xpcom/tests/gtest/TestGCPostBarriers.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * Tests that generational garbage collection post-barriers are correctly
   9  * implemented for nsTArrays that contain JavaScript Values.
  10  */
  11
  12 #include "mozilla/UniquePtr.h"
  13
  14 #include "jsapi.h"
  15 #include "nsTArray.h"
  16
  17 #include "gtest/gtest.h"
  18
  19 #include "js/PropertyAndElement.h"  // JS_GetProperty, JS_SetProperty
  20 #include "js/TracingAPI.h"
  21 #include "js/HeapAPI.h"
  22
  23 #include "mozilla/CycleCollectedJSContext.h"
  24
  25 using namespace mozilla;
  26
  27 template <class ArrayT>
  28 static void TraceArray(JSTracer* trc, void* data) {
  29   ArrayT* array = static_cast<ArrayT*>(data);
  30   for (unsigned i = 0; i < array->Length(); ++i) {
  31     JS::TraceEdge(trc, &array->ElementAt(i), "array-element");
  32   }
  33 }
  34
  35 /*
  36  * Use arrays with initial size much smaller than the final number of elements
  37  * to test that moving Heap<T> elements works correctly.
  38  */
  39 const size_t ElementCount = 100;
  40 const size_t InitialElements = ElementCount / 10;
  41
  42 template <class ArrayT>
  43 static void TestGrow(JSContext* cx) {
  44   JS_GC(cx);
  45
  46   auto array = MakeUnique<ArrayT>();
  47   ASSERT_TRUE(array != nullptr);
  48
  49   JS_AddExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
  50
  51   /*
  52    * Create the array and fill it with new JS objects. With GGC these will be
  53    * allocated in the nursery.
  54    */
  55   JS::RootedValue value(cx);
  56   const char* property = "foo";
  57   for (size_t i = 0; i < ElementCount; ++i) {
  58     JS::RootedObject obj(cx, JS_NewPlainObject(cx));
  59     ASSERT_FALSE(JS::ObjectIsTenured(obj));
  60     value = JS::Int32Value(static_cast<int32_t>(i));
  61     ASSERT_TRUE(JS_SetProperty(cx, obj, property, value));
  62     ASSERT_TRUE(array->AppendElement(obj, fallible));
  63   }
  64
  65   /*
  66    * If postbarriers are not working, we will crash here when we try to mark
  67    * objects that have been moved to the tenured heap.
  68    */
  69   JS_GC(cx);
  70
  71   /*
  72    * Sanity check that our array contains what we expect.
  73    */
  74   ASSERT_EQ(array->Length(), ElementCount);
  75   for (size_t i = 0; i < array->Length(); i++) {
  76     JS::RootedObject obj(cx, array->ElementAt(i));
  77     ASSERT_TRUE(JS::ObjectIsTenured(obj));
  78     ASSERT_TRUE(JS_GetProperty(cx, obj, property, &value));
  79     ASSERT_TRUE(value.isInt32());
  80     ASSERT_EQ(static_cast<int32_t>(i), value.toInt32());
  81   }
  82
  83   JS_RemoveExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
  84 }
  85
  86 template <class ArrayT>
  87 static void TestShrink(JSContext* cx) {
  88   JS_GC(cx);
  89
  90   auto array = MakeUnique<ArrayT>();
  91   ASSERT_TRUE(array != nullptr);
  92
  93   JS_AddExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
  94
  95   /*
  96    * Create the array and fill it with new JS objects. With GGC these will be
  97    * allocated in the nursery.
  98    */
  99   JS::RootedValue value(cx);
 100   const char* property = "foo";
 101   for (size_t i = 0; i < ElementCount; ++i) {
 102     JS::RootedObject obj(cx, JS_NewPlainObject(cx));
 103     ASSERT_FALSE(JS::ObjectIsTenured(obj));
 104     value = JS::Int32Value(static_cast<int32_t>(i));
 105     ASSERT_TRUE(JS_SetProperty(cx, obj, property, value));
 106     ASSERT_TRUE(array->AppendElement(obj, fallible));
 107   }
 108
 109   /* Shrink and compact the array */
 110   array->RemoveElementsAt(InitialElements, ElementCount - InitialElements);
 111   array->Compact();
 112
 113   JS_GC(cx);
 114
 115   ASSERT_EQ(array->Length(), InitialElements);
 116   for (size_t i = 0; i < array->Length(); i++) {
 117     JS::RootedObject obj(cx, array->ElementAt(i));
 118     ASSERT_TRUE(JS::ObjectIsTenured(obj));
 119     ASSERT_TRUE(JS_GetProperty(cx, obj, property, &value));
 120     ASSERT_TRUE(value.isInt32());
 121     ASSERT_EQ(static_cast<int32_t>(i), value.toInt32());
 122   }
 123
 124   JS_RemoveExtraGCRootsTracer(cx, TraceArray<ArrayT>, array.get());
 125 }
 126
 127 template <class ArrayT>
 128 static void TestArrayType(JSContext* cx) {
 129   TestGrow<ArrayT>(cx);
 130   TestShrink<ArrayT>(cx);
 131 }
 132
 133 static void CreateGlobalAndRunTest(JSContext* cx) {
 134   static const JSClass GlobalClass = {"global", JSCLASS_GLOBAL_FLAGS,
 135                                       &JS::DefaultGlobalClassOps};
 136
 137   JS::RealmOptions options;
 138   // dummy
 139   options.behaviors().setReduceTimerPrecisionCallerType(
 140       JS::RTPCallerTypeToken{0});
 141   JS::PersistentRootedObject global(cx);
 142   global = JS_NewGlobalObject(cx, &GlobalClass, nullptr,
 143                               JS::FireOnNewGlobalHook, options);
 144   ASSERT_TRUE(global != nullptr);
 145
 146   JS::Realm* oldRealm = JS::EnterRealm(cx, global);
 147
 148   using ElementT = JS::Heap<JSObject*>;
 149
 150   TestArrayType<nsTArray<ElementT>>(cx);
 151   TestArrayType<FallibleTArray<ElementT>>(cx);
 152   TestArrayType<AutoTArray<ElementT, 1>>(cx);
 153
 154   JS::LeaveRealm(cx, oldRealm);
 155 }
 156
 157 TEST(GCPostBarriers, nsTArray)
 158 {
 159   CycleCollectedJSContext* ccjscx = CycleCollectedJSContext::Get();
 160   ASSERT_TRUE(ccjscx != nullptr);
 161   JSContext* cx = ccjscx->Context();
 162   ASSERT_TRUE(cx != nullptr);
 163
 164   CreateGlobalAndRunTest(cx);
 165 }