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vcglib/apps/nexus/vfile.h

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/****************************************************************************
* VCGLib o o *
* Visual and Computer Graphics Library o o *
* _ O _ *
* Copyright(C) 2004 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* This program 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. *
* *
* This program 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 (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
/****************************************************************************
History
$Log: not supported by cvs2svn $
Revision 1.9 2004/07/20 14:04:32 ponchio
Improved efficience in operator[]
Revision 1.8 2004/07/15 14:32:49 ponchio
Debug.
Revision 1.7 2004/07/05 15:49:39 ponchio
Windows (DevCpp, mingw) port.
Revision 1.6 2004/07/04 15:23:48 ponchio
Debug
Revision 1.5 2004/07/02 17:41:37 ponchio
Debug.
Revision 1.4 2004/07/02 13:02:39 ponchio
Added GetRegion, Read and Write
Revision 1.3 2004/07/01 21:36:54 ponchio
*** empty log message ***
Revision 1.2 2004/06/25 16:47:13 ponchio
Various debug
Revision 1.1 2004/06/24 14:32:45 ponchio
Moved from wrap/nexus
Revision 1.3 2004/06/22 15:32:09 ponchio
Tested
Revision 1.2 2004/06/22 10:27:16 ponchio
*** empty log message ***
Revision 1.1 2004/06/22 00:39:56 ponchio
Created
****************************************************************************/
#ifndef VFILE_H
#define VFILE_H
#ifndef WIN32
#include <unistd.h>
#else
#include <windows.h>
#endif
#include <errno.h>
//#include <hash_map>
#include <map>
#include <list>
#include <string>
/**Vector structure on file with simulated mmapping.
* a priority queue of buffers is used
* TODO: port to over 4Gb usable space
* some mechanism to report errors?
* use an Iterator?
*/
namespace nxs {
template <class T> class VFile {
public:
struct Buffer {
unsigned int key;
unsigned int size; //in number of elements
T *data;
};
private:
#ifdef WIN32
HANDLE fp;
#else
FILE *fp;
#endif
std::list<Buffer> buffers;
typedef typename std::list<Buffer>::iterator list_iterator;
std::map<unsigned int, list_iterator> index; //TODO move to hash_map
Buffer *last_buffer;
unsigned int chunk_size; //default buffer size (expressed in number of T)
unsigned int queue_size;
unsigned int n_elements; //size of the vector
public:
class iterator {
public:
iterator(unsigned int p = 0, VFile *b = 0): n(p), buffer(b) {}
T &operator*() { return (*buffer)[n]; }
void operator++() { n++; }
bool operator!=(const iterator &i) { return i.n != n; }
private:
unsigned int n;
VFile *buffer;
};
VFile(): fp(NULL), last_buffer(NULL) {}
~VFile() { Close(); }
bool Create(const std::string &filename,
unsigned int _chunk_size = 4096/sizeof(T),
unsigned int _queue_size = 1000) {
assert(_chunk_size > 0);
last_buffer = NULL;
chunk_size = _chunk_size;
queue_size = _queue_size;
n_elements = 0;
#ifdef WIN32
fp = CreateFile(filename.c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,
0, NULL);
if(fp == INVALID_HANDLE_VALUE) return false;
#else
fp = fopen(filename.c_str(), "wb+");
if(!fp) return false;
#endif
return true;
}
bool Load(const std:: string &filename,
unsigned int _chunk_size = 4096/sizeof(T),
unsigned int _queue_size = 1000) {
assert(_chunk_size > 0);
last_buffer = NULL;
chunk_size = _chunk_size;
queue_size = _queue_size;
#ifdef WIN32
fp = CreateFile(filename.c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING,
0, NULL);
if(fp == INVALID_HANDLE_VALUE) return false;
#else
fp = fopen(filename.c_str(), "rb+");
if(!fp) return false;
#endif
#ifdef WIN32
n_elements = GetFileSize(fp, NULL)/ sizeof(T);
#else
fseek(fp, 0, SEEK_END);
n_elements = ftell(fp)/ sizeof(T);
#endif
return true;
}
void Close() {
if(fp) {
Flush();
#ifdef WIN32
CloseHandle(fp);
#else
fclose(fp);
#endif
fp = NULL;
}
}
void Flush() {
list_iterator i;
for(i = buffers.begin(); i != buffers.end(); i++)
FlushBuffer(*i);
buffers.clear();
index.clear();
last_buffer = NULL;
}
void FlushBuffer(Buffer buffer) {
SetPosition(buffer.key);
WriteBuffer(buffer.data, buffer.size);
/*#ifdef WIN32
SetFilePointer(fp, buffer.key * chunk_size * sizeof(T), FILE_BEGIN);
unsigned int tmp;
WriteFile(fp, buffer.data, sizeof(T) * buffer.size, &tmp, NULL);
if(tmp != sizeof(T) * buffer.size)
assert(0 && "Could not write");
#else
fseek(fp, buffer.key * chunk_size * sizeof(T), SEEK_SET);
if(buffer.size != fwrite(buffer.data, sizeof(T), buffer.size, fp))
assert(0 && "Could not write");
#endif*/
delete []buffer.data;
}
void Resize(unsigned int elem) {
assert(fp);
Flush();
if(elem > n_elements) {
#ifdef WIN32
if(INVALID_SET_FILE_POINTER == SetFilePointer(fp, elem*sizeof(T)-1, 0, FILE_BEGIN))
#else
if(-1 == fseek(fp, elem*sizeof(T) -1, SEEK_SET))
#endif
assert(0 && "Could not resize");
unsigned char a;
#ifdef WIN32
DWORD tmp;
WriteFile(fp, &a, 1, &tmp, NULL);
#else
fwrite(&a, sizeof(unsigned char), 1, fp);
#endif
} else {
//TODO optimize: we do not need flush for buffers over elem.
