[#29] Add RCU-based node synchronization

[maypok86]

Description

Added RCU mechanism to synchronize nodes to improve throughput for read-heavy workloads.

Related issue(s)

#29

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[maypok86]

RCU implementation benchmark results

reads=100%,writes=0%

BenchmarkCache/Zipf_Theine_reads=100%,writes=0%-8               10349106               112.6 ns/op         8884000 ops/s               0 B/op          0 allocs/op
BenchmarkCache/Zipf_Ristretto_reads=100%,writes=0%-8            49931085                23.92 ns/op       41810856 ops/s              16 B/op          1 allocs/op
BenchmarkCache/Zipf_Bigcache_reads=100%,writes=0%-8             28777293                38.36 ns/op       26065651 ops/s              96 B/op          2 allocs/op
BenchmarkCache/Zipf_Fastcache_reads=100%,writes=0%-8            39766262                30.36 ns/op       32937979 ops/s              47 B/op          0 allocs/op
BenchmarkCache/Zipf_Otter_reads=100%,writes=0%-8                235988992                4.341 ns/op     230386735 ops/s               0 B/op          0 allocs/op

reads=75%,writes=25%

BenchmarkCache/Zipf_Theine_reads=75%,writes=25%-8               11396006               110.0 ns/op         9086818 ops/s               0 B/op          0 allocs/op
BenchmarkCache/Zipf_Ristretto_reads=75%,writes=25%-8            26357984                43.93 ns/op       22764242 ops/s              27 B/op          1 allocs/op
BenchmarkCache/Zipf_Bigcache_reads=75%,writes=25%-8             17619958                61.52 ns/op       16255889 ops/s             106 B/op          1 allocs/op
BenchmarkCache/Zipf_Fastcache_reads=75%,writes=25%-8            20699691                53.26 ns/op       18777461 ops/s              43 B/op          0 allocs/op
BenchmarkCache/Zipf_Otter_reads=75%,writes=25%-8                175828222                6.885 ns/op     145241010 ops/s               2 B/op          0 allocs/op

reads=50%,writes=50%

BenchmarkCache/Zipf_Theine_reads=50%,writes=50%-8               13321800                88.12 ns/op       11347991 ops/s               0 B/op          0 allocs/op
BenchmarkCache/Zipf_Ristretto_reads=50%,writes=50%-8            24131536                46.66 ns/op       21430106 ops/s              34 B/op          1 allocs/op
BenchmarkCache/Zipf_Bigcache_reads=50%,writes=50%-8             15962000                64.46 ns/op       15513236 ops/s             111 B/op          1 allocs/op
BenchmarkCache/Zipf_Fastcache_reads=50%,writes=50%-8            22703031                52.41 ns/op       19081654 ops/s              39 B/op          0 allocs/op
BenchmarkCache/Zipf_Otter_reads=50%,writes=50%-8                98488806                12.23 ns/op       81767462 ops/s               6 B/op          0 allocs/op

reads=25%,writes=75%

BenchmarkCache/Zipf_Theine_reads=25%,writes=75%-8               13288441                93.63 ns/op       10680849 ops/s               0 B/op          0 allocs/op
BenchmarkCache/Zipf_Ristretto_reads=25%,writes=75%-8            18387763                60.40 ns/op       16555249 ops/s              58 B/op          1 allocs/op
BenchmarkCache/Zipf_Bigcache_reads=25%,writes=75%-8             15162562                68.59 ns/op       14578993 ops/s             196 B/op          0 allocs/op
BenchmarkCache/Zipf_Fastcache_reads=25%,writes=75%-8            26483512                47.32 ns/op       21130859 ops/s              23 B/op          0 allocs/op
BenchmarkCache/Zipf_Otter_reads=25%,writes=75%-8                52577490                21.35 ns/op       46847349 ops/s              10 B/op          0 allocs/op

reads=0%,writes=100%

BenchmarkCache/Zipf_Theine_reads=0%,writes=100%-8               29246624                40.11 ns/op       24930841 ops/s               0 B/op          0 allocs/op
BenchmarkCache/Zipf_Ristretto_reads=0%,writes=100%-8             9018708               130.6 ns/op         7656527 ops/s             122 B/op          3 allocs/op
BenchmarkCache/Zipf_Bigcache_reads=0%,writes=100%-8             13730578                81.44 ns/op       12279430 ops/s             262 B/op          0 allocs/op
BenchmarkCache/Zipf_Fastcache_reads=0%,writes=100%-8            24452991                47.78 ns/op       20928754 ops/s               0 B/op          0 allocs/op
BenchmarkCache/Zipf_Otter_reads=0%,writes=100%-8                10735712               121.4 ns/op         8236607 ops/s              64 B/op          1 allocs/op

Considering that cache loads are usually read-heavy, even reads=50%,writes=50% are rare, and otter starts degrading only under very heavy write load, the results are just great.