bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
d40cc5aacc31ed673d9b5b24f98bee78c283062c 0.4f
1c590d34bf61e2ea12c71738e5a746cd74586157 0.4e
7eca4cfa8aad5fce9a04f7d8acadcd0452e2f34e 0.4d
b4d0c3786ad3e47beacf8412157326a32b6d25a4 0.4c
f40273b0ad7b3a6d3012fd37736d0611f41ecf54 0.5
0a28dfe59f8fab54a5118c5be4f40da34a53cdb7 0.5b
12e0fdbc57a0be78f0e817fd1d170a3615cd35da 0.6
4ccf3de52989b14c3d84e1097f59e39a992e00bd 0.6b
eac9c8efcd9bd8244e72fb6821f769f450457a32 0.6c
979c049974485125e1f9357f6bbe9c1b548a64c3 0.7
3a56574f329a368d645853e0f9e09472aee62349 0.8
6a03cff2b0f5d30281e6addefe96b993582f2eac 0.8.1
35fb62a3a673d5322f6274a44ba6456e5e4b3b37 0.9
2be3001847cb18a23c403439d9e7d0ace30804e9 0.9.1
36a957364b1b89c150f2d0e60a99befe0ee08bd3 0.9.2
27230c29bfec36d5540fbe1c976810aefecfd1d2 0.9.3
fb4b6d5fe100b0886f8bc3d6731ec0e5ed5c4694 0.9.4
23889160905a1b09fffe1c07378e9fc1827606eb 0.9.5
bae2e9c838e90a393bae3973a7850280413e091a 1.0
d5cbbe2c49cee22a9fbeb9ea41daa0ac4e26b846 1.0.1
d2375bbee6d47e62ba8e415c86e83a465dc4dce9 1.0.2
2a67430f92f15ea5159c26b09ec4839a0c549a26 1.1
3773e510d433969e277b1863c317b674cbee2065 1.1.1
11a4eb81fb4f4742451591489e2797dc47903277 1.1.2
11efa41037e280d08cfb07c09ad485df30fb0ea8 1.2
02981000012e3adf40c4849bd7b3d5618f9ce82d 1.2.1
196d40e7c885fa6e95f89134809b3ec7bdbca34b 1.3
3ef6c14a1e8e83a31226f5881b7fe6095bbfa6f6 1.3.1
31ec469f9b556f11819937cf68ee53f2be927ebf 1.4
439d7ea6fe3aa4ab9ec274a68846779153789de9 1.4.1
296a0b14a68621f6990c54fdba0083f6f20935bf 1.4.2
4aa619c4c2c09907034d9824ebb1dd0e878206eb 1.4.3
ff2704a8ded37fbebd8b6eb5ec733731d725da8a 1.5
2b01dab594167bc0dd33331dbaa6dca3dca1b3aa 1.5.1
39f725929f0c48c5fb3b90c071fc3066012456ca 1.5.2
fdcf80f26604f233dc4d8f0a5ef9d7470e317e8a 1.5.3
24fe2629c6fd0c74c90bd066e77387c2b02e8437 1.5.4
f786fc4b8764cd2a5526d259cf2f94d8a66924d9 1.6
bf1774d95bde614af3956d92b20e2a0c68c5fec7 1.6.1
c00f03a4982e467fb6b6bd45908767db6df4771d 1.6.2
ff5cec76b1c5b6be9c3bb923aae8c3c6d079d6b9 1.6.3
93d8bff78c96fe7e33237b257558ee97290048a4 1.6.4
333421b9e0f96c7bc788e5667c146a58a9440a55 1.7
4438875ec01bd0fc32be92b0872eb6daeed4d44f 1.7.1
6aff4f144ad356311318b0011df0bb21f2c97429 1.7.2
e3bf16703e2601de99e563cdb3a5d50b64e6d320 1.7.3
a6c855c32ea081da3c3b8ff628f1847ff271482f 1.7.4
2b2155623ee2559caf288fd333f30475966c4525 1.7.5
2616325766e3504c8ae7c84bd15ee610901fe91d 1.8
