Decoding data with zlib wrappers is slow

[oyvindln]

I suspect it may be the adler32 checksum calculation that is slow, as data with gzip or no wrapper decodes significantly faster.

There is an adler32 crate that may help here.

[Takeru Ohta]

Your point is correct. I changed to use the adler32 crate at 4af9f2a .
Below is a brief benchmark result for decoding zlib compressed data by two adler32 implementations.

$ ls -lh /tmp/zlib_data
-rw-rw-rw- 1 ohta ohta 93M Jul 18 00:40 /tmp/zlib_data

# Original implementation version of adler32 checksum
$  time -p cargo run --release --example flate -- -i /tmp/zlib_data -o /dev/null zlib-decode
real 3.11
user 2.75
sys 0.34

# `adler32` crate version
> time -p cargo run --release --example flate -- -i /tmp/zlib_data -o /dev/null zlib-decode
real 2.48
user 2.09
sys 0.32

The improvement is obvious. Thank you for your advice!