wireproto: add request IDs to frames
One of my primary goals with the new wire protocol is to make
operations faster and enable both client and server-side
operations to scale to multiple CPU cores.
One of the ways we make server interactions faster is by reducing
the number of round trips to that server.
With the existing wire protocol, the "batch" command facilitates
executing multiple commands from a single request payload. The way
it works is the requests for multiple commands are serialized. The
server executes those commands sequentially then serializes all
their results. As an optimization for reducing round trips, this
is very effective. The technical implementation, however, is pretty
bad and suffers from a number of deficiencies. For example, it
creates a new place where authorization to run a command must be
checked. (The lack of this checking in older Mercurial releases
was CVE-2018-1000132.)
The principles behind the "batch" command are sound. However, the
execution is not. Therefore, I want to ditch "batch" in the
new wire protocol and have protocol level support for issuing
multiple requests in a single round trip.
This commit introduces support in the frame-based wire protocol to
facilitate this. We do this by adding a "request ID" to each frame.
If a server sees frames associated with different "request IDs," it
handles them as separate requests. All of this happening possibly
as part of the same message from client to server (the same request
body in the case of HTTP).
We /could/ model the exchange the way pipelined HTTP requests do,
where the server processes requests in order they are issued and
received. But this artifically constrains scalability. A better
model is to allow multi-requests to be executed concurrently and
for responses to be sent and handled concurrently. So the
specification explicitly allows this. There is some work to be done
around specifying dependencies between multi-requests. We take
the easy road for now and punt on this problem, declaring that
if order is important, clients must not issue the request until
responses to dependent requests have been received.
This commit focuses on the boilerplate of implementing the request
ID. The server reactor still can't manage multiple, in-flight
request IDs. This will be addressed in a subsequent commit.
Because the wire semantics have changed, we bump the version of the
media type.
Differential Revision: https://phab.mercurial-scm.org/D2869
$ . "$TESTDIR/narrow-library.sh"
initialize nested directories to validate complex include/exclude patterns
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [narrow]
> serveellipses=True
> EOF
$ echo root > root
$ hg add root
$ hg commit -m 'add root'
$ for d in dir1 dir2 dir1/dirA dir1/dirB dir2/dirA dir2/dirB
> do
> mkdir -p $d
> echo $d/foo > $d/foo
> hg add $d/foo
> hg commit -m "add $d/foo"
> echo $d/bar > $d/bar
> hg add $d/bar
> hg commit -m "add $d/bar"
> done
#if execbit
$ chmod +x dir1/dirA/foo
$ hg commit -m "make dir1/dirA/foo executable"
#else
$ hg import --bypass - <<EOF
> # HG changeset patch
> make dir1/dirA/foo executable
>
> diff --git a/dir1/dirA/foo b/dir1/dirA/foo
> old mode 100644
> new mode 100755
> EOF
applying patch from stdin
$ hg update -qr tip
#endif
$ hg log -G -T '{rev} {node|short} {files}\n'
@ 13 c87ca422d521 dir1/dirA/foo
|
o 12 951b8a83924e dir2/dirB/bar
|
o 11 01ae5a51b563 dir2/dirB/foo
|
o 10 5eababdf0ac5 dir2/dirA/bar
|
o 9 99d690663739 dir2/dirA/foo
|
o 8 8e80155d5445 dir1/dirB/bar
|
o 7 406760310428 dir1/dirB/foo
|
o 6 623466a5f475 dir1/dirA/bar
|
o 5 06ff3a5be997 dir1/dirA/foo
|
o 4 33227af02764 dir2/bar
|
o 3 5e1f9d8d7c69 dir2/foo
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da root
$ cd ..
