From d05d8f65589654448861225c3ec3f349d09c2354 Mon Sep 17 00:00:00 2001
From: epriestley <git@epriestley.com>
Date: Thu, 23 Apr 2020 13:54:34 -0700
Subject: [PATCH] Add a very forgiving GC for Differential viewstate
 information

Summary:
Ref T13455. Viewstates are fairly small and will probably grow less quickly than the changeset table, but the data is also not important to retain in the long term: if you revisit a change several months after hiding some files, it's fine if we've forgotten that you adjusted the view parameters.

Add a GC with a long default collection policy (180 days) so installs can manage the size of this table if it becomes necessary.

Test Plan: Ran via `bin/garbage` to adjust the GC policy and collect viewstates.

Maniphest Tasks: T13455

Differential Revision: https://secure.phabricator.com/D21164
---
 src/__phutil_library_map__.php                |  2 ++
 .../DifferentialViewStateGarbageCollector.php | 29 +++++++++++++++++++
 .../storage/DifferentialViewState.php         |  3 ++
 3 files changed, 34 insertions(+)
 create mode 100644 src/applications/differential/garbagecollector/DifferentialViewStateGarbageCollector.php

diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 0ef10f04ea..1618f2078c 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -715,6 +715,7 @@ phutil_register_library_map(array(
     'DifferentialUnitTestResult' => 'applications/differential/constants/DifferentialUnitTestResult.php',
     'DifferentialUpdateRevisionConduitAPIMethod' => 'applications/differential/conduit/DifferentialUpdateRevisionConduitAPIMethod.php',
     'DifferentialViewState' => 'applications/differential/storage/DifferentialViewState.php',
+    'DifferentialViewStateGarbageCollector' => 'applications/differential/garbagecollector/DifferentialViewStateGarbageCollector.php',
     'DifferentialViewStateQuery' => 'applications/differential/query/DifferentialViewStateQuery.php',
     'DiffusionAuditorDatasource' => 'applications/diffusion/typeahead/DiffusionAuditorDatasource.php',
     'DiffusionAuditorFunctionDatasource' => 'applications/diffusion/typeahead/DiffusionAuditorFunctionDatasource.php',
@@ -6803,6 +6804,7 @@ phutil_register_library_map(array(
       'DifferentialDAO',
       'PhabricatorPolicyInterface',
     ),
+    'DifferentialViewStateGarbageCollector' => 'PhabricatorGarbageCollector',
     'DifferentialViewStateQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
     'DiffusionAuditorDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'DiffusionAuditorFunctionDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
diff --git a/src/applications/differential/garbagecollector/DifferentialViewStateGarbageCollector.php b/src/applications/differential/garbagecollector/DifferentialViewStateGarbageCollector.php
new file mode 100644
index 0000000000..e862de22f1
--- /dev/null
+++ b/src/applications/differential/garbagecollector/DifferentialViewStateGarbageCollector.php
@@ -0,0 +1,29 @@
+<?php
+
+final class DifferentialViewStateGarbageCollector
+  extends PhabricatorGarbageCollector {
+
+  const COLLECTORCONST = 'differential.viewstate';
+
+  public function getCollectorName() {
+    return pht('Differential View States');
+  }
+
+  public function getDefaultRetentionPolicy() {
+    return phutil_units('180 days in seconds');
+  }
+
+  protected function collectGarbage() {
+    $table = new DifferentialViewState();
+    $conn = $table->establishConnection('w');
+
+    queryfx(
+      $conn,
+      'DELETE FROM %R WHERE dateModified < %d LIMIT 100',
+      $table,
+      $this->getGarbageEpoch());
+
+    return ($conn->getAffectedRows() == 100);
+  }
+
+}
diff --git a/src/applications/differential/storage/DifferentialViewState.php b/src/applications/differential/storage/DifferentialViewState.php
index 763edd8460..101061f379 100644
--- a/src/applications/differential/storage/DifferentialViewState.php
+++ b/src/applications/differential/storage/DifferentialViewState.php
@@ -23,6 +23,9 @@ final class DifferentialViewState
         'key_object' => array(
           'columns' => array('objectPHID'),
         ),
+        'key_modified' => array(
+          'columns' => array('dateModified'),
+        ),
       ),
     ) + parent::getConfiguration();
   }
-- 
2.51.2