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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_WALK_INL_H_
#define ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_WALK_INL_H_
#include "bump_pointer_space.h"
#include "base/bit_utils.h"
#include "mirror/object-inl.h"
#include "thread-current-inl.h"
namespace art {
namespace gc {
namespace space {
template <typename Visitor>
inline void BumpPointerSpace::Walk(Visitor&& visitor) {
uint8_t* pos = Begin();
uint8_t* end = End();
uint8_t* main_end = pos;
// Internal indirection w/ NO_THREAD_SAFETY_ANALYSIS. Optimally, we'd like to have an annotation
// like
// REQUIRES_AS(visitor.operator(mirror::Object*))
// on Walk to expose the interprocedural nature of locks here without having to duplicate the
// function.
//
// NO_THREAD_SAFETY_ANALYSIS is a workaround. The problem with the workaround of course is that
// it doesn't complain at the callsite. However, that is strictly not worse than the
// ObjectCallback version it replaces.
auto no_thread_safety_analysis_visit = [&](mirror::Object* obj) NO_THREAD_SAFETY_ANALYSIS {
visitor(obj);
};
{
MutexLock mu(Thread::Current(), block_lock_);
// If we have 0 blocks then we need to update the main header since we have bump pointer style
// allocation into an unbounded region (actually bounded by Capacity()).
if (num_blocks_ == 0) {
UpdateMainBlock();
}
main_end = Begin() + main_block_size_;
if (num_blocks_ == 0) {
// We don't have any other blocks, this means someone else may be allocating into the main
// block. In this case, we don't want to try and visit the other blocks after the main block
// since these could actually be part of the main block.
end = main_end;
}
}
// Walk all of the objects in the main block first.
while (pos < main_end) {
mirror::Object* obj = reinterpret_cast<mirror::Object*>(pos);
// No read barrier because obj may not be a valid object.
if (obj->GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>() == nullptr) {
// There is a race condition where a thread has just allocated an object but not set the
// class. We can't know the size of this object, so we don't visit it and exit the function
// since there is guaranteed to be not other blocks.
return;
} else {
no_thread_safety_analysis_visit(obj);
pos = reinterpret_cast<uint8_t*>(GetNextObject(obj));
}
}
// Walk the other blocks (currently only TLABs).
while (pos < end) {
BlockHeader* header = reinterpret_cast<BlockHeader*>(pos);
size_t block_size = header->size_;
pos += sizeof(BlockHeader); // Skip the header so that we know where the objects
mirror::Object* obj = reinterpret_cast<mirror::Object*>(pos);
const mirror::Object* end_obj = reinterpret_cast<const mirror::Object*>(pos + block_size);
CHECK_LE(reinterpret_cast<const uint8_t*>(end_obj), End());
// We don't know how many objects are allocated in the current block. When we hit a null class
// assume its the end. TODO: Have a thread update the header when it flushes the block?
// No read barrier because obj may not be a valid object.
while (obj < end_obj && obj->GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>() != nullptr) {
no_thread_safety_analysis_visit(obj);
obj = GetNextObject(obj);
}
pos += block_size;
}
}
} // namespace space
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_SPACE_BUMP_POINTER_SPACE_WALK_INL_H_