PagedArray.hh

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/*
    Copyright (c) 2002-2009 Tampere University.
 
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/**
 * @file PagedArray.hh
 *
 * Declaration of PagedArray class.
 *
 * @author Pekka Jääskeläinen 2006 (pjaaskel-no.spam-cs.tut.fi)
 * @note rating: red
 */
 
#ifndef TTA_PAGED_ARRAY_HH
#define TTA_PAGED_ARRAY_HH
 
#include <vector>
#include <stdint.h>
 
#include "BaseType.hh"
#include "Exception.hh"
 
#define DEFAULT_PAGE_SIZE 1024
#define UNDEFINED_VALUE (0)
 
/// Type used for indexing the array. Currently, limited to 32 bits.
typedef uint32_t IndexType;
 
/**
 * Models the data contained in array.
 *
 * The array space is divided into pages which are allocated on-demand,
 * that is, the first time an index in that page is accessed for a write 
 * operation. Pages are stored in a table from which they are
 * retrieved using (address / page_size) as index. The offset within the
 * selected page is given by (address % chunk_size). This should result in
 * O(1) access.
 *
 * This allows modeling large arrays without reserving the memory for the
 * array if it's not accessed. The idea behind this implementation is borrowed 
 * from common (paged) virtual memory implementations of operating systems.
 *
 * Please note that this container does not perform any checking for the
 * validity of the indices due to efficiency reasons.
 */
template <
    typename ValueType, 
    int PageSize=DEFAULT_PAGE_SIZE, 
    ValueType DefaultValue=static_cast<ValueType>(UNDEFINED_VALUE)>
class PagedArray {
public:
 
    /// Type for a set of values in a basic array type.
    typedef ValueType* ValueTable;
 
    /// Type for a set of values in a std::vector container.
    typedef std::vector<ValueType> ValueVector;
 
    PagedArray(std::size_t size);
    virtual ~PagedArray();
 
    void write(IndexType index, const ValueTable data, std::size_t size);
    void writeData(IndexType index, const ValueType& data);
    ValueType readData(IndexType index);
    void read(IndexType index, ValueVector& data, size_t size);
    void read(IndexType index, ValueVector& data);
    void read(IndexType index, ValueTable data, size_t size);
    size_t allocatedMemory() const;
    void clear();
 
private:
    void deletePages();
 
    /// Copying not allowed.
    PagedArray(const PagedArray&);
    /// Assignment not allowed.
    PagedArray& operator=(const PagedArray&);
 
    /// Storage for the data pages.
    /// Created pages are stored in table from which they are found
    /// with address / size_of_page.
    ValueType** pageTable_;
    /// Size of the page table.
    std::size_t pageTableSize_;
};
 
#include "PagedArray.icc"
 
#endif