diff --git a/src/applications/cache/PhabricatorCaches.php b/src/applications/cache/PhabricatorCaches.php
index e9baa299a2..c9bd304ccf 100644
--- a/src/applications/cache/PhabricatorCaches.php
+++ b/src/applications/cache/PhabricatorCaches.php
@@ -1,361 +1,394 @@
 <?php
 
 /**
  *
  * @task request    Request Cache
  * @task immutable  Immutable Cache
  * @task setup      Setup Cache
  * @task compress   Compression
  */
 final class PhabricatorCaches extends Phobject {
 
   private static $requestCache;
 
   public static function getNamespace() {
     return PhabricatorEnv::getEnvConfig('phabricator.cache-namespace');
   }
 
   private static function newStackFromCaches(array $caches) {
     $caches = self::addNamespaceToCaches($caches);
     $caches = self::addProfilerToCaches($caches);
     return id(new PhutilKeyValueCacheStack())
       ->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;
   }
 
 
 /* -(  Immutable Cache  )---------------------------------------------------- */
 
 
   /**
    * Gets an immutable cache stack.
    *
    * This stack trades mutability away for improved performance. Normally, it is
    * APC + DB.
    *
    * In the general case with multiple web frontends, this stack can not be
    * cleared, so it is only appropriate for use if the value of a given key is
    * permanent and immutable.
    *
    * @return PhutilKeyValueCacheStack Best immutable stack available.
    * @task immutable
    */
   public static function getImmutableCache() {
     static $cache;
     if (!$cache) {
       $caches = self::buildImmutableCaches();
       $cache = self::newStackFromCaches($caches);
     }
     return $cache;
   }
 
 
   /**
    * Build the immutable cache stack.
    *
    * @return list<PhutilKeyValueCache> List of caches.
    * @task immutable
    */
   private static function buildImmutableCaches() {
     $caches = array();
 
     $apc = new PhutilAPCKeyValueCache();
     if ($apc->isAvailable()) {
       $caches[] = $apc;
     }
 
     $caches[] = new PhabricatorKeyValueDatabaseCache();
 
     return $caches;
   }
 
 
 /* -(  Repository Graph Cache  )--------------------------------------------- */
 
 
   public static function getRepositoryGraphL1Cache() {
     static $cache;
     if (!$cache) {
       $caches = self::buildRepositoryGraphL1Caches();
       $cache = self::newStackFromCaches($caches);
     }
     return $cache;
   }
 
   private static function buildRepositoryGraphL1Caches() {
     $caches = array();
 
     $request = new PhutilInRequestKeyValueCache();
     $request->setLimit(32);
     $caches[] = $request;
 
     $apc = new PhutilAPCKeyValueCache();
     if ($apc->isAvailable()) {
       $caches[] = $apc;
     }
 
     return $caches;
   }
 
   public static function getRepositoryGraphL2Cache() {
     static $cache;
     if (!$cache) {
       $caches = self::buildRepositoryGraphL2Caches();
       $cache = self::newStackFromCaches($caches);
     }
     return $cache;
   }
 
   private static function buildRepositoryGraphL2Caches() {
     $caches = array();
     $caches[] = new PhabricatorKeyValueDatabaseCache();
     return $caches;
   }
 
 
+/* -(  Server State Cache  )------------------------------------------------- */
+
+
+  /**
+   * Highly specialized cache for storing server process state.
+   *
+   * We use this cache to track initial steps in the setup phase, before
+   * configuration is loaded.
+   *
+   * This cache does NOT use the cache namespace (it must be accessed before
+   * we build configuration), and is global across all instances on the host.
+   *
+   * @return PhutilKeyValueCacheStack Best available server state cache stack.
+   * @task setup
+   */
+  public static function getServerStateCache() {
+    static $cache;
+    if (!$cache) {
+      $caches = self::buildSetupCaches('phabricator-server');
+
+      // NOTE: We are NOT adding a cache namespace here! This cache is shared
+      // across all instances on the host.
+
+      $caches = self::addProfilerToCaches($caches);
+      $cache = id(new PhutilKeyValueCacheStack())
+        ->setCaches($caches);
+
+    }
+    return $cache;
+  }
+
+
+
 /* -(  Setup Cache  )-------------------------------------------------------- */
 
 
   /**
    * Highly specialized cache for performing setup checks. We use this cache
    * to determine if we need to run expensive setup checks when the page
    * loads. Without it, we would need to run these checks every time.
    *
    * Normally, this cache is just APC. In the absence of APC, this cache
    * degrades into a slow, quirky on-disk cache.
    *
    * NOTE: Do not use this cache for anything else! It is not a general-purpose
    * cache!
    *
    * @return PhutilKeyValueCacheStack Most qualified available cache stack.
    * @task setup
    */
   public static function getSetupCache() {
     static $cache;
     if (!$cache) {
-      $caches = self::buildSetupCaches();
+      $caches = self::buildSetupCaches('phabricator-setup');
       $cache = self::newStackFromCaches($caches);
     }
     return $cache;
   }
 
 
   /**
    * @task setup
    */
-  private static function buildSetupCaches() {
+  private static function buildSetupCaches($cache_name) {
     // If this is the CLI, just build a setup cache.
     if (php_sapi_name() == 'cli') {
       return array();
     }
 
     // In most cases, we should have APC. This is an ideal cache for our
     // purposes -- it's fast and empties on server restart.
     $apc = new PhutilAPCKeyValueCache();
     if ($apc->isAvailable()) {
       return array($apc);
     }
 
     // If we don't have APC, build a poor approximation on disk. This is still
     // much better than nothing; some setup steps are quite slow.
-    $disk_path = self::getSetupCacheDiskCachePath();
+    $disk_path = self::getSetupCacheDiskCachePath($cache_name);
     if ($disk_path) {
       $disk = new PhutilOnDiskKeyValueCache();
       $disk->setCacheFile($disk_path);
       $disk->setWait(0.1);
       if ($disk->isAvailable()) {
         return array($disk);
       }
     }
 
     return array();
   }
 
 
   /**
    * @task setup
    */
-  private static function getSetupCacheDiskCachePath() {
+  private static function getSetupCacheDiskCachePath($name) {
     // The difficulty here is in choosing a path which will change on server
     // restart (we MUST have this property), but as rarely as possible
     // otherwise (we desire this property to give the cache the best hit rate
     // we can).
 
