On 19/11/2019 11:45, Richard Earnshaw (lists) wrote: > On 19/11/2019 11:24, Eric S. Raymond wrote: >> Richard Earnshaw (lists) <richard.earns...@arm.com>: >>> Well a lot of that is a property of the conversion tool. git svn does a >>> relatively poor job of anything other than straight history (I >>> believe it >>> just ignores the non-linear information. >> >> Yes, svn-git does a *terrible* job on anything other than linear history. >> >> That is a major reason I'm busting my hump to get the conversion done. >> It would be very sad if you guys fell into using that. It does a >> tolerable job of live gatewaying on simple histories, but read this: >> >> http://esr.ibiblio.org/?p=6778 >> >>> I don't believe any tool can >>> recreate information for cherry-picking unless it's recorded in the SVN >>> meta-data. Eric would be better placed to comment here. >> >> You are correct, there is nothing practical that can be done in the >> absence >> of svn:mergeinfo and svnmerge-integrated properties. >> >>> My own observation is that when the SVN commits have merge meta-data, >>> reposurgeon will pick this up and create links across to the relevant >>> branches. It does, however seem to create far more links than a >>> traditional >>> git merge would do, especially when a sequence of commits are >>> referenced. I >>> don't know if that's essentially unfixable, or if it's something Eric >>> intends to work on; but I've seen some cases where there are dozens >>> of links >>> back to a simple sequence of svn commits and where, I suspect, a >>> single link >>> back to the most recent of that sequence would be all that's really >>> wanted. >> >> First I have heard of this. >> >> The intent of the present mergeinfo handing is that it looks for >> mergeinfo declarations that are topologically equivalent to branch >> merges (that is, they merge all revisions on a source branch rather >> than cherry-picking isolated revisions) and rendering those as >> gitspace merge links. There is no attempt to create links >> corresponding to Subversion cherry picks, as this does not fit >> the Git DAG model. >> >> I have cases that demonstrate this feature working in my test suite, >> but they are relatively small and artificial. I would not describe >> my mergeinfo handling as well-tested compared to the rest of the >> analyzer, and I can thus easily believe your bug report. >> >> What I need to troubleshoot this is a test case that is not trivial >> but of a manageable size - over a couple hundred commits the volume >> of diagnostics just overwhelms a Mark One Eyeball. >> >> Many of my test cases were trimmed to that size by doing stripping and >> topological reduction on real repositories; I have a tool for this. >> Do you have a real repository in mind I can start with? The whole gcc >> history is too huge, but if you were able to tell me that the bug is >> exhibited within a few thousand commits of origin and point at where, >> that I could work with. >> >> An issue filed on the reposurgeon tracker would be appreciated. >> > > I was looking at the reposurgeon code last night, and I think I can see > what the problem *might* be, but I haven't had time to produce a testcase. > > Some of our commits have mergeinfo that looks a bit like this: > > 202022-202023,202026,202028-202029,202036,202039-202041,202043-202044,202048-202049,202051-202056,202058-202061,202064-202065,202068-202071,202077,202079-202082,202084,202086-202088,202092-202104,202106-202113,202115-202119,202121,202124-202134,202139,202142-202146,202148-202150,202153-202154,202158-202159,202163-202165,202168,202172,202174,202179-202180,202184-202192,202195,202197,202202-202208,202225-202230,202232-202233,202237-202239,202242,202244-202245,202247,202250-202251,202258-202264,202266,202269,202271-202275,202279,202281-202282,202284,202286,202289-202292,202296-202299,202301-202302,202305,202309,202311-202323,202327-202335,202337,202339,202343-202346,202350,202352,202356-202357,202359-202360,202363-202371,202373-202374,202377,202379-202382,202384,202389,202391-202395,202398-202407,202409,202411,202416-202418,202421 > > > which is a massive long list with a number of holes in it. > > But I suspect the holes are really commits to other branches and that in > the above describes a linear chain along one branch. If so, rather than > producing links to each subgroup (and perhaps dropping single non-list > elements, the description can be mapped back to a contiguous sequence of > commits down a branch and thus should really resolve to a single child > being used for the merge source. At present, I think for the above > we're seeing a child reference created for each subrange in that list. > > I'll see if I can construct a real testcase this evening. > > Incidentally, the mergeinfo pass on the gcc repo is currently taking > about 8 hours on my machine, that's 80-90% of the entire conversion > time. But it might be related to the above. > > R. >
