Release Hermes WeakRef targets after draining jobs

Core/Node-API/Source/env_hermes.cc

@@ -164,6 +164,8 @@ namespace Napi
         // exceptions thrown FROM user callbacks are already handled in
         // AppRuntime::Dispatch's try/catch.
         (void)runtime->drainJobs();
+        // WeakRef targets are kept alive only until the current job finishes.
+        runtime->clearKeptObjects();
     }
 
     Napi::Value Eval(Napi::Env env, const char* source, const char* sourceUrl)

Tests/UnitTests/CMakeLists.txt

@@ -65,6 +65,8 @@ endif()
 
 if(NAPI_JAVASCRIPT_ENGINE STREQUAL "Chakra")
     set(SOURCES ${SOURCES} "Source/Tests.NodeApi.Chakra.cpp")
+elseif(NAPI_JAVASCRIPT_ENGINE STREQUAL "Hermes")
+    set(SOURCES ${SOURCES} "Source/Tests.NodeApi.Hermes.cpp")
 elseif(NAPI_JAVASCRIPT_ENGINE STREQUAL "JavaScriptCore")
     set(SOURCES ${SOURCES} "Source/Tests.NodeApi.JavaScriptCore.cpp")
 endif()

Tests/UnitTests/Source/Scripts/tests.scheduling.ts

@@ -14,10 +14,10 @@ describe("setTimeout", function () {
     });
 
     it("should call the given function after the given delay", function (done) {
-        const startTime = new Date().getTime();
+        const startTime = performance.now();
         setTimeout(() => {
             try {
-                expect(new Date().getTime() - startTime).to.be.at.least(10);
+                expect(performance.now() - startTime).to.be.at.least(10);
                 done();
             }
             catch (e) {
@@ -27,11 +27,11 @@ describe("setTimeout", function () {
     });
 
     it("should call the given nested function after the given delay", function (done) {
-        const startTime = new Date().getTime();
+        const startTime = performance.now();
         setTimeout(() => {
             setTimeout(() => {
                 try {
-                    expect(new Date().getTime() - startTime).to.be.at.least(20);
+                    expect(performance.now() - startTime).to.be.at.least(20);
                     done();
                 }
                 catch (e) {
@@ -42,10 +42,10 @@ describe("setTimeout", function () {
     });
 
     it("should call the given function after the given delay when the delay is a string representing a valid number", function (done) {
-        const startTime = new Date().getTime();
+        const startTime = performance.now();
         setTimeout(() => {
             try {
-                expect(new Date().getTime() - startTime).to.be.at.least(10);
+                expect(performance.now() - startTime).to.be.at.least(10);
                 done();
             }
             catch (e) {
@@ -143,12 +143,12 @@ describe("setInterval", function () {
     });
 
     it("should call the given function at the given interval", function (done) {
-        let startTime = new Date().getTime();
+        const startTime = performance.now();
         let tickCount = 0;
         const id = setInterval(() => {
             try {
                 tickCount++;
-                expect(new Date().getTime() - startTime).to.be.at.least(tickCount * 10);
+                expect(performance.now() - startTime).to.be.at.least(tickCount * 10);
                 if (tickCount > 2) {
                     clearInterval(id);
                     done();

Tests/UnitTests/Source/Tests.NodeApi.Hermes.cpp

@@ -0,0 +1,36 @@
+#include <Babylon/AppRuntime.h>
+#include <gtest/gtest.h>
+#include <napi/env.h>
+
+#include <chrono>
+#include <future>
+#include <stdexcept>
+
+TEST(NodeApi, HermesDrainJobsReleasesWeakRefTargets)
+{
+    std::promise<double> externalBytes;
+    auto completed = externalBytes.get_future();
+    Babylon::AppRuntime runtime{};
+    runtime.Dispatch([&](Napi::Env env) {
+        try
+        {
+            for (size_t i = 0; i < 256; ++i)
+            {
+                {
+                    Napi::HandleScope scope{env};
+                    Napi::Eval(env, "new WeakRef(new Uint8Array(1024 * 1024));", "weakref-job.js");
+                }
+                Napi::DrainJobs(env);
+            }
+            externalBytes.set_value(Napi::Eval(env,
+                "HermesInternal.getInstrumentedStats().js_externalBytes",
+                "weakref-heap.js").As<Napi::Number>().DoubleValue());
+        }
+        catch (const Napi::Error& error)
+        {
+            externalBytes.set_exception(std::make_exception_ptr(std::runtime_error{error.Message()}));
+        }
+    });
+    ASSERT_EQ(completed.wait_for(std::chrono::seconds{30}), std::future_status::ready);
+    EXPECT_LT(completed.get(), 64 * 1024 * 1024);
+}