Add an example event listener, improve documentation, and add a commit discovery event

Summary: Improve documentation around Phabricator events.

Test Plan: Generated and read documentation. Ran test script.

Reviewers: btrahan, jungejason

Reviewed By: jungejason

CC: aran

Maniphest Tasks: T1092

Differential Revision: https://secure.phabricator.com/D2917

scripts/util/emit_test_event.php

@@ -0,0 +1,57 @@
+#!/usr/bin/env php
+<?php
+
+/*
+ * Copyright 2012 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.
+ */
+
+$root = dirname(dirname(dirname(__FILE__)));
+require_once $root.'/scripts/__init_script__.php';
+
+$args = new PhutilArgumentParser($argv);
+$args->setTagline('emit a test event');
+$args->setSynopsis(<<<EOHELP
+**emit_test_event.php** [--listen listener] ...
+  Emit a test event after installing any specified __listener__s.
+EOHELP
+);
+$args->parseStandardArguments();
+$args->parse(
+  array(
+    array(
+      'name'    => 'listen',
+      'param'   => 'listener',
+      'repeat'  => true,
+    ),
+  ));
+
+$console = PhutilConsole::getConsole();
+foreach ($args->getArg('listen') as $listener) {
+  $console->writeOut("Installing '%s'...\n", $listener);
+  newv($listener, array())->register();
+}
+
+
+$console->writeOut("Emitting event...\n");
+
+PhutilEventEngine::dispatchEvent(
+  new PhabricatorEvent(
+    PhabricatorEventType::TYPE_TEST_DIDRUNTEST,
+    array(
+      'time' => time(),
+    )));
+
+$console->writeOut("Done.\n");
+exit(0);

src/__phutil_library_map__.php

@@ -632,6 +632,7 @@ phutil_register_library_map(array(
     'PhabricatorEvent' => 'infrastructure/events/PhabricatorEvent.php',
     'PhabricatorEventEngine' => 'infrastructure/events/PhabricatorEventEngine.php',
     'PhabricatorEventType' => 'infrastructure/events/constant/PhabricatorEventType.php',
+    'PhabricatorExampleEventListener' => 'infrastructure/events/PhabricatorExampleEventListener.php',
     'PhabricatorFeedBuilder' => 'applications/feed/builder/PhabricatorFeedBuilder.php',
     'PhabricatorFeedConstants' => 'applications/feed/constants/PhabricatorFeedConstants.php',
     'PhabricatorFeedController' => 'applications/feed/controller/PhabricatorFeedController.php',
@@ -1647,9 +1648,12 @@ phutil_register_library_map(array(
     'PhabricatorErrorExample' => 'PhabricatorUIExample',
     'PhabricatorEvent' => 'PhutilEvent',
     'PhabricatorEventType' => 'PhutilEventType',
+    'PhabricatorExampleEventListener' => 'PhutilEventListener',
     'PhabricatorFeedController' => 'PhabricatorController',
     'PhabricatorFeedDAO' => 'PhabricatorLiskDAO',
     'PhabricatorFeedPublicStreamController' => 'PhabricatorFeedController',
+    'PhabricatorFeedQuery' => 'PhabricatorIDPagedPolicyQuery',
+    'PhabricatorFeedStory' => 'PhabricatorPolicyInterface',
     'PhabricatorFeedStoryAggregate' => 'PhabricatorFeedStory',
     'PhabricatorFeedStoryAudit' => 'PhabricatorFeedStory',
     'PhabricatorFeedStoryCommit' => 'PhabricatorFeedStory',

src/applications/repository/daemon/PhabricatorRepositoryPullLocalDaemon.php

@@ -374,6 +374,15 @@ final class PhabricatorRepositoryPullLocalDaemon
       }
 
       $this->setCache($repository, $commit_identifier);
+
+      PhutilEventEngine::dispatchEvent(
+        new PhabricatorEvent(
+          PhabricatorEventType::TYPE_DIFFUSION_DIDDISCOVERCOMMIT,
+          array(
+            'repository'  => $repository,
+            'commit'      => $commit,
+          )));
+
     } catch (AphrontQueryDuplicateKeyException $ex) {
       $commit->killTransaction();
       // Ignore. This can happen because we discover the same new commit

