janwas
8a52113e60
please note: format strings must be %hs for char* arguments and %ls for wchar_t* This was SVN commit r7161.
99 lines
2.7 KiB
C++
99 lines
2.7 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 blocks.
|
|
*/
|
|
|
|
#ifndef INCLUDED_BLOCK_CACHE
|
|
#define INCLUDED_BLOCK_CACHE
|
|
|
|
/**
|
|
* ID that uniquely identifies a block within a file
|
|
**/
|
|
class BlockId
|
|
{
|
|
public:
|
|
BlockId();
|
|
BlockId(const fs::wpath& pathname, off_t ofs);
|
|
bool operator==(const BlockId& rhs) const;
|
|
bool operator!=(const BlockId& rhs) const;
|
|
|
|
private:
|
|
u64 m_id;
|
|
};
|
|
|
|
|
|
/**
|
|
* cache of (aligned) file blocks with support for zero-copy IO.
|
|
* absorbs the overhead of rounding up archive IOs to the nearest block
|
|
* boundaries by keeping the last few blocks in memory.
|
|
*
|
|
* the interface is somewhat similar to FileCache; see the note there.
|
|
*
|
|
* not thread-safe (each thread is intended to have its own cache).
|
|
**/
|
|
class BlockCache
|
|
{
|
|
public:
|
|
/**
|
|
* @param numBlocks (the default value is enough to support temp buffers
|
|
* and absorb the cost of unaligned reads from archives.)
|
|
**/
|
|
BlockCache(size_t numBlocks = 16);
|
|
|
|
/**
|
|
* Add a block to the cache.
|
|
*
|
|
* @param id key that will be used to Retrieve the block.
|
|
*
|
|
* call this when the block's IO has completed; its data will
|
|
* satisfy subsequent Retrieve calls for the same id.
|
|
* if CONFIG2_CACHE_READ_ONLY, the memory is made read-only.
|
|
**/
|
|
void Add(BlockId id, const shared_ptr<u8>& buf);
|
|
|
|
/**
|
|
* Attempt to retrieve a block's contents.
|
|
*
|
|
* @return whether the block is in cache.
|
|
*
|
|
* if successful, a shared pointer to the contents is returned.
|
|
* they remain valid until all references are removed and the block
|
|
* is evicted.
|
|
**/
|
|
bool Retrieve(BlockId id, shared_ptr<u8>& buf);
|
|
|
|
/**
|
|
* Invalidate the contents of the cache.
|
|
*
|
|
* this effectively discards the contents of existing blocks
|
|
* (more specifically: prevents them from satisfying Retrieve calls
|
|
* until a subsequent Add with the same id).
|
|
*
|
|
* useful for self-tests: multiple independent IO tests run in the same
|
|
* process and must not influence each other via the cache.
|
|
**/
|
|
void InvalidateAll();
|
|
|
|
private:
|
|
class Impl;
|
|
shared_ptr<Impl> impl;
|
|
};
|
|
|
|
#endif // #ifndef INCLUDED_BLOCK_CACHE
|