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// **************************************************************************
// * This file is part of the FreeFileSync project. It is distributed under *
// * GNU General Public License: http://www.gnu.org/licenses/gpl.html *
// * Copyright (C) 2008-2011 ZenJu (zhnmju123 AT gmx.de) *
// **************************************************************************
//
#include "binary.h"
#include "../shared/file_io.h"
#include <vector>
#include <wx/stopwatch.h>
inline
void setMinSize(std::vector<char>& buffer, size_t minSize)
{
if (buffer.size() < minSize) //this is similar to reserve(), but we need a "properly initialized" array here
buffer.resize(minSize);
}
namespace
{
class BufferSize
{
public:
BufferSize() : bufSize(BUFFER_SIZE_START) {}
void inc()
{
if (bufSize < BUFFER_SIZE_MAX)
bufSize *= 2;
}
void dec()
{
if (bufSize > BUFFER_SIZE_MIN)
bufSize /= 2;
}
operator size_t() const
{
return bufSize;
}
private:
static const size_t BUFFER_SIZE_MIN = 128 * 1024;
static const size_t BUFFER_SIZE_START = 512 * 1024; //512 kb seems to be a reasonable initial buffer size
static const size_t BUFFER_SIZE_MAX = 16 * 1024 * 1024;
/*Tests on Win7 x64 show that buffer size does NOT matter if files are located on different physical disks!
Impact of buffer size when files are on same disk:
buffer MB/s
------------
64 10
128 19
512 40
1024 48
2048 56
4096 56
8192 56
*/
size_t bufSize;
};
}
bool ffs3::filesHaveSameContent(const Zstring& filename1, const Zstring& filename2, CompareCallback& callback)
{
FileInput file1(filename1); //throw (FileError)
FileInput file2(filename2); //throw (FileError)
BufferSize bufferSize;
static std::vector<char> memory1;
static std::vector<char> memory2;
wxLongLong bytesCompared;
wxLongLong lastDelayViolation = wxGetLocalTimeMillis();
do
{
setMinSize(memory1, bufferSize);
setMinSize(memory2, bufferSize);
const wxLongLong startTime = wxGetLocalTimeMillis();
const size_t length1 = file1.read(&memory1[0], bufferSize); //returns actual number of bytes read; throw FileError()
const size_t length2 = file2.read(&memory2[0], bufferSize); //
const wxLongLong stopTime = wxGetLocalTimeMillis();
//-------- dynamically set buffer size to keep callback interval between 200 - 500ms ---------------------
const wxLongLong loopTime = stopTime - startTime;
if (loopTime < 200 && stopTime - lastDelayViolation > 2000) //avoid "flipping back": e.g. DVD-Roms read 32MB at once, so first read may be > 300 ms, but second one will be 0ms!
{
lastDelayViolation = stopTime;
bufferSize.inc(); //practically no costs!
}
else if (loopTime > 500)
{
lastDelayViolation = stopTime;
bufferSize.dec(); //
}
//------------------------------------------------------------------------------------------------
if (length1 != length2 || ::memcmp(&memory1[0], &memory2[0], length1) != 0)
return false;
bytesCompared += length1 * 2;
callback.updateCompareStatus(bytesCompared); //send progress updates
}
while (!file1.eof());
if (!file2.eof()) //highly unlikely, but theoretically possible! (but then again, not in this context where both files have same size...)
return false;
return true;
}
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