/* Copyright (C) 2017 The Android Open Source Project
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This file implements interfaces from the file jvmti.h. This implementation
* is licensed under the same terms as the file jvmti.h. The
* copyright and license information for the file jvmti.h follows.
*
* Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
#ifndef ART_OPENJDKJVMTI_JVMTI_WEAK_TABLE_INL_H_
#define ART_OPENJDKJVMTI_JVMTI_WEAK_TABLE_INL_H_
#include "jvmti_weak_table.h"
#include <limits>
#include <android-base/logging.h>
#include "art_jvmti.h"
#include "gc/allocation_listener.h"
#include "instrumentation.h"
#include "jni_env_ext-inl.h"
#include "jvmti_allocator.h"
#include "mirror/class.h"
#include "mirror/object.h"
#include "nativehelper/scoped_local_ref.h"
#include "runtime.h"
namespace openjdkjvmti {
template <typename T>
void JvmtiWeakTable<T>::Lock() {
allow_disallow_lock_.ExclusiveLock(art::Thread::Current());
}
template <typename T>
void JvmtiWeakTable<T>::Unlock() {
allow_disallow_lock_.ExclusiveUnlock(art::Thread::Current());
}
template <typename T>
void JvmtiWeakTable<T>::AssertLocked() {
allow_disallow_lock_.AssertHeld(art::Thread::Current());
}
template <typename T>
void JvmtiWeakTable<T>::UpdateTableWithReadBarrier() {
update_since_last_sweep_ = true;
auto WithReadBarrierUpdater = [&](const art::GcRoot<art::mirror::Object>& original_root,
art::mirror::Object* original_obj ATTRIBUTE_UNUSED)
REQUIRES_SHARED(art::Locks::mutator_lock_) {
return original_root.Read<art::kWithReadBarrier>();
};
UpdateTableWith<decltype(WithReadBarrierUpdater), kIgnoreNull>(WithReadBarrierUpdater);
}
template <typename T>
bool JvmtiWeakTable<T>::GetTagSlowPath(art::Thread* self, art::mirror::Object* obj, T* result) {
// Under concurrent GC, there is a window between moving objects and sweeping of system
// weaks in which mutators are active. We may receive a to-space object pointer in obj,
// but still have from-space pointers in the table. Explicitly update the table once.
// Note: this will keep *all* objects in the table live, but should be a rare occurrence.
UpdateTableWithReadBarrier();
return GetTagLocked(self, obj, result);
}
template <typename T>
bool JvmtiWeakTable<T>::Remove(art::mirror::Object* obj, /* out */ T* tag) {
art::Thread* self = art::Thread::Current();
art::MutexLock mu(self, allow_disallow_lock_);
Wait(self);
return RemoveLocked(self, obj, tag);
}
template <typename T>
bool JvmtiWeakTable<T>::RemoveLocked(art::mirror::Object* obj, T* tag) {
art::Thread* self = art::Thread::Current();
allow_disallow_lock_.AssertHeld(self);
Wait(self);
return RemoveLocked(self, obj, tag);
}
template <typename T>
bool JvmtiWeakTable<T>::RemoveLocked(art::Thread* self, art::mirror::Object* obj, T* tag) {
auto it = tagged_objects_.find(art::GcRoot<art::mirror::Object>(obj));
if (it != tagged_objects_.end()) {
if (tag != nullptr) {
*tag = it->second;
}
tagged_objects_.erase(it);
return true;
}
if (art::kUseReadBarrier && self->GetIsGcMarking() && !update_since_last_sweep_) {
// Under concurrent GC, there is a window between moving objects and sweeping of system
// weaks in which mutators are active. We may receive a to-space object pointer in obj,
// but still have from-space pointers in the table. Explicitly update the table once.
// Note: this will keep *all* objects in the table live, but should be a rare occurrence.
// Update the table.