     // Unfortunately, we don't have a very good strategy for minimizing the
     // churn rate of the cache. We previously tried to use the parent process
     // PID in some cases, but this was not reliable. See T9599 for one case of
     // this.
 
     $pid_basis = getmypid();
 
     // If possible, we also want to know when the process launched, so we can
     // drop the cache if a process restarts but gets the same PID an earlier
     // process had. "/proc" is not available everywhere (e.g., not on OSX), but
     // check if we have it.
     $epoch_basis = null;
     $stat = @stat("/proc/{$pid_basis}");
     if ($stat !== false) {
       $epoch_basis = $stat['ctime'];
     }
 
     $tmp_dir = sys_get_temp_dir();
 
-    $tmp_path = $tmp_dir.DIRECTORY_SEPARATOR.'phabricator-setup';
+    $tmp_path = $tmp_dir.DIRECTORY_SEPARATOR.$name;
     if (!file_exists($tmp_path)) {
       @mkdir($tmp_path);
     }
 
     $is_ok = self::testTemporaryDirectory($tmp_path);
     if (!$is_ok) {
       $tmp_path = $tmp_dir;
       $is_ok = self::testTemporaryDirectory($tmp_path);
       if (!$is_ok) {
         // We can't find anywhere to write the cache, so just bail.
         return null;
       }
     }
 
     $tmp_name = 'setup-'.$pid_basis;
     if ($epoch_basis) {
       $tmp_name .= '.'.$epoch_basis;
     }
     $tmp_name .= '.cache';
 
     return $tmp_path.DIRECTORY_SEPARATOR.$tmp_name;
   }
 
 
   /**
    * @task setup
    */
   private static function testTemporaryDirectory($dir) {
     if (!@file_exists($dir)) {
       return false;
     }
     if (!@is_dir($dir)) {
       return false;
     }
     if (!@is_writable($dir)) {
       return false;
     }
 
     return true;
   }
 
   private static function addProfilerToCaches(array $caches) {
     foreach ($caches as $key => $cache) {
       $pcache = new PhutilKeyValueCacheProfiler($cache);
       $pcache->setProfiler(PhutilServiceProfiler::getInstance());
       $caches[$key] = $pcache;
     }
     return $caches;
   }
 
   private static function addNamespaceToCaches(array $caches) {
     $namespace = self::getNamespace();
     if (!$namespace) {
       return $caches;
     }
 
     foreach ($caches as $key => $cache) {
       $ncache = new PhutilKeyValueCacheNamespace($cache);
       $ncache->setNamespace($namespace);
       $caches[$key] = $ncache;
     }
 
     return $caches;
   }
 
 
   /**
    * Deflate a value, if deflation is available and has an impact.
    *
    * If the value is larger than 1KB, we have `gzdeflate()`, we successfully
    * can deflate it, and it benefits from deflation, we deflate it. Otherwise
    * we leave it as-is.
    *
    * Data can later be inflated with @{method:inflateData}.
    *
    * @param string String to attempt to deflate.
    * @return string|null Deflated string, or null if it was not deflated.
    * @task compress
    */
   public static function maybeDeflateData($value) {
     $len = strlen($value);
     if ($len <= 1024) {
       return null;
     }
 
     if (!function_exists('gzdeflate')) {
       return null;
     }
 
     $deflated = gzdeflate($value);
     if ($deflated === false) {
       return null;
     }
 
     $deflated_len = strlen($deflated);
     if ($deflated_len >= ($len / 2)) {
       return null;
     }
 
     return $deflated;
   }
 
 
   /**
    * Inflate data previously deflated by @{method:maybeDeflateData}.
    *
    * @param string Deflated data, from @{method:maybeDeflateData}.
    * @return string Original, uncompressed data.
    * @task compress
    */
   public static function inflateData($value) {
     if (!function_exists('gzinflate')) {
       throw new Exception(
         pht(
           '%s is not available; unable to read deflated data!',
           'gzinflate()'));
     }
 
     $value = gzinflate($value);
     if ($value === false) {
       throw new Exception(pht('Failed to inflate data!'));
     }
 
     return $value;
   }
 
 
 }
diff --git a/src/applications/config/check/PhabricatorSetupCheck.php b/src/applications/config/check/PhabricatorSetupCheck.php
index 0c9888cd77..7947f5aa79 100644
--- a/src/applications/config/check/PhabricatorSetupCheck.php
+++ b/src/applications/config/check/PhabricatorSetupCheck.php
@@ -1,271 +1,275 @@
 <?php
 
 abstract class PhabricatorSetupCheck extends Phobject {
 
   private $issues;
 
   abstract protected function executeChecks();
 
   const GROUP_OTHER       = 'other';
   const GROUP_MYSQL       = 'mysql';
   const GROUP_PHP         = 'php';
   const GROUP_IMPORTANT   = 'important';
 
   public function getExecutionOrder() {
     if ($this->isPreflightCheck()) {
       return 0;
     } else {
       return 1000;
     }
   }
 
