Optimize RoutingContext by removing summary generation and othe…

[anuraaga]

…r small tweaks.

• Don't generate a summary array for use in hashing and do the computation directly to reduce allocations
• Make accept headers extraction non-lazy, it was being eagerly evaluated during summary extraction in the old code anyways. It isn't really possible to use routing cache with lazy attributes anyways
• Don't use forEach due to extra Stream allocation and lambda allocation during extraction (current forEach holds a reference to the builder)
• Don't allocate list builder when getAll headers and the header isn't present

After

Benchmark                             Mode  Cnt         Score        Error  Units
RoutersBenchmark.exactMatch          thrpt    5  12921841.803 ▒ 173790.211  ops/s
RoutersBenchmark.exactMatch_wrapped  thrpt    5  12047216.990 ▒ 351620.117  ops/s

Before (wrapped is slower due to double allocation of summary)

Benchmark                             Mode  Cnt        Score         Error  Units
RoutersBenchmark.exactMatch          thrpt    5  7817340.954 ▒  926608.528  ops/s
RoutersBenchmark.exactMatch_wrapped  thrpt    5  6175815.558 ▒ 276154.231  ops/s

[trustin]

Niiiice 👍

[anuraaga]

For reference, I tend to look hard at routing code when trying to squeeze out performance since it's a lot of useful functionality, but not needed in RPC-only frameworks like gRPC upstream. So to be able to compete in performance with RPC frameworks, we need to make sure it's as fast as possible - this means having the router cache and making sure construction of the routing context is as lightweight as possible. Hopefully we find more ways to reduce this extra processing even further :)

[codecov]

Codecov Report

Merging #2295 into master will decrease coverage by 0.1%.
The diff coverage is 63.46%.

@@             Coverage Diff              @@
##             master    #2295      +/-   ##
============================================
- Coverage     73.82%   73.71%   -0.11%     
+ Complexity     9934     9919      -15     
============================================
  Files           871      871              
  Lines         38024    38041      +17     
  Branches       4663     4671       +8     
============================================
- Hits          28070    28041      -29     
- Misses         7572     7621      +49     
+ Partials       2382     2379       -3

Impacted Files	Coverage Δ	Complexity Δ
...va/com/linecorp/armeria/server/RoutingContext.java	100% <ø> (ø)	1 <0> (ø)	⬇️
...a/com/linecorp/armeria/common/HttpHeadersBase.java	72.16% <100%> (+0.1%)	153 <0> (+1)	⬆️
...linecorp/armeria/server/DefaultRoutingContext.java	77.1% <60%> (-18.28%)	28 <7> (ø)
...linecorp/armeria/server/RoutingContextWrapper.java	58.82% <66.66%> (+3.82%)	8 <2> (-1)	⬇️
...n/java/com/linecorp/armeria/server/HttpServer.java	40% <0%> (-20%)	2% <0%> (-1%)
...om/linecorp/armeria/client/HttpSessionHandler.java	61.01% <0%> (-11.02%)	29% <0%> (-4%)
...inecorp/armeria/client/AbstractEventLoopState.java	92.3% <0%> (-7.7%)	6% <0%> (-1%)
...corp/armeria/client/DefaultEventLoopScheduler.java	79.27% <0%> (-7.21%)	30% <0%> (-3%)
...com/linecorp/armeria/client/OneEventLoopState.java	66.66% <0%> (-4.77%)	6% <0%> (-1%)
...com/linecorp/armeria/server/saml/SamlEndpoint.java	62.5% <0%> (-2.5%)	10% <0%> (-1%)
... and 6 more

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[minwoox]

👍

[anuraaga]

@trustin your other PR inspired me to use do/while here :D

[ikhoon]

Nice! 👍