UpdateTableWithReadBarrier();
// And try again.
return RemoveLocked(self, obj, tag);
}
// Not in here.
return false;
}
template <typename T>
bool JvmtiWeakTable<T>::Set(art::mirror::Object* obj, T new_tag) {
art::Thread* self = art::Thread::Current();
art::MutexLock mu(self, allow_disallow_lock_);
Wait(self);
return SetLocked(self, obj, new_tag);
}
template <typename T>
bool JvmtiWeakTable<T>::SetLocked(art::mirror::Object* obj, T new_tag) {
art::Thread* self = art::Thread::Current();
allow_disallow_lock_.AssertHeld(self);
Wait(self);
return SetLocked(self, obj, new_tag);
}
template <typename T>
bool JvmtiWeakTable<T>::SetLocked(art::Thread* self, art::mirror::Object* obj, T new_tag) {
auto it = tagged_objects_.find(art::GcRoot<art::mirror::Object>(obj));
if (it != tagged_objects_.end()) {
it->second = new_tag;
return true;
}
if (art::kUseReadBarrier && self->GetIsGcMarking() && !update_since_last_sweep_) {
// Under concurrent GC, there is a window between moving objects and sweeping of system
// weaks in which mutators are active. We may receive a to-space object pointer in obj,
// but still have from-space pointers in the table. Explicitly update the table once.
// Note: this will keep *all* objects in the table live, but should be a rare occurrence.
// Update the table.
UpdateTableWithReadBarrier();
// And try again.
return SetLocked(self, obj, new_tag);
}
// New element.
auto insert_it = tagged_objects_.emplace(art::GcRoot<art::mirror::Object>(obj), new_tag);
DCHECK(insert_it.second);
return false;
}
template <typename T>
void JvmtiWeakTable<T>::Sweep(art::IsMarkedVisitor* visitor) {
if (DoesHandleNullOnSweep()) {
SweepImpl<true>(visitor);
} else {
SweepImpl<false>(visitor);
}
// Under concurrent GC, there is a window between moving objects and sweeping of system
// weaks in which mutators are active. We may receive a to-space object pointer in obj,
// but still have from-space pointers in the table. We explicitly update the table then
// to ensure we compare against to-space pointers. But we want to do this only once. Once
// sweeping is done, we know all objects are to-space pointers until the next GC cycle,
// so we re-enable the explicit update for the next marking.
update_since_last_sweep_ = false;
}
template <typename T>
template <bool kHandleNull>
void JvmtiWeakTable<T>::SweepImpl(art::IsMarkedVisitor* visitor) {
art::Thread* self = art::Thread::Current();
art::MutexLock mu(self, allow_disallow_lock_);
auto IsMarkedUpdater = [&](const art::GcRoot<art::mirror::Object>& original_root ATTRIBUTE_UNUSED,
art::mirror::Object* original_obj) {
return visitor->IsMarked(original_obj);
};
UpdateTableWith<decltype(IsMarkedUpdater),
kHandleNull ? kCallHandleNull : kRemoveNull>(IsMarkedUpdater);
}
template <typename T>
template <typename Updater, typename JvmtiWeakTable<T>::TableUpdateNullTarget kTargetNull>
ALWAYS_INLINE inline void JvmtiWeakTable<T>::UpdateTableWith(Updater& updater) {
// We optimistically hope that elements will still be well-distributed when re-inserting them.
// So play with the map mechanics, and postpone rehashing. This avoids the need of a side
// vector and two passes.
float original_max_load_factor = tagged_objects_.max_load_factor();
tagged_objects_.max_load_factor(std::numeric_limits<float>::max());
// For checking that a max load-factor actually does what we expect.
size_t original_bucket_count = tagged_objects_.bucket_count();
for (auto it = tagged_objects_.begin(); it != tagged_objects_.end();) {
DCHECK(!it->first.IsNull());
art::mirror::Object* original_obj = it->first.template Read<art::kWithoutReadBarrier>();
art::mirror::Object* target_obj = updater(it->first, original_obj);
if (original_obj != target_obj) {
if (kTargetNull == kIgnoreNull && target_obj == nullptr) {
// Ignore null target, don't do anything.
} else {
T tag = it->second;
it = tagged_objects_.erase(it);
if (target_obj != nullptr) {
tagged_objects_.emplace(art::GcRoot<art::mirror::Object>(target_obj), tag);
DCHECK_EQ(original_bucket_count, tagged_objects_.bucket_count());
} else if (kTargetNull == kCallHandleNull) {
HandleNullSweep(tag);
}
continue; // Iterator was implicitly updated by erase.
}
}
it++;
}
tagged_objects_.max_load_factor(original_max_load_factor);
// TODO: consider rehash here.
