repair: move check for existing transaction earlier
Several benefits:
* Gets close the comment describing it
* Splits off unrelated comment about "backup" argument
* Error checking is customarily done early
* If we added an early return to the method, it would still
consistently fail if there was an existing transaction (so
we would find and fix that case quickly)
One test needs updating with for this change, because we no longer
create the backup bundle before we fail. I don't see much reason to
create that backup bundle. If some command was adding content and then
trying to strip it as well within the transaction, we would have a
backup for the user, but the risk of that not being discovered in
development seems very small.
$ cat >> $HGRCPATH << EOF
> [web]
> push_ssl = false
> allow_push = *
> EOF
$ hg init server
$ cd server
$ touch a
$ hg -q commit -A -m initial
$ cd ..
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid >> $DAEMON_PIDS
compression formats are advertised in compression capability
#if zstd
$ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=zstd,zlib$' > /dev/null
#else
$ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=zlib$' > /dev/null
#endif
$ killdaemons.py
server.compressionengines can replace engines list wholesale
$ hg --config server.compressionengines=none -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
$ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=none$' > /dev/null
$ killdaemons.py
Order of engines can also change
$ hg --config server.compressionengines=none,zlib -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
$ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=none,zlib$' > /dev/null
$ killdaemons.py
Start a default server again
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
Server should send application/mercurial-0.1 to clients if no Accept is used
$ get-with-headers.py --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
200 Script output follows
content-type: application/mercurial-0.1
date: * (glob)
server: * (glob)
transfer-encoding: chunked
Server should send application/mercurial-0.1 when client says it wants it
$ get-with-headers.py --hgproto '0.1' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
200 Script output follows
content-type: application/mercurial-0.1
date: * (glob)
server: * (glob)
transfer-encoding: chunked
Server should send application/mercurial-0.2 when client says it wants it
$ get-with-headers.py --hgproto '0.2' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
200 Script output follows
content-type: application/mercurial-0.2
date: * (glob)
server: * (glob)
transfer-encoding: chunked
$ get-with-headers.py --hgproto '0.1 0.2' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
200 Script output follows
content-type: application/mercurial-0.2
date: * (glob)
server: * (glob)
transfer-encoding: chunked
Requesting a compression format that server doesn't support results will fall back to 0.1
$ get-with-headers.py --hgproto '0.2 comp=aa' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
200 Script output follows
content-type: application/mercurial-0.1
date: * (glob)
server: * (glob)
transfer-encoding: chunked
#if zstd
zstd is used if available
$ get-with-headers.py --hgproto '0.2 comp=zstd' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
$ f --size --hexdump --bytes 36 --sha1 resp
resp: size=248, sha1=4d8d8f87fb82bd542ce52881fdc94f850748
0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 7a 73 74 64 |t follows...zstd|
0020: 28 b5 2f fd |(./.|
#endif
application/mercurial-0.2 is not yet used on non-streaming responses
$ get-with-headers.py --hgproto '0.2' $LOCALIP:$HGPORT '?cmd=heads' -
200 Script output follows
content-length: 41
content-type: application/mercurial-0.1
date: * (glob)
server: * (glob)
e93700bd72895c5addab234c56d4024b487a362f
Now test protocol preference usage
$ killdaemons.py
$ hg --config server.compressionengines=none,zlib -R server serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
No Accept will send 0.1+zlib, even though "none" is preferred b/c "none" isn't supported on 0.1
$ get-with-headers.py --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' Content-Type
200 Script output follows
content-type: application/mercurial-0.1
$ get-with-headers.py $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
$ f --size --hexdump --bytes 28 --sha1 resp
resp: size=227, sha1=35a4c074da74f32f5440da3cbf04
0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 78 |t follows..x|
Explicit 0.1 will send zlib because "none" isn't supported on 0.1
$ get-with-headers.py --hgproto '0.1' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
$ f --size --hexdump --bytes 28 --sha1 resp
resp: size=227, sha1=35a4c074da74f32f5440da3cbf04
0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 78 |t follows..x|
0.2 with no compression will get "none" because that is server's preference
(spec says ZL and UN are implicitly supported)
$ get-with-headers.py --hgproto '0.2' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
$ f --size --hexdump --bytes 32 --sha1 resp
resp: size=432, sha1=ac931b412ec185a02e0e5bcff98dac83
0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 6e 6f 6e 65 |t follows...none|
Client receives server preference even if local order doesn't match
$ get-with-headers.py --hgproto '0.2 comp=zlib,none' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
$ f --size --hexdump --bytes 32 --sha1 resp
resp: size=432, sha1=ac931b412ec185a02e0e5bcff98dac83
0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 6e 6f 6e 65 |t follows...none|
Client receives only supported format even if not server preferred format
$ get-with-headers.py --hgproto '0.2 comp=zlib' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
$ f --size --hexdump --bytes 33 --sha1 resp
resp: size=232, sha1=a1c727f0c9693ca15742a75c30419bc36
0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 7a 6c 69 62 |t follows...zlib|
0020: 78 |x|