1 files changed, 125 insertions, 0 deletions
diff --git a/lib/binary.cpp b/lib/binary.cpp
new file mode 100644
index 00000000..4fdf8899
--- /dev/null
+++ b/lib/binary.cpp
@@ -0,0 +1,125 @@
+// **************************************************************************
+// * 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 <wx/stopwatch.h>
+#include <vector>
+#include <zen/file_io.h>
+#include <zen/int64.h>
+#include <boost/thread/tss.hpp>
+
+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 zen::filesHaveSameContent(const Zstring& filename1, const Zstring& filename2, CompareCallback& callback)
+{
+    FileInput file1(filename1); //throw FileError
+    FileInput file2(filename2); //throw FileError
+
+    static boost::thread_specific_ptr<std::vector<char>> cpyBuf1;
+    static boost::thread_specific_ptr<std::vector<char>> cpyBuf2;
+    if (!cpyBuf1.get())
+        cpyBuf1.reset(new std::vector<char>());
+    if (!cpyBuf2.get())
+        cpyBuf2.reset(new std::vector<char>());
+
+    std::vector<char>& memory1 = *cpyBuf1;
+    std::vector<char>& memory2 = *cpyBuf2;
+
+    BufferSize bufferSize;
+    zen::UInt64 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;
+}