is there any instruction can set the max slot

Question

I'm wondering if there's an instruction to set a maximum slot for transactions. Specifically, I need a way to:

Verify the actual landing slot is less than X. If it isn't, the transaction should be reverted.

Or for such needs i will need to write a program by my own

Answer 1

Since blockhashes last 150 blocks before they're rejected by the cluster, there's a cheeky way to do this by using an older blockhash that is close to expiry, but not quite expired.

For example, you can fetch a blockhash 140 hashes back, and then submit your transaction, knowing that it must land within the next 10 blocks or expire.

Here's the recent blockhashes sysvar:https://explorer.solana.com/address/SysvarRecentB1ockHashes11111111111111111111/blockhashes