aa1f3be38ab127280761889d2dca906ca465b5f4 1.8.1
b032bec2c0a651ca0ddecb65714bfe6770f67d70 1.8.2
3cb1e95676ad089596bd81d0937cad37d6e3b7fb 1.8.3
733af5d9f6b22387913e1d11350fb8cb7c1487dd 1.8.4
de9eb6b1da4fc522b1cab16d86ca166204c24f25 1.9
4a43e23b8c55b4566b8200bf69fe2158485a2634 1.9.1
d629f1e89021103f1753addcef6b310e4435b184 1.9.2
351a9292e430e35766c552066ed3e87c557b803b 1.9.3
384082750f2c51dc917d85a7145748330fa6ef4d 2.0-rc
41453d55b481ddfcc1dacb445179649e24ca861d 2.0
195dbd1cef0c2f9f8bcf4ea303238105f716bda3 2.0.1
6344043924497cd06d781d9014c66802285072e4 2.0.2
db33555eafeaf9df1e18950e29439eaa706d399b 2.1-rc
2aa5b51f310fb3befd26bed99c02267f5c12c734 2.1
53e2cd303ecf8ca7c7eeebd785c34e5ed6b0f4a4 2.1.1
b9bd95e61b49c221c4cca24e6da7c946fc02f992 2.1.2
d9e2f09d5488c395ae9ddbb320ceacd24757e055 2.2-rc
00182b3d087909e3c3ae44761efecdde8f319ef3 2.2
5983de86462c5a9f42a3ad0f5e90ce5b1d221d25 2.2.1
85a358df5bbbe404ca25730c9c459b34263441dc 2.2.2
b013baa3898e117959984fc64c29d8c784d2f28b 2.2.3
a06e2681dd1786e2354d84a5fa9c1c88dd4fa3e0 2.3-rc
7f5094bb3f423fc799e471aac2aee81a7ce57a0b 2.3
072209ae4ddb654eb2d5fd35bff358c738414432 2.3.1
b3f0f9a39c4e1d0250048cd803ab03542d6f140a 2.3.2
d118a4f4fd16d9b558ec3f3e87bfee772861d2b7 2.4-rc
195ad823b5d58c68903a6153a25e3fb4ed25239d 2.4
0c10cf8191469e7c3c8844922e17e71a176cb7cb 2.4.1
a4765077b65e6ae29ba42bab7834717b5072d5ba 2.4.2
f5fbe15ca7449f2c9a3cf817c86d0ae68b307214 2.5-rc
a6088c05e43a8aee0472ca3a4f6f8d7dd914ebbf 2.5
7511d4df752e61fe7ae4f3682e0a0008573b0402 2.5.1
5b7175377babacce80a6c1e12366d8032a6d4340 2.5.2
50c922c1b5145dab8baefefb0437d363b6a6c21c 2.5.3
8a7bd2dccd44ed571afe7424cd7f95594f27c092 2.5.4
292cd385856d98bacb2c3086f8897bc660c2beea 2.6-rc
23f785b38af38d2fca6b8f3db56b8007a84cd73a 2.6
ddc7a6be20212d18f3e27d9d7e6f079a66d96f21 2.6.1
cceaf7af4c9e9e6fa2dbfdcfe9856c5da69c4ffd 2.6.2
009794acc6e37a650f0fae37872e733382ac1c0c 2.6.3
f0d7721d7322dcfb5af33599c2543f27335334bb 2.7-rc
f37b5a17e6a0ee17afde2cdde5393dd74715fb58 2.7
335a558f81dc73afeab4d7be63617392b130117f 2.7.1
e7fa36d2ad3a7944a52dca126458d6f482db3524 2.7.2
1596f2d8f2421314b1ddead8f7d0c91009358994 2.8-rc
d825e4025e39d1c39db943cdc89818abd0a87c27 2.8
209e04a06467e2969c0cc6501335be0406d46ef0 2.8.1
ca387377df7a3a67dbb90b6336b781cdadc3ef41 2.8.2
8862469e16f9236208581b20de5f96bd13cc039d 2.9-rc
3cec5134e9c4bceab6a00c60f52a4f80677a78f2 2.9
