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Revision 1b9e059d3503f935bb3eebb073cfb0f0401e2adf authored by Linus Torvalds on 21 October 2005, 23:40:54 UTC, committed by Junio C Hamano on 23 October 2005, 05:49:52 UTC 
git-rev-list: add "--dense" flag
 
This is what the recent git-rev-list changes have all been gearing up for.

When we use a path filter to git-rev-list, the new "--dense" flag asks
git-rev-list to compress the history so that it _only_ contains commits
that change files in the path filter.  It also rewrites the parent
information so that tools like "gitk" will see the result as a dense
history tree.

For example, on the current kernel archive:

	[torvalds@g5 linux]$ git-rev-list HEAD | wc -l
	9904
	[torvalds@g5 linux]$ git-rev-list HEAD -- kernel | wc -l
	5442
	[torvalds@g5 linux]$ git-rev-list --dense HEAD -- kernel | wc -l
	356

which shows that while we have almost ten thousand commits, we can prune
down the work to slightly more than half by only following the merges
that are interesting. But further, we can then compress the history to
just 356 entries that actually make changes to the kernel subdirectory.

To see this in action, try something like

	gitk --dense -- gitk

to see just the history that affects gitk.  Or, to show that true
parallel development still remains parallel, do

	gitk --dense -- daemon.c

which shows some parallel commits in the current git tree.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
1 parent cf48454
Raw File
patch-id.c 
#include "cache.h"

static void flush_current_id(int patchlen, unsigned char *id, SHA_CTX *c)
{
	unsigned char result[20];
	char name[50];

	if (!patchlen)
		return;

	SHA1_Final(result, c);
	memcpy(name, sha1_to_hex(id), 41);
	printf("%s %s\n", sha1_to_hex(result), name);
	SHA1_Init(c);
}

static int remove_space(char *line)
{
	char *src = line;
	char *dst = line;
	unsigned char c;

	while ((c = *src++) != '\0') {
		if (!isspace(c))
			*dst++ = c;
	}
	return dst - line;
}

static void generate_id_list(void)
{
	static unsigned char sha1[20];
	static char line[1000];
	SHA_CTX ctx;
	int patchlen = 0;

	SHA1_Init(&ctx);
	while (fgets(line, sizeof(line), stdin) != NULL) {
		unsigned char n[20];
		char *p = line;
		int len;

		if (!memcmp(line, "diff-tree ", 10))
			p += 10;

		if (!get_sha1_hex(p, n)) {
			flush_current_id(patchlen, sha1, &ctx);
			memcpy(sha1, n, 20);
			patchlen = 0;
			continue;
		}

		/* Ignore commit comments */
		if (!patchlen && memcmp(line, "diff ", 5))
			continue;

		/* Ignore git-diff index header */
		if (!memcmp(line, "index ", 6))
			continue;

		/* Ignore line numbers when computing the SHA1 of the patch */
		if (!memcmp(line, "@@ -", 4))
			continue;

		/* Compute the sha without whitespace */
		len = remove_space(line);
		patchlen += len;
		SHA1_Update(&ctx, line, len);
	}
	flush_current_id(patchlen, sha1, &ctx);
}

static const char patch_id_usage[] = "git-patch-id < patch";

int main(int argc, char **argv)
{
	if (argc != 1)
		usage(patch_id_usage);

	generate_id_list();
	return 0;
}
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