   /**
    * Should this check execute before we load configuration?
    *
    * The majority of checks (particularly, those checks which examine
    * configuration) should run in the normal setup phase, after configuration
    * loads. However, a small set of critical checks (mostly, tests for PHP
    * setup and extensions) need to run before we can load configuration.
    *
    * @return bool True to execute before configuration is loaded.
    */
   public function isPreflightCheck() {
     return false;
   }
 
   final protected function newIssue($key) {
     $issue = id(new PhabricatorSetupIssue())
       ->setIssueKey($key);
     $this->issues[$key] = $issue;
 
     if ($this->getDefaultGroup()) {
       $issue->setGroup($this->getDefaultGroup());
     }
 
     return $issue;
   }
 
   final public function getIssues() {
     return $this->issues;
   }
 
   protected function addIssue(PhabricatorSetupIssue $issue) {
     $this->issues[$issue->getIssueKey()] = $issue;
     return $this;
   }
 
   public function getDefaultGroup() {
     return null;
   }
 
   final public function runSetupChecks() {
     $this->issues = array();
     $this->executeChecks();
   }
 
   final public static function getOpenSetupIssueKeys() {
     $cache = PhabricatorCaches::getSetupCache();
     return $cache->getKey('phabricator.setup.issue-keys');
   }
 
   final public static function setOpenSetupIssueKeys(
     array $keys,
     $update_database) {
     $cache = PhabricatorCaches::getSetupCache();
     $cache->setKey('phabricator.setup.issue-keys', $keys);
 
+    $server_cache = PhabricatorCaches::getServerStateCache();
+    $server_cache->setKey('phabricator.in-flight', 1);
+
     if ($update_database) {
       $db_cache = new PhabricatorKeyValueDatabaseCache();
       try {
         $json = phutil_json_encode($keys);
         $db_cache->setKey('phabricator.setup.issue-keys', $json);
       } catch (Exception $ex) {
         // Ignore any write failures, since they likely just indicate that we
         // have a database-related setup issue that needs to be resolved.
       }
     }
   }
 
   final public static function getOpenSetupIssueKeysFromDatabase() {
     $db_cache = new PhabricatorKeyValueDatabaseCache();
     try {
       $value = $db_cache->getKey('phabricator.setup.issue-keys');
       if (!strlen($value)) {
         return null;
       }
       return phutil_json_decode($value);
     } catch (Exception $ex) {
       return null;
     }
   }
 
   final public static function getUnignoredIssueKeys(array $all_issues) {
     assert_instances_of($all_issues, 'PhabricatorSetupIssue');
     $keys = array();
     foreach ($all_issues as $issue) {
       if (!$issue->getIsIgnored()) {
         $keys[] = $issue->getIssueKey();
       }
     }
     return $keys;
   }
 
   final public static function getConfigNeedsRepair() {
     $cache = PhabricatorCaches::getSetupCache();
     return $cache->getKey('phabricator.setup.needs-repair');
   }
 
   final public static function setConfigNeedsRepair($needs_repair) {
     $cache = PhabricatorCaches::getSetupCache();
     $cache->setKey('phabricator.setup.needs-repair', $needs_repair);
   }
 
   final public static function deleteSetupCheckCache() {
     $cache = PhabricatorCaches::getSetupCache();
     $cache->deleteKeys(
       array(
         'phabricator.setup.needs-repair',
         'phabricator.setup.issue-keys',
       ));
   }
 
   final public static function willPreflightRequest() {
     $checks = self::loadAllChecks();
 
     foreach ($checks as $check) {
       if (!$check->isPreflightCheck()) {
         continue;
       }
 
       $check->runSetupChecks();
 
       foreach ($check->getIssues() as $key => $issue) {
         return self::newIssueResponse($issue);
       }
     }
 
     return null;
   }
 
   public static function newIssueResponse(PhabricatorSetupIssue $issue) {
     $view = id(new PhabricatorSetupIssueView())
       ->setIssue($issue);
 
     return id(new PhabricatorConfigResponse())
       ->setView($view);
   }
 
   final public static function willProcessRequest() {
     $issue_keys = self::getOpenSetupIssueKeys();
     if ($issue_keys === null) {
       $issues = self::runNormalChecks();
       foreach ($issues as $issue) {
         if ($issue->getIsFatal()) {
           return self::newIssueResponse($issue);
         }
       }
       $issue_keys = self::getUnignoredIssueKeys($issues);
       self::setOpenSetupIssueKeys($issue_keys, $update_database = true);
     } else if ($issue_keys) {
       // If Phabricator is configured in a cluster with multiple web devices,
       // we can end up with setup issues cached on every device. This can cause
       // a warning banner to show on every device so that each one needs to
       // be dismissed individually, which is pretty annoying. See T10876.
 
       // To avoid this, check if the issues we found have already been cleared
       // in the database. If they have, we'll just wipe out our own cache and
       // move on.
       $issue_keys = self::getOpenSetupIssueKeysFromDatabase();
       if ($issue_keys !== null) {
         self::setOpenSetupIssueKeys($issue_keys, $update_database = false);
       }
     }
 
     // Try to repair configuration unless we have a clean bill of health on it.
     // We need to keep doing this on every page load until all the problems
     // are fixed, which is why it's separate from setup checks (which run
     // once per restart).
     $needs_repair = self::getConfigNeedsRepair();
     if ($needs_repair !== false) {
       $needs_repair = self::repairConfig();
       self::setConfigNeedsRepair($needs_repair);
     }
   }
 
