wireproto: define and implement HTTP handshake to upgrade protocol
When clients connect to repositories over HTTP, they issue a request
to the well-known URL "?cmd=capabilities" to fetch the repository
capabilities. This is the handshake portion of the HTTP protocol.
This commit defines a mechanism to use that HTTP request to return
information about modern server features.
If a client sends an X-HgUpgrade-* header containing a list of
client-supported API names, the server responds with a response
containing information about available services. This includes
the normal capabilities string. So if the server doesn't support
any newer services, the client can easily fall back.
By advertising supported services from clients, server operators
can see and log what client support exists in the wild. This will
also help with debugging.
The response contains the base path to API services. We know there
are potential issues with the <repo>/api/ URL space conflicting with
hgwebdir and subrepos. By making the API URL dynamic from the
perspective of the client, the URL for APIs is not subject to backwards
compatibility concerns - at least as long as a ?cmd=capabilities request
is made.
We've also defined the ``cbor`` client capability for the X-HgProto-*
header. This MUST be sent in order to get the modern response from
"?cmd=capabilities". During implementation, I initially always sent
an application/mercurial-cbor response. However, the handshake
mechanism will be more future compatible if the client is in charge
of which formats to request. We already perform content negotiation
from X-HgProto-*, so keying off this for the capabilities response
feels appropriate.
In addition, I initially used application/cbor. However, it is
conceivable that a non-Mercurial server could serve application/cbor.
To rule out this possibility, I've invented a new media type that
is Mercurial specific and can't be confused for generic CBOR.
Differential Revision: https://phab.mercurial-scm.org/D3242
=====================
Test workflow options
=====================
$ . "$TESTDIR/testlib/obsmarker-common.sh"
Test single head enforcing - Setup
=============================================
$ cat << EOF >> $HGRCPATH
> [experimental]
> evolution = all
> EOF
$ hg init single-head-server
$ cd single-head-server
$ cat <<EOF >> .hg/hgrc
> [phases]
> publish = no
> [experimental]
> single-head-per-branch = yes
> EOF
$ mkcommit ROOT
$ mkcommit c_dA0
$ cd ..
$ hg clone single-head-server client
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
Test single head enforcing - with branch only
---------------------------------------------
$ cd client
continuing the current defaultbranch
$ mkcommit c_dB0
$ hg push
pushing to $TESTTMP/single-head-server
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
creating a new branch
$ hg up 'desc("ROOT")'
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ hg branch branch_A
marked working directory as branch branch_A
(branches are permanent and global, did you want a bookmark?)
$ mkcommit c_aC0
$ hg push --new-branch
pushing to $TESTTMP/single-head-server
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
Create a new head on the default branch
$ hg up 'desc("c_dA0")'
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkcommit c_dD0
created new head
$ hg push -f
pushing to $TESTTMP/single-head-server
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
transaction abort!
rollback completed
abort: rejecting multiple heads on branch "default"
(2 heads: 286d02a6e2a2 9bf953aa81f6)
[255]
remerge them
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ mkcommit c_dE0
$ hg push
pushing to $TESTTMP/single-head-server
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
Test single head enforcing - after rewrite
------------------------------------------
$ mkcommit c_dF0
$ hg push
pushing to $TESTTMP/single-head-server
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
$ hg commit --amend -m c_dF1
$ hg push
pushing to $TESTTMP/single-head-server
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 1 files (+1 heads)
1 new obsolescence markers
obsoleted 1 changesets
Check it does to interfer with strip
------------------------------------
setup
$ hg branch branch_A --force
marked working directory as branch branch_A
$ mkcommit c_aG0
created new head
$ hg update 'desc("c_dF1")'
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkcommit c_dH0
$ hg update 'desc("c_aG0")'
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ mkcommit c_aI0
$ hg log -G
@ changeset: 10:49003e504178
|\ branch: branch_A
| | tag: tip
| | parent: 8:a33fb808fb4b
| | parent: 3:840af1c6bc88
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: c_aI0
| |
| | o changeset: 9:fe47ea669cea
| | | parent: 7:99a2dc242c5d
| | | user: test
| | | date: Thu Jan 01 00:00:00 1970 +0000
| | | summary: c_dH0
| | |
| o | changeset: 8:a33fb808fb4b
| |/ branch: branch_A
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: c_aG0
| |
| o changeset: 7:99a2dc242c5d
| | parent: 5:6ed1df20edb1
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: c_dF1
| |
| o changeset: 5:6ed1df20edb1
| |\ parent: 4:9bf953aa81f6
| | | parent: 2:286d02a6e2a2
| | | user: test
| | | date: Thu Jan 01 00:00:00 1970 +0000
| | | summary: c_dE0
| | |
| | o changeset: 4:9bf953aa81f6
| | | parent: 1:134bc3852ad2
| | | user: test
| | | date: Thu Jan 01 00:00:00 1970 +0000
| | | summary: c_dD0
| | |
o | | changeset: 3:840af1c6bc88
| | | branch: branch_A
| | | parent: 0:ea207398892e
| | | user: test
| | | date: Thu Jan 01 00:00:00 1970 +0000
| | | summary: c_aC0
| | |
| o | changeset: 2:286d02a6e2a2
| |/ user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: c_dB0
| |
| o changeset: 1:134bc3852ad2
|/ user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c_dA0
|
o changeset: 0:ea207398892e
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: ROOT
actual stripping
$ hg strip --config extensions.strip= --rev 'desc("c_dH0")'
saved backup bundle to $TESTTMP/client/.hg/strip-backup/fe47ea669cea-a41bf5a9-backup.hg
warning: ignoring unknown working parent 49003e504178!