clone a narrow portion of the master, such that we can widen it later
$ hg clone --narrow ssh://user@dummy/master narrow \
> --include dir1 \
> --include dir2 \
> --exclude dir1/dirA \
> --exclude dir1/dirB \
> --exclude dir2/dirA \
> --exclude dir2/dirB
requesting all changes
adding changesets
adding manifests
adding file changes
added 6 changesets with 4 changes to 4 files
new changesets *:* (glob)
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd narrow
$ cat .hg/narrowspec
[includes]
path:dir1
path:dir2
[excludes]
path:dir1/dirA
path:dir1/dirB
path:dir2/dirA
path:dir2/dirB
$ hg manifest -r tip
dir1/bar
dir1/dirA/bar
dir1/dirA/foo
dir1/dirB/bar
dir1/dirB/foo
dir1/foo
dir2/bar
dir2/dirA/bar
dir2/dirA/foo
dir2/dirB/bar
dir2/dirB/foo
dir2/foo
root
$ find * | sort
dir1
dir1/bar
dir1/foo
dir2
dir2/bar
dir2/foo
$ hg log -G -T '{rev} {node|short}{if(ellipsis, "...")} {files}\n'
@ 5 c87ca422d521... dir1/dirA/foo
|
o 4 33227af02764 dir2/bar
|
o 3 5e1f9d8d7c69 dir2/foo
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da... root
widen the narrow checkout
$ hg tracked --removeexclude dir1/dirA
comparing with ssh://user@dummy/master
searching for changes
no changes found
saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-widen.hg (glob)
adding changesets
adding manifests
adding file changes
added 9 changesets with 6 changes to 6 files
new changesets *:* (glob)
$ cat .hg/narrowspec
[includes]
path:dir1
path:dir2
[excludes]
path:dir1/dirB
path:dir2/dirA
path:dir2/dirB
$ find * | sort
dir1
dir1/bar
dir1/dirA
dir1/dirA/bar
dir1/dirA/foo
dir1/foo
dir2
dir2/bar
dir2/foo
#if execbit
$ test -x dir1/dirA/foo && echo executable
executable
$ test -x dir1/dirA/bar || echo not executable
not executable
#endif
$ hg log -G -T '{rev} {node|short}{if(ellipsis, "...")} {files}\n'
@ 8 c87ca422d521 dir1/dirA/foo
|
o 7 951b8a83924e... dir2/dirB/bar
|
o 6 623466a5f475 dir1/dirA/bar
|
o 5 06ff3a5be997 dir1/dirA/foo
|
o 4 33227af02764 dir2/bar
|
o 3 5e1f9d8d7c69 dir2/foo
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da... root
widen narrow spec again, but exclude a file in previously included spec
$ hg tracked --removeexclude dir2/dirB --addexclude dir1/dirA/bar
comparing with ssh://user@dummy/master
searching for changes
looking for local changes to affected paths
deleting data/dir1/dirA/bar.i
no changes found
saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-widen.hg (glob)
adding changesets
adding manifests
adding file changes
added 11 changesets with 7 changes to 7 files
new changesets *:* (glob)
$ cat .hg/narrowspec
[includes]
path:dir1
path:dir2
[excludes]
path:dir1/dirA/bar
path:dir1/dirB
path:dir2/dirA
$ find * | sort
dir1
dir1/bar
dir1/dirA
dir1/dirA/foo
dir1/foo
dir2
dir2/bar
dir2/dirB
dir2/dirB/bar
dir2/dirB/foo
dir2/foo
$ hg log -G -T '{rev} {node|short}{if(ellipsis, "...")} {files}\n'
@ 10 c87ca422d521 dir1/dirA/foo
|
o 9 951b8a83924e dir2/dirB/bar
|
o 8 01ae5a51b563 dir2/dirB/foo
|
o 7 5eababdf0ac5... dir2/dirA/bar
|
o 6 623466a5f475... dir1/dirA/bar
|
o 5 06ff3a5be997 dir1/dirA/foo
|
o 4 33227af02764 dir2/bar
|
o 3 5e1f9d8d7c69 dir2/foo
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da... root
widen narrow spec yet again, excluding a directory in previous spec
$ hg tracked --removeexclude dir2/dirA --addexclude dir1/dirA
comparing with ssh://user@dummy/master
