Optimize numeric value serialization/deserialization

[letmutx]

We call num.to_string().as_bytes() to serialize and deserialize numbers when setting them in memcache server. Instead, we could use byteorder crate's read_u16, read_u64 etc. and write out the bytes to the server with a specific endianness(big/little) and use the same when deserializing.
deserialization:

rust-memcache/src/value.rs

Line 161 in faed4e1

let s: String = FromMemcacheValue::from_memcache_value(value, 0)?;

serialization:

rust-memcache/src/value.rs

Line 95 in faed4e1

match stream.write_all(self.to_string().as_bytes()) {

rust-memcache/src/value.rs

Line 91 in faed4e1

return self.to_string().as_bytes().len();

[DefinitelyNotAnOrca]

I have been doing some digging on this, and I am not sure if this is the best idea. Specifically because if we did use the byteorder read functions, the memcached commands incr and decr would automatically fail because the read bytes are not the string representation of the number that is being stored (Source: https://github.com/memcached/memcached/wiki/Commands#incrdecr). This is fine on the numbers that cannot be represented within a u64, but I question if it is worth this small optimization, especially because it will have different performance behaviors depending on if a number is positive or negative.

[p14c31355]

@letmutx Hi! I am @YoshitakaNaraoka , Japanese Rustacean egg.
This PR is abandoned for a long time, please assign me.

[aisk]

Hi @YoshitakaNaraoka , since this is an open source project, you don't need to require an assignment before doing the work, and any contribution will be appreciated!

[p14c31355]

@aisk Thank you! I'm going to fork it over and get to work as soon as possible!

[p14c31355]

@aisk I am not familiar with bits (which I find unfortunate).
Am I correct in understanding that pub enum Flags represents the first digit of the bits in the sequence?

[p14c31355]

Through this development experience, I want to deepen my understanding of bits.

[shahab96]

Through this development experience, I want to deepen my understanding of bits.

Along with every value written into memcache, the user is able to provide flags in the form of an integer value. In this crate we currently have two ways to do this, either the user gets the default value of 0 for their flags, or they may implement the ToMemcacheValue trait and implement the get_flags value themselves.

When reading the value back however I don't think we actually read the flags and return them, I will have to look again as I haven't worked on this codebase in a year now