Prototype of mark-and-compact support for Harmony weak maps.

test/cctest/test-weakmaps.cc

+// Copyright 2011 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "v8.h"
+
+#include "global-handles.h"
+#include "snapshot.h"
+#include "cctest.h"
+
+using namespace v8::internal;
+
+
+static Handle<JSWeakMap> AllocateJSWeakMap() {
+  Handle<Map> map = FACTORY->NewMap(JS_WEAK_MAP_TYPE, JSWeakMap::kSize);
+  Handle<JSObject> weakmap_obj = FACTORY->NewJSObjectFromMap(map);
+  Handle<JSWeakMap> weakmap(JSWeakMap::cast(*weakmap_obj));
+  // Do not use handles for the hash table, it would make entries strong.
+  Object* table_obj = ObjectHashTable::Allocate(1)->ToObjectChecked();
+  ObjectHashTable* table = ObjectHashTable::cast(table_obj);
+  weakmap->set_table(table);
+  weakmap->set_next(Smi::FromInt(0));
+  return weakmap;
+}
+
+static void PutIntoWeakMap(Handle<JSWeakMap> weakmap,
+                           Handle<JSObject> key,
+                           int value) {
+  Handle<ObjectHashTable> table = PutIntoObjectHashTable(
+      Handle<ObjectHashTable>(weakmap->table()),
+      Handle<JSObject>(JSObject::cast(*key)),
+      Handle<Smi>(Smi::FromInt(value)));
+  weakmap->set_table(*table);
+}
+
+static int NumberOfWeakCalls = 0;
+static void WeakPointerCallback(v8::Persistent<v8::Value> handle, void* id) {
+  ASSERT(id == reinterpret_cast<void*>(1234));
+  NumberOfWeakCalls++;
+  handle.Dispose();
+}
+
+
+TEST(Weakness) {
+  LocalContext context;
+  v8::HandleScope scope;
+  Handle<JSWeakMap> weakmap = AllocateJSWeakMap();
+  GlobalHandles* global_handles = Isolate::Current()->global_handles();
+
+  // Keep global reference to the key.
+  Handle<Object> key;
+  {
+    v8::HandleScope scope;
+    Handle<Map> map = FACTORY->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
+    Handle<JSObject> object = FACTORY->NewJSObjectFromMap(map);
+    key = global_handles->Create(*object);
+  }
+  CHECK(!global_handles->IsWeak(key.location()));
+
+  // Put entry into weak map.
+  {
+    v8::HandleScope scope;
+    PutIntoWeakMap(weakmap, Handle<JSObject>(JSObject::cast(*key)), 23);
+  }
+  CHECK_EQ(1, weakmap->table()->NumberOfElements());
+
+  // Force a full GC.
+  HEAP->CollectAllGarbage(false);
+  CHECK_EQ(0, NumberOfWeakCalls);
+  CHECK_EQ(1, weakmap->table()->NumberOfElements());
+  CHECK_EQ(0, weakmap->table()->NumberOfDeletedElements());
+
+  // Make the global reference to the key weak.
+  {
+    v8::HandleScope scope;
+    global_handles->MakeWeak(key.location(),
+                             reinterpret_cast<void*>(1234),
+                             &WeakPointerCallback);
+  }
+  CHECK(global_handles->IsWeak(key.location()));
+
+  // Force a full GC.
+  // Perform two consecutive GCs because the first one will only clear
+  // weak references whereas the second one will also clear weak maps.
+  HEAP->CollectAllGarbage(false);
+  CHECK_EQ(1, NumberOfWeakCalls);
+  CHECK_EQ(1, weakmap->table()->NumberOfElements());
+  CHECK_EQ(0, weakmap->table()->NumberOfDeletedElements());
+  HEAP->CollectAllGarbage(false);
+  CHECK_EQ(1, NumberOfWeakCalls);
+  CHECK_EQ(0, weakmap->table()->NumberOfElements());
+  CHECK_EQ(1, weakmap->table()->NumberOfDeletedElements());
+}
+
+
+TEST(Shrinking) {
+  LocalContext context;
+  v8::HandleScope scope;
+  Handle<JSWeakMap> weakmap = AllocateJSWeakMap();
+
+  // Check initial capacity.
+  CHECK_EQ(32, weakmap->table()->Capacity());
+
+  // Fill up weak map to trigger capacity change.
+  {
+    v8::HandleScope scope;
+    Handle<Map> map = FACTORY->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
+    for (int i = 0; i < 32; i++) {
+      Handle<JSObject> object = FACTORY->NewJSObjectFromMap(map);
+      PutIntoWeakMap(weakmap, object, i);
+    }
+  }
+
+  // Check increased capacity.
+  CHECK_EQ(128, weakmap->table()->Capacity());
+
+  // Force a full GC.
+  CHECK_EQ(32, weakmap->table()->NumberOfElements());
+  CHECK_EQ(0, weakmap->table()->NumberOfDeletedElements());
+  HEAP->CollectAllGarbage(false);
+  CHECK_EQ(0, weakmap->table()->NumberOfElements());
+  CHECK_EQ(32, weakmap->table()->NumberOfDeletedElements());
+
+  // Check shrunk capacity.
+  CHECK_EQ(32, weakmap->table()->Capacity());
+}