   /**
    * Test if we've survived through setup on at least one normal request
    * without fataling.
    *
    * If we've made it through setup without hitting any fatals, we switch
    * to render a more friendly error page when encountering issues like
    * database connection failures. This gives users a smoother experience in
    * the face of intermittent failures.
    *
    * @return bool True if we've made it through setup since the last restart.
    */
   final public static function isInFlight() {
-    return (self::getOpenSetupIssueKeys() !== null);
+    $cache = PhabricatorCaches::getServerStateCache();
+    return (bool)$cache->getKey('phabricator.in-flight');
   }
 
   final public static function loadAllChecks() {
     return id(new PhutilClassMapQuery())
       ->setAncestorClass(__CLASS__)
       ->setSortMethod('getExecutionOrder')
       ->execute();
   }
 
   final public static function runNormalChecks() {
     $checks = self::loadAllChecks();
 
     foreach ($checks as $key => $check) {
       if ($check->isPreflightCheck()) {
         unset($checks[$key]);
       }
     }
 
     $issues = array();
     foreach ($checks as $check) {
       $check->runSetupChecks();
       foreach ($check->getIssues() as $key => $issue) {
         if (isset($issues[$key])) {
           throw new Exception(
             pht(
               "Two setup checks raised an issue with key '%s'!",
               $key));
         }
         $issues[$key] = $issue;
         if ($issue->getIsFatal()) {
           break 2;
         }
       }
     }
 
     $ignore_issues = PhabricatorEnv::getEnvConfig('config.ignore-issues');
     foreach ($ignore_issues as $ignorable => $derp) {
       if (isset($issues[$ignorable])) {
         $issues[$ignorable]->setIsIgnored(true);
       }
     }
 
     return $issues;
   }
 
   final public static function repairConfig() {
     $needs_repair = false;
 
     $options = PhabricatorApplicationConfigOptions::loadAllOptions();
     foreach ($options as $option) {
       try {
         $option->getGroup()->validateOption(
           $option,
           PhabricatorEnv::getEnvConfig($option->getKey()));
       } catch (PhabricatorConfigValidationException $ex) {
         PhabricatorEnv::repairConfig($option->getKey(), $option->getDefault());
         $needs_repair = true;
       }
     }
 
     return $needs_repair;
   }
 
 }
diff --git a/src/infrastructure/env/PhabricatorEnv.php b/src/infrastructure/env/PhabricatorEnv.php
index 7ea00957ff..2dfe7d9c62 100644
--- a/src/infrastructure/env/PhabricatorEnv.php
+++ b/src/infrastructure/env/PhabricatorEnv.php
@@ -1,912 +1,912 @@
 <?php
 
 /**
  * Manages the execution environment configuration, exposing APIs to read
  * configuration settings and other similar values that are derived directly
  * from configuration settings.
  *
  *
  * = Reading Configuration =
  *
  * The primary role of this class is to provide an API for reading
  * Phabricator configuration, @{method:getEnvConfig}:
  *
  *   $value = PhabricatorEnv::getEnvConfig('some.key', $default);
  *
  * The class also handles some URI construction based on configuration, via
  * the methods @{method:getURI}, @{method:getProductionURI},
  * @{method:getCDNURI}, and @{method:getDoclink}.
  *
  * For configuration which allows you to choose a class to be responsible for
  * some functionality (e.g., which mail adapter to use to deliver email),
  * @{method:newObjectFromConfig} provides a simple interface that validates
  * the configured value.
  *
  *
  * = Unit Test Support =
  *
  * In unit tests, you can use @{method:beginScopedEnv} to create a temporary,
  * mutable environment. The method returns a scope guard object which restores
  * the environment when it is destroyed. For example:
  *
  *   public function testExample() {
  *     $env = PhabricatorEnv::beginScopedEnv();
  *     $env->overrideEnv('some.key', 'new-value-for-this-test');
  *
  *     // Some test which depends on the value of 'some.key'.
  *
  *   }
  *
  * Your changes will persist until the `$env` object leaves scope or is
  * destroyed.
  *
  * You should //not// use this in normal code.
  *
  *
  * @task read     Reading Configuration
  * @task uri      URI Validation
  * @task test     Unit Test Support
  * @task internal Internals
  */
 final class PhabricatorEnv extends Phobject {
 
   private static $sourceStack;
   private static $repairSource;
   private static $overrideSource;
   private static $requestBaseURI;
   private static $cache;
   private static $localeCode;
   private static $readOnly;
   private static $readOnlyReason;
 
   const READONLY_CONFIG = 'config';
   const READONLY_UNREACHABLE = 'unreachable';
   const READONLY_SEVERED = 'severed';
   const READONLY_MASTERLESS = 'masterless';
 
   /**
    * @phutil-external-symbol class PhabricatorStartup
    */
   public static function initializeWebEnvironment() {
     self::initializeCommonEnvironment(false);
   }
 
   public static function initializeScriptEnvironment($config_optional) {
     self::initializeCommonEnvironment($config_optional);
 
     // NOTE: This is dangerous in general, but we know we're in a script context
     // and are not vulnerable to CSRF.
     AphrontWriteGuard::allowDangerousUnguardedWrites(true);
 
     // There are several places where we log information (about errors, events,
     // service calls, etc.) for analysis via DarkConsole or similar. These are
     // useful for web requests, but grow unboundedly in long-running scripts and
     // daemons. Discard data as it arrives in these cases.
     PhutilServiceProfiler::getInstance()->enableDiscardMode();
     DarkConsoleErrorLogPluginAPI::enableDiscardMode();
     DarkConsoleEventPluginAPI::enableDiscardMode();
   }
 
 
   private static function initializeCommonEnvironment($config_optional) {
     PhutilErrorHandler::initialize();
 
     self::resetUmask();
     self::buildConfigurationSourceStack($config_optional);
 
