notice->reply_to) {
-            try {
-                $parent_notice = $notice->getParent();
-
-                try {
-                    $other[] = Activitypub_profile::from_profile($parent_notice->getProfile());
-                } catch (Exception $e) {
-                    // Local user can be ignored
-                }
-
-                foreach ($parent_notice->getAttentionProfiles() as $mention) {
-                    try {
-                        $other[] = Activitypub_profile::from_profile($mention);
-                    } catch (Exception $e) {
-                        // Local user can be ignored
-                    }
-                }
-            } catch (NoParentNoticeException $e) {
-                // This is not a reply to something (has no parent)
-            } catch (NoResultException $e) {
-                // Parent author's profile not found! Complain louder?
-                common_log(LOG_ERR, "Parent notice's author not found: ".$e->getMessage());
-            }
-        }
-
-        // Is an Announce?
-        if ($notice->isRepeat()) {
-            $repeated_notice = Notice::getKV('id', $notice->repeat_of);
-            if ($repeated_notice instanceof Notice) {
-                $other = array_merge($other,
-                                     Activitypub_profile::from_profile_collection(
-                                         $repeated_notice->getAttentionProfiles()
-                                     ));
-
-                try {
-                    $other[] = Activitypub_profile::from_profile($repeated_notice->getProfile());
-                } catch (Exception $e) {
-                    // Local user can be ignored
-                }
-
-                // That was it
-                $postman = new Activitypub_postman($profile, $other);
-                $postman->announce($repeated_notice);
-            }
-
-            // either made the announce or found nothing to repeat
-            return true;
-        }
-
-        // That was it
-        $postman = new Activitypub_postman($profile, $other);
-        $postman->create_note($notice);
-        return true;
-    }
-
     /**
      * Override the "from ActivityPub" bit in notice lists to link to the
      * original post and show the domain it came from.

plugins/ActivityPub/lib/activitypubqueuehandler.php

@@ -0,0 +1,135 @@
+<?php
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GNU social is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * ActivityPub queue handler for notice distribution
+ *
+ * @package   GNUsocial
+ * @author    Bruno Casteleiro <brunoccast@fc.up.pt>
+ * @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+
+defined('GNUSOCIAL') || die();
+
+/**
+ * @copyright 2019 Free Software Foundation, Inc http://www.fsf.org
+ * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
+ */
+class ActivityPubQueueHandler extends QueueHandler
+{
+    /**
+     * Getter of the queue transport name.
+     * 
+     * @return string transport name
+     */
+    public function transport(): string
+    {
+        return 'activitypub';
+    }
+
+    /**
+     * Notice distribution handler.
+     *
+     * @param Notice $notice notice to be distributed.
+     * @return bool true on success, false otherwise
+     * @throws HTTP_Request2_Exception
+     * @throws InvalidUrlException
+     * @throws ServerException
+     * @author Diogo Cordeiro <diogo@fc.up.pt>
+     */
+    public function handle($notice): bool
+    {
+        if (!($notice instanceof Notice)) {
+            common_log(LOG_ERR, "Got a bogus notice, not distributing");
+            return true;
+        }
+
+        $profile = $notice->getProfile();
+
+        if (!$profile->isLocal()) {
+            return true;
+        }
+
+        // Ignore activity/non-post/share-verb notices
+        $is_valid_verb = ($notice->verb == ActivityVerb::POST ||
+                          $notice->verb == ActivityVerb::SHARE);
+
+        if ($notice->source == 'activity' || !$is_valid_verb) {
+            common_log(LOG_ERR, "Ignoring distribution of notice:{$notice->id}: activity source or invalid Verb");
+            return true;
+        }
+        
+        $other = Activitypub_profile::from_profile_collection(
+            $notice->getAttentionProfiles()
+        );
+
+        // Handling a reply?
+        if ($notice->reply_to) {
+            try {
+                $parent_notice = $notice->getParent();
+
+                try {
+                    $other[] = Activitypub_profile::from_profile($parent_notice->getProfile());
+                } catch (Exception $e) {
+                    // Local user can be ignored
+                }
+
+                foreach ($parent_notice->getAttentionProfiles() as $mention) {
+                    try {
+                        $other[] = Activitypub_profile::from_profile($mention);
+                    } catch (Exception $e) {
+                        // Local user can be ignored
+                    }
+                }
+            } catch (NoParentNoticeException $e) {
+                // This is not a reply to something (has no parent)
+            } catch (NoResultException $e) {
+                // Parent author's profile not found! Complain louder?
+                common_log(LOG_ERR, "Parent notice's author not found: ".$e->getMessage());
+            }
+        }
+
+        // Handling an Announce?
+        if ($notice->isRepeat()) {
+            $repeated_notice = Notice::getKV('id', $notice->repeat_of);
+            if ($repeated_notice instanceof Notice) {
+                $other = array_merge($other,
+                                     Activitypub_profile::from_profile_collection(
+                                         $repeated_notice->getAttentionProfiles()
+                                     ));
+
+                try {
+                    $other[] = Activitypub_profile::from_profile($repeated_notice->getProfile());
+                } catch (Exception $e) {
+                    // Local user can be ignored
+                }
+
+                // That was it
+                $postman = new Activitypub_postman($profile, $other);
+                $postman->announce($repeated_notice);
+            }
+
+            // either made the announce or found nothing to repeat
+            return true;
+        }
+
+        // That was it
+        $postman = new Activitypub_postman($profile, $other);
+        $postman->create_note($notice);
+        return true;
+    }
+}