#ifndef WIN32
int fd = fileno(fp);
ftruncate(fd, elem*sizeof(T));
#else
SetFilePointer(fp, elem*sizeof(T), 0, FILE_BEGIN);
SetEndOfFile(fp);
#endif
}
n_elements = elem;
}
/** Remember that T is a valid pointer only until next call of
* getElement or setElement
*/
T &operator[](unsigned int n) {
assert(n < n_elements);
unsigned int chunk = n/chunk_size;
unsigned int offset = n - chunk*chunk_size;
assert(offset < chunk_size * sizeof(T));
if(last_buffer && last_buffer->key == chunk)
return *(last_buffer->data + offset);
if(index.count(chunk)) {
last_buffer = &*index[chunk];
return *((*(index[chunk])).data + offset);
}
if(buffers.size() > queue_size) {
Buffer &buffer= buffers.back();
assert(buffer.key != chunk);
FlushBuffer(buffer);
index.erase(buffer.key);
buffers.pop_back();
}
Buffer buffer;
buffer.key = chunk;
buffer.size = chunk_size;
if(buffer.size + chunk * chunk_size > n_elements)
buffer.size = n_elements - chunk * chunk_size;
buffer.data = new T[buffer.size];
buffers.push_front(buffer);
index[buffer.key] = buffers.begin();
last_buffer = &*buffers.begin();
SetPosition(chunk);
ReadBuffer(buffer.data, buffer.size);
return *(buffer.data + offset);
}
/** you can get a region instead of an element but:
1)region must be Chunk aligned.
2)you get impredictable results if regions overlap or mix with operator[]
*/
T *GetRegion(unsigned int start, unsigned int size, bool flush = true) {
assert(start + size <= n_elements);
assert((size % chunk_size) == 0);
assert((start % chunk_size) == 0);
if(size == 0) return NULL;
unsigned int chunk = start/chunk_size;
if(index.count(chunk))
return ((*(index[chunk])).data);
while(flush && buffers.size() > queue_size) {
Buffer &buffer= buffers.back();
FlushBuffer(buffer);
index.erase(buffer.key);
buffers.pop_back();
}
Buffer buffer;
buffer.key = chunk;
buffer.size = size;
buffer.data = new T[buffer.size];
buffers.push_front(buffer);
index[chunk] = buffers.begin();
SetPosition(chunk);
ReadBuffer(buffer.data, buffer.size);
return buffer.data;
}
void PushBack(const T &t) {
Resize(n_elements+1);
operator[](n_elements-1) = t;
}
unsigned int Size() { return n_elements; }
unsigned int ChunkSize() { return chunk_size; }
unsigned int QueueSize() { return queue_size; }
iterator Begin() { return iterator(0, this); }
iterator End() { return iterator(Size(), this); }
protected:
void SetPosition(unsigned int chunk) {
#ifdef WIN32
SetFilePointer(fp, chunk * chunk_size * sizeof(T), 0, FILE_BEGIN);
#else
fseek(fp, chunk * chunk_size * sizeof(T), SEEK_SET);
#endif
}
void ReadBuffer(T *data, unsigned int size) {
#ifdef WIN32
DWORD tmp;
ReadFile(fp, data, sizeof(T) * size, &tmp, NULL);
if(tmp != sizeof(T) * size)
assert(0 && "Could not read");
#else
if(size != fread(data, sizeof(T), size, fp))
assert(0 && "Could not read");
#endif
}
void WriteBuffer(T *data, unsigned int size) {
#ifdef WIN32
DWORD tmp;
WriteFile(fp, data, sizeof(T) * size, &tmp, NULL);
if(tmp != sizeof(T) * size)
assert(0 && "Could not write");
#else
if(size != fwrite(data, sizeof(T), size, fp))
assert(0 && "Could not write");
#endif
}
};
}//namespace
#endif
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