add pagelet_server_is_done primitive

Summary: In order to fix the hhvm crash from pageletserver error handler flushing output after the output buffer has closed, we need a way to tell if the pagelet thread is done; currently there is no good way to do this from inside the thread itself.

Reviewed By: jano

Differential Revision: D3858448

fbshipit-source-id: 826930f6667b8b3f067e39dd7ae6ed4b0eb5a08a

hphp/runtime/ext/server/ext_server.cpp

@@ -46,6 +46,7 @@ static struct ServerExtension final : Extension {
     HHVM_FE(pagelet_server_task_result);
     HHVM_FE(pagelet_server_tasks_started);
     HHVM_FE(pagelet_server_flush);
+    HHVM_FE(pagelet_server_is_done);
     HHVM_FE(xbox_send_message);
     HHVM_FE(xbox_post_message);
     HHVM_FE(xbox_task_start);
@@ -139,6 +140,16 @@ void HHVM_FUNCTION(pagelet_server_flush) {
   }
 }
 
+bool HHVM_FUNCTION(pagelet_server_is_done) {
+  PageletTransport *job =
+    dynamic_cast<PageletTransport *>(g_context->getTransport());
+  if (job) {
+    return job->isDone();
+  }
+  // if we aren't in a pagelet thread, this call is meaningless
+  return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // xbox
 

hphp/runtime/ext/server/ext_server.h

@@ -47,6 +47,7 @@ String HHVM_FUNCTION(pagelet_server_task_result,
                      int64_t timeout_ms);
 int64_t HHVM_FUNCTION(pagelet_server_tasks_started);
 void HHVM_FUNCTION(pagelet_server_flush);
+bool HHVM_FUNCTION(pagelet_server_is_done);
 bool HHVM_FUNCTION(xbox_send_message,
                    const String& msg,
                    VRefParam ret,

hphp/runtime/ext/server/ext_server.php

@@ -87,6 +87,13 @@ function pagelet_server_tasks_started(): int;
 <<__HipHopSpecific, __Native>>
 function pagelet_server_flush(): void;
 
+/**
+ * Determine whether or not the pagelet thread we are executing on has finished
+ * and closed its output buffer.
+ */
+<<__HipHopSpecific, __Native>>
+function pagelet_server_is_done(): bool;
+
 /**
  * Sends an xbox message and waits for response. Please read server
  *   documentation for what an xbox is.