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
Issue746: renaming files brought by the second parent of a merge was
broken.
Create source repository:
$ hg init t
$ cd t
$ echo a > a
$ hg ci -Am a
adding a
$ cd ..
Fork source repository:
$ hg clone t t2
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd t2
$ echo b > b
$ hg ci -Am b
adding b
Update source repository:
$ cd ../t
$ echo a >> a
$ hg ci -m a2
Merge repositories:
$ hg pull ../t2
pulling from ../t2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets d2ae7f538514
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st
M b
Rename b as c:
$ hg mv b c
$ hg st
A c
R b
Rename back c as b:
$ hg mv c b
$ hg st
M b
$ cd ..
Issue 1476: renaming a first parent file into another first parent
file while none of them belong to the second parent was broken
$ hg init repo1476
$ cd repo1476
$ echo a > a
$ hg ci -Am adda
adding a
$ echo b1 > b1
$ echo b2 > b2
$ hg ci -Am changea
adding b1
adding b2
$ hg up -C 0
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo c1 > c1
$ echo c2 > c2
$ hg ci -Am addcandd
adding c1
adding c2
created new head
Merge heads:
$ hg merge
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg mv -Af c1 c2
Commit issue 1476:
$ hg ci -m merge
$ hg log -r tip -C -v | grep copies
copies: c2 (c1)
$ hg rollback
repository tip rolled back to revision 2 (undo commit)
working directory now based on revisions 2 and 1
$ hg up -C .
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
Merge heads again:
$ hg merge
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg mv -Af b1 b2
Commit issue 1476 with a rename on the other side:
$ hg ci -m merge
$ hg log -r tip -C -v | grep copies
copies: b2 (b1)
$ cd ..