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[PATCH v2 11/13] rerere: explain "rerere forget" codepath

From
Junio C Hamano <gitster@pobox.com>
Date
Jul 1, 2015, 06:04 UTC
Message-ID
<1435730699-9124-12-git-send-email-gitster@pobox.com>
In-Reply-To
<1435730699-9124-1-git-send-email-gitster@pobox.com>

Explain the internals of rerere as in-code comments, while sprinkling "NEEDSWORK" comment to highlight iffy bits and questionable assumptions.

This covers the codepath that implements "rerere forget".
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 rerere.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
diff --git a/rerere.c b/rerere.c
index 3d9c33b..3782be6 100644
--- a/rerere.c
+++ b/rerere.c
@@ -413,6 +413,10 @@ static int handle_cache(const char *path, unsigned char *sha1, const char *outpu
 	strbuf_init(&io.input, 0);
 	strbuf_attach(&io.input, result.ptr, result.size, result.size);
 
+	/*
+	 * Grab the conflict ID and optionally write the original
+	 * contents with conflict markers out.
+	 */
 	hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 	strbuf_release(&io.input);
 	if (io.io.output)
@@ -777,9 +781,15 @@ static int rerere_forget_one_path(const char *path, struct string_list *rr)
 	int ret;
 	struct string_list_item *item;
 
+	/*
+	 * Recreate the original conflict from the stages in the
+	 * index and compute the conflict ID
+	 */
 	ret = handle_cache(path, sha1, NULL);
 	if (ret < 1)
 		return error("Could not parse conflict hunks in '%s'", path);
+
+	/* Nuke the recorded resolution for the conflict */
 	hex = xstrdup(sha1_to_hex(sha1));
 	filename = rerere_path(hex, "postimage");
 	if (unlink(filename))
@@ -787,9 +797,18 @@ static int rerere_forget_one_path(const char *path, struct string_list *rr)
 			? error("no remembered resolution for %s", path)
 			: error("cannot unlink %s: %s", filename, strerror(errno)));
 
+	/*
+	 * Update the preimage so that the user can resolve the
+	 * conflict in the working tree, run us again to record
+	 * the postimage.
+	 */
 	handle_cache(path, sha1, rerere_path(hex, "preimage"));
 	fprintf(stderr, "Updated preimage for '%s'\n", path);
 
+	/*
+	 * And remember that we can record resolution for this
+	 * conflict when the user is done.
+	 */
 	item = string_list_insert(rr, path);
 	free(item->util);
 	item->util = hex;
@@ -808,6 +827,11 @@ int rerere_forget(struct pathspec *pathspec)
 
 	fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
 
+	/*
+	 * The paths may have been resolved (incorrectly);
+	 * recover the original conflicted state and then
+	 * find the conflicted paths.
+	 */
 	unmerge_cache(pathspec);
 	find_conflict(&conflict);
 	for (i = 0; i < conflict.nr; i++) {
-- 
2.5.0-rc0-209-g5e1f148
Previous: Junio C HamanoNext: Junio C Hamano
Message 12 of 39 in “"rerere" minor clean-up”
  1. 00/13 "rerere" minor clean-upJunio C Hamano, Jul 1, 2015
  2. 01/13 rerere: fix an off-by-one non-bugJunio C Hamano, Jul 1, 2015
  3. 02/13 rerere: plug conflict ID leaksJunio C Hamano, Jul 1, 2015
  4. 03/13 rerere: lift PATH_MAX limitationJunio C Hamano, Jul 1, 2015
  5. 04/13 rerere: write out each record of MERGE_RR in one goJunio C Hamano, Jul 1, 2015
  6. 05/13 rerere: report autoupdated paths only after actually updating themJunio C Hamano, Jul 1, 2015
  7. 06/13 rerere: drop want_sp parameter from is_cmarker()Junio C Hamano, Jul 1, 2015
  8. 07/13 rerere: stop looping unnecessarilyJunio C Hamano, Jul 1, 2015
  9. 08/13 rerere: explain the rerere I/O abstractionJunio C Hamano, Jul 1, 2015
  10. 09/13 rerere: explain MERGE_RR management helpersJunio C Hamano, Jul 1, 2015
  11. 10/13 rerere: explain the primary codepathJunio C Hamano, Jul 1, 2015
  12. 11/13 rerere: explain "rerere forget" codepathJunio C Hamano, Jul 1, 2015
  13. 12/13 rerere: explain the remainderJunio C Hamano, Jul 1, 2015
  14. 13/13 rerere: refactor "replay" part of do_plain_rerere()Junio C Hamano, Jul 1, 2015
  15. 00/18 "rerere" preparatory clean-upJunio C Hamano, Jul 17, 2015
  16. 01/18 rerere: fix an off-by-one non-bugJunio C Hamano, Jul 17, 2015
  17. Junio C HamanoJul 24, 2015
  18. 02/18 rerere: plug conflict ID leaksJunio C Hamano, Jul 17, 2015
  19. 03/18 rerere: lift PATH_MAX limitationJunio C Hamano, Jul 17, 2015
  20. 04/18 rerere: write out each record of MERGE_RR in one goJunio C Hamano, Jul 17, 2015
  21. 05/18 rerere: report autoupdated paths only after actually updating themJunio C Hamano, Jul 17, 2015
  22. 06/18 rerere: drop want_sp parameter from is_cmarker()Junio C Hamano, Jul 17, 2015
  23. Philip OakleyJul 18, 2015
  24. Eric SunshineJul 18, 2015
  25. 07/18 rerere: stop looping unnecessarilyJunio C Hamano, Jul 17, 2015
  26. Junio C HamanoJul 24, 2015
  27. 08/18 rerere: explain the rerere I/O abstractionJunio C Hamano, Jul 17, 2015
  28. Junio C HamanoJul 24, 2015
  29. 09/18 rerere: explain MERGE_RR management helpersJunio C Hamano, Jul 17, 2015
  30. 10/18 rerere: explain the primary codepathJunio C Hamano, Jul 17, 2015
  31. 11/18 rerere: explain "rerere forget" codepathJunio C Hamano, Jul 17, 2015
  32. 12/18 rerere: explain the remainderJunio C Hamano, Jul 17, 2015
  33. 13/18 rerere: refactor "replay" part of do_plain_rerere()Junio C Hamano, Jul 17, 2015
  34. 14/18 rerere: further de-dent do_plain_rerere()Junio C Hamano, Jul 17, 2015
  35. 15/18 rerere: further clarify do_rerere_one_path()Junio C Hamano, Jul 17, 2015
  36. 16/18 rerere: call conflict-ids IDsJunio C Hamano, Jul 17, 2015
  37. 17/18 rerere: use "struct rerere_id" instead of "char *" for conflict IDJunio C Hamano, Jul 17, 2015
  38. Eric SunshineJul 18, 2015
  39. 18/18 rerere: un-nest merge() furtherJunio C Hamano, Jul 17, 2015

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