b96cb15ec9e04d8ac5ee08b34fcbbe4200588965 2.9.1
3f83fc5cfe715d292069ee8417c83804f6c6c1e4 2.9.2
564f55b251224f16508dd1311452db7780dafe2b 3.0-rc
2195ac506c6ababe86985b932f4948837c0891b5 3.0
269c80ee5b3cb3684fa8edc61501b3506d02eb10 3.0.1
2d8cd3d0e83c7336c0cb45a9f88638363f993848 3.0.2
6c36dc6cd61a0e1b563f1d51e55bdf4dacf12162 3.1-rc
3178e49892020336491cdc6945885c4de26ffa8b 3.1
5dc91146f35369949ea56b40172308158b59063a 3.1.1
f768c888aaa68d12dd7f509dcc7f01c9584357d0 3.1.2
7f8d16af8cae246fa5a48e723d48d58b015aed94 3.2-rc
ced632394371a36953ce4d394f86278ae51a2aae 3.2
643c58303fb0ec020907af28b9e486be299ba043 3.2.1
902554884335e5ca3661d63be9978eb4aec3f68a 3.2.2
6dad422ecc5adb63d9fa649eeb8e05a5f9bc4900 3.2.3
1265a3a71d75396f5d4cf6935ae7d9ba5407a547 3.2.4
db8e3f7948b1fdeb9ad12d448fc3525759908b9f 3.3-rc
fbdd5195528fae4f41feebc1838215c110b25d6a 3.3
5b4ed033390bf6e2879c8f5c28c84e1ee3b87231 3.3.1
07a92bbd02e5e3a625e0820389b47786b02b2cea 3.3.2
2e2e9a0750f91a6fe0ad88e4de34f8efefdcab08 3.3.3
e89f909edffad558b56f4affa8239e4832f88de0 3.4-rc
8cc6036bca532e06681c5a8fa37efaa812de67b5 3.4
ed18f4acf435a2824c6f49fba40f42b9df5da7ad 3.4.1
540cd0ddac49c1125b2e013aa2ff18ecbd4dd954 3.4.2
96a38d44ba093bd1d1ecfd34119e94056030278b 3.5-rc
21aa1c313b05b1a85f8ffa1120d51579ddf6bf24 3.5
1a45e49a6bed023deb229102a8903234d18054d3 3.5.1
9a466b9f9792e3ad7ae3fc6c43c3ff2e136b718d 3.5.2
b66e3ca0b90c3095ea28dfd39aa24247bebf5c20 3.6-rc
47dd34f2e7272be9e3b2a5a83cd0d20be44293f4 3.6
1aa5083cbebbe7575c88f3402ab377539b484897 3.6.1
2d437a0f3355834a9485bbbeb30a52a052c98f19 3.6.2
ea389970c08449440587712117f178d33bab3f1e 3.6.3
158bdc8965720ca4061f8f8d806563cfc7cdb62e 3.7-rc
2408645de650d8a29a6ce9e7dce601d8dd0d1474 3.7
b698abf971e7377d9b7ec7fc8c52df45255b0329 3.7.1
d493d64757eb45ada99fcb3693e479a51b7782da 3.7.2
ae279d4a19e9683214cbd1fe8298cf0b50571432 3.7.3
740156eedf2c450aee58b1a90b0e826f47c5da64 3.8-rc
f85de28eae32e7d3064b1a1321309071bbaaa069 3.8
a56296f55a5e1038ea5016dace2076b693c28a56 3.8.1
aaabed77791a75968a12b8c43ad263631a23ee81 3.8.2
a9764ab80e11bcf6a37255db7dd079011f767c6c 3.8.3
26a5d605b8683a292bb89aea11f37a81b06ac016 3.8.4
519bb4f9d3a47a6e83c2b414d58811ed38f503c2 3.9-rc
299546f84e68dbb9bd026f0f3a974ce4bdb93686 3.9
ccd436f7db6d5d7b9af89715179b911d031d44f1 3.9.1
149433e68974eb5c63ccb03f794d8b57339a80c4 3.9.2
438173c415874f6ac653efc1099dec9c9150e90f 4.0-rc