     // Force a valid timezone. If both PHP and Phabricator configuration are
     // invalid, use UTC.
     $tz = self::getEnvConfig('phabricator.timezone');
     if ($tz) {
       @date_default_timezone_set($tz);
     }
     $ok = @date_default_timezone_set(date_default_timezone_get());
     if (!$ok) {
       date_default_timezone_set('UTC');
     }
 
     // Prepend '/support/bin' and append any paths to $PATH if we need to.
     $env_path = getenv('PATH');
     $phabricator_path = dirname(phutil_get_library_root('phabricator'));
     $support_path = $phabricator_path.'/support/bin';
     $env_path = $support_path.PATH_SEPARATOR.$env_path;
     $append_dirs = self::getEnvConfig('environment.append-paths');
     if (!empty($append_dirs)) {
       $append_path = implode(PATH_SEPARATOR, $append_dirs);
       $env_path = $env_path.PATH_SEPARATOR.$append_path;
     }
     putenv('PATH='.$env_path);
 
     // Write this back into $_ENV, too, so ExecFuture picks it up when creating
     // subprocess environments.
     $_ENV['PATH'] = $env_path;
 
 
     // If an instance identifier is defined, write it into the environment so
     // it's available to subprocesses.
     $instance = self::getEnvConfig('cluster.instance');
     if (strlen($instance)) {
       putenv('PHABRICATOR_INSTANCE='.$instance);
       $_ENV['PHABRICATOR_INSTANCE'] = $instance;
     }
 
     PhabricatorEventEngine::initialize();
 
     // TODO: Add a "locale.default" config option once we have some reasonable
     // defaults which aren't silly nonsense.
     self::setLocaleCode('en_US');
   }
 
   public static function beginScopedLocale($locale_code) {
     return new PhabricatorLocaleScopeGuard($locale_code);
   }
 
   public static function getLocaleCode() {
     return self::$localeCode;
   }
 
   public static function setLocaleCode($locale_code) {
     if (!$locale_code) {
       return;
     }
 
     if ($locale_code == self::$localeCode) {
       return;
     }
 
     try {
       $locale = PhutilLocale::loadLocale($locale_code);
       $translations = PhutilTranslation::getTranslationMapForLocale(
         $locale_code);
 
       $override = self::getEnvConfig('translation.override');
       if (!is_array($override)) {
         $override = array();
       }
 
       PhutilTranslator::getInstance()
         ->setLocale($locale)
         ->setTranslations($override + $translations);
 
       self::$localeCode = $locale_code;
     } catch (Exception $ex) {
       // Just ignore this; the user likely has an out-of-date locale code.
     }
   }
 
   private static function buildConfigurationSourceStack($config_optional) {
     self::dropConfigCache();
 
     $stack = new PhabricatorConfigStackSource();
     self::$sourceStack = $stack;
 
     $default_source = id(new PhabricatorConfigDefaultSource())
       ->setName(pht('Global Default'));
     $stack->pushSource($default_source);
 
     $env = self::getSelectedEnvironmentName();
     if ($env) {
       $stack->pushSource(
         id(new PhabricatorConfigFileSource($env))
           ->setName(pht("File '%s'", $env)));
     }
 
     $stack->pushSource(
       id(new PhabricatorConfigLocalSource())
         ->setName(pht('Local Config')));
 
     // If the install overrides the database adapter, we might need to load
     // the database adapter class before we can push on the database config.
     // This config is locked and can't be edited from the web UI anyway.
     foreach (self::getEnvConfig('load-libraries') as $library) {
       phutil_load_library($library);
     }
 
     // If custom libraries specify config options, they won't get default
     // values as the Default source has already been loaded, so we get it to
     // pull in all options from non-phabricator libraries now they are loaded.
     $default_source->loadExternalOptions();
 
     // If this install has site config sources, load them now.
     $site_sources = id(new PhutilClassMapQuery())
       ->setAncestorClass('PhabricatorConfigSiteSource')
       ->setSortMethod('getPriority')
       ->execute();
 
     foreach ($site_sources as $site_source) {
       $stack->pushSource($site_source);
     }
 
     $master = PhabricatorDatabaseRef::getMasterDatabaseRef();
     if (!$master) {
       self::setReadOnly(true, self::READONLY_MASTERLESS);
     } else if ($master->isSevered()) {
       $master->checkHealth();
       if ($master->isSevered()) {
         self::setReadOnly(true, self::READONLY_SEVERED);
       }
     }
 
     try {
       $stack->pushSource(
         id(new PhabricatorConfigDatabaseSource('default'))
           ->setName(pht('Database')));
     } catch (AphrontSchemaQueryException $exception) {
       // If the database is not available, just skip this configuration
       // source. This happens during `bin/storage upgrade`, `bin/conf` before
       // schema setup, etc.
     } catch (AphrontConnectionQueryException $ex) {
       if (!$config_optional) {
         throw $ex;
       }
     } catch (AphrontInvalidCredentialsQueryException $ex) {
       if (!$config_optional) {
         throw $ex;
       }
     }
   }
 
   public static function repairConfig($key, $value) {
     if (!self::$repairSource) {
       self::$repairSource = id(new PhabricatorConfigDictionarySource(array()))
         ->setName(pht('Repaired Config'));
       self::$sourceStack->pushSource(self::$repairSource);
     }
     self::$repairSource->setKeys(array($key => $value));
     self::dropConfigCache();
   }
 
   public static function overrideConfig($key, $value) {
     if (!self::$overrideSource) {
       self::$overrideSource = id(new PhabricatorConfigDictionarySource(array()))
         ->setName(pht('Overridden Config'));
       self::$sourceStack->pushSource(self::$overrideSource);
     }
     self::$overrideSource->setKeys(array($key => $value));
     self::dropConfigCache();
   }
 
   public static function getUnrepairedEnvConfig($key, $default = null) {
     foreach (self::$sourceStack->getStack() as $source) {
       if ($source === self::$repairSource) {
         continue;
       }
       $result = $source->getKeys(array($key));
       if ($result) {
         return $result[$key];
       }
     }
     return $default;
   }
 
   public static function getSelectedEnvironmentName() {
     $env_var = 'PHABRICATOR_ENV';
 
