compress/lzw: add Reset method to Reader and Writer
We add a Reset method which clears any internal state of an encoder
or a decoder to let it be reused again as a new Writer or Reader respectively.
We also export the encoder and decoder structs, renaming them
to be Reader and Writer, and we guarantee that the underlying types
from the constructors will always be Reader and Writer respectively.
Benchmark results by reusing the encoder:
on cpu: Intel(R) Core(TM) i5-8265U CPU @ 1.60GHz
name time/op
Decoder/1e4-8 93.6µs ± 1%
Decoder/1e-Reuse4-8 87.7µs ± 1%
Decoder/1e5-8 877µs ± 1%
Decoder/1e-Reuse5-8 860µs ± 3%
Decoder/1e6-8 8.79ms ± 1%
Decoder/1e-Reuse6-8 8.82ms ± 4%
Encoder/1e4-8 168µs ± 2%
Encoder/1e-Reuse4-8 160µs ± 1%
Encoder/1e5-8 1.64ms ± 1%
Encoder/1e-Reuse5-8 1.61ms ± 2%
Encoder/1e6-8 16.2ms ± 6%
Encoder/1e-Reuse6-8 15.8ms ± 2%
name speed
Decoder/1e4-8 107MB/s ± 1%
Decoder/1e-Reuse4-8 114MB/s ± 1%
Decoder/1e5-8 114MB/s ± 1%
Decoder/1e-Reuse5-8 116MB/s ± 3%
Decoder/1e6-8 114MB/s ± 1%
Decoder/1e-Reuse6-8 113MB/s ± 5%
Encoder/1e4-8 59.7MB/s ± 2%
Encoder/1e-Reuse4-8 62.4MB/s ± 1%
Encoder/1e5-8 61.1MB/s ± 1%
Encoder/1e-Reuse5-8 62.0MB/s ± 2%
Encoder/1e6-8 61.7MB/s ± 5%
Encoder/1e-Reuse6-8 63.4MB/s ± 2%
name alloc/op
Decoder/1e4-8 21.8kB ± 0%
Decoder/1e-Reuse4-8 50.0B ± 0%
Decoder/1e5-8 21.8kB ± 0%
Decoder/1e-Reuse5-8 70.4B ± 2%
Decoder/1e6-8 21.9kB ± 0%
Decoder/1e-Reuse6-8 271B ± 3%
Encoder/1e4-8 77.9kB ± 0%
Encoder/1e-Reuse4-8 4.17kB ± 0%
Encoder/1e5-8 77.9kB ± 0%
Encoder/1e-Reuse5-8 4.27kB ± 0%
Encoder/1e6-8 77.9kB ± 0%
Encoder/1e-Reuse6-8 5.22kB ± 0%
name allocs/op
Decoder/1e4-8 2.00 ± 0%
Decoder/1e-Reuse4-8 1.00 ± 0%
Decoder/1e5-8 2.00 ± 0%
Decoder/1e-Reuse5-8 1.00 ± 0%
Decoder/1e6-8 2.00 ± 0%
Decoder/1e-Reuse6-8 1.00 ± 0%
Encoder/1e4-8 3.00 ± 0%
Encoder/1e-Reuse4-8 2.00 ± 0%
Encoder/1e5-8 3.00 ± 0%
Encoder/1e-Reuse5-8 2.00 ± 0%
Encoder/1e6-8 3.00 ± 0%
Encoder/1e-Reuse6-8 2.00 ± 0%
Fixes #26535
Change-Id: Icde613fea6234a5bdce95f1e49910f5687e30b22
Reviewed-on: https://go-review.googlesource.com/c/go/+/273667
Trust: Agniva De Sarker <agniva.quicksilver@gmail.com>
Trust: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>