RoutingPolicy: don't build deep unions #6433
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In very long routing policies, especially when they have lots of continue statements, we might compile them into fairly complicated structures with Call statements. Sets.union is a shallow operation that never coalesces, so it seems plausible that building a deep union will cause stack overflows on containment checks. To fix this, materialize the sets as we go. This should not in practice be very expensive unless we are in a case that would cause a stack overflow with the prior approach.
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This change is |
progwriter
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Nov 17, 2020
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Reviewed 1 of 1 files at r1.
Reviewable status:complete! all files reviewed, all discussions resolved (waiting on @anothermattbrown and @corinaminer)
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The bug reported by @dannypetrov took place on Arista with a route-map with 1146 terms. |
Codecov Report
@@ Coverage Diff @@
## master #6433 +/- ##
============================================
- Coverage 73.12% 73.10% -0.02%
- Complexity 35324 35343 +19
============================================
Files 2819 2820 +1
Lines 142996 143133 +137
Branches 17218 17233 +15
============================================
+ Hits 104565 104640 +75
- Misses 30168 30214 +46
- Partials 8263 8279 +16 |
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In very long routing policies, especially when they have lots of
continue statements, we might compile them into fairly complicated
structures with Call statements. Sets.union is a shallow operation that
never coalesces, so it seems plausible that building a deep union will
cause stack overflows on containment checks.
To fix this, materialize the sets as we go. This should not in practice
be very expensive unless we are in a case that would cause a stack
overflow with the prior approach.