     $env = idx($_SERVER, $env_var);
 
     if (!$env) {
       $env = getenv($env_var);
     }
 
     if (!$env) {
       $env = idx($_ENV, $env_var);
     }
 
     if (!$env) {
       $root = dirname(phutil_get_library_root('phabricator'));
       $path = $root.'/conf/local/ENVIRONMENT';
       if (Filesystem::pathExists($path)) {
         $env = trim(Filesystem::readFile($path));
       }
     }
 
     return $env;
   }
 
 
 /* -(  Reading Configuration  )---------------------------------------------- */
 
 
   /**
    * Get the current configuration setting for a given key.
    *
    * If the key is not found, then throw an Exception.
    *
    * @task read
    */
   public static function getEnvConfig($key) {
-    if (isset(self::$cache[$key])) {
-      return self::$cache[$key];
-    }
-
-    if (array_key_exists($key, self::$cache)) {
-      return self::$cache[$key];
-    }
-
     if (!self::$sourceStack) {
       throw new Exception(
         pht(
           'Trying to read configuration "%s" before configuration has been '.
           'initialized.',
           $key));
     }
 
+    if (isset(self::$cache[$key])) {
+      return self::$cache[$key];
+    }
+
+    if (array_key_exists($key, self::$cache)) {
+      return self::$cache[$key];
+    }
+
     $result = self::$sourceStack->getKeys(array($key));
     if (array_key_exists($key, $result)) {
       self::$cache[$key] = $result[$key];
       return $result[$key];
     } else {
       throw new Exception(
         pht(
           "No config value specified for key '%s'.",
           $key));
     }
   }
 
   /**
    * Get the current configuration setting for a given key. If the key
    * does not exist, return a default value instead of throwing. This is
    * primarily useful for migrations involving keys which are slated for
    * removal.
    *
    * @task read
    */
   public static function getEnvConfigIfExists($key, $default = null) {
     try {
       return self::getEnvConfig($key);
     } catch (Exception $ex) {
       return $default;
     }
   }
 
 
   /**
    * Get the fully-qualified URI for a path.
    *
    * @task read
    */
   public static function getURI($path) {
     return rtrim(self::getAnyBaseURI(), '/').$path;
   }
 
 
   /**
    * Get the fully-qualified production URI for a path.
    *
    * @task read
    */
   public static function getProductionURI($path) {
     // If we're passed a URI which already has a domain, simply return it
     // unmodified. In particular, files may have URIs which point to a CDN
     // domain.
     $uri = new PhutilURI($path);
     if ($uri->getDomain()) {
       return $path;
     }
 
     $production_domain = self::getEnvConfig('phabricator.production-uri');
     if (!$production_domain) {
       $production_domain = self::getAnyBaseURI();
     }
     return rtrim($production_domain, '/').$path;
   }
 
   public static function getAllowedURIs($path) {
     $uri = new PhutilURI($path);
     if ($uri->getDomain()) {
       return $path;
     }
 
     $allowed_uris = self::getEnvConfig('phabricator.allowed-uris');
     $return = array();
     foreach ($allowed_uris as $allowed_uri) {
       $return[] = rtrim($allowed_uri, '/').$path;
     }
 
     return $return;
   }
 
 
   /**
    * Get the fully-qualified production URI for a static resource path.
    *
    * @task read
    */
   public static function getCDNURI($path) {
     $alt = self::getEnvConfig('security.alternate-file-domain');
     if (!$alt) {
       $alt = self::getAnyBaseURI();
     }
     $uri = new PhutilURI($alt);
     $uri->setPath($path);
     return (string)$uri;
   }
 
 
   /**
    * Get the fully-qualified production URI for a documentation resource.
    *
    * @task read
    */
   public static function getDoclink($resource, $type = 'article') {
     $uri = new PhutilURI('https://secure.phabricator.com/diviner/find/');
     $uri->setQueryParam('name', $resource);
     $uri->setQueryParam('type', $type);
     $uri->setQueryParam('jump', true);
     return (string)$uri;
   }
 
 
   /**
    * Build a concrete object from a configuration key.
    *
    * @task read
    */
   public static function newObjectFromConfig($key, $args = array()) {
     $class = self::getEnvConfig($key);
     return newv($class, $args);
   }
 
   public static function getAnyBaseURI() {
     $base_uri = self::getEnvConfig('phabricator.base-uri');
 
     if (!$base_uri) {
       $base_uri = self::getRequestBaseURI();
     }
 
     if (!$base_uri) {
       throw new Exception(
         pht(
           "Define '%s' in your configuration to continue.",
           'phabricator.base-uri'));
     }
 
     return $base_uri;
   }
 
   public static function getRequestBaseURI() {
     return self::$requestBaseURI;
   }
 
   public static function setRequestBaseURI($uri) {
     self::$requestBaseURI = $uri;
   }
 
   public static function isReadOnly() {
     if (self::$readOnly !== null) {
       return self::$readOnly;
     }
     return self::getEnvConfig('cluster.read-only');
   }
 
   public static function setReadOnly($read_only, $reason) {
     self::$readOnly = $read_only;
     self::$readOnlyReason = $reason;
   }
 
