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Diffstat (limited to 'libartbase/base/bounded_fifo.h')
-rw-r--r-- | libartbase/base/bounded_fifo.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/libartbase/base/bounded_fifo.h b/libartbase/base/bounded_fifo.h new file mode 100644 index 0000000000..444f31a55b --- /dev/null +++ b/libartbase/base/bounded_fifo.h @@ -0,0 +1,75 @@ +/* + * 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_LIBARTBASE_BASE_BOUNDED_FIFO_H_ +#define ART_LIBARTBASE_BASE_BOUNDED_FIFO_H_ + +#include <android-base/logging.h> + +#include "base/bit_utils.h" + +namespace art { + +// A bounded fifo is a fifo which has a bounded size. The power of two version uses a bit mask to +// avoid needing to deal with wrapping integers around or using a modulo operation. +template <typename T, const size_t kMaxSize> +class BoundedFifoPowerOfTwo { + static_assert(IsPowerOfTwo(kMaxSize), "kMaxSize must be a power of 2."); + + public: + BoundedFifoPowerOfTwo() { + clear(); + } + + void clear() { + back_index_ = 0; + size_ = 0; + } + + bool empty() const { + return size() == 0; + } + + size_t size() const { + return size_; + } + + void push_back(const T& value) { + ++size_; + DCHECK_LE(size_, kMaxSize); + // Relies on integer overflow behavior. + data_[back_index_++ & mask_] = value; + } + + const T& front() const { + DCHECK_GT(size_, 0U); + return data_[(back_index_ - size_) & mask_]; + } + + void pop_front() { + DCHECK_GT(size_, 0U); + --size_; + } + + private: + static const size_t mask_ = kMaxSize - 1; + size_t back_index_, size_; + T data_[kMaxSize]; +}; + +} // namespace art + +#endif // ART_LIBARTBASE_BASE_BOUNDED_FIFO_H_ |