Remove FetchEvent singleton (#1422)

Author: TartanLlama

runtime/fastly/builtins/fetch-event.cpp

@@ -532,7 +532,6 @@ namespace {
 
 api::Engine *ENGINE;
 
-PersistentRooted<JSObject *> INSTANCE;
 JS::PersistentRootedObjectVector *FETCH_HANDLERS;
 
 void inc_pending_promise_count(JSObject *self) {
@@ -798,6 +797,10 @@ bool response_promise_then_handler(JSContext *cx, JS::HandleObject event, JS::Ha
   // very different.)
   JS::RootedObject response_obj(cx, &args[0].toObject());
 
+  // Store the FetchEvent on the Response so it can be accessed later
+  JS::SetReservedSlot(response_obj, static_cast<uint32_t>(Response::Slots::FetchEvent),
+                      JS::ObjectValue(*event));
+
   if (Response::is_upstream(response_obj)) {
     JS::RootedObject headers(cx, Response::headers(cx, response_obj));
     // Calling get_list() transitions to Mode::ContentOnly or Mode::CachedInContent.
@@ -1059,7 +1062,6 @@ JSObject *FetchEvent::create(JSContext *cx) {
     return nullptr;
   }
 
-  INSTANCE.init(cx, self);
   return self;
 }
 
@@ -1085,12 +1087,6 @@ bool FetchEvent::reset(JSContext *cx, JS::HandleObject self) {
   return true;
 }
 
-JS::HandleObject FetchEvent::instance() {
-  MOZ_ASSERT(INSTANCE);
-  MOZ_ASSERT(is_instance(INSTANCE));
-  return INSTANCE;
-}
-
 bool FetchEvent::is_active(JSObject *self) {
   MOZ_ASSERT(is_instance(self));
   // Note: we also treat the FetchEvent as active if it's in `responseStreaming`

runtime/fastly/builtins/fetch/request-response.cpp

@@ -1754,7 +1754,14 @@ bool RequestOrResponse::body_reader_then_handler(JSContext *cx, JS::HandleObject
     // `responseDone`.
     if (Response::is_instance(body_owner)) {
       ENGINE->decr_event_loop_interest();
-      FetchEvent::set_state(FetchEvent::instance(), FetchEvent::State::responseDone);
+      JS::RootedValue fetch_event_val(
+          cx, JS::GetReservedSlot(body_owner, static_cast<uint32_t>(Response::Slots::FetchEvent)));
+      if (!fetch_event_val.isObject()) {
+        JS_ReportErrorASCII(cx, "Response does not have an associated FetchEvent");
+        return false;
+      }
+      JS::RootedObject fetch_event(cx, &fetch_event_val.toObject());
+      FetchEvent::set_state(fetch_event, FetchEvent::State::responseDone);
     }
 
     auto res = body.close();
@@ -1844,7 +1851,14 @@ bool RequestOrResponse::body_reader_catch_handler(JSContext *cx, JS::HandleObjec
   // a response at all failed.)
   if (Response::is_instance(body_owner)) {
     ENGINE->decr_event_loop_interest();
-    FetchEvent::set_state(FetchEvent::instance(), FetchEvent::State::responseDone);
+    JS::RootedValue fetch_event_val(
+        cx, JS::GetReservedSlot(body_owner, static_cast<uint32_t>(Response::Slots::FetchEvent)));
+    if (!fetch_event_val.isObject()) {
+      JS_ReportErrorASCII(cx, "Response does not have an associated FetchEvent");
+      return false;
+    }
+    JS::RootedObject fetch_event(cx, &fetch_event_val.toObject());
+    FetchEvent::set_state(fetch_event, FetchEvent::State::responseDone);
   }
   return true;
 }

runtime/fastly/builtins/fetch/request-response.h

@@ -22,6 +22,7 @@ class RequestOrResponse final {
     Backend,
     CacheEntry,
     SourceRequest, // Tracks the original Request when body is proxied via TransformStream
+    FetchEvent,
     Count,
   };
 
@@ -174,6 +175,7 @@ class Request final : public builtins::BuiltinImpl<Request> {
     Backend = static_cast<int>(RequestOrResponse::Slots::Backend),
     CacheEntry = static_cast<int>(RequestOrResponse::Slots::CacheEntry),
     SourceRequest = static_cast<int>(RequestOrResponse::Slots::SourceRequest),
+    FetchEvent = static_cast<int>(RequestOrResponse::Slots::FetchEvent),
     Method = static_cast<int>(RequestOrResponse::Slots::Count),
     OverrideCacheKey,
     CacheOverride,
@@ -265,6 +267,7 @@ class Response final : public builtins::FinalizableBuiltinImpl<Response> {
     Backend = static_cast<int>(RequestOrResponse::Slots::Backend),
     CacheEntry = static_cast<int>(RequestOrResponse::Slots::CacheEntry),
     SourceRequest = static_cast<int>(RequestOrResponse::Slots::SourceRequest),
+    FetchEvent = static_cast<int>(RequestOrResponse::Slots::FetchEvent),
     IsUpstream = static_cast<int>(RequestOrResponse::Slots::Count),
     Status,
     StatusMessage,

runtime/fastly/handler.cpp

@@ -36,15 +36,15 @@ void handle_incoming(host_api::Request req) {
     start = system_clock::now();
   }
 
-  __wasilibc_initialize_environ();
+  __wasilibc_ensure_environ();
 
   if (ENGINE->debug_logging_enabled()) {
     printf("Running JS handleRequest function for Fastly Compute service version %s\n",
            getenv("FASTLY_SERVICE_VERSION"));
     fflush(stdout);
   }
 
-  HandleObject fetch_event = FetchEvent::instance();
+  RootedObject fetch_event(ENGINE->cx(), FetchEvent::create(ENGINE->cx()));
   if (!FetchEvent::init_request(ENGINE->cx(), fetch_event, req.req, req.body)) {
     ENGINE->dump_pending_exception("initialization of FetchEvent");
     return;
@@ -176,13 +176,6 @@ int main(int argc, const char *argv[]) {
       HANDLE_ERROR(ENGINE->cx(), *req.to_err());
       return -1;
     }
-
-    // The FetchEvent instance is a singleton that we re-initialize here. It's originally
-    // initialized during engine setup.
-    if (!FetchEvent::reset(fastly::runtime::ENGINE->cx(), FetchEvent::instance())) {
-      fprintf(stderr, "Failed to reset FetchEvent instance for new request, exiting process.\n");
-      return -1;
-    }
   }
 
   if (fastly::runtime::ENGINE->debug_logging_enabled()) {