   public static function getReadOnlyMessage() {
     $reason = self::getReadOnlyReason();
     switch ($reason) {
       case self::READONLY_MASTERLESS:
         return pht(
           'Phabricator is in read-only mode (no writable database '.
           'is configured).');
       case self::READONLY_UNREACHABLE:
         return pht(
           'Phabricator is in read-only mode (unreachable master).');
       case self::READONLY_SEVERED:
         return pht(
           'Phabricator is in read-only mode (major interruption).');
     }
 
     return pht('Phabricator is in read-only mode.');
   }
 
   public static function getReadOnlyURI() {
     return urisprintf(
       '/readonly/%s/',
       self::getReadOnlyReason());
   }
 
   public static function getReadOnlyReason() {
     if (!self::isReadOnly()) {
       return null;
     }
 
     if (self::$readOnlyReason !== null) {
       return self::$readOnlyReason;
     }
 
     return self::READONLY_CONFIG;
   }
 
 
 /* -(  Unit Test Support  )-------------------------------------------------- */
 
 
   /**
    * @task test
    */
   public static function beginScopedEnv() {
     return new PhabricatorScopedEnv(self::pushTestEnvironment());
   }
 
 
   /**
    * @task test
    */
   private static function pushTestEnvironment() {
     self::dropConfigCache();
     $source = new PhabricatorConfigDictionarySource(array());
     self::$sourceStack->pushSource($source);
     return spl_object_hash($source);
   }
 
 
   /**
    * @task test
    */
   public static function popTestEnvironment($key) {
     self::dropConfigCache();
     $source = self::$sourceStack->popSource();
     $stack_key = spl_object_hash($source);
     if ($stack_key !== $key) {
       self::$sourceStack->pushSource($source);
       throw new Exception(
         pht(
           'Scoped environments were destroyed in a different order than they '.
           'were initialized.'));
     }
   }
 
 
 /* -(  URI Validation  )----------------------------------------------------- */
 
 
   /**
    * Detect if a URI satisfies either @{method:isValidLocalURIForLink} or
    * @{method:isValidRemoteURIForLink}, i.e. is a page on this server or the
    * URI of some other resource which has a valid protocol. This rejects
    * garbage URIs and URIs with protocols which do not appear in the
    * `uri.allowed-protocols` configuration, notably 'javascript:' URIs.
    *
    * NOTE: This method is generally intended to reject URIs which it may be
    * unsafe to put in an "href" link attribute.
    *
    * @param string URI to test.
    * @return bool True if the URI identifies a web resource.
    * @task uri
    */
   public static function isValidURIForLink($uri) {
     return self::isValidLocalURIForLink($uri) ||
            self::isValidRemoteURIForLink($uri);
   }
 
 
   /**
    * Detect if a URI identifies some page on this server.
    *
    * NOTE: This method is generally intended to reject URIs which it may be
    * unsafe to issue a "Location:" redirect to.
    *
    * @param string URI to test.
    * @return bool True if the URI identifies a local page.
    * @task uri
    */
   public static function isValidLocalURIForLink($uri) {
     $uri = (string)$uri;
 
     if (!strlen($uri)) {
       return false;
     }
 
     if (preg_match('/\s/', $uri)) {
       // PHP hasn't been vulnerable to header injection attacks for a bunch of
       // years, but we can safely reject these anyway since they're never valid.
       return false;
     }
 
     // Chrome (at a minimum) interprets backslashes in Location headers and the
     // URL bar as forward slashes. This is probably intended to reduce user
     // error caused by confusion over which key is "forward slash" vs "back
     // slash".
     //
     // However, it means a URI like "/\evil.com" is interpreted like
     // "//evil.com", which is a protocol relative remote URI.
     //
     // Since we currently never generate URIs with backslashes in them, reject
     // these unconditionally rather than trying to figure out how browsers will
     // interpret them.
     if (preg_match('/\\\\/', $uri)) {
       return false;
     }
 
     // Valid URIs must begin with '/', followed by the end of the string or some
     // other non-'/' character. This rejects protocol-relative URIs like
     // "//evil.com/evil_stuff/".
     return (bool)preg_match('@^/([^/]|$)@', $uri);
   }
 
 
   /**
    * Detect if a URI identifies some valid linkable remote resource.
    *
    * @param string URI to test.
    * @return bool True if a URI idenfies a remote resource with an allowed
    *              protocol.
    * @task uri
    */
   public static function isValidRemoteURIForLink($uri) {
     try {
       self::requireValidRemoteURIForLink($uri);
       return true;
     } catch (Exception $ex) {
       return false;
     }
   }
 
 
   /**
    * Detect if a URI identifies a valid linkable remote resource, throwing a
    * detailed message if it does not.
    *
    * A valid linkable remote resource can be safely linked or redirected to.
    * This is primarily a protocol whitelist check.
    *
    * @param string URI to test.
    * @return void
    * @task uri
    */
   public static function requireValidRemoteURIForLink($raw_uri) {
     $uri = new PhutilURI($raw_uri);
 
     $proto = $uri->getProtocol();
     if (!strlen($proto)) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid linkable resource. A valid linkable '.
           'resource URI must specify a protocol.',
           $raw_uri));
     }
 
     $protocols = self::getEnvConfig('uri.allowed-protocols');
     if (!isset($protocols[$proto])) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid linkable resource. A valid linkable '.
           'resource URI must use one of these protocols: %s.',
           $raw_uri,
           implode(', ', array_keys($protocols))));
     }
 
     $domain = $uri->getDomain();
     if (!strlen($domain)) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid linkable resource. A valid linkable '.
           'resource URI must specify a domain.',
           $raw_uri));
     }
   }
 
