Mercurial > hg
view tests/test-backout.t @ 26623:5a95fe44121d
clonebundles: support for seeding clones from pre-generated bundles
Cloning can be an expensive operation for servers because the server
generates a bundle from existing repository data at request time. For
a large repository like mozilla-central, this consumes 4+ minutes
of CPU time on the server. It also results in significant network
utilization. Multiplied by hundreds or even thousands of clients and
the ensuing load can result in difficulties scaling the Mercurial server.
Despite generation of bundles being deterministic until the next
changeset is added, the generation of bundles to service a clone request
is not cached. Each clone thus performs redundant work. This is
wasteful.
This patch introduces the "clonebundles" extension and related
client-side functionality to help alleviate this deficiency. The
client-side feature is behind an experimental flag and is not enabled by
default.
It works as follows:
1) Server operator generates a bundle and makes it available on a
server (likely HTTP).
2) Server operator defines the URL of a bundle file in a
.hg/clonebundles.manifest file.
3) Client `hg clone`ing sees the server is advertising bundle URLs.
4) Client fetches and applies the advertised bundle.
5) Client performs equivalent of `hg pull` to fetch changes made since
the bundle was created.
Essentially, the server performs the expensive work of generating a
bundle once and all subsequent clones fetch a static file from
somewhere. Scaling static file serving is a much more manageable
problem than scaling a Python application like Mercurial. Assuming your
repository grows less than 1% per day, the end result is 99+% of CPU
and network load from clones is eliminated, allowing Mercurial servers
to scale more easily. Serving static files also means data can be
transferred to clients as fast as they can consume it, rather than as
fast as servers can generate it. This makes clones faster.
Mozilla has implemented similar functionality of this patch on
hg.mozilla.org using a custom extension. We are hosting bundle files in
Amazon S3 and CloudFront (a CDN) and have successfully offloaded
>1 TB/day in data transfer from hg.mozilla.org, freeing up significant
bandwidth and CPU resources. The positive impact has been stellar and
I believe it has proved its value to be included in Mercurial core. I
feel it is important for the client-side support to be enabled in core
by default because it means that clients will get faster, more reliable
clones and will enable server operators to reduce load without
requiring any client-side configuration changes (assuming clients are
up to date, of course).
The scope of this feature is narrowly and specifically tailored to
cloning, despite "serve pulls from pre-generated bundles" being a valid
and useful feature. I would eventually like for Mercurial servers to
support transferring *all* repository data via statically hosted files.
You could imagine a server that siphons all pushed data to bundle files
and instructs clients to apply a stream of bundles to reconstruct all
repository data. This feature, while useful and powerful, is
significantly more work to implement because it requires the server
component have awareness of discovery and a mapping of which changesets
are in which files. Full, clone bundles, by contrast, are much simpler.
The wire protocol command is named "clonebundles" instead of something
more generic like "staticbundles" to leave the door open for a new, more
powerful and more generic server-side component with minimal backwards
compatibility implications. The name "bundleclone" is used by Mozilla's
extension and would cause problems since there are subtle differences
in Mozilla's extension.
Mozilla's experience with this idea has taught us that some form of
"content negotiation" is required. Not all clients will support all
bundle formats or even URLs (advanced TLS requirements, etc). To ensure
the highest uptake possible, a server needs to advertise multiple
versions of bundles and clients need to be able to choose the most
appropriate from that list one. The "attributes" in each
server-advertised entry facilitate this filtering and sorting. Their
use will become apparent in subsequent patches.