eab27446995210c334c3d06f1a659e3b9b5da769 4.0
b3b1ae98f6a0e14c1e1ba806a6c18e193b6dae5c 4.0.1
e69874dc1f4e142746ff3df91e678a09c6fc208c 4.0.2
a1dd2c0c479e0550040542e392e87bc91262517e 4.1-rc
e1526da1e6d84e03146151c9b6e6950fe9a83d7d 4.1
25703b624d27e3917d978af56d6ad59331e0464a 4.1.1
ed5b25874d998ababb181a939dd37a16ea644435 4.1.2
77eaf9539499a1b8be259ffe7ada787d07857f80 4.1.3
616e788321cc4ae9975b7f0c54c849f36d82182b 4.2-rc
bb96d4a497432722623ae60d9bc734a1e360179e 4.2
c850f0ed54c1d42f9aa079ad528f8127e5775217 4.2.1
26c49ed51a698ec016d2b4c6b44ca3c3f73cc788 4.2.2
857876ebaed4e315f63157bd157d6ce553c7ab73 4.3-rc
5544af8622863796a0027566f6b646e10d522c4c 4.3
943c91326b23954e6e1c6960d0239511f9530258 4.2.3
3fee7f7d2da04226914c2258cc2884dc27384fd7 4.3.1
920977f72c7b70acfdaf56ab35360584d7845827 4.3.2
2f427b57bf9019c6dc3750baa539dc22c1be50f6 4.3.3
1e2454b60e5936f5e77498cab2648db469504487 4.4-rc
0ccb43d4cf01d013ae05917ec4f305509f851b2d 4.4
cabc840ffdee8a72f3689fb77dd74d04fdc2bc04 4.4.1
a92b9f8e11ba330614cdfd6af0e03b15c1ff3797 4.4.2
27b6df1b5adbdf647cf5c6675b40575e1b197c60 4.5-rc
d334afc585e29577f271c5eda03378736a16ca6b 4.5
369aadf7a3264b03c8b09efce715bc41e6ab4a9b 4.5.1
8bba684efde7f45add05f737952093bb2aa07155 4.5.2
7de7bd407251af2bc98e5b809c8598ee95830daf 4.5.3
ed5448edcbfa747b9154099e18630e49024fd47b 4.6rc0
1ec874717d8a93b19e0d50628443e0ee5efab3a9 4.6rc1
6614cac550aea66d19c601e45efd1b7bd08d7c40 4.6
9c5ced5276d6e7d54f7c3dadf5247b7ee98ec79c 4.6.1
0b63a6743010dfdbf8a8154186e119949bdaa1cc 4.6.2
e90130af47ce8dd53a3109aed9d15876b3e7dee8 4.7rc0
33ac6a72308a215e6086fbced347ec10aa963b0a 4.7
ede3bf31fe63677fdf5bd8db687977d4e3d792ed 4.7.1
5405cb1a79010ac50c58cd84e6f50c4556bf2a4c 4.7.2
956ec6f1320df26f3133ec40f3de866ea0695fd7 4.8rc0
a91a2837150bdcb27ae76b3646e6c93cd6a15904 4.8
1c8c54cf97256f4468da2eb4dbee24f7f3888e71 4.8.1
197f092b2cd9691e2a55d198f717b231af9be6f9 4.8.2
593718ff5844cad7a27ee3eb5adad89ac8550949 4.9rc0
83377b4b4ae0e9a6b8e579f7b0a693b8cf5c3b10 4.9
4ea21df312ec7159c5b3633096b6ecf68750b0dd 4.9.1
4a8d9ed864754837a185a642170cde24392f9abf 5.0rc0
07e479ef7c9639be0029f00e6a722b96dcc05fee 5.0
c3484ddbdb9621256d597ed86b90d229c59c2af9 5.0.1
97ada9b8d51bef24c5cb4cdca4243f0db694ab6e 5.0.2
e386b5f4f8360dbb43a576dd9b1368e386fefa5b 5.1rc0
e91930d712e8507d1bc1b2dffd96c83edc4cbed3 5.1
