n-api: Reference and external tests

 - Add a test project to addons-napi that covers the
   N-API reference and external APIs
 - Fix a bug in napi_typeof that was found by the new tests

Backport-PR-URL: #19447
PR-URL: #12551
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

src/node_api.cc

@@ -1465,6 +1465,10 @@ napi_status napi_typeof(napi_env env,
     // This test has to come before IsObject because IsFunction
     // implies IsObject
     *result = napi_function;
+  } else if (v->IsExternal()) {
+    // This test has to come before IsObject because IsExternal
+    // implies IsObject
+    *result = napi_external;
   } else if (v->IsObject()) {
     *result = napi_object;
   } else if (v->IsBoolean()) {
@@ -1475,8 +1479,6 @@ napi_status napi_typeof(napi_env env,
     *result = napi_symbol;
   } else if (v->IsNull()) {
     *result = napi_null;
-  } else if (v->IsExternal()) {
-    *result = napi_external;
   } else {
     // Should not get here unless V8 has added some new kind of value.
     return napi_set_last_error(env, napi_invalid_arg);

test/addons-napi/common.h

@@ -50,3 +50,6 @@
 
 #define DECLARE_NAPI_PROPERTY(name, func)                                \
   { (name), 0, (func), 0, 0, 0, napi_default, 0 }
+
+#define DECLARE_NAPI_GETTER(name, func)                                  \
+  { (name), 0, 0, (func), 0, 0, napi_default, 0 }

test/addons-napi/test_reference/binding.gyp

@@ -0,0 +1,8 @@
+{
+  "targets": [
+    {
+      "target_name": "test_reference",
+      "sources": [ "test_reference.c" ]
+    }
+  ]
+}

test/addons-napi/test_reference/test.js

@@ -0,0 +1,87 @@
+'use strict';
+// Flags: --expose-gc
+
+const common = require('../../common');
+const assert = require('assert');
+
+const test_reference = require(`./build/${common.buildType}/test_reference`);
+
+// This test script uses external values with finalizer callbacks
+// in order to track when values get garbage-collected. Each invocation
+// of a finalizer callback increments the finalizeCount property.
+assert.strictEqual(test_reference.finalizeCount, 0);
+
+{
+  // External value without a finalizer
+  let value = test_reference.createExternal();
+  assert.strictEqual(test_reference.finalizeCount, 0);
+  assert.strictEqual(typeof value, 'object');
+  test_reference.checkExternal(value);
+  value = null;
+  global.gc();
+  assert.strictEqual(test_reference.finalizeCount, 0);
+}
+
+{
+  // External value with a finalizer
+  let value = test_reference.createExternalWithFinalize();
+  assert.strictEqual(test_reference.finalizeCount, 0);
+  assert.strictEqual(typeof value, 'object');
+  test_reference.checkExternal(value);
+  value = null;
+  global.gc();
+  assert.strictEqual(test_reference.finalizeCount, 1);
+}
+
+{
+  // Weak reference
+  let value = test_reference.createExternalWithFinalize();
+  assert.strictEqual(test_reference.finalizeCount, 0);
+  test_reference.createReference(value, 0);
+  assert.strictEqual(test_reference.referenceValue, value);
+  value = null;
+  global.gc(); // Value should be GC'd because there is only a weak ref
+  assert.strictEqual(test_reference.referenceValue, undefined);
+  assert.strictEqual(test_reference.finalizeCount, 1);
+  test_reference.deleteReference();
+}
+
+{
+  // Strong reference
+  let value = test_reference.createExternalWithFinalize();
+  assert.strictEqual(test_reference.finalizeCount, 0);
+  test_reference.createReference(value, 1);
+  assert.strictEqual(test_reference.referenceValue, value);
+  value = null;
+  global.gc(); // Value should NOT be GC'd because there is a strong ref
+  assert.strictEqual(test_reference.finalizeCount, 0);
+  test_reference.deleteReference();
+  global.gc(); // Value should be GC'd because the strong ref was deleted
+  assert.strictEqual(test_reference.finalizeCount, 1);
+}
+
+{
+  // Strong reference, increment then decrement to weak reference
+  let value = test_reference.createExternalWithFinalize();
+  assert.strictEqual(test_reference.finalizeCount, 0);
+  test_reference.createReference(value, 1);
+  value = null;
+  global.gc(); // Value should NOT be GC'd because there is a strong ref
+  assert.strictEqual(test_reference.finalizeCount, 0);
+
+  assert.strictEqual(test_reference.incrementRefcount(), 2);
+  global.gc(); // Value should NOT be GC'd because there is a strong ref
+  assert.strictEqual(test_reference.finalizeCount, 0);
+
+  assert.strictEqual(test_reference.decrementRefcount(), 1);
+  global.gc(); // Value should NOT be GC'd because there is a strong ref
+  assert.strictEqual(test_reference.finalizeCount, 0);
+
+  assert.strictEqual(test_reference.decrementRefcount(), 0);
+  global.gc(); // Value should be GC'd because the ref is now weak!
+  assert.strictEqual(test_reference.finalizeCount, 1);
+
+  test_reference.deleteReference();
+  global.gc(); // Value was already GC'd
+  assert.strictEqual(test_reference.finalizeCount, 1);
+}

