Every interaction with Ekubo starts with a call to lock
Ekubo is a singleton AMM that utilizes the "till" pattern. All pools and tokens are represented as state in a single contract. The till pattern was publicly introduced at EthCC and is also described here. This is how Ekubo allows all token payments to be deferred until the end of your transaction.
Even though the entrypoint for all methods is named #lock, Ekubo protocol supports reentrancy. Locks can be nested, meaning any contract you call can also interact with Ekubo.
Every interaction with Ekubo starts with ICore#lock. In order to interact with Ekubo, you must first implement the ILocker interface in your calling contract:
You must then make all your swaps and position updates within the #locked callback. If you call any of these methods outside of a locked callback, the call will revert.
To know what you must do within the callback, encode your parameters into the data argument of the call to lock. The shared_locker.cairo contains some useful functions for constructing the call to lock as well as consuming the locked callback data.