ctxlock: use safe implementation of keyify

[BradLugo]

I noticed while trying to implement some examples of libindex that .Index() method will panic on an empty claircore.Manifest. I tracked this down to keyify panicing when it receives an empty string as input. I didn't really try to figure out the exact bug here because reflect.StringHeader is marked as deprecated anyway, so I tried the following function:

func keyify(key string) []byte {
	h := fnv.New64a()
	p := unsafe.StringData(key)
	b := unsafe.Slice((*byte)(p), len(key))
	h.Write(b)
	return h.Sum(nil)
}

That seemed to fix the problem, but then I was curious if this caused a performance hit, so I ran BenchmarkUncontended between that implementation and the previous implementation. The results looked similiar. Since the safe implementation was there and ready for benchmarking, I figured I'd test it as well. Here are the results from the tests:

safe benchmark

❯ go test -bench BenchmarkUncontended ./pkg/ctxlock -benchtime 1m
goos: darwin
goarch: arm64
pkg: github.com/quay/claircore/pkg/ctxlock
BenchmarkUncontended-10           742704             89153 ns/op            1256 B/op         17 allocs/op
--- BENCH: BenchmarkUncontended-10
    bench_test.go:10: using embedded database
    adapter.go:32: info Dialing PostgreSQL server host=localhost
    adapter.go:32: info Exec sql=CREATE ROLE rolef6286f908286622b LOGIN PASSWORD 'rolef6286f908286622b'; args=[] time=15.2385ms commandTag=CREATE ROLE pid=89492
    adapter.go:32: info Exec commandTag=CREATE DATABASE pid=89492 sql=CREATE DATABASE db8ebf054880a36f1c WITH OWNER rolef6286f908286622b ENCODING 'UTF8'; args=[] time=46.004875ms
    adapter.go:32: info closed connection pid=89492
    adapter.go:32: info Dialing PostgreSQL server host=localhost
    adapter.go:32: info Exec sql=CREATE EXTENSION IF NOT EXISTS "uuid-ossp"; args=[] time=1.931208ms commandTag=CREATE EXTENSION pid=89493
    adapter.go:32: info closed connection pid=89493
    db.go:78: config: {Host:localhost Database:db8ebf054880a36f1c User:rolef6286f908286622b Password:rolef6286f908286622b Port:39363}
    testing.go:98: {"level":"debug","zlog.testname":"BenchmarkUncontended","component":"internal/ctxlock/Locker.reconnect","gen":"1","caller":"ctxlock.go:153","message":"set up"}
        ... [output truncated]
PASS
ok      github.com/quay/claircore/pkg/ctxlock   70.941s

Results:
BenchmarkUncontended-10 742704 89153 ns/op 1256 B/op 17 allocs/op

old_unsafe benchmark

❯ go test -bench BenchmarkUncontended ./pkg/ctxlock -benchtime 1m -tags old_safe
goos: darwin
goarch: arm64
pkg: github.com/quay/claircore/pkg/ctxlock
BenchmarkUncontended-10           818978             87649 ns/op            1256 B/op         17 allocs/op
--- BENCH: BenchmarkUncontended-10
    bench_test.go:10: using embedded database
    adapter.go:32: info Dialing PostgreSQL server host=localhost
    adapter.go:32: info Exec time=15.076875ms commandTag=CREATE ROLE pid=93451 sql=CREATE ROLE rolee5605a7b4266a8ae LOGIN PASSWORD 'rolee5605a7b4266a8ae'; args=[]
    adapter.go:32: info Exec pid=93451 sql=CREATE DATABASE dba83bd9aa5e678d8c WITH OWNER rolee5605a7b4266a8ae ENCODING 'UTF8'; args=[] time=41.451375ms commandTag=CREATE DATABASE
    adapter.go:32: info closed connection pid=93451
    adapter.go:32: info Dialing PostgreSQL server host=localhost
    adapter.go:32: info Exec sql=CREATE EXTENSION IF NOT EXISTS "uuid-ossp"; args=[] time=1.554459ms commandTag=CREATE EXTENSION pid=93452
    adapter.go:32: info closed connection pid=93452
    db.go:78: config: {Host:localhost Database:dba83bd9aa5e678d8c User:rolee5605a7b4266a8ae Password:rolee5605a7b4266a8ae Port:33326}
    testing.go:98: {"level":"debug","component":"internal/ctxlock/Locker.reconnect","zlog.testname":"BenchmarkUncontended","gen":"1","caller":"ctxlock.go:153","message":"set up"}
        ... [output truncated]
PASS
ok      github.com/quay/claircore/pkg/ctxlock   76.170s

Results:
BenchmarkUncontended-10 818978 87649 ns/op 1256 B/op 17 allocs/op

new_unsafe benchmark

❯ go test -bench BenchmarkUncontended ./pkg/ctxlock -benchtime 1m -tags new_unsafe
goos: darwin
goarch: arm64
pkg: github.com/quay/claircore/pkg/ctxlock
BenchmarkUncontended-10           776305             87822 ns/op            1256 B/op         17 allocs/op
--- BENCH: BenchmarkUncontended-10
    bench_test.go:10: using embedded database
    adapter.go:32: info Dialing PostgreSQL server host=localhost
    adapter.go:32: info Exec commandTag=CREATE ROLE pid=97744 sql=CREATE ROLE role1400dd44238cf4d0 LOGIN PASSWORD 'role1400dd44238cf4d0'; args=[] time=15.369417ms
    adapter.go:32: info Exec pid=97744 sql=CREATE DATABASE db5b1fbd8ee021771 WITH OWNER role1400dd44238cf4d0 ENCODING 'UTF8'; args=[] time=43.988333ms commandTag=CREATE DATABASE
    adapter.go:32: info closed connection pid=97744
    adapter.go:32: info Dialing PostgreSQL server host=localhost
    adapter.go:32: info Exec sql=CREATE EXTENSION IF NOT EXISTS "uuid-ossp"; args=[] time=1.493459ms commandTag=CREATE EXTENSION pid=97745
    adapter.go:32: info closed connection pid=97745
    db.go:78: config: {Host:localhost Database:db5b1fbd8ee021771 User:role1400dd44238cf4d0 Password:role1400dd44238cf4d0 Port:37605}
    testing.go:98: {"level":"debug","zlog.testname":"BenchmarkUncontended","component":"internal/ctxlock/Locker.reconnect","gen":"1","caller":"ctxlock.go:153","message":"set up"}
        ... [output truncated]
PASS
ok      github.com/quay/claircore/pkg/ctxlock   72.663s

Results:
BenchmarkUncontended-10 776305 87822 ns/op 1256 B/op 17 allocs/op

It seems that all implementations have similar performance. Therefore, I propose we remove all unsafe implementations.

I've attached a patch with the changes required to run the benchmarks described above. I encourage reviewers to run them as well, especially folks who have non-darwin systems.

benchmarks.patch

[crozzy]

LGTM