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authorjon@blackcubes.dyndns.org <jon@blackcubes.dyndns.org>2005-06-06 15:39:40 +0000
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-06 09:07:26 -0700
commita3437b8c26a63d971437c8b6ac6f6d4f632be548 (patch)
tree0e99213a652fbf3fbe2fa6e3d2562808fc776543 /epoch.h
parentd925ffbd064802bc8a6ab0bccf0c43b00a7fe710 (diff)
downloadgit-a3437b8c26a63d971437c8b6ac6f6d4f632be548.tar.gz
[PATCH] Modify git-rev-list to linearise the commit history in merge order.
This patch linearises the GIT commit history graph into merge order which is defined by invariants specified in Documentation/git-rev-list.txt. The linearisation produced by this patch is superior in an objective sense to that produced by the existing git-rev-list implementation in that the linearisation produced is guaranteed to have the minimum number of discontinuities, where a discontinuity is defined as an adjacent pair of commits in the output list which are not related in a direct child-parent relationship. With this patch a graph like this: a4 --- | \ \ | b4 | |/ | | a3 | | | | | a2 | | | | c3 | | | | | c2 | b3 | | | /| | b2 | | | c1 | | / | b1 a1 | | | a0 | | / root Sorts like this: = a4 | c3 | c2 | c1 ^ b4 | b3 | b2 | b1 ^ a3 | a2 | a1 | a0 = root Instead of this: = a4 | c3 ^ b4 | a3 ^ c2 ^ b3 ^ a2 ^ b2 ^ c1 ^ a1 ^ b1 ^ a0 = root A test script, t/t6000-rev-list.sh, includes a test which demonstrates that the linearisation produced by --merge-order has less discontinuities than the linearisation produced by git-rev-list without the --merge-order flag specified. To see this, do the following: cd t ./t6000-rev-list.sh cd trash cat actual-default-order cat actual-merge-order The existing behaviour of git-rev-list is preserved, by default. To obtain the modified behaviour, specify --merge-order or --merge-order --show-breaks on the command line. This version of the patch has been tested on the git repository and also on the linux-2.6 repository and has reasonable performance on both - ~50-100% slower than the original algorithm. This version of the patch has incorporated a functional equivalent of the Linus' output limiting algorithm into the merge-order algorithm itself. This operates per the notes associated with Linus' commit 337cb3fb8da45f10fe9a0c3cf571600f55ead2ce. This version has incorporated Linus' feedback regarding proposed changes to rev-list.c. (see: [PATCH] Factor out filtering in rev-list.c) This version has improved the way sort_first_epoch marks commits as uninteresting. For more details about this change, refer to Documentation/git-rev-list.txt and http://blackcubes.dyndns.org/epoch/. Signed-off-by: Jon Seymour <jon.seymour@gmail.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'epoch.h')
-rw-r--r--epoch.h20
1 files changed, 20 insertions, 0 deletions
diff --git a/epoch.h b/epoch.h
new file mode 100644
index 0000000000..585110bdd6
--- /dev/null
+++ b/epoch.h
@@ -0,0 +1,20 @@
+#ifndef EPOCH_H
+#define EPOCH_H
+
+
+// return codes for emitter_func
+#define STOP 0
+#define CONTINUE 1
+#define DO 2
+typedef int (*emitter_func) (struct commit *);
+
+int sort_list_in_merge_order(struct commit_list *list, emitter_func emitter);
+
+#define UNINTERESTING (1u<<2)
+#define BOUNDARY (1u<<3)
+#define VISITED (1u<<4)
+#define DISCONTINUITY (1u<<5)
+#define DUPCHECK (1u<<6)
+
+
+#endif /* EPOCH_H */