WebsocketProviderV2

[fselmo]

What was wrong?

Related to Issue #2880

• The current WebsocketProvider doesn't keep an open connection and doesn't allow for subscription support
• Missing support for eth_subscribe

How was it fixed?

• Started as an expirement a few months back. I put together a new version of the Websocket Provider that maintains an open connection and processes responses asynchronously using all the middleware and formatters we're used to.
• I polished up as much as I could of that hacky version and abstracted a lot of the logic into classes, a transient async response processing cache, and kept going along the same route until it passed all the integration tests. Very open to suggestions on improvements.

Features:

• Persistent connection async websocket provider support
• Debug logging where appropriate around the transient async response processing cache and websocket connection
• eth_subscribe (and eth_unsubscribe) support

Usage (from the docs added):

>>> import asyncio
>>> from web3 import AsyncWeb3
>>> from web3.providers import WebsocketProviderV2

>>> LOG = True  # toggle debug logging
>>> if LOG:
...     import logging
...     logger = logging.getLogger("web3.providers.WebsocketProviderV2")
...     logger.setLevel(logging.DEBUG)
...     logger.addHandler(logging.StreamHandler())

>>> async def ws_v2_subscription_example():
...     async with AsyncWeb3.persistent_websocket(
...         WebsocketProviderV2(f"ws://127.0.0.1:8546")
...     ) as w3:
...         # subscribe to new block headers
...         subscription_id = await w3.eth.subscribe("newHeads")
...
...         unsubscribed = False
...         while not unsubscribed:
...             async for response in w3.listen_to_websocket():
...                 print(f"{response}\n")
...                 # handle responses here
...
...                 if some_condition:
...                     # unsubscribe from new block headers
...                     unsubscribed = await w3.eth.unsubscribe(subscription_id)
...                     break
...
...         # still an open connection, make any other requests and get
...         # responses via send / receive
...         latest_block = await w3.eth.get_block("latest")
...         print(f"Latest block: {latest_block}")
...
...         # the connection closes automatically when exiting the context
...         # manager / `async with` block

>>> asyncio.run(ws_v2_subscription_example())

Todo:

• Add entry to the release notes
• Fix failing docs
• Add documentation for WebsocketProviderV2
• Fix failing EthereumTesterProvider / eth-tester based core tests

Cute Animal Picture

[fselmo]

This is ready for an initial review... sorry for the PR size here 😔

cc: @DefiDebauchery

[reedsa]

🚢 Nothing stands out in my mind, lgtm! Will be curious to see adoption feedback and see if there are challenges migrating to v2.

[kclowes]

This looks good to me from a code perspective! I'll take some time on Monday to play around with the UI. It'll be awesome to get this in!

[kclowes]

Left a nit on the docs, but looks great otherwise!