bundle2: extract logic for seeking bundle2 part into own class
Currently, unbundlepart classes support bi-directional seeking.
Most consumers of unbundlepart only ever seek forward - typically
as part of moving to the end of the bundle part so they can move
on to the next one. But regardless of the actual usage of the
part, instances maintain an index mapping offsets within the
underlying raw payload to offsets within the decoded payload.
Maintaining the mapping of offset data can be expensive in terms of
memory use. Furthermore, many bundle2 consumers don't have access
to an underlying seekable stream. This includes all compressed
bundles. So maintaining offset data when the underlying stream
can't be seeked anyway is wasteful. And since many bundle2 streams
can't be seeked, it seems like a bad idea to expose a seek API
in bundle2 parts by default. If you provide them, people will
attempt to use them.
Seekable bundle2 parts should be the exception, not the rule. This
commit starts the process dividing unbundlepart into 2 classes: a
base class that supports linear, one-time reads and a child class
that supports bi-directional seeking. In this first commit, we
split various methods and attributes out into a new
"seekableunbundlepart" class. Previous instantiators of "unbundlepart"
now instantiate "seekableunbundlepart." This preserves backwards
compatibility. The coupling between the classes is still tight:
"unbundlepart" cannot be used on its own. This will be addressed
in subsequent commits.
Differential Revision: https://phab.mercurial-scm.org/D1386
$ hg init test
$ cd test
$ echo 0 >> afile
$ hg add afile
$ hg commit -m "0.0"
$ echo 1 >> afile
$ hg commit -m "0.1"
$ echo 2 >> afile
$ hg commit -m "0.2"
$ echo 3 >> afile
$ hg commit -m "0.3"
$ hg update -C 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo 1 >> afile
$ hg commit -m "1.1"
created new head
$ echo 2 >> afile
$ hg commit -m "1.2"
$ echo a line > fred
$ echo 3 >> afile
$ hg add fred
$ hg commit -m "1.3"
$ hg mv afile adifferentfile
$ hg commit -m "1.3m"
$ hg update -C 3
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ hg mv afile anotherfile
$ hg commit -m "0.3m"
$ hg debugindex -f 1 afile
rev flag offset length size ..... link p1 p2 nodeid (re)
0 0000 0 3 2 ..... 0 -1 -1 362fef284ce2 (re)
1 0000 3 5 4 ..... 1 0 -1 125144f7e028 (re)
2 0000 8 7 6 ..... 2 1 -1 4c982badb186 (re)
3 0000 15 9 8 ..... 3 2 -1 19b1fc555737 (re)
$ hg debugindex adifferentfile
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 75 ..... 7 2565f3199a74 000000000000 000000000000 (re)
$ hg debugindex anotherfile
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 75 ..... 8 2565f3199a74 000000000000 000000000000 (re)
$ hg debugindex fred
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 8 ..... 6 12ab3bcc5ea4 000000000000 000000000000 (re)
$ hg debugindex --manifest
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 48 ..... 0 43eadb1d2d06 000000000000 000000000000 (re)
1 48 48 ..... 1 8b89697eba2c 43eadb1d2d06 000000000000 (re)
2 96 48 ..... 2 626a32663c2f 8b89697eba2c 000000000000 (re)
3 144 48 ..... 3 f54c32f13478 626a32663c2f 000000000000 (re)
4 192 .. ..... 6 de68e904d169 626a32663c2f 000000000000 (re)
5 2.. .. ..... 7 09bb521d218d de68e904d169 000000000000 (re)
6 3.. 54 ..... 8 1fde233dfb0f f54c32f13478 000000000000 (re)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
4 files, 9 changesets, 7 total revisions
$ cd ..
$ for i in 0 1 2 3 4 5 6 7 8; do
> echo
> echo ---- hg clone -r "$i" test test-"$i"
> hg clone -r "$i" test test-"$i"
> cd test-"$i"
> hg verify
> cd ..
> done
---- hg clone -r 0 test test-0
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
new changesets f9ee2f85a263
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
---- hg clone -r 1 test test-1
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets f9ee2f85a263:34c2bf6b0626
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 2 changesets, 2 total revisions
---- hg clone -r 2 test test-2
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files
new changesets f9ee2f85a263:e38ba6f5b7e0
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 3 changesets, 3 total revisions
---- hg clone -r 3 test test-3
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 1 files
new changesets f9ee2f85a263:eebf5a27f8ca
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 4 changesets, 4 total revisions
---- hg clone -r 4 test test-4
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets f9ee2f85a263:095197eb4973
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 2 changesets, 2 total revisions
---- hg clone -r 5 test test-5
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files
new changesets f9ee2f85a263:1bb50a9436a7
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 3 changesets, 3 total revisions
---- hg clone -r 6 test test-6
adding changesets
adding manifests
adding file changes
added 4 changesets with 5 changes to 2 files
new changesets f9ee2f85a263:7373c1169842
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
2 files, 4 changesets, 5 total revisions
---- hg clone -r 7 test test-7
adding changesets
adding manifests
adding file changes
added 5 changesets with 6 changes to 3 files
new changesets f9ee2f85a263:a6a34bfa0076
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
3 files, 5 changesets, 6 total revisions
---- hg clone -r 8 test test-8
adding changesets
adding manifests
adding file changes
added 5 changesets with 5 changes to 2 files
new changesets f9ee2f85a263:aa35859c02ea
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
2 files, 5 changesets, 5 total revisions
$ cd test-8
$ hg pull ../test-7
pulling from ../test-7
searching for changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 2 changes to 3 files (+1 heads)
new changesets 095197eb4973:a6a34bfa0076
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
4 files, 9 changesets, 7 total revisions
$ cd ..
$ hg clone test test-9
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd test-9
$ hg branch foobar
marked working directory as branch foobar
(branches are permanent and global, did you want a bookmark?)
$ echo file2 >> file2
$ hg add file2
$ hg commit -m "changeset9"
$ echo file3 >> file3
$ hg add file3
$ hg commit -m "changeset10"
$ cd ..
$ hg clone -r 9 -u foobar test-9 test-10
adding changesets
adding manifests
adding file changes
added 6 changesets with 6 changes to 3 files
new changesets f9ee2f85a263:7100abb79635
updating to branch foobar
2 files updated, 0 files merged, 0 files removed, 0 files unresolved