Initial inspiration and credit for the idea of cloning from static files
belongs to Augie Fackler and his "lookaside clone" extension proof of
concept.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 09 Oct 2015 11:22:01 -0700 |
parents | d8463a743d7d |
children | 520defbc0335 |
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$ hg init basic $ cd basic should complain $ hg backout abort: please specify a revision to backout [255] $ hg backout -r 0 0 abort: please specify just one revision [255] basic operation (this also tests that editor is invoked if the commit message is not specified explicitly) $ echo a > a $ hg commit -d '0 0' -A -m a adding a $ echo b >> a $ hg commit -d '1 0' -m b $ hg status --rev tip --rev "tip^1" M a $ HGEDITOR=cat hg backout -d '2 0' tip --tool=true reverting a Backed out changeset a820f4f40a57 HG: Enter commit message. Lines beginning with 'HG:' are removed. HG: Leave message empty to abort commit. HG: -- HG: user: test HG: branch 'default' HG: changed a changeset 2:2929462c3dff backs out changeset 1:a820f4f40a57 $ cat a a $ hg summary parent: 2:2929462c3dff tip Backed out changeset a820f4f40a57 branch: default commit: (clean) update: (current) phases: 3 draft commit option $ cd .. $ hg init commit $ cd commit $ echo tomatoes > a $ hg add a $ hg commit -d '0 0' -m tomatoes $ echo chair > b $ hg add b $ hg commit -d '1 0' -m chair $ echo grapes >> a $ hg commit -d '2 0' -m grapes $ hg backout --commit -d '4 0' 1 --tool=:fail 0 files updated, 0 files merged, 1 files removed, 0 files unresolved changeset 3:1c2161e97c0a backs out changeset 1:22cb4f70d813 $ hg summary parent: 3:1c2161e97c0a tip Backed out changeset 22cb4f70d813 branch: default commit: (clean) update: (current) phases: 4 draft $ echo ypples > a $ hg commit -d '5 0' -m ypples $ hg backout --commit -d '6 0' 2 --tool=:fail 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges [1] $ hg summary parent: 4:ed99997b793d tip ypples branch: default commit: 1 unresolved (clean) update: (current) phases: 5 draft file that was removed is recreated (this also tests that editor is not invoked if the commit message is specified explicitly) $ cd .. $ hg init remove $ cd remove $ echo content > a $ hg commit -d '0 0' -A -m a adding a $ hg rm a $ hg commit -d '1 0' -m b $ HGEDITOR=cat hg backout -d '2 0' tip --tool=true -m "Backed out changeset 76862dcce372" adding a changeset 2:de31bdc76c0d backs out changeset 1:76862dcce372 $ cat a content $ hg summary parent: 2:de31bdc76c0d tip Backed out changeset 76862dcce372 branch: default commit: (clean) update: (current) phases: 3 draft backout of backout is as if nothing happened $ hg backout -d '3 0' --merge tip --tool=true removing a changeset 3:7f6d0f120113 backs out changeset 2:de31bdc76c0d $ test -f a [1] $ hg summary parent: 3:7f6d0f120113 tip Backed out changeset de31bdc76c0d branch: default commit: (clean) update: (current) phases: 4 draft Test that 'hg rollback' restores dirstate just before opening transaction: in-memory dirstate changes should be written into '.hg/journal.dirstate' as expected. $ echo 'removed soon' > b $ hg commit -A -d '4 0' -m 'prepare for subsequent removing' adding b $ echo 'newly added' > c $ hg add c $ hg remove b $ hg commit -d '5 0' -m 'prepare for subsequent backout' $ touch -t 200001010000 c $ hg status -A C c $ hg debugstate --nodates n 644 12 set c $ hg backout -d '6 0' -m 'to be rollback-ed soon' -r . adding b removing c changeset 6:4bfec048029d backs out changeset 5:fac0b729a654 $ hg rollback -q $ hg status -A A b R c $ hg debugstate --nodates a 0 -1 unset b r 0 0 set c across branch $ cd .. $ hg init branch $ cd branch $ echo a > a $ hg ci -Am0 adding a $ echo b > b $ hg ci -Am1 adding b $ hg co -C 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg summary parent: 0:f7b1eb17ad24 0 branch: default commit: (clean) update: 1 new changesets (update) phases: 2 draft should fail $ hg backout 1 abort: cannot backout change that is not an ancestor [255] $ echo c > c $ hg ci -Am2 adding c created new head $ hg summary parent: 2:db815d6d32e6 tip 2 branch: default commit: (clean) update: 1 new changesets, 2 branch heads (merge) phases: 3 draft should fail $ hg backout 1 abort: cannot backout change that is not