Revert^8 "Make sure that const-class linkage is preserved."
Replaced two ReaderMutexLocks with WriterMutexLocks.
Removed some unnecessary debugging output.
Test: m test-art-host
Bug: 30627598
Original-Change-Id: Ie9b721464b4e9a5dcce8df8095548e983bba1fe8
This reverts commit 2c8c6b63da6ecb2ac701cc30f9b4fa4a8eea5cc8.
Change-Id: I3a1aeecf64e4b202cef61cceb248d48106a2f4a6
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 319991b..3137769 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -1981,13 +1981,36 @@
void Visit(ObjPtr<mirror::ClassLoader> class_loader)
REQUIRES_SHARED(Locks::classlinker_classes_lock_, Locks::mutator_lock_) OVERRIDE {
ClassTable* const class_table = class_loader->GetClassTable();
- if (!done_ && class_table != nullptr && !class_table->Visit(*visitor_)) {
- // If the visitor ClassTable returns false it means that we don't need to continue.
- done_ = true;
+ if (!done_ && class_table != nullptr) {
+ DefiningClassLoaderFilterVisitor visitor(class_loader, visitor_);
+ if (!class_table->Visit(visitor)) {
+ // If the visitor ClassTable returns false it means that we don't need to continue.
+ done_ = true;
+ }
}
}
private:
+ // Class visitor that limits the class visits from a ClassTable to the classes with
+ // the provided defining class loader. This filter is used to avoid multiple visits
+ // of the same class which can be recorded for multiple initiating class loaders.
+ class DefiningClassLoaderFilterVisitor : public ClassVisitor {
+ public:
+ DefiningClassLoaderFilterVisitor(ObjPtr<mirror::ClassLoader> defining_class_loader,
+ ClassVisitor* visitor)
+ : defining_class_loader_(defining_class_loader), visitor_(visitor) { }
+
+ bool operator()(ObjPtr<mirror::Class> klass) OVERRIDE REQUIRES_SHARED(Locks::mutator_lock_) {
+ if (klass->GetClassLoader() != defining_class_loader_) {
+ return true;
+ }
+ return (*visitor_)(klass);
+ }
+
+ ObjPtr<mirror::ClassLoader> const defining_class_loader_;
+ ClassVisitor* const visitor_;
+ };
+
ClassVisitor* const visitor_;
// If done is true then we don't need to do any more visiting.
bool done_;
@@ -2474,56 +2497,109 @@
}
} else {
ScopedObjectAccessUnchecked soa(self);
- ObjPtr<mirror::Class> cp_klass;
- if (FindClassInBaseDexClassLoader(soa, self, descriptor, hash, class_loader, &cp_klass)) {
- // The chain was understood. So the value in cp_klass is either the class we were looking
- // for, or not found.
- if (cp_klass != nullptr) {
- return cp_klass.Ptr();
- }
- // TODO: We handle the boot classpath loader in FindClassInBaseDexClassLoader. Try to unify
- // this and the branch above. TODO: throw the right exception here.
+ ObjPtr<mirror::Class> result_ptr;
+ bool descriptor_equals;
+ bool known_hierarchy =
+ FindClassInBaseDexClassLoader(soa, self, descriptor, hash, class_loader, &result_ptr);
+ if (result_ptr != nullptr) {
+ // The chain was understood and we found the class. We still need to add the class to
+ // the class table to protect from racy programs that can try and redefine the path list
+ // which would change the Class<?> returned for subsequent evaluation of const-class.
+ DCHECK(known_hierarchy);
+ DCHECK(result_ptr->DescriptorEquals(descriptor));
+ descriptor_equals = true;
+ } else {
+ // Either the chain wasn't understood or the class wasn't found.
+ //
+ // If the chain was understood but we did not find the class, let the Java-side
+ // rediscover all this and throw the exception with the right stack trace. Note that
+ // the Java-side could still succeed for racy programs if another thread is actively
+ // modifying the class loader's path list.
- // We'll let the Java-side rediscover all this and throw the exception with the right stack
- // trace.
- }
-
- if (Runtime::Current()->IsAotCompiler()) {
- // Oops, compile-time, can't run actual class-loader code.
