setdiscovery: limit the size of all sample (issue4411)
Further digging on this issue show that the limit on the sample size used in
discovery never works for heads. Here is a quote from the code itself:
desiredlen = size - len(always)
if desiredlen <= 0:
# This could be bad if there are very many heads, all unknown to the
# server. We're counting on long request support here.
The long request support never landed and evolution make the "very many heads,
all unknown to the server" case quite common.
We implement a simple and stupid hard limit of sample size for all query. This
should prevent HTTP 414 error with the current state of the code.
Function to test discovery between two repos in both directions, using both the local shortcut
(which is currently not activated by default) and the full remotable protocol:
$ testdesc() { # revs_a, revs_b, dagdesc
> if [ -d foo ]; then rm -rf foo; fi
> hg init foo
> cd foo
> hg debugbuilddag "$3"
> hg clone . a $1 --quiet
> hg clone . b $2 --quiet
> echo
> echo "% -- a -> b tree"
> hg -R a debugdiscovery b --verbose --old
> echo
> echo "% -- a -> b set"
> hg -R a debugdiscovery b --verbose --debug
> echo
> echo "% -- b -> a tree"
> hg -R b debugdiscovery a --verbose --old
> echo
> echo "% -- b -> a set"
> hg -R b debugdiscovery a --verbose --debug
> cd ..
> }
Small superset:
$ testdesc '-ra1 -ra2' '-rb1 -rb2 -rb3' '
> +2:f +1:a1:b1
> <f +4 :a2
> +5 :b2
> <f +3 :b3'
% -- a -> b tree
comparing with b
searching for changes
unpruned common: 01241442b3c2 66f7d451a68b b5714e113bc0
common heads: 01241442b3c2 b5714e113bc0
local is subset
% -- a -> b set
comparing with b
query 1; heads
searching for changes
all local heads known remotely
common heads: 01241442b3c2 b5714e113bc0
local is subset
% -- b -> a tree
comparing with a
searching for changes
unpruned common: 01241442b3c2 b5714e113bc0
common heads: 01241442b3c2 b5714e113bc0
remote is subset
% -- b -> a set
comparing with a
query 1; heads
searching for changes
all remote heads known locally
common heads: 01241442b3c2 b5714e113bc0
remote is subset
Many new:
$ testdesc '-ra1 -ra2' '-rb' '
> +2:f +3:a1 +3:b
> <f +30 :a2'
% -- a -> b tree
comparing with b
searching for changes
unpruned common: bebd167eb94d
common heads: bebd167eb94d
% -- a -> b set
comparing with b
query 1; heads
searching for changes
taking initial sample
searching: 2 queries
query 2; still undecided: 29, sample size is: 29
2 total queries
common heads: bebd167eb94d
% -- b -> a tree
comparing with a
searching for changes
unpruned common: 66f7d451a68b bebd167eb94d
common heads: bebd167eb94d
% -- b -> a set
comparing with a
query 1; heads
searching for changes
taking initial sample
searching: 2 queries
query 2; still undecided: 2, sample size is: 2
2 total queries
common heads: bebd167eb94d
Both sides many new with stub:
$ testdesc '-ra1 -ra2' '-rb' '
> +2:f +2:a1 +30 :b
> <f +30 :a2'
% -- a -> b tree
comparing with b
searching for changes
unpruned common: 2dc09a01254d
common heads: 2dc09a01254d
% -- a -> b set
comparing with b
query 1; heads
searching for changes
taking initial sample
searching: 2 queries
query 2; still undecided: 29, sample size is: 29
2 total queries
common heads: 2dc09a01254d
% -- b -> a tree
comparing with a
searching for changes
unpruned common: 2dc09a01254d 66f7d451a68b
common heads: 2dc09a01254d
% -- b -> a set
comparing with a
query 1; heads
searching for changes
taking initial sample
searching: 2 queries
query 2; still undecided: 29, sample size is: 29
2 total queries
common heads: 2dc09a01254d
Both many new:
$ testdesc '-ra' '-rb' '
> +2:f +30 :b
> <f +30 :a'
% -- a -> b tree
comparing with b
searching for changes
unpruned common: 66f7d451a68b
common heads: 66f7d451a68b
% -- a -> b set
comparing with b
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 31, sample size is: 31
2 total queries
common heads: 66f7d451a68b
% -- b -> a tree
comparing with a
searching for changes
unpruned common: 66f7d451a68b
common heads: 66f7d451a68b
% -- b -> a set
comparing with a
