Fix #1526 trailing slash to any route

[lammel]

This PR fixes #1526 to handle a corner case for a request with trailing slash that shall match an any route just below the request path.

GET /users/ will now correctly match the any route /users/*

[codecov]

Codecov Report

Merging #1563 into master will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1563      +/-   ##
==========================================
+ Coverage   84.85%   84.96%   +0.10%     
==========================================
  Files          28       28              
  Lines        2166     2168       +2     
==========================================
+ Hits         1838     1842       +4     
+ Misses        213      211       -2     
  Partials      115      115              

Impacted Files	Coverage Δ
router.go	97.15% <100.00%> (+0.02%)	⬆️
response.go	76.31% <0.00%> (+5.26%)	⬆️

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[lammel]

Benchmarks are showing slight improvements for complex routes (5 to 15% faster) and a slowdown for the ParseAPI routes (around +17%)

pkg: github.com/labstack/echo/v4
BenchmarkRouterStaticRoutes-8    	   67260	     16516 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGitHubAPI-8       	   32832	     34217 ns/op	       2 B/op	       0 allocs/op
BenchmarkRouterParseAPI-8        	  199347	      5694 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGooglePlusAPI-8   	  112566	     10480 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/labstack/echo/v4	5.279s

WIth this fix:

pkg: github.com/labstack/echo/v4
BenchmarkRouterStaticRoutes-8    	   68384	     16857 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGitHubAPI-8       	   34982	     32503 ns/op	       2 B/op	       0 allocs/op
BenchmarkRouterParseAPI-8        	  169191	      6680 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGooglePlusAPI-8   	  128191	      8870 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/labstack/echo/v4	7.078s

[lammel]

@vishr Comments welcome. A duplicate check for cn.findChildByKind(akind) when the route search is exhausted (search = "") and we need to lookup if a any child is still down the route tree is the cause for the slight performance decrease for some benchmarks.
Did not have time to optimize that away, not sure that is easily possible.

Overall I think it is acceptable as it is.

[lammel]

Update for the benchmarks against current master. Again a little ups and downs.
Benchmarks do not to be very reliable as we have up to 10% deviation for the same code per run.

Results for master:

master$ /usr/bin/go test -benchmem -run=^$ github.com/labstack/echo/v4 -bench '^(BenchmarkRouterStaticRoutes|BenchmarkRouterGitHubAPI|BenchmarkRouterParseAPI|BenchmarkRouterGooglePlusAPI)$' -benchtime 10s -cpu 2
goos: linux
goarch: amd64
pkg: github.com/labstack/echo/v4
BenchmarkRouterStaticRoutes-2    	  779059	     14300 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGitHubAPI-2       	  394016	     29629 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterParseAPI-2        	 2559226	      4633 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGooglePlusAPI-2   	 1500585	      8078 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/labstack/echo/v4	60.088s

with the latest commits of this PR:

bugfix/1526-..$ /usr/bin/go test -benchmem -run=^$ github.com/labstack/echo/v4 -bench '^(BenchmarkRouterStaticRoutes|BenchmarkRouterGitHubAPI|BenchmarkRouterParseAPI|BenchmarkRouterGooglePlusAPI)$' -benchtime 10s
goos: linux
goarch: amd64
pkg: github.com/labstack/echo/v4
BenchmarkRouterStaticRoutes-16     	  774600	     14568 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGitHubAPI-16        	  353102	     32341 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterParseAPI-16         	 2439986	      4926 ns/op	       0 B/op	       0 allocs/op
BenchmarkRouterGooglePlusAPI-16    	 1545140	      7864 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/labstack/echo/v4	60.229s

[jeanphilippe-mh]

Thanks you for this fix @lammel 🙏, i've had the same issue with echo v4.1.16 that breaks CORS policy. I've rollbacked to 4.1.14 through go.mod and it's working like a charm again!
Waiting for Echo release 4.1.17 now 👍