an ancestor [255] $ hg summary parent: 2:db815d6d32e6 tip 2 branch: default commit: (clean) update: 1 new changesets, 2 branch heads (merge) phases: 3 draft backout with merge $ cd .. $ hg init merge $ cd merge $ echo line 1 > a $ echo line 2 >> a $ hg commit -d '0 0' -A -m a adding a $ hg summary parent: 0:59395513a13a tip a branch: default commit: (clean) update: (current) phases: 1 draft remove line 1 $ echo line 2 > a $ hg commit -d '1 0' -m b $ echo line 3 >> a $ hg commit -d '2 0' -m c $ hg backout --merge -d '3 0' 1 --tool=true reverting a created new head changeset 3:26b8ccb9ad91 backs out changeset 1:5a50a024c182 merging with changeset 3:26b8ccb9ad91 merging a 0 files updated, 1 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -d '4 0' -m d $ hg summary parent: 4:c7df5e0b9c09 tip d branch: default commit: (clean) update: (current) phases: 5 draft check line 1 is back $ cat a line 1 line 2 line 3 $ cd .. backout should not back out subsequent changesets $ hg init onecs $ cd onecs $ echo 1 > a $ hg commit -d '0 0' -A -m a adding a $ echo 2 >> a $ hg commit -d '1 0' -m b $ echo 1 > b $ hg commit -d '2 0' -A -m c adding b $ hg summary parent: 2:882396649954 tip c branch: default commit: (clean) update: (current) phases: 3 draft without --merge $ hg backout -d '3 0' 1 --tool=true 1 files updated, 0 files merged, 0 files removed, 0 files unresolved changeset 22bca4c721e5 backed out, don't forget to commit. $ hg locate b b $ hg update -C tip 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg locate b b $ hg summary parent: 2:882396649954 tip c branch: default commit: (clean) update: (current) phases: 3 draft with --merge $ hg backout --merge -d '3 0' 1 --tool=true reverting a created new head changeset 3:3202beb76721 backs out changeset 1:22bca4c721e5 merging with changeset 3:3202beb76721 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg locate b b $ hg update -C tip 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg locate b [1] $ cd .. $ hg init m $ cd m $ echo a > a $ hg commit -d '0 0' -A -m a adding a $ echo b > b $ hg commit -d '1 0' -A -m b adding b $ echo c > c $ hg commit -d '2 0' -A -m b adding c $ hg update 1 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ echo d > d $ hg commit -d '3 0' -A -m c adding d created new head $ hg merge 2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg commit -d '4 0' -A -m d $ hg summary parent: 4:b2f3bb92043e tip d branch: default commit: (clean) update: (current) phases: 5 draft backout of merge should fail $ hg backout 4 abort: cannot backout a merge changeset [255] backout of merge with bad parent should fail $ hg backout --parent 0 4 abort: cb9a9f314b8b is not a parent of b2f3bb92043e [255] backout of non-merge with parent should fail $ hg backout --parent 0 3 abort: cannot use --parent on non-merge changeset [255] backout with valid parent should be ok $ hg backout -d '5 0' --parent 2 4 --tool=true removing d changeset 5:10e5328c8435 backs out changeset 4:b2f3bb92043e $ hg summary parent: 5:10e5328c8435 tip Backed out changeset b2f3bb92043e branch: default commit: (clean) update: (current) phases: 6 draft $ hg rollback repository tip rolled back to revision 4 (undo commit) working directory now based on revision 4 $ hg update -C 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg summary parent: 4:b2f3bb92043e tip d branch: default commit: (clean) update: (current) phases: 5 draft $ hg backout -d '6 0' --parent 3 4 --tool=true removing c changeset 5:033590168430 backs out changeset 4:b2f3bb92043e $ hg summary parent: 5:033590168430 tip Backed out changeset b2f3bb92043e branch: default commit: (clean) update: (current) phases: 6 draft $ cd .. named branches $ hg init named_branches $ cd named_branches $ echo default > default $ hg ci -d '0 0' -Am default adding default $ hg branch branch1 marked working directory as branch branch1 (branches are permanent and global, did you want a bookmark?) $ echo branch1 > file1 $ hg ci -d '1 0' -Am file1 adding file1 $ hg branch branch2 marked working directory as branch branch2 $ echo branch2 > file2 $ hg ci -d '2 0' -Am file2 adding file2 without --merge $ hg backout -r 1 --tool=true 0 files updated, 0 files merged, 1 files removed, 0 files unresolved changeset