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Diffstat (limited to 'js/src/jsapi-tests/testPersistentRooted.cpp')
| -rw-r--r-- | js/src/jsapi-tests/testPersistentRooted.cpp | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/js/src/jsapi-tests/testPersistentRooted.cpp b/js/src/jsapi-tests/testPersistentRooted.cpp new file mode 100644 index 000000000..e765d8c7a --- /dev/null +++ b/js/src/jsapi-tests/testPersistentRooted.cpp @@ -0,0 +1,224 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "js/Class.h" +#include "jsapi-tests/tests.h" + +using namespace JS; + +struct BarkWhenTracedClass { + static int finalizeCount; + static int traceCount; + + static const JSClass class_; + static void finalize(JSFreeOp* fop, JSObject* obj) { finalizeCount++; } + static void trace(JSTracer* trc, JSObject* obj) { traceCount++; } + static void reset() { finalizeCount = 0; traceCount = 0; } +}; + +int BarkWhenTracedClass::finalizeCount; +int BarkWhenTracedClass::traceCount; + +static const JSClassOps BarkWhenTracedClassClassOps = { + nullptr, + nullptr, + nullptr, + nullptr, + nullptr, + nullptr, + nullptr, + BarkWhenTracedClass::finalize, + nullptr, + nullptr, + nullptr, + BarkWhenTracedClass::trace +}; + +const JSClass BarkWhenTracedClass::class_ = { + "BarkWhenTracedClass", + JSCLASS_FOREGROUND_FINALIZE, + &BarkWhenTracedClassClassOps +}; + +struct Kennel { + PersistentRootedObject obj; + Kennel() { } + explicit Kennel(JSContext* cx) : obj(cx) { } + Kennel(JSContext* cx, const HandleObject& woof) : obj(cx, woof) { } + void init(JSContext* cx, const HandleObject& woof) { + obj.init(cx, woof); + } + void clear() { + obj = nullptr; + } +}; + +// A function for allocating a Kennel and a barker. Only allocating +// PersistentRooteds on the heap, and in this function, helps ensure that the +// conservative GC doesn't find stray references to the barker. Ugh. +MOZ_NEVER_INLINE static Kennel* +Allocate(JSContext* cx) +{ + RootedObject barker(cx, JS_NewObject(cx, &BarkWhenTracedClass::class_)); + if (!barker) + return nullptr; + + return new Kennel(cx, barker); +} + +// Do a GC, expecting |n| barkers to be finalized. +static bool +GCFinalizesNBarkers(JSContext* cx, int n) +{ + int preGCTrace = BarkWhenTracedClass::traceCount; + int preGCFinalize = BarkWhenTracedClass::finalizeCount; + + JS_GC(cx); + + return (BarkWhenTracedClass::finalizeCount == preGCFinalize + n && + BarkWhenTracedClass::traceCount > preGCTrace); +} + +// PersistentRooted instances protect their contents from being recycled. +BEGIN_TEST(test_PersistentRooted) +{ + BarkWhenTracedClass::reset(); + + mozilla::UniquePtr<Kennel> kennel(Allocate(cx)); + CHECK(kennel.get()); + + // GC should be able to find our barker. + CHECK(GCFinalizesNBarkers(cx, 0)); + + kennel = nullptr; + + // Now GC should not be able to find the barker. + JS_GC(cx); + CHECK(BarkWhenTracedClass::finalizeCount == 1); + + return true; +} +END_TEST(test_PersistentRooted) + +// GC should not be upset by null PersistentRooteds. +BEGIN_TEST(test_PersistentRootedNull) +{ + BarkWhenTracedClass::reset(); + + Kennel kennel(cx); + CHECK(!kennel.obj); + + JS_GC(cx); + CHECK(BarkWhenTracedClass::finalizeCount == 0); + + return true; +} +END_TEST(test_PersistentRootedNull) + +// Copy construction works. +BEGIN_TEST(test_PersistentRootedCopy) +{ + BarkWhenTracedClass::reset(); + + mozilla::UniquePtr<Kennel> kennel(Allocate(cx)); + CHECK(kennel.get()); + + CHECK(GCFinalizesNBarkers(cx, 0)); + + // Copy construction! AMAZING! + mozilla::UniquePtr<Kennel> newKennel(new Kennel(*kennel)); + + CHECK(GCFinalizesNBarkers(cx, 0)); + + kennel = nullptr; + + CHECK(GCFinalizesNBarkers(cx, 0)); + + newKennel = nullptr; + + // Now that kennel and nowKennel are both deallocated, GC should not be + // able to find the barker. + JS_GC(cx); + CHECK(BarkWhenTracedClass::finalizeCount == 1); + + return true; +} +END_TEST(test_PersistentRootedCopy) + +// Assignment works. +BEGIN_TEST(test_PersistentRootedAssign) +{ + BarkWhenTracedClass::reset(); + + mozilla::UniquePtr<Kennel> kennel(Allocate(cx)); + CHECK(kennel.get()); + + CHECK(GCFinalizesNBarkers(cx, 0)); + + // Allocate a new, empty kennel. + mozilla::UniquePtr<Kennel> kennel2(new Kennel(cx)); + + // Assignment! ASTONISHING! + *kennel2 = *kennel; + + // With both kennels referring to the same barker, it is held alive. + CHECK(GCFinalizesNBarkers(cx, 0)); + + kennel2 = nullptr; + + // The destination of the assignment alone holds the barker alive. + CHECK(GCFinalizesNBarkers(cx, 0)); + + // Allocate a second barker. + kennel2 = mozilla::UniquePtr<Kennel>(Allocate(cx)); + CHECK(kennel2.get()); + + *kennel = *kennel2; + + // Nothing refers to the first kennel any more. + CHECK(GCFinalizesNBarkers(cx, 1)); + + kennel = nullptr; + kennel2 = nullptr; + + // Now that kennel and kennel2 are both deallocated, GC should not be + // able to find the barker. + JS_GC(cx); + CHECK(BarkWhenTracedClass::finalizeCount == 2); + + return true; +} +END_TEST(test_PersistentRootedAssign) + +static PersistentRootedObject gGlobalRoot; + +// PersistentRooted instances can initialized in a separate step to allow for global PersistentRooteds. +BEGIN_TEST(test_GlobalPersistentRooted) +{ + BarkWhenTracedClass::reset(); + + CHECK(!gGlobalRoot.initialized()); + + { + RootedObject barker(cx, JS_NewObject(cx, &BarkWhenTracedClass::class_)); + CHECK(barker); + + gGlobalRoot.init(cx, barker); + } + + CHECK(gGlobalRoot.initialized()); + + // GC should be able to find our barker. + CHECK(GCFinalizesNBarkers(cx, 0)); + + gGlobalRoot.reset(); + CHECK(!gGlobalRoot.initialized()); + + // Now GC should not be able to find the barker. + JS_GC(cx); + CHECK(BarkWhenTracedClass::finalizeCount == 1); + + return true; +} +END_TEST(test_GlobalPersistentRooted) |