Below graph is a part of filelog tree of "mercurial/commands.py" in the repository of Mercurial itself. A .. B ....... D -- E ... F -- G \ / / \ / / ..... C ----------- A: df78d8ccac4c B: 574869103985 C: 938dd667ca21 D: 1c0c413cccdd E: c6b912f8b5b2 F: 1e84f1014f33 G: 8db4d406b3d3 "def clone(....)" line in "mercurial/commands.py" is modified at rev "A", and no other revision between "A" to "G" modifies that line: "G" doesn't, too. Then, "hg annotate" should show rev "A" for "def clone(....)" line as source revision against every revisions between "A" to "G", but it shows not "A" but "C" against "G". I found the cause of this issue in the "hist" cache management in "filectx.annotate()". For consistent annotation, "hist[C]" should be kept until building "hist[G]" up, in this case. But in filelog tree above, "G" merges "F" and its ancestor "C", and this causes: - "hist[C]" is purged just after building "hist[E]" up unexpectedly, - "hist[C]" is re-built up just before building "hist[G]" up, and - "hist[C]" is built up incorrectly, because "pcache[C]" is empty at that time: this causes mis-recognition as "all lines are new at C" I already confirmed that changing "hist" or "pcache" purge policy can fix this issue. For example: ==================== --- a/mercurial/context.py Sat Feb 09 17:54:01 2013 +0000 +++ b/mercurial/context.py Tue Feb 26 01:58:13 2013 +0900 @@ -719,7 +719,7 @@ needed[p] -= 1 hist[f] = curr - pcache[f] = [] + del pcache[f] return zip(hist[base][0], hist[base][1].splitlines(True)) ==================== But, such changes seem to decrease performance (by scanning same revisions again and again) and/or resource efficiency (by keeping useless entries). Are there any other ideas ?
Fixed by http://selenic.com/repo/hg/rev/0fd0612dc855 FUJIWARA Katsunori <foozy@lares.dti.ne.jp> annotate: increase refcount of each revisions correctly (issue3841) Before this patch, refcount (managed in "needed") of parents of each revisions in "visit" is increased, only when parent is not annotated yet (examined by "p not in hist"). But this causes less refcount of the revision like "A" in the tree below ("A" is assumed as the second parent of "C"): A --- B --- C \ / \-----/ Steps of annotation for "C" in this case are shown below: 1. for "C" 1.1 increase refcount of "B" 1.2 increase refcount of "A" (=> 1) 1.3 defer annotation for "C" 2. for "A" 2.1 annotate for "A" (=> put result into "hist[A]") 2.2 clear "pcache[A]" ("pcache[A] = []") 3. for "B" 3.1 not increase refcount of "A", because "A not in hist" is False 3.2 annotate for "B" 3.3 decrease refcount of "A" (=> 0) 3.4 delete "hist[A]", even though "A" is still needed by "C" 3.5 clear "pcache[B]" 4. for "C", again 4.1 not increase refcount of "B", because "B not in hist" is False 4.2 increase refcount of "A" (=> 1) 4.3 defer annotation for "C" 5. for "A", again 5.1 annotate for "A" (=> put result into "hist[A]", again) 5.2 clear "pcache[A]" 6. for "C", once again 6.1 not increase refcount of "B", because "B not in hist" is False 6.2 not increase refcount of "A", because "A not in hist" is False 6.3 annotate for "C" 6.4 decrease refcount of "A", and delete "hist[A]" 6.5 decrease refcount of "B", and delete "hist[B]" 6.6 clear "pcache[C]" At step (5.1), annotation for "A" mis-recognizes that all lines are created at "A", because "pcache[A]" already cleared at step (2.2) prevents from scanning ancestors of "A". So, annotation for "C" or its descendants loses information about "A" or its ancestors. The root cause of this problem is that refcount of "A" is decreased at step (3.3), even though it isn't increased at step (3.1). To increase refcount correctly, this patch increases refcount of each parents of each revisions: - regardless of "p not in hist" or not, and - only once for each revisions in "visit" (by "not pcached") In fact, this problem should occur only on legacy repositories in which a filelog includes the merging between the revision and its ancestor (as the second parent), because: - tree is scanned in depth-first without such merging, revisions in "visit" refer different revisions as parent each other - recent Mercurial doesn't allow such merging changelog and manifest can include such merging someway, but filelogs can't, because "localrepository._filecommit()" converts such merging request to linear history. This patch tests merging cases below: these cases are from filelog of "mercurial/commands.py" in the repository of Mercurial itself. - both parents are same 10 --- 11 --- 12 \_/ filelogrev: changesetid: 10 00ea3613f82c 11 fc4a6e5b5812 12 4f802588cdfb - the second parent is also ancestor of the first one 37 --- 38 --- 39 --- 40 \________/ filelogrev: changesetid: 37 f8d56da6ac8f 38 38919e1c254d 39 d3400605d246 40 f06a4a3b86a7 (please test the fix)