bf1602f437f3 backed out, don't forget to commit. $ hg branch branch2 $ hg status -A R file1 C default C file2 $ hg summary parent: 2:45bbcd363bf0 tip file2 branch: branch2 commit: 1 removed update: (current) phases: 3 draft with --merge (this also tests that editor is invoked if '--edit' is specified explicitly regardless of '--message') $ hg update -qC $ HGEDITOR=cat hg backout --merge -d '3 0' -r 1 -m 'backout on branch1' --tool=true --edit removing file1 backout on branch1 HG: Enter commit message. Lines beginning with 'HG:' are removed. HG: Leave message empty to abort commit. HG: -- HG: user: test HG: branch 'branch2' HG: removed file1 created new head changeset 3:d4e8f6db59fb backs out changeset 1:bf1602f437f3 merging with changeset 3:d4e8f6db59fb 0 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg summary parent: 2:45bbcd363bf0 file2 parent: 3:d4e8f6db59fb tip backout on branch1 branch: branch2 commit: 1 removed (merge) update: (current) phases: 4 draft $ hg update -q -C 2 on branch2 with branch1 not merged, so file1 should still exist: $ hg id 45bbcd363bf0 (branch2) $ hg st -A C default C file1 C file2 $ hg summary parent: 2:45bbcd363bf0 file2 branch: branch2 commit: (clean) update: 1 new changesets, 2 branch heads (merge) phases: 4 draft on branch2 with branch1 merged, so file1 should be gone: $ hg merge 0 files updated, 0 files merged, 1 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg ci -d '4 0' -m 'merge backout of branch1' $ hg id 22149cdde76d (branch2) tip $ hg st -A C default C file2 $ hg summary parent: 4:22149cdde76d tip merge backout of branch1 branch: branch2 commit: (clean) update: (current) phases: 5 draft on branch1, so no file1 and file2: $ hg co -C branch1 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg id bf1602f437f3 (branch1) $ hg st -A C default C file1 $ hg summary parent: 1:bf1602f437f3 file1 branch: branch1 commit: (clean) update: (current) phases: 5 draft $ cd .. backout of empty changeset (issue4190) $ hg init emptycommit $ cd emptycommit $ touch file1 $ hg ci -Aqm file1 $ hg branch -q branch1 $ hg ci -qm branch1 $ hg backout -v 1 resolving manifests nothing changed [1] $ cd .. Test usage of `hg resolve` in case of conflict (issue4163) $ hg init issue4163 $ cd issue4163 $ touch foo $ hg add foo $ cat > foo << EOF > one > two > three > four > five > six > seven > height > nine > ten > EOF $ hg ci -m 'initial' $ cat > foo << EOF > one > two > THREE > four > five > six > seven > height > nine > ten > EOF $ hg ci -m 'capital three' $ cat > foo << EOF > one > two > THREE > four > five > six > seven > height > nine > TEN > EOF $ hg ci -m 'capital ten' $ hg backout -r 'desc("capital three")' --tool internal:fail 0 files updated, 0 files merged, 0 files removed, 1 files unresolved use 'hg resolve' to retry unresolved file merges [1] $ hg status $ hg debugmergestate * version 2 records local: b71750c4b0fdf719734971e3ef90dbeab5919a2d other: a30dd8addae3ce71b8667868478542bc417439e6 file: foo (state "u", hash 0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33) local path: foo (flags "") ancestor path: foo (node f89532f44c247a0e993d63e3a734dd781ab04708) other path: foo (node f50039b486d6fa1a90ae51778388cad161f425ee) $ mv .hg/merge/state2 .hg/merge/state2-moved $ hg debugmergestate * version 1 records local: b71750c4b0fdf719734971e3ef90dbeab5919a2d file: foo (state "u", hash 0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33) local path: foo (flags "") ancestor path: foo (node f89532f44c247a0e993d63e3a734dd781ab04708) other path: foo (node not stored in v1 format) $ mv .hg/merge/state2-moved .hg/merge/state2 $ hg resolve -l # still unresolved U foo $ hg summary parent: 2:b71750c4b0fd tip capital ten branch: default commit: 1 unresolved (clean) update: (current) phases: 3 draft $ hg resolve --all --debug picked tool ':merge' for foo (binary False symlink False) merging foo my foo@b71750c4b0fd+ other foo@a30dd8addae3 ancestor foo@913609522437 premerge successful (no more unresolved files) $ hg status M foo ? foo.orig $ hg resolve -l R foo $ hg summary parent: 2:b71750c4b0fd tip capital ten branch: default commit: 1 modified, 1 unknown update: (current) phases: 3 draft $ cat foo one two three four five six seven height nine TEN