Garbage collect Drydock logs after 30 days

Summary:
Ref T9252. Drydock logs are almost exclusively useful as a diagnostic tool for debugging immediate problems, so GC them fairly aggressively.

(I expect 99% of the usefulness of these logs to be within the first 24 hours, basically "why isn't my thing working". I can't really think of any cases where having old logs would be useful.)

Test Plan:
  - Ran GC, saw it hit the log table (with no effect).
  - Changed TTL from 30 days to 30 seconds, ran GC, saw it wipe recent logs.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9252

Differential Revision: https://secure.phabricator.com/D14197

src/__phutil_library_map__.php

@@ -845,6 +845,7 @@ phutil_register_library_map(array(
     'DrydockLeaseWorker' => 'applications/drydock/worker/DrydockLeaseWorker.php',
     'DrydockLog' => 'applications/drydock/storage/DrydockLog.php',
     'DrydockLogController' => 'applications/drydock/controller/DrydockLogController.php',
+    'DrydockLogGarbageCollector' => 'applications/drydock/garbagecollector/DrydockLogGarbageCollector.php',
     'DrydockLogListController' => 'applications/drydock/controller/DrydockLogListController.php',
     'DrydockLogListView' => 'applications/drydock/view/DrydockLogListView.php',
     'DrydockLogQuery' => 'applications/drydock/query/DrydockLogQuery.php',
@@ -4586,6 +4587,7 @@ phutil_register_library_map(array(
       'PhabricatorPolicyInterface',
     ),
     'DrydockLogController' => 'DrydockController',
+    'DrydockLogGarbageCollector' => 'PhabricatorGarbageCollector',
     'DrydockLogListController' => 'DrydockLogController',
     'DrydockLogListView' => 'AphrontView',
     'DrydockLogQuery' => 'DrydockQuery',

src/applications/drydock/garbagecollector/DrydockLogGarbageCollector.php

@@ -0,0 +1,22 @@
+<?php
+
+final class DrydockLogGarbageCollector
+  extends PhabricatorGarbageCollector {
+
+  public function collectGarbage() {
+    $log_table = new DrydockLog();
+    $conn_w = $log_table->establishConnection('w');
+
+    $now = PhabricatorTime::getNow();
+    $ttl = phutil_units('30 days in seconds');
+
+    queryfx(
+      $conn_w,
+      'DELETE FROM %T WHERE epoch <= %d LIMIT 100',
+      $log_table->getTableName(),
+      $now - $ttl);
+
+    return ($conn_w->getAffectedRows() == 100);
+  }
+
+}