 
   /**
    * Detect if a URI identifies a valid fetchable remote resource.
    *
    * @param string URI to test.
    * @param list<string> Allowed protocols.
    * @return bool True if the URI is a valid fetchable remote resource.
    * @task uri
    */
   public static function isValidRemoteURIForFetch($uri, array $protocols) {
     try {
       self::requireValidRemoteURIForFetch($uri, $protocols);
       return true;
     } catch (Exception $ex) {
       return false;
     }
   }
 
 
   /**
    * Detect if a URI identifies a valid fetchable remote resource, throwing
    * a detailed message if it does not.
    *
    * A valid fetchable remote resource can be safely fetched using a request
    * originating on this server. This is a primarily an address check against
    * the outbound address blacklist.
    *
    * @param string URI to test.
    * @param list<string> Allowed protocols.
    * @return pair<string, string> Pre-resolved URI and domain.
    * @task uri
    */
   public static function requireValidRemoteURIForFetch(
     $uri,
     array $protocols) {
 
     $uri = new PhutilURI($uri);
 
     $proto = $uri->getProtocol();
     if (!strlen($proto)) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid fetchable resource. A valid fetchable '.
           'resource URI must specify a protocol.',
           $uri));
     }
 
     $protocols = array_fuse($protocols);
     if (!isset($protocols[$proto])) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid fetchable resource. A valid fetchable '.
           'resource URI must use one of these protocols: %s.',
           $uri,
           implode(', ', array_keys($protocols))));
     }
 
     $domain = $uri->getDomain();
     if (!strlen($domain)) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid fetchable resource. A valid fetchable '.
           'resource URI must specify a domain.',
           $uri));
     }
 
     $addresses = gethostbynamel($domain);
     if (!$addresses) {
       throw new Exception(
         pht(
           'URI "%s" is not a valid fetchable resource. The domain "%s" could '.
           'not be resolved.',
           $uri,
           $domain));
     }
 
     foreach ($addresses as $address) {
       if (self::isBlacklistedOutboundAddress($address)) {
         throw new Exception(
           pht(
             'URI "%s" is not a valid fetchable resource. The domain "%s" '.
             'resolves to the address "%s", which is blacklisted for '.
             'outbound requests.',
             $uri,
             $domain,
             $address));
       }
     }
 
     $resolved_uri = clone $uri;
     $resolved_uri->setDomain(head($addresses));
 
     return array($resolved_uri, $domain);
   }
 
 
   /**
    * Determine if an IP address is in the outbound address blacklist.
    *
    * @param string IP address.
    * @return bool True if the address is blacklisted.
    */
   public static function isBlacklistedOutboundAddress($address) {
     $blacklist = self::getEnvConfig('security.outbound-blacklist');
 
     return PhutilCIDRList::newList($blacklist)->containsAddress($address);
   }
 
   public static function isClusterRemoteAddress() {
     $cluster_addresses = self::getEnvConfig('cluster.addresses');
     if (!$cluster_addresses) {
       return false;
     }
 
     $address = idx($_SERVER, 'REMOTE_ADDR');
     if (!$address) {
       throw new Exception(
         pht(
           'Unable to test remote address against cluster whitelist: '.
           'REMOTE_ADDR is not defined.'));
     }
 
     return self::isClusterAddress($address);
   }
 
   public static function isClusterAddress($address) {
     $cluster_addresses = self::getEnvConfig('cluster.addresses');
     if (!$cluster_addresses) {
       throw new Exception(
         pht(
           'Phabricator is not configured to serve cluster requests. '.
           'Set `cluster.addresses` in the configuration to whitelist '.
           'cluster hosts before sending requests that use a cluster '.
           'authentication mechanism.'));
     }
 
     return PhutilCIDRList::newList($cluster_addresses)
       ->containsAddress($address);
   }
 
 /* -(  Internals  )---------------------------------------------------------- */
 
 
   /**
    * @task internal
    */
   public static function envConfigExists($key) {
     return array_key_exists($key, self::$sourceStack->getKeys(array($key)));
   }
 
 
   /**
    * @task internal
    */
   public static function getAllConfigKeys() {
     return self::$sourceStack->getAllKeys();
   }
 
   public static function getConfigSourceStack() {
     return self::$sourceStack;
   }
 
   /**
    * @task internal
    */
   public static function overrideTestEnvConfig($stack_key, $key, $value) {
     $tmp = array();
 
     // If we don't have the right key, we'll throw when popping the last
     // source off the stack.
     do {
       $source = self::$sourceStack->popSource();
       array_unshift($tmp, $source);
       if (spl_object_hash($source) == $stack_key) {
         $source->setKeys(array($key => $value));
         break;
       }
     } while (true);
 
     foreach ($tmp as $source) {
       self::$sourceStack->pushSource($source);
     }
 
     self::dropConfigCache();
   }
 
   private static function dropConfigCache() {
     self::$cache = array();
   }
 
   private static function resetUmask() {
     // Reset the umask to the common standard umask. The umask controls default
     // permissions when files are created and propagates to subprocesses.
 
     // "022" is the most common umask, but sometimes it is set to something
     // unusual by the calling environment.
 
     // Since various things rely on this umask to work properly and we are
     // not aware of any legitimate reasons to adjust it, unconditionally
     // normalize it until such reasons arise. See T7475 for discussion.
     umask(022);
   }
 
 
   /**
    * Get the path to an empty directory which is readable by all of the system
    * user accounts that Phabricator acts as.
    *
    * In some cases, a binary needs some valid HOME or CWD to continue, but not
    * all user accounts have valid home directories and even if they do they
    * may not be readable after a `sudo` operation.
    *
    * @return string Path to an empty directory suitable for use as a CWD.
    */
   public static function getEmptyCWD() {
     $root = dirname(phutil_get_library_root('phabricator'));
     return $root.'/support/empty/';
   }
 
 
 }