Experimental JS API based on tracking values

CMakeLists.txt

@@ -39,6 +39,7 @@ option(AVM_RELEASE "Build an AtomVM release" OFF)
 option(AVM_CREATE_STACKTRACES "Create stacktraces" ON)
 option(AVM_BUILD_RUNTIME_ONLY "Only build the AtomVM runtime" OFF)
 option(COVERAGE "Build for code coverage" OFF)
+option(AVM_USE_WASM_MJS "Use ES modules for Emscripten platform" OFF)
 option(AVM_PRINT_PROCESS_CRASH_DUMPS "Print crash reports when processes die with non-standard reasons" ON)
 
 # JIT & execution of precompiled code

src/platforms/emscripten/src/CMakeLists.txt

@@ -28,8 +28,12 @@ add_subdirectory(../../../libAtomVM libAtomVM)
 target_link_libraries(AtomVM PUBLIC libAtomVM)
 target_compile_options(libAtomVM PUBLIC -O3 -fno-exceptions -fno-rtti -pthread -sINLINING_LIMIT -sUSE_ZLIB=1)
 target_compile_definitions(libAtomVM PRIVATE WITH_ZLIB)
-target_link_options(AtomVM PRIVATE -sEXPORTED_RUNTIME_METHODS=ccall -sUSE_ZLIB=1 -O3 -pthread -sFETCH -lwebsocket.js --pre-js ${CMAKE_CURRENT_SOURCE_DIR}/atomvm.pre.js)
-
+if (AVM_USE_WASM_MJS)
+    target_link_options(AtomVM PRIVATE -sEXPORTED_RUNTIME_METHODS=ccall,cwrap,stringToNewUTF8 -sEMULATE_FUNCTION_POINTER_CASTS=1 -sEXPORTED_FUNCTIONS=_malloc,_cast,_call,_next_tracked_object_key,_main -sEXPORT_ES6=1 -sUSE_ZLIB=1 -O3 -pthread -sFETCH -lwebsocket.js --pre-js ${CMAKE_CURRENT_SOURCE_DIR}/atomvm.pre.js)
+    set(CMAKE_EXECUTABLE_SUFFIX ".mjs")
+else()
+    target_link_options(AtomVM PRIVATE -sEXPORTED_RUNTIME_METHODS=ccall -sUSE_ZLIB=1 -O3 -pthread -sFETCH -lwebsocket.js --pre-js ${CMAKE_CURRENT_SOURCE_DIR}/atomvm.pre.js)
+endif()
 if (CMAKE_BUILD_TYPE STREQUAL "Debug")
     target_link_options(AtomVM PRIVATE -sASSERTIONS=2 -sSAFE_HEAP -sSTACK_OVERFLOW_CHECK)
 endif()

src/platforms/emscripten/src/atomvm.pre.js

@@ -17,10 +17,60 @@
  *
  * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
  */
-Module['cast'] = function(name, message) {
-    ccall("cast", 'void', ['string', 'string'], [name, message]);
+Module["cast"] = function (name, message) {
+  ccall("cast", "void", ["string", "string"], [name, message]);
 };
-Module['call'] = async function(name, message) {
-    const promiseId = ccall("call", 'integer', ['string', 'string'], [name, message]);
-    return promiseMap.get(promiseId).promise;
+Module["call"] = async function (name, message) {
+  const promiseId = ccall(
+    "call",
+    "integer",
+    ["string", "string"],
+    [name, message],
+  );
+  return promiseMap.get(promiseId).promise;
 };
+
+// experimental API
+Module["nextTrackedObjectKey"] = function () {
+  return ccall("next_tracked_object_key", "integer", [], []);
+};
+Module["trackedObjectsMap"] = new Map();
+Module["onTrackedObjectDelete"] = (key) => {
+  Module["trackedObjectsMap"].delete(key);
+};
+Module["onGetTrackedObjects"] = (keys) => {
+  const getTrackedObject = (key) => Module["trackedObjectsMap"].get(key);
+  return keys.map(getTrackedObject);
+};
+Module["onRunTrackedJs"] = (scriptString, isDebug) => {
+  const trackValue = (value) => {
+    const key = Module["nextTrackedObjectKey"]();
+    Module["trackedObjectsMap"].set(key, value);
+    return key;
+  };
+
+  let result;
+  try {
+    const indirectEval = eval;
+    result = indirectEval(scriptString);
+  } catch (_e) {
+    return null;
+  }
+  isDebug && ensureValidResult(result);
+  return result?.map(trackValue) ?? [];
+};
+
+function ensureValidResult(result) {
+  const isIndex = (k) => typeof k === "number";
+
+  if (result === null) {
+    return;
+  }
+  if (Array.isArray(result) && keys.every(isIndex)) {
+    return;
+  }
+
+  const message =
+    "Evaluated script returned invalid value. Expected number array or null";
+  throw new Error(message);
+}

src/platforms/emscripten/src/lib/emscripten_sys.h

@@ -113,6 +113,7 @@ struct EmscriptenPlatformData
     pthread_mutex_t poll_mutex;
     pthread_cond_t poll_cond;
     struct ListHead messages;
+    atomic_size_t next_tracked_object_key;
     ErlNifResourceType *promise_resource_type;
     ErlNifResourceType *htmlevent_user_data_resource_type;
     ErlNifResourceType *websocket_resource_type;
@@ -134,6 +135,7 @@ void sys_enqueue_emscripten_cast_message(GlobalContext *glb, const char *target,
 em_promise_t sys_enqueue_emscripten_call_message(GlobalContext *glb, const char *target, const char *message);
 void sys_enqueue_emscripten_htmlevent_message(GlobalContext *glb, int32_t target_pid, term message, term user_data, HeapFragment *heap);
 void sys_enqueue_emscripten_unregister_htmlevent_message(GlobalContext *glb, struct HTMLEventUserDataResource *rsrc);
+size_t sys_get_next_tracked_object_key(GlobalContext *glb);
 void sys_promise_resolve_int_and_destroy(em_promise_t promise, em_promise_result_t result, int value);
 void sys_promise_resolve_str_and_destroy(em_promise_t promise, em_promise_result_t result, int value);
 

src/platforms/emscripten/src/lib/platform_defaultatoms.def

@@ -24,3 +24,4 @@ X(WEBSOCKET_ATOM, "\x9", "websocket")
 X(WEBSOCKET_OPEN_ATOM, "\xE", "websocket_open")
 X(WEBSOCKET_CLOSE_ATOM, "\xF", "websocket_close")
 X(WEBSOCKET_ERROR_ATOM, "\xF", "websocket_error")
+X(BADVALUE_ATOM, "\x8", "badvalue")