Introduce a request cache mechanism

Summary:
Ref T8424. This adds a standard KeyValueCache to serve as a request cache.

In particular, I need to cache Spaces (they are frequently accessed, sometimes by multiple viewers) but not have them survive longer than the scope of one request.

This request cache is explicitly destroyed by each web request and each daemon request.

In the very long term, building this kind of construct supports reusing PHP interpreters to run web requests (see some discussion in T2312).

Test Plan:
  - Added and executed unit tests.
  - Ran every daemon.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8424

Differential Revision: https://secure.phabricator.com/D13153

Author: epriestley

src/__phutil_library_map__.php

@@ -1495,6 +1495,7 @@
     'PhabricatorCacheSpec' => 'applications/cache/spec/PhabricatorCacheSpec.php',
     'PhabricatorCacheTTLGarbageCollector' => 'applications/cache/garbagecollector/PhabricatorCacheTTLGarbageCollector.php',
     'PhabricatorCaches' => 'applications/cache/PhabricatorCaches.php',
+    'PhabricatorCachesTestCase' => 'applications/cache/__tests__/PhabricatorCachesTestCase.php',
     'PhabricatorCalendarApplication' => 'applications/calendar/application/PhabricatorCalendarApplication.php',
     'PhabricatorCalendarController' => 'applications/calendar/controller/PhabricatorCalendarController.php',
     'PhabricatorCalendarDAO' => 'applications/calendar/storage/PhabricatorCalendarDAO.php',
@@ -4852,6 +4853,7 @@
     'PhabricatorCacheSetupCheck' => 'PhabricatorSetupCheck',
     'PhabricatorCacheSpec' => 'Phobject',
     'PhabricatorCacheTTLGarbageCollector' => 'PhabricatorGarbageCollector',
+    'PhabricatorCachesTestCase' => 'PhabricatorTestCase',
     'PhabricatorCalendarApplication' => 'PhabricatorApplication',
     'PhabricatorCalendarController' => 'PhabricatorController',
     'PhabricatorCalendarDAO' => 'PhabricatorLiskDAO',

src/applications/cache/PhabricatorCaches.php

@@ -1,12 +1,16 @@
 <?php
 
 /**
+ *
+ * @task request    Request Cache
  * @task immutable  Immutable Cache
  * @task setup      Setup Cache
  * @task compress   Compression
  */
 final class PhabricatorCaches {
 
+  private static $requestCache;
+
   public static function getNamespace() {
     return PhabricatorEnv::getEnvConfig('phabricator.cache-namespace');
   }
@@ -18,8 +22,39 @@ private static function newStackFromCaches(array $caches) {
       ->setCaches($caches);
   }
 
+/* -(  Request Cache  )------------------------------------------------------ */
+
+
+  /**
+   * Get a request cache stack.
+   *
+   * This cache stack is destroyed after each logical request. In particular,
+   * it is destroyed periodically by the daemons, while `static` caches are
+   * not.
+   *
+   * @return PhutilKeyValueCacheStack Request cache stack.
+   */
+  public static function getRequestCache() {
+    if (!self::$requestCache) {
+      self::$requestCache = new PhutilInRequestKeyValueCache();
+    }
+    return self::$requestCache;
+  }
+
+
+  /**
+   * Destroy the request cache.
+   *
+   * This is called at the beginning of each logical request.
+   *
+   * @return void
+   */
+  public static function destroyRequestCache() {
+    self::$requestCache = null;
+  }
+
 
-/* -(  Local Cache  )-------------------------------------------------------- */
+/* -(  Immutable Cache  )---------------------------------------------------- */
 
 
   /**

src/applications/cache/__tests__/PhabricatorCachesTestCase.php

@@ -0,0 +1,41 @@
+<?php
+
+final class PhabricatorCachesTestCase
+  extends PhabricatorTestCase {
+
+  public function testRequestCache() {
+    $cache = PhabricatorCaches::getRequestCache();
+
+    $test_key = 'unit.'.Filesystem::readRandomCharacters(8);
+
+    $default_value = pht('Default');
+    $new_value = pht('New Value');
+
+    $this->assertEqual(
+      $default_value,
+      $cache->getKey($test_key, $default_value));
+
+    // Set a key, verify it persists.
+    $cache = PhabricatorCaches::getRequestCache();
+    $cache->setKey($test_key, $new_value);
+    $this->assertEqual(
+      $new_value,
+      $cache->getKey($test_key, $default_value));
+
+    // Refetch the cache, verify it's really a cache.
+    $cache = PhabricatorCaches::getRequestCache();
+    $this->assertEqual(
+      $new_value,
+      $cache->getKey($test_key, $default_value));
+
+    // Destroy the cache.
+    PhabricatorCaches::destroyRequestCache();
+
+    // Now, the value should be missing again.
+    $cache = PhabricatorCaches::getRequestCache();
+    $this->assertEqual(
+      $default_value,
+      $cache->getKey($test_key, $default_value));
+  }
+
+}

src/applications/fact/daemon/PhabricatorFactDaemon.php

@@ -9,6 +9,8 @@ final class PhabricatorFactDaemon extends PhabricatorDaemon {
   protected function run() {
     $this->setEngines(PhabricatorFactEngine::loadAllEngines());
     while (!$this->shouldExit()) {
+      PhabricatorCaches::destroyRequestCache();
+
       $iterators = $this->getAllApplicationIterators();
       foreach ($iterators as $iterator_name => $iterator) {
         $this->processIteratorWithCursor($iterator_name, $iterator);

src/applications/repository/daemon/PhabricatorRepositoryPullLocalDaemon.php

@@ -73,6 +73,7 @@ protected function run() {
     $queue = array();
 
     while (!$this->shouldExit()) {
+      PhabricatorCaches::destroyRequestCache();
       $pullable = $this->loadPullableRepositories($include, $exclude);
 
       // If any repositories have the NEEDS_UPDATE flag set, pull them

src/infrastructure/daemon/bot/PhabricatorBot.php

@@ -106,6 +106,8 @@ public function getConfig($key, $default = null) {
 
   private function runLoop() {
     do {
+      PhabricatorCaches::destroyRequestCache();
+
       $this->stillWorking();
 
       $messages = $this->protocolAdapter->getNextMessages($this->pollFrequency);

src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php

@@ -4,6 +4,8 @@ final class PhabricatorTaskmasterDaemon extends PhabricatorDaemon {
 
   protected function run() {
     do {
+      PhabricatorCaches::destroyRequestCache();
+
       $tasks = id(new PhabricatorWorkerLeaseQuery())
         ->setLimit(1)
         ->execute();

src/infrastructure/daemon/workers/PhabricatorTriggerDaemon.php

@@ -65,6 +65,8 @@ protected function run() {
     $this->nextCollection = PhabricatorTime::getNow();
 
     do {
+      PhabricatorCaches::destroyRequestCache();
+
       $lock = PhabricatorGlobalLock::newLock('trigger');
 
       try {

webroot/index.php

@@ -13,6 +13,8 @@
 
 try {
   PhabricatorStartup::loadCoreLibraries();
+  PhabricatorCaches::destroyRequestCache();
+
   $sink = new AphrontPHPHTTPSink();
 
   try {