src/docs/userguide/events.diviner

@@ -9,12 +9,68 @@ Phabricator allows you to install custom runtime event listeners which can react
 to certain things happening (like a Maniphest Task being edited) and run custom
 code to perform logging, synchronize with other systems, or modify workflows.
 
-NOTE: This feature is new and experimental, so few events are available and
-things might not be completely stable.
+These listeners are PHP classes which you install beside Phabricator, and which
+Phabricator loads at runtime and runs in-process. They are the most direct and
+powerful way to respond to events.
+
+= Installing Event Listeners =
+
+To install event listeners, follow these steps:
+
+  - Write a listener class which extends @{class:PhutilEventListener}.
+  - Add it to a libphutil library, or create a new library (for instructions,
+    see @{article:libphutil Libraries User Guide}.
+  - Configure Phabricator to load the library by adding it to `load-libraries`
+    in the Phabricator config.
+  - Configure Phabricator to install the event listener by adding the class
+    name to `events.listeners` in the Phabricator config.
+
+You can verify your listener is registered in the "Events" tab of DarkConsole.
+It should appear at the top under "Registered Event Listeners". You can also
+see any events the page emitted there. For details on DarkConsole, see
+@{article:Using DarkConsole}.
+
+= Example Listener =
+
+Phabricator includes an example event listener,
+@{class:PhabricatorExampleEventListener}, which may be useful as a starting
+point in developing your own listeners. This listener listens for a test
+event that is emitted by the script `scripts/util/emit_test_event.php`.
+
+If you run this script normally, it should output something like this:
+
+  $ ./scripts/util/emit_test_event.php
+  Emitting event...
+  Done.
+
+This is because there are no listeners for the event, so nothing reacts to it
+when it is emitted. You can add the example listener by either adding it to
+your `events.listeners` configuration or with the `--listen` command-line flag:
+
+  $ ./scripts/util/emit_test_event.php --listen PhabricatorExampleEventListener
+  Installing 'PhabricatorExampleEventListener'...
+  Emitting event...
+  PhabricatorExampleEventListener got test event at 1341344566
+  Done.
+
+This time, the listener was installed and had its callback invoked when the
+test event was emitted.
 
 = Available Events =
 
-== PhabricatorEventType::TYPE_MANIPHEST_WILLEDITTASK ==
+You can find a list of all Phabricator events in @{class:PhabricatorEventType}.
+
+== All Events ==
+
+The special constant `PhutilEventType::TYPE_ALL` will let you listen for all
+events. Normally, you want to listen only to specific events, but if you're
+writing a generic handler you can listen to all events with this constant
+rather than by enumerating each event.
+
+== Maniphest: Will Edit Task ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_MANIPHEST_WILLEDITTASK`.
 
 This event is dispatched before a task is edited, and allows you to respond to
 or alter the edit. Data available on this event:
@@ -26,14 +82,41 @@ or alter the edit. Data available on this event:
   - ##mail## If this edit originates from email, the
     @{class:PhabricatorMetaMTAReceivedMail} object.
 
