Fix class unloading with the CC collector.
Avoid unnecessarily decoding dex cache and class loader weak roots,
which would trigger read barriers.
Re-enable 141-class-unload with the CC collector.
Bug: 12687968
Bug: 24468364
Change-Id: Ib4c19f25000873cab0e06047040442d135285745
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index f649972..dde1001 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -368,10 +368,12 @@
mirror::Class::SetStatus(java_lang_Object, mirror::Class::kStatusLoaded, self);
java_lang_Object->SetObjectSize(sizeof(mirror::Object));
- runtime->SetSentinel(heap->AllocObject<true>(self,
- java_lang_Object.Get(),
- java_lang_Object->GetObjectSize(),
- VoidFunctor()));
+ // Allocate in non-movable so that it's possible to check if a JNI weak global ref has been
+ // cleared without triggering the read barrier and unintentionally mark the sentinel alive.
+ runtime->SetSentinel(heap->AllocNonMovableObject<true>(self,
+ java_lang_Object.Get(),
+ java_lang_Object->GetObjectSize(),
+ VoidFunctor()));
// Object[] next to hold class roots.
Handle<mirror::Class> object_array_class(hs.NewHandle(
@@ -886,10 +888,12 @@
mirror::Class* java_lang_Object = GetClassRoot(kJavaLangObject);
java_lang_Object->SetObjectSize(sizeof(mirror::Object));
- Runtime::Current()->SetSentinel(heap->AllocObject<true>(self,
- java_lang_Object,
- java_lang_Object->GetObjectSize(),
- VoidFunctor()));
+ // Allocate in non-movable so that it's possible to check if a JNI weak global ref has been
+ // cleared without triggering the read barrier and unintentionally mark the sentinel alive.
+ runtime->SetSentinel(heap->AllocNonMovableObject<true>(self,
+ java_lang_Object,
+ java_lang_Object->GetObjectSize(),
+ VoidFunctor()));
CHECK_EQ(oat_file->GetOatHeader().GetDexFileCount(),
static_cast<uint32_t>(dex_caches->GetLength()));
@@ -2324,17 +2328,22 @@
// Clean up pass to remove null dex caches.
// Null dex caches can occur due to class unloading and we are lazily removing null entries.
JavaVMExt* const vm = self->GetJniEnv()->vm;
- for (auto it = dex_caches_.begin(); it != dex_caches_.end();) {
- mirror::Object* dex_cache_root = self->DecodeJObject(*it);
- if (dex_cache_root == nullptr) {
- vm->DeleteWeakGlobalRef(self, *it);
+ for (auto it = dex_caches_.begin(); it != dex_caches_.end(); ) {
+ DexCacheData data = *it;
+ if (self->IsJWeakCleared(data.weak_root)) {
+ vm->DeleteWeakGlobalRef(self, data.weak_root);
it = dex_caches_.erase(it);
} else {
++it;
}
}
- dex_caches_.push_back(vm->AddWeakGlobalRef(self, dex_cache.Get()));
+ jweak dex_cache_jweak = vm->AddWeakGlobalRef(self, dex_cache.Get());
dex_cache->SetDexFile(&dex_file);
+ DexCacheData data;
+ data.weak_root = dex_cache_jweak;
+ data.dex_file = dex_cache->GetDexFile();
+ data.resolved_types = dex_cache->GetResolvedTypes();
+ dex_caches_.push_back(data);
}
mirror::DexCache* ClassLinker::RegisterDexFile(const DexFile& dex_file, LinearAlloc* linear_alloc) {
@@ -2381,10 +2390,16 @@
const DexFile& dex_file,
bool allow_failure) {
// Search assuming unique-ness of dex file.
- for (jweak weak_root : dex_caches_) {
- mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(self->DecodeJObject(weak_root));
- if (dex_cache != nullptr && dex_cache->GetDexFile() == &dex_file) {
- return dex_cache;
+ for (const DexCacheData& data : dex_caches_) {
+ // Avoid decoding (and read barriers) other unrelated dex caches.
+ if (data.dex_file == &dex_file) {
+ mirror::DexCache* dex_cache =
+ down_cast<mirror::DexCache*>(self->DecodeJObject(data.weak_root));
+ if (dex_cache != nullptr) {
+ return dex_cache;
+ } else {
+ break;
+ }
}
}
if (allow_failure) {
@@ -2392,8 +2407,8 @@
}
std::string location(dex_file.GetLocation());
// Failure, dump diagnostic and abort.
- for (jobject weak_root : dex_caches_) {
- mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(self->DecodeJObject(weak_root));
+ for (const DexCacheData& data : dex_caches_) {
+ mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(self->DecodeJObject(data.weak_root));
if (dex_cache != nullptr) {
LOG(ERROR) << "Registered dex file " << dex_cache->GetDexFile()->GetLocation();
}
@@ -2405,10 +2420,13 @@
void ClassLinker::FixupDexCaches(ArtMethod* resolution_method) {
Thread* const self = Thread::Current();
ReaderMutexLock mu(self, dex_lock_);
- for (jobject weak_root : dex_caches_) {
- mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(self->DecodeJObject(weak_root));
- if (dex_cache != nullptr) {
- dex_cache->Fixup(resolution_method, image_pointer_size_);
+ for (const DexCacheData& data : dex_caches_) {
+ if (!self->IsJWeakCleared(data.weak_root)) {
+ mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(
+ self->DecodeJObject(data.weak_root));
+ if (dex_cache != nullptr) {
+ dex_cache->Fixup(resolution_method, image_pointer_size_);
+ }
}
}
}
@@ -3346,15 +3364,18 @@
Thread* const self = Thread::Current();
ReaderMutexLock mu(self, dex_lock_);
// Locate the dex cache of the original interface/Object
- for (jobject weak_root : dex_caches_) {
- mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(self->DecodeJObject(weak_root));
- if (dex_cache != nullptr &&
- proxy_method->HasSameDexCacheResolvedTypes(dex_cache->GetResolvedTypes(),
+ for (const DexCacheData& data : dex_caches_) {
+ if (!self->IsJWeakCleared(data.weak_root) &&
+ proxy_method->HasSameDexCacheResolvedTypes(data.resolved_types,
image_pointer_size_)) {
- ArtMethod* resolved_method = dex_cache->GetResolvedMethod(
- proxy_method->GetDexMethodIndex(), image_pointer_size_);
- CHECK(resolved_method != nullptr);
- return resolved_method;
+ mirror::DexCache* dex_cache = down_cast<mirror::DexCache*>(
+ self->DecodeJObject(data.weak_root));
+ if (dex_cache != nullptr) {
+ ArtMethod* resolved_method = dex_cache->GetResolvedMethod(
+ proxy_method->GetDexMethodIndex(), image_pointer_size_);
+ CHECK(resolved_method != nullptr);
+ return resolved_method;
+ }
}
}
}