I've been unsuccessful so far in creating a simple reproducer. However, r278216 on the gcc 'ranger' branch is an example of what I mean. The property list for this is $ svn propget svn:mergeinfo -r278216 FILE:///home/rearnsha/tmp/gcc-mirror/branches/ranger /trunk:274955-274956,274958,274961-274962,274964,274966,274975-274976,274980-274988,274990-274992,274994,274996-275000,275004-275005,275007-275012,275021-275023,275025-275028,275030-275032,275034,275049-275050,275055,275059,275062-275063,275174,275177-275178,275187-275188,275190-275191,275195-275200,275204-275205,275210-275211,275223,275227,275231,275235-275240,275242-275243,275258,275260,275264-275271,275274,275284-275285,275290-275293,275295,275297-275299,275303,275313-275316,275318,275320,275322,275324,275328-275338,275341-275344,275352-275358,275362,275364-275365,275367-275369,275376-275377,275387-275391,275395-275404,275406,275408-275409,275411,275414,275421,275426,275442,275444,275449-275450,275452-275458,275460,275462,275464,275472-275473,275475-275478,275482-275484,275486,275488-275489,275493,275497,275501-275508,275513-275514,275517-275518,275521-275522,275524-275537,275539-275541,275544,275551,275555,275557-275589,275591-275594,275597-275606,275608,275611,275613,275617,275622,275631-275635,275639-275644,275648,275650-275652,275655,275657,275667,275680,275682-275683,275685,275689,275691,275695-275704,275709,275713,275717-275719,275723,275726-275727,275729-275731,275735-275736,275741,275743-275755,275757-275759,275763,275768-275800,275802-275809,275813-275814,275833,275836-275875,275896-275899,275901,275905-275907,275919,275924-275926,275928,275930-275972,275976-275979,275981-275982,275986,275989-275990,275992,275994,275996,275998-275999,276001-276002,276004,276006-276007,276011,276015,276017-276022,276026-276027,276030,276035-276036,276041,276045-276059,276063-276065,276085,276089,276091-276100,276102-276103,276105-276107,276111-276112,276119-276123,276125,276127-276128,276132-276135,276139-276159,276162-276168,276172-276180,276183-276184,276186-276188,276190-276193,276196,276211-276213,276227-276228,276236,276240,276244,276248-276249,276251,276253-276256,276260,276264-276272,276276,276294-276341,276343,276359-276361,276371-276376,276380,276382,276386-276389,276391-276396,276401-276405,276407-276411,276415-276418,276420,276422,276424,276426-276434,276438-276449,276452-276457,276459,276461-276466,276468-276474,276479,276484,276487-276489,276491-276498,276502-276508,276510,276515-276516,276518-276519,276525,276527,276530,276532,276539,276542-276543,276555-276556,276560-276564,276566-276568,276571-276572,276574-276577,276579-276582,276584-276585,276587-276597,276600-276603,276605,276618,276621-276624,276626-276627,276629-276630,276634-276640,276644-276645,276648-276651,276653-276655,276657-276661,276663-276665,276668,276670-276671,276674-276675,276679-276681,276685-276686,276688-276695,276698,276700,276702-276703,276705-276709,276711,276721-276722,276725,276750-276758,276760,276762-276764,276766-276768,276770-276771,276773,276786-276787,276789-276792,276796,276804,276807-276824,276826-276836,276839-276843,276846-276851,276854,276858-276861,276864-276866,276870-276876,276878,276882,276885-276892,276894,276896-276903,276906-276908,276912-276916,276920-276926,276928,276933-276943,276947-276956,276958-276964,276967-276972,276976-276978,276982-277000,277005,277008-277011,277015,277023,277033,277049,277054,277056-277063,277065,277067-277068,277070-277071,277073,277076,277080,277082-277084,277088-277103,277105,277107-277108,277110-277115,277120-277121,277126,277128-277130,277133-277135,277140-277143,277150-277151,277153,277155-277158,277164-277192,277194,277199-277205,277209-277211,277214-277217,277221,277223-277241,277260-277262,277264,277266-277268,277270-277271,277276-277293,277297,277299-277302,277306-277311,277313-277314,277320-277323,277333,277335-277349,277351-277352,277358,277362-277363,277365-277369,277371-277375,277394-277395,277403-277404,277406-277410,277415-277416,277419,277421,277424-277427,277433-277438,277440-277442,277446,277448-277451,277455,277458-277459,277462,277468-277470,277472,277475-277476,277480-277487,277491-277492,277499,277501-277504,277507-277510,277512-277514,277516-277517,277524-277525,277527,277533-277535,277537,277544-277546,277550-277569,277571-277573,277575-277579,277588-277589,277591-277593,277595,277599-277607,277609-277610,277612-277624,277627-277637,277639,277643,277648-277649,277653-277664,277666-277667,277672,277674-277686,277697-277699,277703-277709,277711,277714-277715,277719,277723,277728,277730,277732-277735,277740-277743,277749,277752-277760,277764,277766-277769,277771-277780,277782,277784-277799,277801,277810,277812-277824,277826-277839,277845-277854,277859-277866,277870-277873,277875-277893,277895,277899-277936,277940-277956,277958-277966,277969,277972-277979,277990-277991,277993-277995,277999-278000,278003-278009,278013,278016-278017,278019-278028,278032-278035,278038,278041,278044-278049,278051,278053-278058,278062,278064-278066,278068-278070,278074-278091,278093-278096,278098-278107,278111-278129,278131-278142,278144-278153,278156-278157,278159,278179,278184-278185,278189-278196,278199-278200 and in the conversion we get about 35 links back to different revisions in trunk. I don't know if the SHA codes are stable, but in my conversion, done last night, it comes out at 44b84e63a8b00b9881fbb93d3af1536c2338aa72 There's another example at r277770 on the same branch, which has even more links. R.