-== PhabricatorEventType::TYPE_DIFFERENTIAL_WILLSENDMAIL ==
+This is similar to the next event (did edit task) but occurs before the edit
+begins.
+
+== Maniphest: Did Edit Task ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_MANIPHEST_DIDEDITTASK`.
+
+This event is dispatched after a task is edited, and allows you to react to the
+edit. Data available on this event:
+
+  - ##task## The @{class:ManiphestTask} that was edited.
+  - ##transactions## The list of edits (objects of class
+    @{class:ManiphestTransaction}) that were applied.
+  - ##new## A boolean indicating if this task was newly created.
+  - ##mail## If this edit originates from email, the
+    @{class:PhabricatorMetaMTAReceivedMail} object.
+
+This is similar to the previous event (will edit task) but occurs after the
+edit completes.
+
+== Differential: Will Send Mail ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_DIFFERENTIAL_WILLSENDMAIL`
 
 This event is dispatched before Differential sends an email, and allows you to
 edit the message that will be sent.  Data available on this event:
 
   - ##mail## The @{class:PhabricatorMetaMTAMail} being edited.
 
-== PhabricatorEventType::TYPE_DIFFERENTIAL_WILLMARKGENERATED ==
+== Differential: Will Mark Generated ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_DIFFERENTIAL_WILLMARKGENERATED`.
 
 This event is dispatched before Differential decides if a file is generated (and
 doesn't need to be reviewed) or not.  Data available on this event:
@@ -41,3 +124,92 @@ doesn't need to be reviewed) or not.  Data available on this event:
   - ##corpus## Body of the file.
   - ##is_generated## Boolean indicating if this file should be treated as
     generated.
+
+== Diffusion: Did Discover Commit ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_DIFFUSION_DIDDISCOVERCOMMIT`.
+
+This event is dispatched when the daemons discover a commit for the first time.
+This event happens very early in the pipeline, and not all commit information
+will be available yet. Data available on this event:
+
+  - `commit` The @{class:PhabricatorRepositoryCommit} that was discovered.
+  - `repository` The @{class:PhabricatorRepository} the commit was discovered
+    in.
+
+== Edge: Will Edit Edges ==
+
+NOTE: Edge events are low-level events deep in the core. It is more difficult to
+correct implement listeners for these events than for higher-level events.
+
+The constant for this event is
+`PhabricatorEventType::TYPE_EDGE_WILLEDITEDGES`.
+
+This event is dispatched before @{class:PhabricatorEdgeEditor} makes an edge
+edit.
+
+  - `id` An identifier for this edit operation.
+  - `add` A list of dictionaries, each representing a new edge.
+  - `rem` A list of dictionaries, each representing a removed edge.
+
+This is similar to the next event (did edit edges) but occurs before the
+edit begins.
+
+== Edge: Did Edit Edges ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_EDGE_DIDEDITEDGES`.
+
+This event is dispatched after @{class:PhabricatorEdgeEditor} makes an edge
+edit, but before it commits the transactions. Data available on this event:
+
+  - `id` An identifier for this edit operation. This is the same ID as
+    the one included in the corresponding "will edit edges" event.
+  - `add` A list of dictionaries, each representing a new edge.
+  - `rem` A list of dictionaries, each representing a removed edge.
+
+This is similar to the previous event (will edit edges) but occurs after the
+edit completes.
+
+== Test: Did Run Test ==
+
+The constant for this event is
+`PhabricatorEventType::TYPE_TEST_DIDRUNTEST`.
+
+This is a test event for testing event listeners. See above for details.
+
+= Debugging Listeners =
+
+If you're having problems with your listener, try these steps:
+
+  - If you're getting an error about Phabricator being unable to find the
+    listener class, make sure you've added it to a libphutil library and
+    configured Phabricator to load the library with `load-libraries`.
+  - Make sure the listener is registered. It should appear in the "Events" tab
+    of DarkConsole. If it's not there, you may have forgotten to add it to
+    `events.listeners`.
+  - Make sure it calls `listen()` on the right events in its `register()`
+    method. If you don't listen for the events you're interested in, you
+    won't get a callback.
+  - Make sure the events you're listening for are actually happening. If they
+    occur on a normal page they should appear in the "Events" tab of
+    DarkConsole. If they occur on a POST, you could add a `phlog()`
+    to the source code near the event and check your error log to make sure the
+    code ran.
+  - You can check if your callback is getting invoked by adding `phlog()` with
+    a message and checking the error log.
+  - You can try listening to `PhutilEventType::TYPE_ALL` instead of a specific
+    event type to get all events, to narrow down whether problems are caused
+    by the types of events you're listening to.
+  - You can edit the `emit_test_event.php` script to emit other types of
+    events instead, to test that your listener reacts to them properly. You
+    might have to use fake data, but this gives you an easy way to test the
+    at least the basics.
+
+= Next Steps =
+
+Continue by:
+
+  - taking a look at @{class:PhabricatorExampleEventListener}; or
+  - building a library with @{article:@{article:libphutil Libraries User Guide}.

