PoC fix for asyncpoll blocked forever after close

hhvm.diff

diff --git a/hphp/runtime/base/file-await.cpp b/hphp/runtime/base/file-await.cpp
index 6414eac085..78a3cdb366 100644
--- a/hphp/runtime/base/file-await.cpp
+++ b/hphp/runtime/base/file-await.cpp
@@ -21,6 +21,12 @@ void FileEventHandler::handlerReady(uint16_t events) noexcept {
 
 /////////////////////////////////////////////////////////////////////////////
 
+void FileAwait::jj_cancel() {
+  if (m_file) {
+    m_file->unregisterHandler();
+  }
+}
+
 FileAwait::FileAwait(
   int fd,
   uint16_t events,
diff --git a/hphp/runtime/base/file-await.h b/hphp/runtime/base/file-await.h
index 972ea43a53..a543904f6a 100644
--- a/hphp/runtime/base/file-await.h
+++ b/hphp/runtime/base/file-await.h
@@ -46,6 +46,8 @@ struct FileAwait : AsioExternalThreadEvent {
     CLOSED,
   };
 
+  void jj_cancel();
+
   FileAwait(int fd, uint16_t events, std::chrono::nanoseconds timeout);
   ~FileAwait();
   void unserialize(TypedValue& c) override;
diff --git a/hphp/runtime/ext/asio/ext_external-thread-event-wait-handle.h b/hphp/runtime/ext/asio/ext_external-thread-event-wait-handle.h
index 9c62636952..d6b24595c9 100644
--- a/hphp/runtime/ext/asio/ext_external-thread-event-wait-handle.h
+++ b/hphp/runtime/ext/asio/ext_external-thread-event-wait-handle.h
@@ -55,6 +55,10 @@ struct c_ExternalThreadEventWaitHandle final : c_WaitableWaitHandle {
   }
   ObjectData* getPrivData() { return m_privData.get(); }
 
+  // Yes I know, there's probably a good reason why this wasn't here, but this
+  // is just a PoC so bear with me.
+  AsioExternalThreadEvent* getEvent() { return m_event; }
+
   void abandon(bool sweeping);
   bool cancel(const Object& exception);
   void process();
diff --git a/hphp/runtime/ext/hsl/ext_hsl_os.cpp b/hphp/runtime/ext/hsl/ext_hsl_os.cpp
index 9a20a4f1a2..af4842ffa7 100644
--- a/hphp/runtime/ext/hsl/ext_hsl_os.cpp
+++ b/hphp/runtime/ext/hsl/ext_hsl_os.cpp
@@ -586,6 +586,18 @@ void HHVM_FUNCTION(HSL_os_close, const Object& obj) {
   HSLFileDescriptor::get(obj)->close();
 }
 
+void HHVM_FUNCTION(HSL_os_cancel_async_poll, const Object& obj) {
+  if (!obj->instanceof(c_ExternalThreadEventWaitHandle::classof())) {
+    SystemLib::throwInvalidArgumentExceptionObject(
+      "Argument must be ExternalThreadEventWaitHandle");
+  }
+  c_ExternalThreadEventWaitHandle* handle =
+    wait_handle<c_ExternalThreadEventWaitHandle>(obj.get());
+  AsioExternalThreadEvent* event = handle->getEvent();
+  FileAwait* file_await = static_cast<FileAwait*>(event);
+  file_await->jj_cancel();
+}
+
 Array HHVM_FUNCTION(HSL_os_pipe) {
   int fds[2];
   throw_errno_if_minus_one(retry_on_eintr(-1, ::pipe, fds));
@@ -1202,6 +1214,7 @@ struct OSExtension final : Extension {
     HHVM_FALIAS(HH\\Lib\\_Private\\_OS\\read, HSL_os_read);
     HHVM_FALIAS(HH\\Lib\\_Private\\_OS\\write, HSL_os_write);
     HHVM_FALIAS(HH\\Lib\\_Private\\_OS\\close, HSL_os_close);
+    HHVM_FALIAS(HH\\Lib\\_Private\\_OS\\cancel_async_poll, HSL_os_cancel_async_poll);
 
     HHVM_FALIAS(HH\\Lib\\_Private\\_OS\\request_stdio_fd, HSL_os_request_stdio_fd);
     HHVM_RC_INT(HH\\Lib\\_Private\\_OS\\STDIN_FILENO, STDIN_FILENO);
diff --git a/hphp/runtime/ext/hsl/ext_hsl_os.php b/hphp/runtime/ext/hsl/ext_hsl_os.php
index 506465508e..01978f80f1 100644
--- a/hphp/runtime/ext/hsl/ext_hsl_os.php
+++ b/hphp/runtime/ext/hsl/ext_hsl_os.php
@@ -55,6 +55,9 @@ function write(FileDescriptor $fd, string $data): int;
 <<__Native>>
 function close(FileDescriptor $fd): void;
 
+<<__Native>>
+function cancel_async_poll(WaitHandle $wait_handle): void;
+
 <<__Native>>
 function pipe(): varray<FileDescriptor>;
 

hsl-experimental.diff

diff --git a/src/network/_Private/CancelablePoller.php b/src/network/_Private/CancelablePoller.php
index 9cc13c8..5cb382a 100644
--- a/src/network/_Private/CancelablePoller.php
+++ b/src/network/_Private/CancelablePoller.php
@@ -39,6 +39,7 @@ final class CancelablePoller {
   public function cancelAll(int $result): void {
     $ex = new PollCancelledException($result);
     foreach ($this->polls as $poll) {
+      _OS\cancel_async_poll($poll);
       \HH\Asio\cancel($poll, $ex);
     }
   }