It's just a config wrapper that passes "use less memory at the
expense of compression" parameters by default, so that we don't
accidentally construct resource-hungry (de)compressors.
Also includes a benchmark that measures the memory cost of the
small variants vs. the stock variants. The savings are significant
on both compressors (~8x less memory) and decompressors (~1.4x less,
not including the savings from the significantly smaller
window on the compression side - with those savings included it's
more like ~140x smaller).
BenchmarkSmallEncoder-8 56174 19354 ns/op 31 B/op 0 allocs/op
BenchmarkSmallEncoderWithBuild-8 2900 382940 ns/op 1746547 B/op 36 allocs/op
BenchmarkStockEncoder-8 48921 25761 ns/op 286 B/op 0 allocs/op
BenchmarkStockEncoderWithBuild-8 426 2630241 ns/op 13843842 B/op 124 allocs/op
BenchmarkSmallDecoder-8 123814 9344 ns/op 0 B/op 0 allocs/op
BenchmarkSmallDecoderWithBuild-8 41547 27455 ns/op 27694 B/op 31 allocs/op
BenchmarkStockDecoder-8 129832 9417 ns/op 1 B/op 0 allocs/op
BenchmarkStockDecoderWithBuild-8 25561 51751 ns/op 39607 B/op 92 allocs/op
Signed-off-by: David Anderson <danderson@tailscale.com>