Blog
Technical writings on smart contracts, security research, and software engineering.
Decoding Ethereum Events
Observability is an often overlooked part of software development and subsequent deployment. I myself am guilty of chucking in a handful of unstructured log messages and calling it a day. As the complexity of the application increases, this usually ends up forcing our hands to implement either structured logging or perhaps a tracing system.
The standard way of observing smart contracts is through logs (also referred to as events). These are a bit more sophisticated than a standard print statement, and actually possess some additional properties. The most interesting of these properties is that we can prove certain events happened, as all the logs emitted during a block are Merkleized into the receipts root field of the block header. This actually allows us to prove that a certain event happened without needing to re-execute the block, and it is used quite heavily in bridging protocols, for example.
[Read more →]Bulk Storage Extraction
Most Dapp developers have heard of and probably use the excellent Multicall contract to bundle their eth_calls and reduce latency for bulk ETL in their applications (we do too, we even have a python library for it: Manifold).
Unfortunately, we cannot use this same trick when getting storage slots, as we discovered when developing our storage explorer, forcing developers to issue an eth_getStorageAt for each slot they want to query. Luckily, Geth has a trick up its sleeve, the “State Override Set”, which, with a little ingenuity, we can leverage to get bulk storage extraction.