- ObjPtr<mirror::Throwable> pre_allocated = Runtime::Current()->GetPreAllocatedNoClassDefFoundError();
- self->SetException(pre_allocated);
- return nullptr;
- }
-
- ScopedLocalRef<jobject> class_loader_object(soa.Env(),
- soa.AddLocalReference<jobject>(class_loader.Get()));
- std::string class_name_string(DescriptorToDot(descriptor));
- ScopedLocalRef<jobject> result(soa.Env(), nullptr);
- {
- ScopedThreadStateChange tsc(self, kNative);
- ScopedLocalRef<jobject> class_name_object(soa.Env(),
- soa.Env()->NewStringUTF(class_name_string.c_str()));
- if (class_name_object.get() == nullptr) {
- DCHECK(self->IsExceptionPending()); // OOME.
+ if (Runtime::Current()->IsAotCompiler()) {
+ // Oops, compile-time, can't run actual class-loader code.
+ ObjPtr<mirror::Throwable> pre_allocated =
+ Runtime::Current()->GetPreAllocatedNoClassDefFoundError();
+ self->SetException(pre_allocated);
return nullptr;
}
- CHECK(class_loader_object.get() != nullptr);
- result.reset(soa.Env()->CallObjectMethod(class_loader_object.get(),
- WellKnownClasses::java_lang_ClassLoader_loadClass,
- class_name_object.get()));
+
+ ScopedLocalRef<jobject> class_loader_object(
+ soa.Env(), soa.AddLocalReference<jobject>(class_loader.Get()));
+ std::string class_name_string(DescriptorToDot(descriptor));
+ ScopedLocalRef<jobject> result(soa.Env(), nullptr);
+ {
+ ScopedThreadStateChange tsc(self, kNative);
+ ScopedLocalRef<jobject> class_name_object(
+ soa.Env(), soa.Env()->NewStringUTF(class_name_string.c_str()));
+ if (class_name_object.get() == nullptr) {
+ DCHECK(self->IsExceptionPending()); // OOME.
+ return nullptr;
+ }
+ CHECK(class_loader_object.get() != nullptr);
+ result.reset(soa.Env()->CallObjectMethod(class_loader_object.get(),
+ WellKnownClasses::java_lang_ClassLoader_loadClass,
+ class_name_object.get()));
+ }
+ if (self->IsExceptionPending()) {
+ // If the ClassLoader threw, pass that exception up.
+ // However, to comply with the RI behavior, first check if another thread succeeded.
+ result_ptr = LookupClass(self, descriptor, hash, class_loader.Get());
+ if (result_ptr != nullptr && !result_ptr->IsErroneous()) {
+ self->ClearException();
+ return EnsureResolved(self, descriptor, result_ptr);
+ }
+ return nullptr;
+ } else if (result.get() == nullptr) {
+ // broken loader - throw NPE to be compatible with Dalvik
+ ThrowNullPointerException(StringPrintf("ClassLoader.loadClass returned null for %s",
+ class_name_string.c_str()).c_str());
+ return nullptr;
+ }
+ result_ptr = soa.Decode<mirror::Class>(result.get());
+ // Check the name of the returned class.
+ descriptor_equals = result_ptr->DescriptorEquals(descriptor);
}
- if (self->IsExceptionPending()) {
- // If the ClassLoader threw, pass that exception up.
- return nullptr;
- } else if (result.get() == nullptr) {
- // broken loader - throw NPE to be compatible with Dalvik
- ThrowNullPointerException(StringPrintf("ClassLoader.loadClass returned null for %s",
- class_name_string.c_str()).c_str());
- return nullptr;
- } else {
- // success, return mirror::Class*
- return soa.Decode<mirror::Class>(result.get()).Ptr();
+
+ // Try to insert the class to the class table, checking for mismatch.
+ ObjPtr<mirror::Class> old;
+ {
+ WriterMutexLock mu(self, *Locks::classlinker_classes_lock_);
+ ClassTable* const class_table = InsertClassTableForClassLoader(class_loader.Get());
+ old = class_table->Lookup(descriptor, hash);
+ if (old == nullptr) {
+ old = result_ptr; // For the comparison below, after releasing the lock.
+ if (descriptor_equals) {
+ class_table->InsertWithHash(result_ptr.Ptr(), hash);
+ Runtime::Current()->GetHeap()->WriteBarrierEveryFieldOf(class_loader.Get());
+ } // else throw below, after releasing the lock.