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 31, sample size is: 31
2 total queries
common heads: 66f7d451a68b
Both many new skewed:
$ testdesc '-ra' '-rb' '
> +2:f +30 :b
> <f +50 :a'
% -- a -> b tree
comparing with b
searching for changes
unpruned common: 66f7d451a68b
common heads: 66f7d451a68b
% -- a -> b set
comparing with b
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 51, sample size is: 51
2 total queries
common heads: 66f7d451a68b
% -- b -> a tree
comparing with a
searching for changes
unpruned common: 66f7d451a68b
common heads: 66f7d451a68b
% -- b -> a set
comparing with a
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 31, sample size is: 31
2 total queries
common heads: 66f7d451a68b
Both many new on top of long history:
$ testdesc '-ra' '-rb' '
> +1000:f +30 :b
> <f +50 :a'
% -- a -> b tree
comparing with b
searching for changes
unpruned common: 7ead0cba2838
common heads: 7ead0cba2838
% -- a -> b set
comparing with b
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 1049, sample size is: 11
sampling from both directions
searching: 3 queries
query 3; still undecided: 31, sample size is: 31
3 total queries
common heads: 7ead0cba2838
% -- b -> a tree
comparing with a
searching for changes
unpruned common: 7ead0cba2838
common heads: 7ead0cba2838
% -- b -> a set
comparing with a
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 1029, sample size is: 11
sampling from both directions
searching: 3 queries
query 3; still undecided: 15, sample size is: 15
3 total queries
common heads: 7ead0cba2838
One with >200 heads, which used to use up all of the sample:
$ hg init manyheads
$ cd manyheads
$ echo "+300:r @a" >dagdesc
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3 *r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3*r+3" >>dagdesc # 20 heads
$ echo "@b *r+3" >>dagdesc # one more head
$ hg debugbuilddag <dagdesc
reading DAG from stdin
$ hg heads -t --template . | wc -c
\s*261 (re)
$ hg clone -b a . a
adding changesets
adding manifests
adding file changes
added 1340 changesets with 0 changes to 0 files (+259 heads)
updating to branch a
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg clone -b b . b
adding changesets
adding manifests
adding file changes
added 304 changesets with 0 changes to 0 files
updating to branch b
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R a debugdiscovery b --debug --verbose
comparing with b
query 1; heads
searching for changes
taking quick initial sample
searching: 2 queries
query 2; still undecided: 1240, sample size is: 100
sampling from both directions
searching: 3 queries
query 3; still undecided: 1140, sample size is: 200
sampling from both directions
searching: 4 queries
query 4; still undecided: 940, sample size is: 200
sampling from both directions
searching: 5 queries
query 5; still undecided: 740, sample size is: 200
sampling from both directions
searching: 6 queries
query 6; still undecided: 540, sample size is: 200
sampling from both directions
searching: 7 queries
query 7; still undecided: 44, sample size is: 44
7 total queries
common heads: 3ee37d65064a
Test actual protocol when pulling one new head in addition to common heads
$ hg clone -U b c
$ hg -R c id -ir tip
513314ca8b3a
$ hg -R c up -qr default
$ touch c/f
$ hg -R c ci -Aqm "extra head"
$ hg -R c id -i
e64a39e7da8b
$ hg serve -R c -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
$ cat hg.pid >> $DAEMON_PIDS
$ hg -R b incoming http://localhost:$HGPORT/ -T '{node|short}\n'
comparing with http://localhost:$HGPORT/
searching for changes
e64a39e7da8b
$ "$TESTDIR/killdaemons.py" $DAEMON_PIDS
$ cut -d' ' -f6- access.log | grep -v cmd=known # cmd=known uses random sampling
"GET /?cmd=capabilities HTTP/1.1" 200 -
"GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D513314ca8b3ae4dac8eec56966265b00fcf866db
"GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:common=513314ca8b3ae4dac8eec56966265b00fcf866db&heads=e64a39e7da8b0d54bc63e81169aff001c13b3477
$ cat errors.log
$ cd ..