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Revision 9de0834663f28bee9e6b2c4647ed6128241ed26f authored by Linus Torvalds on 17 October 2006, 02:58:54 UTC, committed by Junio C Hamano on 17 October 2006, 04:27:44 UTC 
Fix hash function in xdiff library
 
Jim Mayering noticed that xdiff library took insanely long time
when comparing files with many identical lines.

This was because the hash function used in the library is broken
on 64-bit architectures and caused too many collisions.

http://thread.gmane.org/gmane.comp.version-control.git/28962/focus=28994

Acked-by: Davide Libenzi <davidel@xmaliserver.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
1 parent 6fe5b7f
Raw File
show-index.c 
#include "cache.h"

int main(int argc, char **argv)
{
	int i;
	unsigned nr;
	unsigned int entry[6];
	static unsigned int top_index[256];

	if (fread(top_index, sizeof(top_index), 1, stdin) != 1)
		die("unable to read idex");
	nr = 0;
	for (i = 0; i < 256; i++) {
		unsigned n = ntohl(top_index[i]);
		if (n < nr)
			die("corrupt index file");
		nr = n;
	}
	for (i = 0; i < nr; i++) {
		unsigned offset;

		if (fread(entry, 24, 1, stdin) != 1)
			die("unable to read entry %u/%u", i, nr);
		offset = ntohl(entry[0]);
		printf("%u %s\n", offset, sha1_to_hex((void *)(entry+1)));
	}
	return 0;
}
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