How stop Repeat when first results are found in Gremlin TinkerPop Graph - graph

Question

How can I stop traversing further down a graph using a Repeat when the first results are found?
I have tried to use an aggregate variable but it seem that the until step ignores it.
Se demo
https://gremlify.com/2gr4460avv1
I cannot get the this line to work in the until step:
sack().is(within('level'))
eg. with the following graph:
g.addV('User 0').as('0').
property(single, 'name', 'v0').
addV('User 1').as('1').
property(single, 'name', 'v1').
addV('User 2').as('2').
property(single, 'name', 'v2').
addV('User 3').as('3').
property(single, 'name', 'v3').
addV('User 4').as('4').
property(single, 'name', 'v3').
addV('Subject 1').as('5').
property(single, 'name', 's1').
addE('Trust').from('0').to('1').property("distance", 1).
addE('Trust').from('0').to('2').property("distance", 1).
addE('Trust').from('0').to('3').property("distance", 1).
addE('Trust').from('1').to('2').property("distance", 1).
addE('Trust').from('1').to('4').property("distance", 1).
addE('Audit').from('2').to('5').property("distance", 0).
addE('Trust').from('2').to('3').property("distance", 1).
addE('Audit').from('3').to('5').property("distance", 0).
addE('Trust').from('3').to('0').property("distance", 1).
addE('Audit').from('4').to('2').property("distance", 0)
Query:
g.withSack(0).V().has("name", "v0").
repeat(outE("Trust", "Audit").as("e").sack(sum).by('distance').
inV().simplePath().
choose(
select("e").hasLabel("Trust"),
choose(
select("e").has("distance", gte(0)),
aggregate('allow'),
aggregate('distrust')
)
)
).
until(
has('name', 's1').
or().
sack().is(gte(3)).
or().
sack().is(within('level')).
or().
where(within('distrust'))
).
has('name', 's1').
sack(sum).by(constant(1)).sack().aggregate('level').
path()
Result:
==>[v[0],e[13][0-Trust->4],v[4],e[17][4-Audit->10],v[10],2]
==>[v[0],e[14][0-Trust->6],v[6],e[19][6-Audit->10],v[10],2]
==>[v[0],e[12][0-Trust->2],v[2],e[16][2-Trust->8],v[8],e[21][8-Audit->10],v[10],3]
==>[v[0],e[12][0-Trust->2],v[2],e[15][2-Trust->4],v[4],e[17][4-Audit->10],v[10],3]
==>[v[0],e[13][0-Trust->4],v[4],e[18][4-Trust->6],v[6],e[19][6-Audit->10],v[10],3]
But I want the gremlin to stop at the level of the first result. e.g. so the result should look like this.
==>[v[0],e[13][0-Trust->4],v[4],e[17][4-Audit->10],v[10],2]
==>[v[0],e[14][0-Trust->6],v[6],e[19][6-Audit->10],v[10],2]
The query should find one or more result at the same degree if they exist, then stop looking for longer routes.
The idea is that in a very large graph the query stops early if it finds one or more results at the same degree.
PS! withComputer() would be nice, but I need to filter untrusted user away from the route calculation dynamically and cannot see how this can be done using the shortestPath() function.

Answer 1

I did not yet have time to try with your data set, but here is an example that uses a data set I had to hand that shows how to end a repeat based on the sack value having exceeded a given threshold.
gremlin> g.withSideEffect('level',3000).
......1> withSack(0).
......2> V(44).
......3> repeat(outE().sack(sum).by('dist').inV().simplePath()).
......4> until(where(gt('level')).by(sack()).by().or().loops().is(3)).
......5> path().
......6> by('code').
......7> by('dist').
......8> limit(3)
==>[SAF,549,DFW,4736,LHR]
==>[SAF,549,DFW,4933,CDG]
==>[SAF,549,DFW,5127,FRA]
I added the loops test just to avoid any runaway queries, but it is not needed if the dataset is well understood to not have that potential.
gremlin> g.withSideEffect('level',3000).
......1> withSack(0).
......2> V(44).
......3> repeat(outE().sack(sum).by('dist').inV().simplePath()).
......4> until(where(gt('level')).by(sack()).by()).
......5> path().
......6> by('code').
......7> by('dist').
......8> limit(3)
==>[SAF,549,DFW,4736,LHR]
==>[SAF,549,DFW,4933,CDG]
==>[SAF,549,DFW,5127,FRA]
The key takeaway here is that where(predicate('string')) is a special case of where such that the string is treated as the name of a "variable" and not a literal string, as in where(within('my-list')).
Note also that if all you really want is a depth counter, you can just use loops and not worry about managing a sack.
Here is one last example, that adds an and step to the until. This will stop when distances greater than 3000 are found AND those distances are between 3001 and 4500 miles, or loops gets to 3.
gremlin> g.withSideEffect('level',3000).
......1> withSack(0).
......2> V(44).
......3> repeat(outE().sack(sum).by('dist').inV().simplePath()).
......4> until(and((where(gt('level')).by(sack()).by()),
......5> sack().is(between(3001,4500))).
......6> or().loops().is(3)).
......7> path().
......8> by('code').
......9> by('dist').
.....10> limit(3)
==>[SAF,549,DFW,3368,LIM]
==>[SAF,549,DFW,3702,OGG]
==>[SAF,549,DFW,3733,KEF]