+ }
}
+ if (UNLIKELY(old != result_ptr)) {
+ // Return `old` (even if `!descriptor_equals`) to mimic the RI behavior for parallel
+ // capable class loaders. (All class loaders are considered parallel capable on Android.)
+ mirror::Class* loader_class = class_loader->GetClass();
+ const char* loader_class_name =
+ loader_class->GetDexFile().StringByTypeIdx(loader_class->GetDexTypeIndex());
+ LOG(WARNING) << "Initiating class loader of type " << DescriptorToDot(loader_class_name)
+ << " is not well-behaved; it returned a different Class for racing loadClass(\""
+ << DescriptorToDot(descriptor) << "\").";
+ return EnsureResolved(self, descriptor, old);
+ }
+ if (UNLIKELY(!descriptor_equals)) {
+ std::string result_storage;
+ const char* result_name = result_ptr->GetDescriptor(&result_storage);
+ std::string loader_storage;
+ const char* loader_class_name = class_loader->GetClass()->GetDescriptor(&loader_storage);
+ ThrowNoClassDefFoundError(
+ "Initiating class loader of type %s returned class %s instead of %s.",
+ DescriptorToDot(loader_class_name).c_str(),
+ DescriptorToDot(result_name).c_str(),
+ DescriptorToDot(descriptor).c_str());
+ return nullptr;
+ }
+ // success, return mirror::Class*
+ return result_ptr.Ptr();
}
UNREACHABLE();
}
@@ -3609,12 +3685,6 @@
Runtime::Current()->GetHeap()->WriteBarrierEveryFieldOf(klass);
}
-bool ClassLinker::RemoveClass(const char* descriptor, ObjPtr<mirror::ClassLoader> class_loader) {
- WriterMutexLock mu(Thread::Current(), *Locks::classlinker_classes_lock_);
- ClassTable* const class_table = ClassTableForClassLoader(class_loader);
- return class_table != nullptr && class_table->Remove(descriptor);
-}
-
mirror::Class* ClassLinker::LookupClass(Thread* self,
const char* descriptor,
size_t hash,
@@ -3665,7 +3735,8 @@
REQUIRES_SHARED(Locks::classlinker_classes_lock_, Locks::mutator_lock_) OVERRIDE {
ClassTable* const class_table = class_loader->GetClassTable();
ObjPtr<mirror::Class> klass = class_table->Lookup(descriptor_, hash_);
- if (klass != nullptr) {
+ // Add `klass` only if `class_loader` is its defining (not just initiating) class loader.
+ if (klass != nullptr && klass->GetClassLoader() == class_loader) {
result_->push_back(klass);
}
}
@@ -3684,6 +3755,7 @@
const size_t hash = ComputeModifiedUtf8Hash(descriptor);
ObjPtr<mirror::Class> klass = boot_class_table_.Lookup(descriptor, hash);
if (klass != nullptr) {
+ DCHECK(klass->GetClassLoader() == nullptr);
result.push_back(klass);
}
LookupClassesVisitor visitor(descriptor, hash, &result);
@@ -7972,8 +8044,8 @@
REQUIRES_SHARED(Locks::classlinker_classes_lock_, Locks::mutator_lock_) OVERRIDE {
ClassTable* const class_table = class_loader->GetClassTable();
if (class_table != nullptr) {
- num_zygote_classes += class_table->NumZygoteClasses();
- num_non_zygote_classes += class_table->NumNonZygoteClasses();
+ num_zygote_classes += class_table->NumZygoteClasses(class_loader);
+ num_non_zygote_classes += class_table->NumNonZygoteClasses(class_loader);
}
}
@@ -7984,13 +8056,13 @@
size_t ClassLinker::NumZygoteClasses() const {
CountClassesVisitor visitor;
VisitClassLoaders(&visitor);
- return visitor.num_zygote_classes + boot_class_table_.NumZygoteClasses();
+ return visitor.num_zygote_classes + boot_class_table_.NumZygoteClasses(nullptr);
}
size_t ClassLinker::NumNonZygoteClasses() const {
CountClassesVisitor visitor;
VisitClassLoaders(&visitor);
- return visitor.num_non_zygote_classes + boot_class_table_.NumNonZygoteClasses();
+ return visitor.num_non_zygote_classes + boot_class_table_.NumNonZygoteClasses(nullptr);
}
size_t ClassLinker::NumLoadedClasses() {