[Spike] Cancelling Transactions

[solanoepalacio]

Currently we have no way of handling timeouts for a given transaction. This causes that if a transaction is submitted to a blockchain is never included in a block, then the workflow will be stucked undefinetly, never throwing a timeout error.

This causes the following issues:

• The workflow stucked will keep a wallet busy and never release it, making one of the wallets in the pool unusable
• The workflow stucked doesn't throw an error, and thus is harder to have visibility over the problem
• If the pod is restarted while this long living transaction is open, it will cause make the wallet un-usable because of the stucked pending transaction

The proposed solution is that it would be better to have an error than a stucked transaction. If we make the transaction throw an error, then we'll have this benefits:

• The workflow queue and the wallet will be unlocked
• The failed transaction can be retried automatically with a new gas configuration
• If the transaction has been retried enough times, the error will trigger an alert for someone to solve the issue manually

A transaction can be cancelled by sending an empty transaction (value = 0) to the same rpc node, using a higher gas price.

In some ocassions this mechanism could lead to complex situations, so it's important to keep this feature behind a feature flag

[solanoepalacio]

I'm thinking that might be ideal to be able to:

• enable/disable automatic transaction cancellation
• request the cancel of a transaction using an api which could someday be turned into a button on the relayer operations center