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// Copyright 2015 Google Inc.
//
// 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.
//
////////////////////////////////////////////////////////////////////////////////
//
// LRU cache decorator for binary_parse::PagedByteArray subclasses.
#ifndef PIEX_BINARY_PARSE_CACHED_PAGED_BYTE_ARRAY_H_
#define PIEX_BINARY_PARSE_CACHED_PAGED_BYTE_ARRAY_H_
#include <mutex>
#include <vector>
#if !defined(WIN32_LEAN_AND_MEAN)
#define WIN32_LEAN_AND_MEAN
#endif
#include "src/binary_parse/range_checked_byte_ptr.h"
namespace piex {
namespace binary_parse {
class CachedPagedByteArray : public PagedByteArray {
public:
// Decorates 'paged_byte_array' with a LRU cache layer of the size
// 'cache_size'.
explicit CachedPagedByteArray(const PagedByteArray* paged_byte_array,
size_t cache_size);
virtual size_t length() const { return paged_byte_array_->length(); }
virtual size_t pageSize() const { return paged_byte_array_->pageSize(); }
virtual void getPage(size_t page_index, const unsigned char** begin,
const unsigned char** end,
PagedByteArray::PagePtr* page) const;
private:
struct CachedPage {
size_t index;
PagedByteArray::PagePtr page;
const unsigned char* begin;
const unsigned char* end;
};
// Disallow copy construction and assignment.
CachedPagedByteArray(const CachedPagedByteArray&);
void operator=(const CachedPagedByteArray&);
// Gets the index of the page if it is in the cache and returns true, else
// returns false.
bool getFromCache(size_t page_index, size_t* cache_index) const;
mutable std::mutex mutex_;
const PagedByteArray* paged_byte_array_;
const size_t cache_size_;
mutable std::vector<CachedPage> cached_pages_;
};
} // namespace binary_parse
} // namespace piex
#endif // PIEX_BINARY_PARSE_CACHED_PAGED_BYTE_ARRAY_H_
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