Make "exception" on Future a private property

Summary: Depends on D21034. Ref T11968. Continue modernizing Future.

Test Plan: Ran tests, created a revision.

Maniphest Tasks: T11968

Differential Revision: https://secure.phabricator.com/D21035

src/future/Future.php

@@ -9,8 +9,7 @@ abstract class Future extends Phobject {
 
   private $hasResult = false;
   private $result;
-
-  protected $exception;
+  private $exception;
 
   /**
    * Is this future's process complete? Specifically, can this future be
@@ -37,23 +36,34 @@ abstract class Future extends Phobject {
           'timeout.'));
     }
 
+    if (!$this->hasResult()) {
       $graph = new FutureIterator(array($this));
       $graph->resolveAll();
+    }
 
-    if ($this->exception) {
-      throw $this->exception;
+    if ($this->hasException()) {
+      throw $this->getException();
     }
 
     return $this->getResult();
   }
 
-  public function setException(Exception $ex) {
-    $this->exception = $ex;
-    return $this;
+  final public function updateFuture() {
+    if ($this->hasException()) {
+      return;
     }
 
-  public function getException() {
-    return $this->exception;
+    if ($this->hasResult()) {
+      return;
+    }
+
+    try {
+      $this->isReady();
+    } catch (Exception $ex) {
+      $this->setException($ex);
+    } catch (Throwable $ex) {
+      $this->setException($ex);
+    }
   }
 
   /**
@@ -125,8 +135,23 @@ abstract class Future extends Phobject {
     return $this;
   }
 
-  final protected function hasResult() {
+  final public function hasResult() {
     return $this->hasResult;
   }
 
+  final private function setException($exception) {
+    // NOTE: The parameter may be an Exception or a Throwable.
+    $this->exception = $exception;
+    return $this;
+  }
+
+  final private function getException() {
+    return $this->exception;
+  }
+
+  final public function hasException() {
+    return ($this->exception !== null);
+  }
+
+
 }

src/future/FutureIterator.php

@@ -180,6 +180,7 @@ final class FutureIterator extends Phobject implements Iterator {
     $this->isTimeout = false;
 
     $check = $this->getWorkingSet();
+
     $resolve = null;
     do {
       $read_sockets    = array();
@@ -188,12 +189,17 @@ final class FutureIterator extends Phobject implements Iterator {
       $wait_time       = 1;
       foreach ($check as $wait => $key) {
         $future = $this->futures[$key];
-        try {
-          if ($future->getException()) {
+
+        $future->updateFuture();
+
+        if ($future->hasException()) {
+          if ($resolve === null) {
             $resolve = $wait;
+          }
           continue;
         }
-          if ($future->isReady()) {
+
+        if ($future->hasResult()) {
           if ($resolve === null) {
             $resolve = $wait;
           }
@@ -224,12 +230,8 @@ final class FutureIterator extends Phobject implements Iterator {
         } else {
           $wait_time = min($wait_time, $future->getDefaultWait());
         }
-        } catch (Exception $ex) {
-          $this->futures[$key]->setException($ex);
-          $resolve = $wait;
-          break;
-        }
       }
+
       if ($resolve === null) {
 
         // Check for a setUpdateInterval() timeout.
@@ -253,6 +255,7 @@ final class FutureIterator extends Phobject implements Iterator {
 
     $this->key = $this->wait[$resolve];
     unset($this->wait[$resolve]);
+
     $this->updateWorkingSet();
   }
 

src/future/FutureProxy.php

@@ -27,25 +27,29 @@ abstract class FutureProxy extends Future {
   }
 
   public function isReady() {
-    return $this->getProxiedFuture()->isReady();
+    if ($this->hasResult()) {
+      return true;
+    }
+
+    $proxied = $this->getProxiedFuture();
+
+    $is_ready = $proxied->isReady();
+
+    if ($proxied->hasResult()) {
+      $result = $proxied->getResult();
+      $result = $this->didReceiveResult($result);
+      $this->setResult($result);
+    }
+
+    return $is_ready;
   }
 
   public function resolve() {
-    $result = $this->getProxiedFuture()->resolve();
-    $result = $this->didReceiveResult($result);
-    $this->setResult($result);
+    $this->getProxiedFuture()->resolve();
+    $this->isReady();
     return $this->getResult();
   }
 
-  public function setException(Exception $ex) {
-    $this->getProxiedFuture()->setException($ex);
-    return $this;
-  }
-
-  public function getException() {
-    return $this->getProxiedFuture()->getException();
-  }
-
   public function getReadSockets() {
     return $this->getProxiedFuture()->getReadSockets();
   }