Provide a hook for aborted workflow

Summary:
We start Sandcastle push when `arc diff` starts.
If `arc diff` throws then HHVM waits for finishing the futures.
We need to kill them sooner.

Test Plan: Will implement the hook.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D3713

scripts/arcanist.php

@@ -319,25 +319,27 @@ try {
   $config->didRunWorkflow($command, $workflow, $err);
   exit((int)$err);
 
-} catch (ArcanistUsageException $ex) {
+} catch (Exception $ex) {
+  $is_usage = ($ex instanceof ArcanistUsageException);
+  if ($is_usage) {
     echo phutil_console_format(
       "**Usage Exception:** %s\n",
       $ex->getMessage());
+  }
+
+  $config->didAbortWorkflow($command, $workflow, $ex);
+
   if ($config_trace_mode) {
     echo "\n";
     throw $ex;
   }
 
-  exit(1);
+  if (!$is_usage) {
-} catch (Exception $ex) {
-  if ($config_trace_mode) {
-    throw $ex;
-  }
-
     echo phutil_console_format(
       "**Exception**\n%s\n%s\n",
       $ex->getMessage(),
       "(Run with --trace for a full exception trace.)");
+  }
 
   exit(1);
 }

src/configuration/ArcanistConfiguration.php

@@ -29,7 +29,7 @@
  *    - create, replace, or disable workflows by overriding buildWorkflow()
  *      and buildAllWorkflows();
  *    - add additional steps before or after workflows run by overriding
- *      willRunWorkflow() or didRunWorkflow(); and
+ *      willRunWorkflow() or didRunWorkflow() or didAbortWorkflow(); and
  *    - add new flags to existing workflows by overriding
  *      getCustomArgumentsForCommand().
  *
@@ -93,6 +93,14 @@ class ArcanistConfiguration {
     // This is a hook.
   }
 
+  public function didAbortWorkflow(
+    $command,
+    ArcanistBaseWorkflow $workflow,
+    Exception $ex) {
+
+    // This is a hook.
+  }
+
   public function getCustomArgumentsForCommand($command) {
     return array();
   }