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Start work on new FileIndex base class 

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Ted John 2017-08-29 19:18:13 +01:00
parent aad2cb60e2
commit 4f3669f279
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src/openrct2/core/FileIndex.hpp Normal file
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#pragma region Copyright (c) 2017 OpenRCT2 Developers
/*****************************************************************************
* OpenRCT2, an open source clone of Roller Coaster Tycoon 2.
*
* OpenRCT2 is the work of many authors, a full list can be found in contributors.md
* For more information, visit https://github.com/OpenRCT2/OpenRCT2
*
* OpenRCT2 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 3 of the License, or
* (at your option) any later version.
*
* A full copy of the GNU General Public License can be found in licence.txt
*****************************************************************************/
#pragma endregion
#pragma once
#include <string>
#include "../common.h"
template<typename TItem>
class FileIndex
{
private:
struct DirectoryStats
{
uint32 TotalFiles = 0;
uint64 TotalFileSize = 0;
uint32 FileDateModifiedChecksum = 0;
uint32 PathChecksum = 0;
}
struct ScanResult
{
DirectoryStats const Stats;
std::vector<std::string> const Files;
ScanResult(DirectoryStats stats, std::vector<std::string> files)
: Stats(stats),
Files(files)
{
}
};
struct FileIndexHeader
{
uint32 MagicNumber = 0;
uint8 VersionA = 0;
uint8 VersionB = 0;
uint16 LanguageId = 0;
DirectoryStats DirectoryStats;
uint32 NumItems = 0;
};
constexpr uint8 FILE_INDEX_VERSION = 4;
uint32 _magicNumber;
uint8 _version;
std::string _indexPath;
std::string _pattern;
std::vector<std::string> _paths;
public:
FileIndex(uint32 magicNumber,
uint8 version,
std::string indexPath,
std::string pattern,
std::vector<std::string> paths) :
_magicNumber(magicNumber),
_version(version),
_indexPath(indexPath),
_pattern(pattern),
_paths(paths)
{
}
/**
* Queries and directories and loads the index header. If the index is up to date,
* the items are loaded from the index and returned, otherwise the index is rebuilt.
*/
std::vector<TItem> LoadOrBuild()
{
std::vector<TItem> items;
auto scanResult = Scan();
auto readIndexResult = ReadIndexFile(scanResult.Stats);
if (std::get<0>(readIndexResult))
{
// Index was loaded
items = std::get<1>(readIndexResult);
}
else
{
// Index was not loaded
for (auto filePath : scanResult.Files)
{
auto item = Create(filePath);
items.push_back(item);
}
WriteIndexFile(items);
}
return items;
}
/**
* Loads the given file and creates the item representing the data to store in the index.
*/
virtual TItem Create(const std::string &path) abstract;
/**
* Serialises an index item to the given stream.
*/
virtual void Serialise(IStream * stream, const TItem item);
/**
* Deserialises an index item from the given stream.
*/
virtual TItem Deserialise(IStream * stream) abstract;
private:
ScanResult Scan()
{
ScanResult scanResult;
for (const auto directory : _paths)
{
auto pattern = Path::Combine(directory, _pattern);
auto scanner = Path::ScanDirectory(pattern, true);
while (scanner->Next())
{
auto fileInfo = scanner->GetFileInfo();
auto path = std::string(scanner->GetPath());
scanResult.Files.push(path);
scanResult.TotalFiles++;
scanResult.TotalFileSize += fileInfo->Size;
scanResult.FileDateModifiedChecksum ^=
(uint32)(fileInfo->LastModified >> 32) ^
(uint32)(fileInfo->LastModified & 0xFFFFFFFF);
scanResult.FileDateModifiedChecksum = ror32(result->FileDateModifiedChecksum, 5);
scanResult.PathChecksum += GetPathChecksum(path);
}
delete scanner;
}
}
std::tuple<bool, std::vector<TItem>> ReadIndexFile(const DirectoryStats &stats)
{
bool loadedItems = false;
std::vector<TItem> items;
try
{
auto fs = FileStream(path, FILE_MODE_OPEN);
// Read header, check if we need to re-scan
auto header = fs.ReadValue<FileIndexHeader>();
if (header.MagicNumber == _magicNumber &&
header.VersionA == FILE_INDEX_VERSION &&
header.VersionB == _version &&
header.TotalFiles == scanResult.TotalFiles &&
header.TotalFileSize == scanResult.TotalFileSize &&
header.FileDateModifiedChecksum == scanResult.FileDateModifiedChecksum &&
header.PathChecksum == scanResult.PathChecksum)
{
// Directory is the same, just read the saved items
for (uint32 i = 0; i < header.NumItems; i++)
{
auto item = Deserialise(fs);
items.push_back(item);
}
loadedItems = true;
}
}
catch (const Exception &)
{
Console::Error::WriteLine("Unable to load index.");
}
return std::make_tuple(loadedItems, items);
}
void WriteIndexFile(const DirectoryStats &stats, const std::vector<TItem> &items)
{
try
{
auto fs = FileStream(_indexPath, FILE_MODE_WRITE);
// Write header
FileIndexHeader header = { 0 };
header.MagicNumber = _magicNumber;
header.Version = SCENARIO_REPOSITORY_VERSION;
header.LanguageId = gCurrentLanguage;
header.DirectoryStats = stats;
header.NumItems = items.size();
fs.WriteValue(header);
// Write items
for (const auto item : items)
{
Serialise(fs, item);
}
return true;
}
catch (const Exception &)
{
Console::Error::WriteLine("Unable to save index.");
return false;
}
}
};