Improve the EVA protocol: devos50 edition

[drew2a]

During the ultimate stress test of the EVA protocol made by @devos50 we figured out some improvements that could be done to the EVA protocol.

Packet loss

Problem

During massive use of binary transfers provided by EVA protocol, some packets seem to be dropped by a socket.

Solution

EVA protocol has been designed as an abstract protocol, that uses ipv8 as a transport layer. That means EVA doesn't care much about balancing socket load.
However, it seems like a good idea to add a tool to the protocol to have the ability to limit ipv8 and socket load.

This tool will be variable max_simultaneous_transfers and it will be set to 10 by default.

Missed messages resending for WriteRequest

Problem

EVA doesn't support handling lost WriteRequest packets and performs only one attempt to send WriteRequest.

Solution

@devos50 added this support in https://github.com/devos50/accountable-dfl/blob/main/accdfl/util/eva_protocol.py in a similar way as it was implemented for resend_acknowledge. I've merged his changes to this PR.

Future support for EVA protocol

@devos50 requested to add the Future object as a returned parameter to thesend_binary function.
See the example of use: https://github.com/devos50/accountable-dfl/blob/main/accdfl/core/community.py#L230

Shutdown method for EVA protocol

@devos50 requested to add this method because he has a necessity to fast shut down the entire EVA stack:

task: <Task pending name='DFLCommunity:eva_terminate_by_timeout 11587' coro=<delay_runner() running at /home/spandey/venv3/lib/python3.9/site-packages/ipv8/taskmanager.py:23> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f8508a060d0>()]> cb=[TaskManager.register_task.<locals>.done_cb() at /home/spandey/venv3/lib/python3.9/site-packages/ipv8/taskmanager.py:128]>

[devos50]

Tested the changes in my experiment - seems to work great! 👍

[drew2a]

@kozlovsky @devos50 what do you think guys about the latest refactoring (see the most resend commit)?

a04f735

UPD: we've discussed this refactoring with @kozlovsky and decided to rewrite it.

[drew2a]

@devos50 changes are ready to test! 🚀

Please note that in the latest commit d6c09e3 EVA's interface has been slightly changed:

• All callbacks now should be async
• Proxy methods have been removed

By a proxy method I mean:

    def eva_send_binary(self, peer: Peer, info: bytes, data: bytes, nonce: int = None) -> Future:
        return self.eva_protocol.send_binary(peer, info, data, nonce)

Here is an example of EVA usage:

     import os
     from ipv8.community import Community
     class MyCommunity(EVAProtocolMixin, Community):
         community_id = os.urandom(20)
    
         def __init__(self, *args, **kwargs):
             super().__init__(*args, **kwargs)
             self.eva_init()
    
             self.eva.register_receive_callback(self.on_receive)
             self.eva.register_send_complete_callback(self.on_send_complete)
             self.eva.register_error_callback(self.on_error)
    
         async def my_function(self, peer):
             await self.eva.send_binary(peer, b'info1', b'data1')
             await self.eva.send_binary(peer, b'info2', b'data2')
             await self.eva.send_binary(peer, b'info3', b'data3')
    
         async def on_receive(self, result):
             self.logger.info(f'Data has been received: {result}')
    
         async def on_send_complete(self, result):
             self.logger.info(f'Transfer has been completed: {result}')
    
         async def on_error(self, peer, exception):
             self.logger.error(f'Error has been occurred: {exception}')

[devos50]

Still haven't been able to test out the changes in an experiment setting - I hope to do so later this afternoon.

[drew2a]

@devos50 thank you in advance for testing!