}
template <typename T>
template <typename Storage, class Allocator>
struct JvmtiWeakTable<T>::ReleasableContainer {
using allocator_type = Allocator;
explicit ReleasableContainer(const allocator_type& alloc, size_t reserve = 10)
: allocator(alloc),
data(reserve > 0 ? allocator.allocate(reserve) : nullptr),
size(0),
capacity(reserve) {
}
~ReleasableContainer() {
if (data != nullptr) {
allocator.deallocate(data, capacity);
capacity = 0;
size = 0;
}
}
Storage* Release() {
Storage* tmp = data;
data = nullptr;
size = 0;
capacity = 0;
return tmp;
}
void Resize(size_t new_capacity) {
CHECK_GT(new_capacity, capacity);
Storage* tmp = allocator.allocate(new_capacity);
DCHECK(tmp != nullptr);
if (data != nullptr) {
memcpy(tmp, data, sizeof(Storage) * size);
}
Storage* old = data;
data = tmp;
allocator.deallocate(old, capacity);
capacity = new_capacity;
}
void Pushback(const Storage& elem) {
if (size == capacity) {
size_t new_capacity = 2 * capacity + 1;
Resize(new_capacity);
}
data[size++] = elem;
}
Allocator allocator;
Storage* data;
size_t size;
size_t capacity;
};
template <typename T>
jvmtiError JvmtiWeakTable<T>::GetTaggedObjects(jvmtiEnv* jvmti_env,
jint tag_count,
const T* tags,
jint* count_ptr,
jobject** object_result_ptr,
T** tag_result_ptr) {
if (tag_count < 0) {
return ERR(ILLEGAL_ARGUMENT);
}
if (tag_count > 0) {
for (size_t i = 0; i != static_cast<size_t>(tag_count); ++i) {
if (tags[i] == 0) {
return ERR(ILLEGAL_ARGUMENT);
}
}
}
if (tags == nullptr) {
return ERR(NULL_POINTER);
}
if (count_ptr == nullptr) {
return ERR(NULL_POINTER);
}
art::Thread* self = art::Thread::Current();
art::MutexLock mu(self, allow_disallow_lock_);
Wait(self);
art::JNIEnvExt* jni_env = self->GetJniEnv();
constexpr size_t kDefaultSize = 10;
size_t initial_object_size;
size_t initial_tag_size;
if (tag_count == 0) {
initial_object_size = (object_result_ptr != nullptr) ? tagged_objects_.size() : 0;
initial_tag_size = (tag_result_ptr != nullptr) ? tagged_objects_.size() : 0;
} else {
initial_object_size = initial_tag_size = kDefaultSize;
}
JvmtiAllocator<void> allocator(jvmti_env);
ReleasableContainer<jobject, JvmtiAllocator<jobject>> selected_objects(allocator,
initial_object_size);
ReleasableContainer<T, JvmtiAllocator<T>> selected_tags(allocator, initial_tag_size);
size_t count = 0;
for (auto& pair : tagged_objects_) {
bool select;
if (tag_count > 0) {
select = false;
for (size_t i = 0; i != static_cast<size_t>(tag_count); ++i) {
if (tags[i] == pair.second) {
select = true;
break;
}
}
} else {
select = true;
}
if (select) {
art::mirror::Object* obj = pair.first.template Read<art::kWithReadBarrier>();
if (obj != nullptr) {
count++;
if (object_result_ptr != nullptr) {
selected_objects.Pushback(jni_env->AddLocalReference<jobject>(obj));
}
if (tag_result_ptr != nullptr) {
selected_tags.Pushback(pair.second);
}
}
}
}
if (object_result_ptr != nullptr) {
*object_result_ptr = selected_objects.Release();
}
if (tag_result_ptr != nullptr) {
*tag_result_ptr = selected_tags.Release();
}
*count_ptr = static_cast<jint>(count);
return ERR(NONE);
}
template <typename T>
art::mirror::Object* JvmtiWeakTable<T>::Find(T tag) {
art::Thread* self = art::Thread::Current();
art::MutexLock mu(self, allow_disallow_lock_);
Wait(self);
for (auto& pair : tagged_objects_) {
if (tag == pair.second) {
art::mirror::Object* obj = pair.first.template Read<art::kWithReadBarrier>();
if (obj != nullptr) {
return obj;
}
}
}
return nullptr;
}
} // namespace openjdkjvmti
#endif // ART_OPENJDKJVMTI_JVMTI_WEAK_TABLE_INL_H_