src/infrastructure/events/PhabricatorEvent.php

@@ -16,6 +16,10 @@
  * limitations under the License.
  */
 
+
+/**
+ * @group events
+ */
 final class PhabricatorEvent extends PhutilEvent {
 
   private $user;

src/infrastructure/events/PhabricatorEventEngine.php

@@ -16,6 +16,9 @@
  * limitations under the License.
  */
 
+/**
+ * @group events
+ */
 final class PhabricatorEventEngine {
 
   public static function initialize() {

src/infrastructure/events/PhabricatorExampleEventListener.php

@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * Copyright 2012 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.
+ */
+
+/**
+ * Example event listener. For details about installing Phabricator event hooks,
+ * refer to @{article:Events User Guide: Installing Event Listeners}.
+ *
+ * @group events
+ */
+final class PhabricatorExampleEventListener extends PhutilEventListener {
+
+  public function register() {
+    // When your listener is installed, its register() method will be called.
+    // You should listen() to any events you are interested in here.
+
+    $this->listen(PhabricatorEventType::TYPE_TEST_DIDRUNTEST);
+  }
+
+  public function handleEvent(PhutilEvent $event) {
+    // When an event you have called listen() for in your register() method
+    // occurs, this method will be invoked. You should respond to the event.
+
+    // In this case, we just echo a message out so the event test script will
+    // do something visible.
+
+    $console = PhutilConsole::getConsole();
+    $console->writeOut(
+      "PhabricatorExampleEventListener got test event at %d\n",
+      $event->getValue('time'));
+  }
+
+}
+
+
+
+
+

src/infrastructure/events/constant/PhabricatorEventType.php

@@ -16,14 +16,25 @@
  * limitations under the License.
  */
 
+/**
+ * For detailed explanations of these events, see
+ * @{article:Events User Guide: Installing Event Listeners}.
+ *
+ * @group events
+ */
 final class PhabricatorEventType extends PhutilEventType {
 
-  const TYPE_MANIPHEST_WILLEDITTASK = 'maniphest.willEditTask';
-  const TYPE_MANIPHEST_DIDEDITTASK = 'maniphest.didEditTask';
-  const TYPE_DIFFERENTIAL_WILLSENDMAIL = 'differential.willSendMail';
+  const TYPE_MANIPHEST_WILLEDITTASK         = 'maniphest.willEditTask';
+  const TYPE_MANIPHEST_DIDEDITTASK          = 'maniphest.didEditTask';
+
+  const TYPE_DIFFERENTIAL_WILLSENDMAIL      = 'differential.willSendMail';
   const TYPE_DIFFERENTIAL_WILLMARKGENERATED = 'differential.willMarkGenerated';
 
-  const TYPE_EDGE_WILLEDITEDGES     = 'edge.willEditEdges';
-  const TYPE_EDGE_DIDEDITEDGES      = 'edge.didEditEdges';
+  const TYPE_DIFFUSION_DIDDISCOVERCOMMIT    = 'diffusion.didDiscoverCommit';
+
+  const TYPE_EDGE_WILLEDITEDGES             = 'edge.willEditEdges';
+  const TYPE_EDGE_DIDEDITEDGES              = 'edge.didEditEdges';
+
+  const TYPE_TEST_DIDRUNTEST                = 'test.didRunTest';
 
 }