100 lines
3.3 KiB
C++
100 lines
3.3 KiB
C++
// Copyright 2021 The Tint Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef FUZZERS_TINT_SPIRV_TOOLS_FUZZER_MUTATOR_CACHE_H_
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#define FUZZERS_TINT_SPIRV_TOOLS_FUZZER_MUTATOR_CACHE_H_
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#include <cassert>
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#include <list>
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#include <memory>
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#include <unordered_map>
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#include <utility>
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#include <vector>
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#include "fuzzers/tint_spirv_tools_fuzzer/mutator.h"
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namespace tint {
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namespace fuzzers {
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namespace spvtools_fuzzer {
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/// Implementation of a fixed size LRU cache. That is, when the number of
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/// elements reaches a certain threshold, the element that wasn't used for the
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/// longest period of time is removed from the cache when a new element is
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/// inserted. All operations have amortized constant time complexity.
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class MutatorCache {
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public:
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/// SPIR-V binary that is being mutated.
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using Key = std::vector<uint32_t>;
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/// Mutator that is used to mutate the `Key`.
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using Value = std::unique_ptr<Mutator>;
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/// Constructor.
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/// @param max_size - the maximum number of elements the cache can store. May
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/// not be equal to 0.
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explicit MutatorCache(size_t max_size);
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/// Retrieves a pointer to a value, associated with a given `key`.
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///
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/// If the key is present in the cache, its usage is updated and the
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/// (non-null) pointer to the value is returned. Otherwise, `nullptr` is
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/// returned.
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///
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/// @param key - may not exist in this cache.
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/// @return non-`nullptr` pointer to a value if `key` exists in the cache.
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/// @return `nullptr` if `key` doesn't exist in this cache.
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Value::pointer Get(const Key& key);
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/// Inserts a `key`-`value` pair into the cache.
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///
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/// If the `key` is already present, the `value` replaces the old value and
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/// the usage of `key` is updated. If the `key` is not present, then:
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/// - if the number of elements in the cache is equal to `max_size`, the
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/// key-value pair, where the usage of the key wasn't updated for the
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/// longest period of time, is removed from the cache.
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/// - a new `key`-`value` pair is inserted into the cache.
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///
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/// @param key - a key.
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/// @param value - may not be a `nullptr`.
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void Put(const Key& key, Value value);
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/// Removes `key` and an associated value from the cache.
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///
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/// @param key - a key.
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/// @return a non-`nullptr` pointer to the removed value, associated with
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/// `key`.
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/// @return `nullptr` if `key` is not present in the cache.
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Value Remove(const Key& key);
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private:
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struct KeyHash {
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size_t operator()(const std::vector<uint32_t>& vec) const;
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};
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using Entry = std::pair<const Key*, Value>;
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using Map = std::unordered_map<Key, std::list<Entry>::iterator, KeyHash>;
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void UpdateUsage(Map::iterator it);
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Map map_;
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std::list<Entry> entries_;
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const size_t max_size_;
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};
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} // namespace spvtools_fuzzer
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} // namespace fuzzers
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} // namespace tint
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#endif // FUZZERS_TINT_SPIRV_TOOLS_FUZZER_MUTATOR_CACHE_H_
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