a4e32fd539ab41489a51b2aa88bda9a73b839562 5.1.1
181e52f2b62f4768aa0d988936c929dc7c4a41a0 5.1.2
59338f9561099de77c684c00f76507f11e46ebe8 5.2rc0
ca3dca416f8d5863ca6f5a4a6a6bb835dcd5feeb 5.2
a50fecefa691c9b72a99e49aa6fe9dd13943c2bf 5.2.1
b4c82b70418022e67cc0e69b1aa3c3aa43aa1d29 5.2.2
84a0102c05c7852c8215ef6cf21d809927586b69 5.3rc0
e4344e463c0c888a2f437b78b5982ecdf3f6650a 5.3rc1
7f5410dfc8a64bb587d19637deb95d378fd1eb5c 5.3
6d121acbb82e65fe4dd3c2318a1b61981b958492 5.3.1
8fca7e8449a847e3cf1054f2c07b51237699fad3 5.3.2
26ce8e7515036d3431a03aaeb7bc72dd96cb1112 5.4rc0
cf3e07d7648a4371ce584d15dd692e7a6845792f 5.4
065704cbdbdbb05dcd6bb814eb9bbdd982211b28 5.4.1
0ea9c86fac8974cd74dc12ea681c8986eb6da6c4 5.4.2
28163c5de797e5416f9b588940f4608269b4d50a 5.5rc0
7fc3c5fbc65f6fe85d70ea63923b8767dda4f2e0 5.5
f62bb5d07848ca598aa860a517394130b61bf2ee 5.5.1
07731064ac41dacdf0ec869ebd05c2e848c14fbf 5.5.2
0e06a7ab9e0d5c65af4e511aee1e0342998799df 5.6rc0
18c17d63fdabd009e70bf994e5efb7db422f4f7f 5.6
1d5189a57405ceca5aa244052c9f948977f4699b 5.6.1
9da65e3cf3706ff41e08b311381c588440c27baf 5.7rc0
0e2e7300f4302b02412b0b734717697049494c4c 5.7
d5d9177c0045d206db575bae6daa98e2cb2fe5bc 5.7.1
f67b8946bb1b6cfa8328dbf8d6a9128b69ccdcb4 5.8rc0
8d2b62d716b095507effaa8d56f87cd27ba659ab 5.8rc1
067f2c53fb24506c9e9fb4639871b13b19a85f8a 5.8
411dc27fd9fd076d6a031a08fcaace659afe2fe3 5.8.1
d7515d29761d5ada7d9c765f517db67db75dea9a 5.9rc0
2813d406b03607cdb8c06cb04c44efcc9a79d9a2 5.9rc1
53221078e0de65d1a821ce5311dec45a7a978301 5.9
86a60679cf619e14cee9442f865fcf31b142cb9f 5.9.1
750920b18aaaddd654756be40dec59d90f2643be 5.9.2
6ee0244fc1cf889ae543d2ce0ec45201ae0be6e1 5.9.3
a44bb185f6bdbecc754996d8386722e2f0123b0a 6.0rc0
5d08b289e2e526259d7d5ea32b70fe76d5b327d7 6.0
799fdf4cca80cb9ae40537a90995e6bd163ebc0b 6.0.1
75676122c2bf7594ac732b7388db4c74c648b365 6.0.2
dcec16e799ddb6d33fcd11b04af530250a417a58 6.0.3
c00d3ce4e94bb0ee8d809e25e1dcb2a5fab84e2c 6.1rc0
d4486810a1795fba9521449b8885ced034f3a6dd 6.1
5bd6bcd31dd1ebb63b8914b00064f96297267af7 6.1.1
0ddd5e1f5f67438af85d12e4ce6c39021dde9916 6.1.2
6b10151b962108f65bfa12b3918b1021ca334f73 6.1.3
0cc5f74ff7f0f4ac2427096bddbe102dbc2453ae 6.1.4
288de6f5d724bba7bf1669e2838f196962bb7528 6.2rc0
094a5fa3cf52f936e0de3f1e507c818bee5ece6b 6.2
f69bffd00abe3a1b94d1032eb2c92e611d16a192 6.2.1
b5c8524827d20fe2e0ca8fb1234a0fe35a1a36c7 6.2.2