forked from 0ad/0ad
157 lines
3.4 KiB
C++
157 lines
3.4 KiB
C++
/* Copyright (C) 2009 Wildfire Games.
|
|
* This file is part of 0 A.D.
|
|
*
|
|
* 0 A.D. is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* 0 A.D. is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
/*
|
|
* cache for aligned I/O m_blocks.
|
|
*/
|
|
|
|
#include "precompiled.h"
|
|
#include "block_cache.h"
|
|
|
|
#include "lib/config2.h" // CONFIG2_CACHE_READ_ONLY
|
|
#include "lib/file/common/file_stats.h"
|
|
#include "lib/lockfree.h"
|
|
#include "lib/allocators/pool.h"
|
|
#include "lib/fnv_hash.h"
|
|
#include "io_align.h"
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
|
|
BlockId::BlockId()
|
|
: m_id(0)
|
|
{
|
|
}
|
|
|
|
BlockId::BlockId(const Path& pathname, off_t ofs)
|
|
{
|
|
m_id = fnv_hash64(pathname.string().c_str(), pathname.string().length());
|
|
const size_t indexBits = 16;
|
|
m_id <<= indexBits;
|
|
const off_t blockIndex = off_t(ofs / BLOCK_SIZE);
|
|
debug_assert(blockIndex < off_t(1) << indexBits);
|
|
m_id |= blockIndex;
|
|
}
|
|
|
|
bool BlockId::operator==(const BlockId& rhs) const
|
|
{
|
|
return m_id == rhs.m_id;
|
|
}
|
|
|
|
bool BlockId::operator!=(const BlockId& rhs) const
|
|
{
|
|
return !operator==(rhs);
|
|
}
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
|
|
struct Block
|
|
{
|
|
Block(BlockId id, const shared_ptr<u8>& buf)
|
|
{
|
|
this->id = id;
|
|
this->buf = buf;
|
|
}
|
|
|
|
// block is "valid" and can satisfy Retrieve() requests if a
|
|
// (non-default-constructed) ID has been assigned.
|
|
BlockId id;
|
|
|
|
// this block is "in use" if use_count != 1.
|
|
shared_ptr<u8> buf;
|
|
};
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
|
|
class BlockCache::Impl
|
|
{
|
|
public:
|
|
Impl(size_t numBlocks)
|
|
: m_maxBlocks(numBlocks)
|
|
{
|
|
}
|
|
|
|
void Add(BlockId id, const shared_ptr<u8>& buf)
|
|
{
|
|
if(m_blocks.size() > m_maxBlocks)
|
|
{
|
|
#if CONFIG2_CACHE_READ_ONLY
|
|
mprotect((void*)m_blocks.front().buf.get(), BLOCK_SIZE, PROT_READ);
|
|
#endif
|
|
m_blocks.pop_front(); // evict oldest block
|
|
}
|
|
|
|
#if CONFIG2_CACHE_READ_ONLY
|
|
mprotect((void*)buf.get(), BLOCK_SIZE, PROT_WRITE|PROT_READ);
|
|
#endif
|
|
m_blocks.push_back(Block(id, buf));
|
|
}
|
|
|
|
bool Retrieve(BlockId id, shared_ptr<u8>& buf)
|
|
{
|
|
// (linear search is ok since we only expect to manage a few blocks)
|
|
for(size_t i = 0; i < m_blocks.size(); i++)
|
|
{
|
|
Block& block = m_blocks[i];
|
|
if(block.id == id)
|
|
{
|
|
buf = block.buf;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
void InvalidateAll()
|
|
{
|
|
// note: don't check whether any references are held etc. because
|
|
// this should only be called at the end of the (test) program.
|
|
m_blocks.clear();
|
|
}
|
|
|
|
private:
|
|
size_t m_maxBlocks;
|
|
typedef std::deque<Block> Blocks;
|
|
Blocks m_blocks;
|
|
};
|
|
|
|
|
|
//-----------------------------------------------------------------------------
|
|
|
|
BlockCache::BlockCache(size_t numBlocks)
|
|
: impl(new Impl(numBlocks))
|
|
{
|
|
}
|
|
|
|
void BlockCache::Add(BlockId id, const shared_ptr<u8>& buf)
|
|
{
|
|
impl->Add(id, buf);
|
|
}
|
|
|
|
bool BlockCache::Retrieve(BlockId id, shared_ptr<u8>& buf)
|
|
{
|
|
return impl->Retrieve(id, buf);
|
|
}
|
|
|
|
void BlockCache::InvalidateAll()
|
|
{
|
|
return impl->InvalidateAll();
|
|
}
|