test/addons-napi/test_reference/test_reference.c

@@ -0,0 +1,153 @@
+#include <node_api.h>
+#include "../common.h"
+#include <stdlib.h>
+
+static int test_value = 1;
+static int finalize_count = 0;
+static napi_ref test_reference = NULL;
+
+napi_value GetFinalizeCount(napi_env env, napi_callback_info info) {
+  napi_value result;
+  NAPI_CALL(env, napi_create_number(env, finalize_count, &result));
+  return result;
+}
+
+void FinalizeExternal(napi_env env, void* data, void* hint) {
+  free(data);
+  finalize_count++;
+}
+
+napi_value CreateExternal(napi_env env, napi_callback_info info) {
+  int* data = &test_value;
+
+  napi_value result;
+  NAPI_CALL(env,
+    napi_create_external(env,
+                         data,
+                         NULL, /* finalize_cb */
+                         NULL, /* finalize_hint */
+                         &result));
+
+  finalize_count = 0;
+  return result;
+}
+
+napi_value CreateExternalWithFinalize(napi_env env, napi_callback_info info) {
+  int* data = malloc(sizeof(int));
+  *data = test_value;
+
+  napi_value result;
+  NAPI_CALL(env,
+    napi_create_external(env,
+                         data,
+                         FinalizeExternal,
+                         NULL, /* finalize_hint */
+                         &result));
+
+  finalize_count = 0;
+  return result;
+}
+
+napi_value CheckExternal(napi_env env, napi_callback_info info) {
+  size_t argc = 1;
+  napi_value arg;
+  NAPI_CALL(env, napi_get_cb_info(env, info, &argc, &arg, NULL, NULL));
+
+  NAPI_ASSERT(env, argc == 1, "Expected one argument.");
+
+  napi_valuetype argtype;
+  NAPI_CALL(env, napi_typeof(env, arg, &argtype));
+
+  NAPI_ASSERT(env, argtype == napi_external, "Expected an external value.")
+
+  int* data;
+  NAPI_CALL(env, napi_get_value_external(env, arg, &data));
+
+  NAPI_ASSERT(env, data != NULL && *data == test_value,
+    "An external data value of 1 was expected.")
+
+  return NULL;
+}
+
+napi_value CreateReference(napi_env env, napi_callback_info info) {
+  NAPI_ASSERT(env, test_reference == NULL,
+    "The test allows only one reference at a time.");
+
+  size_t argc = 2;
+  napi_value args[2];
+  NAPI_CALL(env, napi_get_cb_info(env, info, &argc, args, NULL, NULL));
+  NAPI_ASSERT(env, argc == 2, "Expected two arguments.");
+
+  uint32_t initial_refcount;
+  NAPI_CALL(env, napi_get_value_uint32(env, args[1], &initial_refcount));
+
+  NAPI_CALL(env,
+    napi_create_reference(env, args[0], initial_refcount, &test_reference));
+
+  NAPI_ASSERT(env, test_reference != NULL,
+    "A reference should have been created.");
+
+  return NULL;
+}
+
+napi_value DeleteReference(napi_env env, napi_callback_info info) {
+  NAPI_ASSERT(env, test_reference != NULL,
+    "A reference must have been created.");
+
+  NAPI_CALL(env, napi_delete_reference(env, test_reference));
+  test_reference = NULL;
+  return NULL;
+}
+
+napi_value IncrementRefcount(napi_env env, napi_callback_info info) {
+  NAPI_ASSERT(env, test_reference != NULL,
+    "A reference must have been created.");
+
+  uint32_t refcount;
+  NAPI_CALL(env, napi_reference_ref(env, test_reference, &refcount));
+
+  napi_value result;
+  NAPI_CALL(env, napi_create_number(env, refcount, &result));
+  return result;
+}
+
+napi_value DecrementRefcount(napi_env env, napi_callback_info info) {
+  NAPI_ASSERT(env, test_reference != NULL,
+    "A reference must have been created.");
+
+  uint32_t refcount;
+  NAPI_CALL(env, napi_reference_unref(env, test_reference, &refcount));
+
+  napi_value result;
+  NAPI_CALL(env, napi_create_number(env, refcount, &result));
+  return result;
+}
+
+napi_value GetReferenceValue(napi_env env, napi_callback_info info) {
+  NAPI_ASSERT(env, test_reference != NULL,
+    "A reference must have been created.");
+
+  napi_value result;
+  NAPI_CALL(env, napi_get_reference_value(env, test_reference, &result));
+  return result;
+}
+
+void Init(napi_env env, napi_value exports, napi_value module, void* priv) {
+  napi_property_descriptor descriptors[] = {
+    DECLARE_NAPI_GETTER("finalizeCount", GetFinalizeCount),
+    DECLARE_NAPI_PROPERTY("createExternal", CreateExternal),
+    DECLARE_NAPI_PROPERTY("createExternalWithFinalize",
+      CreateExternalWithFinalize),
+    DECLARE_NAPI_PROPERTY("checkExternal", CheckExternal),
+    DECLARE_NAPI_PROPERTY("createReference", CreateReference),
+    DECLARE_NAPI_PROPERTY("deleteReference", DeleteReference),
+    DECLARE_NAPI_PROPERTY("incrementRefcount", IncrementRefcount),
+    DECLARE_NAPI_PROPERTY("decrementRefcount", DecrementRefcount),
+    DECLARE_NAPI_GETTER("referenceValue", GetReferenceValue),
+  };
+
+  NAPI_CALL_RETURN_VOID(env, napi_define_properties(
+    env, exports, sizeof(descriptors) / sizeof(*descriptors), descriptors));
+}
+
+NAPI_MODULE(addon, Init)