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/* Copyright (C) 2018 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/>.
*/
#include "precompiled.h"
#include "CacheLoader.h"
#include "maths/MD5.h"
#include "ps/CLogger.h"
#include "ps/Util.h"
#include <iomanip>
CCacheLoader::CCacheLoader(PIVFS vfs, const std::wstring& fileExtension) :
m_VFS(vfs), m_FileExtension(fileExtension)
{
}
Status CCacheLoader::TryLoadingCached(const VfsPath& sourcePath, const MD5& initialHash, u32 version, VfsPath& loadPath)
{
VfsPath archiveCachePath = ArchiveCachePath(sourcePath);
// Try the archive cache file first
if (CanUseArchiveCache(sourcePath, archiveCachePath))
{
loadPath = archiveCachePath;
return INFO::OK;
}
// Fail if no source or archive cache
// Note: this is not always an error case, because for instance there
// are some uncached .pmd/psa files in the game with no source .dae.
// This test fails (correctly) in that valid situation, so it seems
// best to leave the error handling to the caller.
Status err = m_VFS->GetFileInfo(sourcePath, NULL);
if (err < 0)
{
return err;
}
// Look for loose cache of source file
VfsPath looseCachePath = LooseCachePath(sourcePath, initialHash, version);
// If the loose cache file exists, use it
if (m_VFS->GetFileInfo(looseCachePath, NULL) >= 0)
{
loadPath = looseCachePath;
return INFO::OK;
}
// No cache - we'll need to regenerate it
loadPath = looseCachePath;
return INFO::SKIPPED;
}
bool CCacheLoader::CanUseArchiveCache(const VfsPath& sourcePath, const VfsPath& archiveCachePath)
{
// We want to use the archive cache whenever possible,
// unless it's superseded by a source file that the user has edited
size_t archiveCachePriority = 0;
size_t sourcePriority = 0;
bool archiveCacheExists = (m_VFS->GetFilePriority(archiveCachePath, &archiveCachePriority) >= 0);
// Can't use it if there's no cache
if (!archiveCacheExists)
return false;
bool sourceExists = (m_VFS->GetFilePriority(sourcePath, &sourcePriority) >= 0);
// Must use the cache if there's no source
if (!sourceExists)
return true;
// If source file is from a higher-priority mod than archive cache,
// don't use the old cache
if (archiveCachePriority < sourcePriority)
return false;
// If source file is more recent than the archive cache (i.e. the user has edited it),
// don't use the old cache
CFileInfo sourceInfo, archiveCacheInfo;
if (m_VFS->GetFileInfo(sourcePath, &sourceInfo) >= 0 &&
m_VFS->GetFileInfo(archiveCachePath, &archiveCacheInfo) >= 0)
{
const double howMuchNewer = difftime(sourceInfo.MTime(), archiveCacheInfo.MTime());
const double threshold = 2.0; // FAT timestamp resolution [seconds]
if (howMuchNewer > threshold)
return false;
}
// Otherwise we can use the cache
return true;
}
VfsPath CCacheLoader::ArchiveCachePath(const VfsPath& sourcePath) const
{
return sourcePath.ChangeExtension(sourcePath.Extension().string() + L".cached" + m_FileExtension);
}
VfsPath CCacheLoader::LooseCachePath(const VfsPath& sourcePath, const MD5& initialHash, u32 version)
{
CFileInfo fileInfo;
if (m_VFS->GetFileInfo(sourcePath, &fileInfo) < 0)
{
debug_warn(L"source file disappeared"); // this should never happen
return VfsPath();
}
u64 mtime = (u64)fileInfo.MTime() & ~1; // skip lowest bit, since zip and FAT don't preserve it
u64 size = (u64)fileInfo.Size();
// Construct a hash of the file data and settings.
MD5 hash = initialHash;
hash.Update((const u8*)&mtime, sizeof(mtime));
hash.Update((const u8*)&size, sizeof(size));
hash.Update((const u8*)&version, sizeof(version));
// these are local cached files, so we don't care about endianness etc
u8 digest[MD5::DIGESTSIZE];
hash.Final(digest);
// Get the mod path
OsPath path;
m_VFS->GetRealPath(sourcePath, path);
return VfsPath("cache") /
path_name_only(path.BeforeCommon(sourcePath).Parent().string().c_str()) /
sourcePath.ChangeExtension(sourcePath.Extension().string() +
L"." +
// Use a short prefix of the full hash (we don't need high collision-resistance)
wstring_from_utf8(Hexify(digest, 8)) +
m_FileExtension);
}
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