searching for changes
looking for local changes to affected paths
deleting data/dir1/dirA/foo.i
no changes found
saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-widen.hg (glob)
adding changesets
adding manifests
adding file changes
added 13 changesets with 8 changes to 8 files
new changesets *:* (glob)
$ cat .hg/narrowspec
[includes]
path:dir1
path:dir2
[excludes]
path:dir1/dirA
path:dir1/dirA/bar
path:dir1/dirB
$ find * | sort
dir1
dir1/bar
dir1/foo
dir2
dir2/bar
dir2/dirA
dir2/dirA/bar
dir2/dirA/foo
dir2/dirB
dir2/dirB/bar
dir2/dirB/foo
dir2/foo
$ hg log -G -T '{rev} {node|short}{if(ellipsis, "...")} {files}\n'
@ 12 c87ca422d521... dir1/dirA/foo
|
o 11 951b8a83924e dir2/dirB/bar
|
o 10 01ae5a51b563 dir2/dirB/foo
|
o 9 5eababdf0ac5 dir2/dirA/bar
|
o 8 99d690663739 dir2/dirA/foo
|
o 7 8e80155d5445... dir1/dirB/bar
|
o 6 623466a5f475... dir1/dirA/bar
|
o 5 06ff3a5be997... dir1/dirA/foo
|
o 4 33227af02764 dir2/bar
|
o 3 5e1f9d8d7c69 dir2/foo
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da... root
include a directory that was previously explicitly excluded
$ hg tracked --removeexclude dir1/dirA
comparing with ssh://user@dummy/master
searching for changes
no changes found
saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-widen.hg (glob)
adding changesets
adding manifests
adding file changes
added 13 changesets with 9 changes to 9 files
new changesets *:* (glob)
$ cat .hg/narrowspec
[includes]
path:dir1
path:dir2
[excludes]
path:dir1/dirA/bar
path:dir1/dirB
$ find * | sort
dir1
dir1/bar
dir1/dirA
dir1/dirA/foo
dir1/foo
dir2
dir2/bar
dir2/dirA
dir2/dirA/bar
dir2/dirA/foo
dir2/dirB
dir2/dirB/bar
dir2/dirB/foo
dir2/foo
$ hg log -G -T '{rev} {node|short}{if(ellipsis, "...")} {files}\n'
@ 12 c87ca422d521 dir1/dirA/foo
|
o 11 951b8a83924e dir2/dirB/bar
|
o 10 01ae5a51b563 dir2/dirB/foo
|
o 9 5eababdf0ac5 dir2/dirA/bar
|
o 8 99d690663739 dir2/dirA/foo
|
o 7 8e80155d5445... dir1/dirB/bar
|
o 6 623466a5f475... dir1/dirA/bar
|
o 5 06ff3a5be997 dir1/dirA/foo
|
o 4 33227af02764 dir2/bar
|
o 3 5e1f9d8d7c69 dir2/foo
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da... root
$ cd ..
clone a narrow portion of the master, such that we can widen it later
$ hg clone --narrow ssh://user@dummy/master narrow2 --include dir1/dirA
requesting all changes
adding changesets
adding manifests
adding file changes
added 5 changesets with 2 changes to 2 files
new changesets *:* (glob)
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd narrow2
$ find * | sort
dir1
dir1/dirA
dir1/dirA/bar
dir1/dirA/foo
$ hg tracked --addinclude dir1
comparing with ssh://user@dummy/master
searching for changes
no changes found
saved backup bundle to $TESTTMP/narrow2/.hg/strip-backup/*-widen.hg (glob)
adding changesets
adding manifests
adding file changes
added 10 changesets with 6 changes to 6 files
new changesets *:* (glob)
$ find * | sort
dir1
dir1/bar
dir1/dirA
dir1/dirA/bar
dir1/dirA/foo
dir1/dirB
dir1/dirB/bar
dir1/dirB/foo
dir1/foo
$ hg log -G -T '{rev} {node|short}{if(ellipsis, "...")} {files}\n'
@ 9 c87ca422d521 dir1/dirA/foo
|
o 8 951b8a83924e... dir2/dirB/bar
|
o 7 8e80155d5445 dir1/dirB/bar
|
o 6 406760310428 dir1/dirB/foo
|
o 5 623466a5f475 dir1/dirA/bar
|
o 4 06ff3a5be997 dir1/dirA/foo
|
o 3 33227af02764... dir2/bar
|
o 2 594bc4b13d4a dir1/bar
|
o 1 47f480a08324 dir1/foo
|
o 0 2a4f0c3b67da... root