async-substrate-interface

Async Substrate Interface

This project provides an asynchronous interface for interacting with Substrate-based blockchains. It is based on the py-substrate-interface project.

Additionally, this project uses bt-decode instead of py-scale-codec for faster SCALE decoding.

Installation

To install the package, use the following command:

pip install async-substrate-interface

Usage

Here are examples of how to use the sync and async interfaces:

from async_substrate_interface import SubstrateInterface

def main():
    substrate = SubstrateInterface(
        url="wss://rpc.polkadot.io"
    )
    with substrate:
        result = substrate.query(
            module='System',
            storage_function='Account',
            params=['5CZs3T15Ky4jch1sUpSFwkUbYEnsCfe1WCY51fH3SPV6NFnf']
        )

        print(result)

main()

import asyncio
from async_substrate_interface import AsyncSubstrateInterface

async def main():
    substrate = AsyncSubstrateInterface(
        url="wss://rpc.polkadot.io"
    )
    async with substrate:
        result = await substrate.query(
            module='System',
            storage_function='Account',
            params=['5CZs3T15Ky4jch1sUpSFwkUbYEnsCfe1WCY51fH3SPV6NFnf']
        )

        print(result)

asyncio.run(main())

Caching

There are a few different cache types used in this library to improve the performance overall. The one with which you are probably familiar is the typical functools.lru_cache used in sync_substrate.SubstrateInterface.

By default, it uses a max cache size of 512 for smaller returns, and 16 for larger ones. These cache sizes are user-configurable using the respective env vars, SUBSTRATE_CACHE_METHOD_SIZE and SUBSTRATE_RUNTIME_CACHE_SIZE.

They are applied only on methods whose results cannot change — such as the block hash for a given block number (small, 512 default), or the runtime for a given runtime version (large, 16 default).

Additionally, in AsyncSubstrateInterface, because of its asynchronous nature, we developed our own asyncio-friendly LRU caches. The primary one is the CachedFetcher which wraps the same methods as functools.lru_cache does in SubstrateInterface, but the key difference here is that each request is assigned a future that is returned when the initial request completes. So, if you were to do:

bn = 5000
bh1, bh2 = await asyncio.gather(
    asi.get_block_hash(bn),
    asi.get_block_hash(bn)
)

it would actually only make one single network call, and return the result to both requests. Like SubstrateInterface, it also takes the SUBSTRATE_CACHE_METHOD_SIZE and SUBSTRATE_RUNTIME_CACHE_SIZE vars to set cache size.

The third and final caching mechanism we use is async_substrate_interface.async_substrate.DiskCachedAsyncSubstrateInterface, which functions the same as the normal AsyncSubstrateInterface, but that also saves this cache to the disk, so the cache is preserved between runs. This is product for a fairly nice use-case (such as btcli). As you may call different networks with entirely different results, this cache is keyed by the uri supplied at instantiation of the DiskCachedAsyncSubstrateInterface object, so DiskCachedAsyncSubstrateInterface(network_1) and DiskCachedAsyncSubstrateInterface(network_2) will not share the same on-disk cache.

As with the other two caches, this also takes SUBSTRATE_CACHE_METHOD_SIZE and SUBSTRATE_RUNTIME_CACHE_SIZE env vars.

ENV VARS

The following environment variables are used within async-substrate-interface

• NO_CACHE (default 0): if set to 1, when using the DiskCachedAsyncSubstrateInterface class, no persistent on-disk cache will be stored, instead using only in-memory cache.
• CACHE_LOCATION (default ~/.cache/async-substrate-interface): this determines the location for the cache file, if using DiskCachedAsyncSubstrateInterface
• SUBSTRATE_CACHE_METHOD_SIZE (default 512): the cache size (either in-memory or on-disk) of the smaller return-size methods (see the Caching section for more info)
• SUBSTRATE_RUNTIME_CACHE_SIZE (default 16): the cache size (either in-memory or on-disk) of the larger return-size methods (see the Caching section for more info)

Contributing

Contributions are welcome! Please open an issue or submit a pull request to the staging branch.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contact

For any questions or inquiries, please join the Bittensor Development Discord server: Church of Rao.