forked from mia/Aegisub
280 lines
8.8 KiB
C++
280 lines
8.8 KiB
C++
// Copyright (c) 2009, Niels Martin Hansen
|
|
// All rights reserved.
|
|
//
|
|
// Redistribution and use in source and binary forms, with or without
|
|
// modification, are permitted provided that the following conditions are met:
|
|
//
|
|
// * Redistributions of source code must retain the above copyright notice,
|
|
// this list of conditions and the following disclaimer.
|
|
// * Redistributions in binary form must reproduce the above copyright notice,
|
|
// this list of conditions and the following disclaimer in the documentation
|
|
// and/or other materials provided with the distribution.
|
|
// * Neither the name of the Aegisub Group nor the names of its contributors
|
|
// may be used to endorse or promote products derived from this software
|
|
// without specific prior written permission.
|
|
//
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
|
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
|
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
// POSSIBILITY OF SUCH DAMAGE.
|
|
//
|
|
// Aegisub Project http://www.aegisub.org/
|
|
|
|
/// @file block_cache.h
|
|
/// @ingroup utility
|
|
/// @brief Template class for creating caches for blocks of data
|
|
|
|
#pragma once
|
|
|
|
#include <algorithm>
|
|
#include <list>
|
|
#include <vector>
|
|
|
|
/// @class BasicDataBlockFactory
|
|
/// @brief Simple factory for allocating blocks for DataBlockCache
|
|
/// @tparam BlockT Type of blocks to produce
|
|
///
|
|
/// This is the default block factory class used by DataBlockCache if another isn't specified.
|
|
/// It allocates blocks on the heap using operator new and the default constructor, and does
|
|
/// nothing special to initialise the blocks.
|
|
///
|
|
/// Custom block factories could use a large internally pre-allocated buffer to create the
|
|
/// requested blocks in to avoid the default allocator.
|
|
template <typename BlockT>
|
|
struct BasicDataBlockFactory {
|
|
typedef std::unique_ptr<BlockT> BlockType;
|
|
|
|
/// @brief Allocates a block and returns it
|
|
/// @param i Index of the block to allocate
|
|
/// @return A pointer to the allocated block
|
|
///
|
|
/// This default implementation does not use the i parameter. Custom implementations
|
|
/// of block factories should use i to determine what data to fill into the block.
|
|
std::unique_ptr<BlockT> ProduceBlock(size_t i)
|
|
{
|
|
(void)i;
|
|
return std::unique_ptr<BlockT>(new BlockT);
|
|
}
|
|
|
|
/// @brief Retrieve the amount of memory consumed by a single block
|
|
/// @return Number of bytes consumed by a block
|
|
///
|
|
/// All blocks must consume the same amount of memory. The size of a block
|
|
/// is used to manage and limit the size of the cache.
|
|
size_t GetBlockSize() const
|
|
{
|
|
return sizeof(BlockT);
|
|
}
|
|
};
|
|
|
|
|
|
|
|
/// @class DataBlockCache
|
|
/// @brief Cache for blocks of data in a stream or similar
|
|
/// @tparam BlockT Type of blocks to store
|
|
/// @tparam MacroblockExponent Controls the number of blocks per macroblock, for tuning memory usage
|
|
/// @tparam BlockFactoryT Type of block factory, see BasicDataBlockFactory class for detail on these
|
|
template <
|
|
typename BlockT,
|
|
int MacroblockExponent = 6,
|
|
typename BlockFactoryT = BasicDataBlockFactory<BlockT>
|
|
>
|
|
class DataBlockCache {
|
|
/// Type of an array of blocks
|
|
typedef std::vector<typename BlockFactoryT::BlockType> BlockArray;
|
|
|
|
struct MacroBlock {
|
|
/// This macroblock's position in the age list
|
|
/// Is valid iff blocks.size() > 0
|
|
typename std::list<MacroBlock*>::iterator position;
|
|
|
|
/// The blocks contained in the macroblock
|
|
BlockArray blocks;
|
|
|
|
#ifdef _MSC_VER
|
|
MacroBlock() { }
|
|
MacroBlock(MacroBlock&& rgt) : position(rgt.position), blocks(std::move(rgt.blocks)) { }
|
|
MacroBlock& operator=(MacroBlock&& rgt) {
|
|
position = rgt.position;
|
|
blocks = std::move(rgt.blocks);
|
|
return *this;
|
|
}
|
|
#endif
|
|
};
|
|
|
|
/// Type of an array of macro blocks
|
|
typedef std::vector<MacroBlock> MacroBlockArray;
|
|
|
|
/// The data in the cache
|
|
MacroBlockArray data;
|
|
|
|
/// Type of a list of macro blocks
|
|
typedef std::list<MacroBlock*> AgeList;
|
|
|
|
/// The data sorted by how long it's been since they were used
|
|
AgeList age;
|
|
|
|
/// Number of blocks per macroblock
|
|
size_t macroblock_size;
|
|
|
|
/// Bitmask to extract the inside-macroblock index for a block by bitwise and
|
|
size_t macroblock_index_mask;
|
|
|
|
/// Factory object for blocks
|
|
BlockFactoryT factory;
|
|
|
|
/// @brief Dispose of all blocks in a macroblock and mark it empty
|
|
/// @param mb_index Index of macroblock to clear
|
|
void KillMacroBlock(MacroBlock &mb)
|
|
{
|
|
if (mb.blocks.empty())
|
|
return;
|
|
|
|
mb.blocks.clear();
|
|
age.erase(mb.position);
|
|
}
|
|
|
|
public:
|
|
#ifdef _MSC_VER
|
|
DataBlockCache(DataBlockCache&& rgt)
|
|
: data(std::move(rgt.data))
|
|
, age(std::move(rgt.age))
|
|
, macroblock_size(rgt.macroblock_size)
|
|
, macroblock_index_mask(rgt.macroblock_index_mask)
|
|
, factory(std::move(rgt.factory))
|
|
{ }
|
|
#endif
|
|
|
|
/// @brief Constructor
|
|
/// @param block_count Total number of blocks the cache will manage
|
|
/// @param factory Factory object to use for producing blocks
|
|
///
|
|
/// Note that the block_count is the maximum block index the cache will ever see,
|
|
/// it is an error to request a block number greater than block_count.
