Limitation on the number of events per operation in Smart Contracts

Agora
1

Hello everyone,

I wanted to start a discussion about the limitation in Smart Contracts: an operation cannot emit more than 25 events.

From what I understand, this limit was introduced after the Certik audit.

Even a simple operation, like a transferFrom in an MRC20, can emit an event, so this limit can quickly become restrictive.

Some questions and points for discussion:

  • Why exactly was this limit introduced?

  • Are there any strategies to mitigate this issue, knowing that it is not possible to suppress event emission when one Smart Contract calls another?

Thanks for your feedback and experiences!

2

Hello!
Thanks for raising the topic. I think this is a really annoying issue that could block a lot of contract builders.
Even very simple uses case are made impossible due to this limitation:
like sending MRC20 token to more than 25 wallet.

I think the limit has been set to avoid node spamming, but i don”t know the details.
Why this limit is not handeled with gasCost instead of set an hardcoded limit?

I don’t know neither what is the rational behind the 25 number.

We can imagine several kind of mitigation for this:

  • Increase the 25 limit

  • remove the MRC20 events (by modifying the bytecode during a node update)

  • Having a “no event” mode for contract call would be nice but we have to think about the implications. Considering that events are ephemeral anyway it might be possible to do it.

1 Like
3

Hi!

A “no event” mode is a good option. When developing a smart contract, you can choose the “no event” mode (for the entire SC), or when using call(at: Address, functionName: string, args: Args, coins: number, noEvents: bool) — adding the boolean noEvents.

Additionally, in massa-web3, you can add an option like { noEvents: true } in call(.., { Options }).

1 Like