polyvox/include/PolyVox/FilePager.h

/*******************************************************************************
Copyright (c) 2005-2009 David Williams

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

    1. The origin of this software must not be misrepresented; you must not
    claim that you wrote the original software. If you use this software
    in a product, an acknowledgment in the product documentation would be
    appreciated but is not required.

    2. Altered source versions must be plainly marked as such, and must not be
    misrepresented as being the original software.

    3. This notice may not be removed or altered from any source
    distribution. 	
*******************************************************************************/

#ifndef __PolyVox_FilePager_H__
#define __PolyVox_FilePager_H__

#include "PolyVox/Impl/PlatformDefinitions.h"

#include "PolyVox/PagedVolume.h"
#include "PolyVox/Region.h"

#include <cstdlib>
#include <ctime>
#include <fstream>
#include <stdexcept>
#include <string>
#include <vector>

namespace PolyVox
{
	/**
	 * Provides an interface for performing paging of data.
	 */
	template <typename VoxelType>
	class FilePager : public PagedVolume<VoxelType>::Pager
	{
	public:
		/// Constructor
		FilePager(const std::string& strFolderName = ".")
			:PagedVolume<VoxelType>::Pager()
			,m_strFolderName(strFolderName)
		{
			// Add the trailing slash, assuming the user dind't already do it.
				if ((m_strFolderName.back() != '/') && (m_strFolderName.back() != '\\'))
			{
					m_strFolderName.append("/");
			}

			// Build a unique postfix to avoid filename conflicts between multiple pagers/runs.
			// Not a very robust solution but this class is meant as an example for testing really.
			std::stringstream ss;
			ss << time(0) << "--"; // Avoid multiple runs using the same filenames.
			ss << this; // Avoid multiple FilePagers using the same filenames.
			m_strPostfix = ss.str();
		}

		/// Destructor
		virtual ~FilePager()
		{
			for(std::vector<std::string>::iterator iter = m_vecCreatedFiles.begin(); iter < m_vecCreatedFiles.end(); iter++)
			{
				POLYVOX_LOG_WARNING_IF(std::remove(iter->c_str()) != 0, "Failed to delete '", *iter, "' when destroying FilePager");
			}

			m_vecCreatedFiles.clear();
		}

		virtual void pageIn(const Region& region, typename PagedVolume<VoxelType>::Chunk* pChunk)
		{
			POLYVOX_ASSERT(pChunk, "Attempting to page in NULL chunk");
			POLYVOX_ASSERT(pChunk->getData(), "Chunk must have valid data");

			std::stringstream ssFilename;
			ssFilename << m_strFolderName << "/"
				<< region.getLowerX() << "_" << region.getLowerY() << "_" << region.getLowerZ() << "_"
				 << region.getUpperX() << "_" << region.getUpperY() << "_" << region.getUpperZ()
				 << "--" << m_strPostfix;

			std::string filename = ssFilename.str();

			// FIXME - This should be replaced by C++ style IO, but currently this causes problems with
			// the gameplay-cubiquity integration. See: https://github.com/blackberry/GamePlay/issues/919

			FILE* pFile = fopen(filename.c_str(), "rb");
			if(pFile)
			{
				POLYVOX_LOG_TRACE("Paging in data for ", region);

				/*fseek(pFile, 0L, SEEK_END);
				size_t fileSizeInBytes = ftell(pFile);
				fseek(pFile, 0L, SEEK_SET);
				
				uint8_t* buffer = new uint8_t[fileSizeInBytes];
				fread(buffer, sizeof(uint8_t), fileSizeInBytes, pFile);
				pChunk->setData(buffer, fileSizeInBytes);
				delete[] buffer;*/

				fread(pChunk->getData(), sizeof(uint8_t), pChunk->getDataSizeInBytes(), pFile);

				if(ferror(pFile))
				{
					POLYVOX_THROW(std::runtime_error, "Error reading in chunk data, even though a file exists.");
				}

				fclose(pFile);
			}
			else
			{
				POLYVOX_LOG_TRACE("No data found for ", region, " during paging in.");

				// Just fill with zeros. This feels hacky... perhaps we should just throw
				// an exception and let the calling code handle it and fill with zeros.
				uint32_t noOfVoxels = region.getWidthInVoxels() * region.getHeightInVoxels() * region.getDepthInVoxels();
				std::fill(pChunk->getData(), pChunk->getData() + noOfVoxels, VoxelType());
			}
		}

		virtual void pageOut(const Region& region, typename PagedVolume<VoxelType>::Chunk* pChunk)
		{
			POLYVOX_ASSERT(pChunk, "Attempting to page out NULL chunk");
			POLYVOX_ASSERT(pChunk->getData(), "Chunk must have valid data");

			POLYVOX_LOG_TRACE("Paging out data for ", region);

			std::stringstream ssFilename;
			ssFilename << m_strFolderName << "/"
				<< region.getLowerX() << "_" << region.getLowerY() << "_" << region.getLowerZ() << "_"
				<< region.getUpperX() << "_" << region.getUpperY() << "_" << region.getUpperZ()
				<< "--" << m_strPostfix;

			std::string filename = ssFilename.str();

			// FIXME - This should be replaced by C++ style IO, but currently this causes problems with
			// the gameplay-cubiquity integration. See: https://github.com/blackberry/GamePlay/issues/919

			FILE* pFile = fopen(filename.c_str(), "wb");
			if(!pFile)
			{
				POLYVOX_THROW(std::runtime_error, "Unable to open file to write out chunk data.");
			}

			//The file has been created, so add it to the list to delete on shutdown.
			m_vecCreatedFiles.push_back(filename);

			fwrite(pChunk->getData(), sizeof(uint8_t), pChunk->getDataSizeInBytes(), pFile);

			if(ferror(pFile))
			{
				POLYVOX_THROW(std::runtime_error, "Error writing out chunk data.");
			}

			fclose(pFile);
		}

	protected:
		std::string m_strFolderName;
		std::string m_strPostfix;

		std::vector<std::string> m_vecCreatedFiles;
	};
}

#endif //__PolyVox_FilePager_H__