|
|
///
|
|
/// The factory object passed must respond well to copying.
|
|
DataBlockCache(size_t block_count, BlockFactoryT factory = BlockFactoryT())
|
|
: factory(std::move(factory))
|
|
{
|
|
SetBlockCount(block_count);
|
|
}
|
|
|
|
|
|
/// @brief Change the number of blocks in cache
|
|
/// @param block_count New number of blocks to hold
|
|
///
|
|
/// This will completely de-allocate the cache and re-allocate it with the new block count.
|
|
void SetBlockCount(size_t block_count)
|
|
{
|
|
if (data.size() > 0)
|
|
Age(0);
|
|
|
|
macroblock_size = 1 << MacroblockExponent;
|
|
|
|
macroblock_index_mask = ~(((~0) >> MacroblockExponent) << MacroblockExponent);
|
|
|
|
data.resize((block_count + macroblock_size - 1) >> MacroblockExponent);
|
|
}
|
|
|
|
|
|
/// @brief Clean up the cache
|
|
/// @param max_size Target maximum size of the cache in bytes
|
|
///
|
|
/// Passing a max_size of 0 (zero) causes the cache to be completely flushed
|
|
/// in a fast manner.
|
|
///
|
|
/// The max_size is not a hard limit, the cache size might somewhat exceed the max
|
|
/// after the aging operation, though it shouldn't be by much.
|
|
void Age(size_t max_size)
|
|
{
|
|
// Quick way out: get rid of everything
|
|
if (max_size == 0)
|
|
{
|
|
size_t block_count = data.size();
|
|
data.clear();
|
|
data.resize(block_count);
|
|
age.clear();
|
|
return;
|
|
}
|
|
|
|
// Sum up data size until we hit the max
|
|
size_t cur_size = 0;
|
|
size_t block_size = factory.GetBlockSize();
|
|
auto it = age.begin();
|
|
for (; it != age.end() && cur_size < max_size; ++it)
|
|
{
|
|
auto& ba = (*it)->blocks;
|
|
cur_size += (ba.size() - std::count(ba.begin(), ba.end(), nullptr)) * block_size;
|
|
}
|
|
// Hit max, clear all remaining blocks
|
|
for (; it != age.end(); )
|
|
KillMacroBlock(**it++);
|
|
}
|
|
|
|
|
|
/// @brief Obtain a data block from the cache
|
|
/// @param i Index of the block to retrieve
|
|
/// @param[out] created On return, tells whether the returned block was created during the operation
|
|
/// @return A pointer to the block in cache
|
|
///
|
|
/// It is legal to pass 0 (null) for created, in this case nothing is returned in it.
|
|
BlockT *Get(size_t i, bool *created = nullptr)
|
|
{
|
|
size_t mbi = i >> MacroblockExponent;
|
|
assert(mbi < data.size());
|
|
|
|
MacroBlock &mb = data[mbi];
|
|
|
|
if (mb.blocks.empty())
|
|
mb.blocks.resize(macroblock_size);
|
|
else
|
|
age.erase(mb.position);
|
|
|
|
// Move this macroblock to the front of the age list
|
|
age.push_front(&mb);
|
|
mb.position = age.begin();
|
|
|
|
size_t block_index = i & macroblock_index_mask;
|
|
assert(block_index < mb.blocks.size());
|
|
|
|
BlockT *b = mb.blocks[block_index].get();
|
|
|
|
if (!b)
|
|
{
|
|
mb.blocks[block_index] = factory.ProduceBlock(i);
|
|
b = mb.blocks[block_index].get();
|
|
assert(b != nullptr);
|
|
|
|
if (created) *created = true;
|
|
}
|
|
else
|
|
if (created) *created = false;
|
|
|
|
return b;
|
|
}
|
|
|
|
|
|
/// @brief Speculatively add blocks not present to the cache
|
|
/// @param forward Assume forwards linear access is plausible
|
|
/// @param backward Assume backwards linear access is plausible
|
|
/// @return Number of blocks added to the cache
|
|
///
|
|
/// Assuming forwards and/or backwards linear access causes the macroblock access data to be
|
|
/// used for speculating in macroblocks that may be accessed soon, and also allocate block
|
|
/// in macroblocks that may otherwise not have been accessed recently.
|
|
///
|
|
/// @todo Implement this.
|
|
size_t Speculate(bool forward, bool backward)
|
|
{
|
|
(void)forward;
|
|
(void)backward;
|
|
return 0;
|
|
}
|
|
};
|