Lars Gullik Bjønnes wrote:
>I think you should submit the complete patch again.
>
Complete patch attached.
process_block does lead to a significant improvement.
Warm cache
ben [11:26:45]
/share/install/linux/extras/lyx/lyx-HEAD/lyx-devel/src/support/tests $
time crccheck.do_crc /share/mp3/bassic/EI.mp3
CRC: 3089166751
real 0m0.448s
user 0m0.450s
sys 0m0.000s
ben [11:26:49]
/share/install/linux/extras/lyx/lyx-HEAD/lyx-devel/src/support/tests $
time crccheck.process_block /share/mp3/bassic/EI.mp3
CRC: 3089166751
real 0m0.150s
user 0m0.130s
sys 0m0.020s
ben [11:39:13] /share/install/linux/extras/lyx/lyx-HEAD $ ls -al
/share/mp3/bassic/EI.mp3
-rw-r--r-- 1 ben users 5661289 Nov 5 08:45
/share/mp3/bassic/EI.mp3
--- lyx-devel/src/support/lyxsum.C.orig.cvs Mon Dec 3 09:20:46 2001
+++ lyx-devel/src/support/lyxsum.C Mon Dec 3 11:29:17 2001
@@ -10,8 +10,6 @@
#include <config.h>
-#include <fstream>
-#include <iterator>
#include <algorithm>
#include <boost/crc.hpp>
@@ -31,23 +29,88 @@
} // namespace
-
-// And this would be the file interface.
-unsigned long lyx::sum(string const & file)
+// Various implementations of lyx::sum(), depending on what methods
+// are available. Order is faster to slowest.
+#if defined(HAVE_MMAP) && defined(HAVE_MUNMAP)
+ #ifdef WITH_WARNINGS
+ #warning lyx::sum() using mmap (lightning fast)
+ #endif
+
+ #include <sys/types.h>
+ #include <sys/stat.h>
+ #include <fcntl.h>
+ #include <unistd.h>
+ #include <sys/mman.h>
+
+ unsigned long lyx::sum(string const & file)
+ {
+ int fd = open(file.c_str(), O_RDONLY);
+ if( !fd ) return 0;
+
+ struct stat info;
+ fstat(fd, &info);
+
+ void * mm = mmap(0, info.st_size, PROT_READ,
+ MAP_PRIVATE, fd, 0);
+ if (mm == MAP_FAILED) {
+ close(fd);
+ return 0;
+ }
+
+ char *beg = static_cast<char*>(mm);
+ char *end = beg + info.st_size;
+
+ boost::crc_32_type crc;
+ crc.process_block(beg,end);
+ unsigned long result = crc.checksum();
+
+ munmap( mm, info.st_size );
+ close(fd);
+
+ return result;
+ }
+#else // No mmap
+ #include <fstream>
+ #include <iterator>
+
+ #if HAVE_DECL_ISTREAMBUF_ITERATOR
+ #ifdef WITH_WARNINGS
+ #warning lyx::sum() using istreambuf_iterator (fast)
+ #endif
+ unsigned long lyx::sum(string const & file)
+ {
+ std::ifstream ifs(file.c_str());
+ if (!ifs) return 0;
+
+ std::istreambuf_iterator<char> beg(ifs);
+ std::istreambuf_iterator<char> end;
+
+ return do_crc(beg,end);
+ }
+ #else
+ #ifdef WITH_WARNINGS
+ #warning lyx::sum() using istream_iterator (slow as a snail)
+ #endif
+ unsigned long lyx::sum(string const & file)
+ {
+ std::ifstream ifs(file.c_str());
+ if (!ifs) return 0;
+
+ ifs.unsetf(std::ios::skipws);
+ std::istream_iterator<char> beg(ifs);
+ std::istream_iterator<char> end;
+
+ return do_crc(beg,end);
+ }
+ #endif
+#endif // mmap
+
+#if 0
+#include <iostream>
+int main(int /*argc*/, char * argv[])
{
- std::ifstream ifs(file.c_str());
- if (!ifs) return 0;
-
-#ifdef HAVE_DECL_ISTREAMBUF_ITERATOR
- // This is a lot faster...
- std::istreambuf_iterator<char> beg(ifs);
- std::istreambuf_iterator<char> end;
-#else
- // than this.
- ifs.unsetf(std::ios::skipws);
- std::istream_iterator<char> beg(ifs);
- std::istream_iterator<char> end;
-#endif
+ std::string const fil(argv[1]);
- return do_crc(beg, end);
+ std::cout << "CRC: " << lyx::sum(fil) << std::endl;
}
+#endif
--- lyx-devel/src/support/ChangeLog.orig Mon Dec 3 11:32:13 2001
+++ lyx-devel/src/support/ChangeLog Mon Dec 3 11:36:32 2001
@@ -1,3 +1,8 @@
+2001-12-03 Ben Stanley <[EMAIL PROTECTED]>
+
+ * lyxsum.C: Added mmap version of CRC and made it selected
+ by default where available. Used process_block for crc for speedup.
+
2001-12-01 John Levon <[EMAIL PROTECTED]>
* filetools.C: more robust failure for DirList()
