Initialize P2P communication

[sukrawidhyawan]

Description

Initialize basic p2p Communication. For now available service is maintained connected peers & get more peers. Package service in p2p native will separate from unit test and just functional test (script for test not yet add in this PR) and the rest package still in unit test

Breakdown

• Add P2P strategy (design not fix yet)
• Add native strategy
• Available native service: resolvePeers & getMorePeers
• Peer cycling mechanism (WIP)

Reference Issue

Close #12 #71

Step to Test (optional)

• run go run main.go, go run main.go -postfix 2, go run main.go -postfix 3 in 3 separate terminal tabs to run 3 nodes based on 3 different configuration files
• while they are running, observe the ResolvedPeers and UnresolvedPeers populated and cycled through by running go run api/client/GetHostInfo/client.go -ip 127.0.0.1:3001, go run api/client/GetHostInfo/client.go -ip 127.0.0.1:3002 and go run api/client/GetHostInfo/client.go -ip 127.0.0.1:3001 to observe the the state of the 3 nodes seperately

[capt4ce]

Waiting for my enhancement to be included

[astaphobia]

GetMorePreers, 'GetPeerInfo' and SendPeers try to new handshake connection more and more and more.
or need to figure it out how to control this connection for more efficient way.

[capt4ce]

we'll get back to this if it is still in concern in the future #97

[andy-shi88]

another thought: p2p/native/service/client.go:NewPeerService() is lazyly instantiated, using traditional way of keeping it singleton is not enough, may consider using sync.once to avoid multiple go routine instantiating it.

[capt4ce]

another thought: p2p/native/service/client.go:NewPeerService() is lazyly instantiated, using traditional way of keeping it singleton is not enough, may consider using sync.once to avoid multiple go routine instantiating it.

Good point. Changed the implementation to use sync.Once

[andy-shi88]

and for secure random, we can use https://golang.org/pkg/crypto/rand/

[capt4ce]

@andy-shi88 Thanks, @sukrawidhyawan has perform it.
Just keeping a note here that we need to analyze the performance of crypto/random