mirror of
https://gitea.wildfiregames.com/0ad/0ad
synced 2026-07-07 07:25:47 -07:00
c0ed950657
this snowballed into a massive search+destroy of the hodgepodge of mostly equivalent types we had in use (int, uint, unsigned, unsigned int, i32, u32, ulong, uintN). it is more efficient to use 64-bit types in 64-bit mode, so the preferred default is size_t (for anything remotely resembling a size or index). tile coordinates are ssize_t to allow more efficient conversion to/from floating point. flags are int because we almost never need more than 15 distinct bits, bit test/set is not slower and int is fastest to type. finally, some data that is pretty much directly passed to OpenGL is now typed accordingly. after several hours, the code now requires fewer casts and less guesswork. other changes: - unit and player IDs now have an "invalid id" constant in the respective class to avoid casting and -1 - fix some endian/64-bit bugs in the map (un)packing. added a convenience function to write/read a size_t. - ia32: change CPUID interface to allow passing in ecx (required for cache topology detection, which I need at work). remove some unneeded functions from asm, replace with intrinsics where possible. This was SVN commit r5942.
90 lines
3 KiB
C++
90 lines
3 KiB
C++
/**
|
|
* =========================================================================
|
|
* File : file_cache.h
|
|
* Project : 0 A.D.
|
|
* Description : cache of file contents (supports zero-copy IO)
|
|
* =========================================================================
|
|
*/
|
|
|
|
// license: GPL; see lib/license.txt
|
|
|
|
#ifndef INCLUDED_FILE_CACHE
|
|
#define INCLUDED_FILE_CACHE
|
|
|
|
#include "vfs_path.h"
|
|
|
|
/**
|
|
* cache of file contents with support for zero-copy IO.
|
|
* this works by reserving a region of the cache, using it as the IO buffer,
|
|
* and returning the memory directly to users. optional write-protection
|
|
* via MMU ensures that the shared contents aren't inadvertently changed.
|
|
*
|
|
* (unique copies of) VFS pathnames are used as lookup key and owner tag.
|
|
*
|
|
* to ensure efficient operation and prevent fragmentation, only one
|
|
* reference should be active at a time. in other words, read a file,
|
|
* process it, and only then start reading the next file.
|
|
*
|
|
* rationale: this is rather similar to BlockCache; however, the differences
|
|
* (Reserve's size parameter, eviction policies) are enough to warrant
|
|
* separate implementations.
|
|
**/
|
|
class FileCache
|
|
{
|
|
public:
|
|
/**
|
|
* @param size maximum amount [bytes] of memory to use for the cache.
|
|
* (managed as a virtual memory region that's committed on-demand)
|
|
**/
|
|
FileCache(size_t size);
|
|
|
|
/**
|
|
* Reserve a chunk of the cache's memory region.
|
|
*
|
|
* @param size required number of bytes (more may be allocated due to
|
|
* alignment and/or internal fragmentation)
|
|
* @return memory suitably aligned for IO; never fails.
|
|
*
|
|
* it is expected that this data will be Add()-ed once its IO completes.
|
|
**/
|
|
shared_ptr<u8> Reserve(size_t size);
|
|
|
|
/**
|
|
* Add a file's contents to the cache.
|
|
*
|
|
* the cache will be able to satisfy subsequent Retrieve() calls by
|
|
* returning this data; if CONFIG2_CACHE_READ_ONLY, the buffer is made
|
|
* read-only. if need be and no references are currently attached to it,
|
|
* the memory can also be commandeered by Reserve().
|
|
*
|
|
* @param pathname key that will be used to Retrieve file contents.
|
|
* @param cost is the expected cost of retrieving the file again and
|
|
* influences how/when it is evicted from the cache.
|
|
**/
|
|
void Add(const VfsPath& pathname, shared_ptr<u8> data, size_t size, size_t cost = 1);
|
|
|
|
/**
|
|
* Remove a file's contents from the cache (if it exists).
|
|
*
|
|
* this ensures subsequent reads of the files see the current, presumably
|
|
* recently changed, contents of the file.
|
|
*
|
|
* this would typically be called in response to a notification that a
|
|
* file has changed.
|
|
**/
|
|
void Remove(const VfsPath& pathname);
|
|
|
|
/**
|
|
* Attempt to retrieve a file's contents from the file cache.
|
|
*
|
|
* @return whether the contents were successfully retrieved; if so,
|
|
* data references the read-only file contents.
|
|
**/
|
|
bool Retrieve(const VfsPath& pathname, shared_ptr<u8>& data, size_t& size);
|
|
|
|
private:
|
|
class Impl;
|
|
shared_ptr<Impl> impl;
|
|
};
|
|
|
|
#endif // #ifndef INCLUDED_FILE_CACHE
|