Is it common to have close account instruction inside my solana program

Question

In my Solana program, users can create program-owned accounts.

Although maybe they want to close it because it is no longer necessary and want to recoup the account rent/fees.

1. I assume that closing program accounts can only occur from within the program itself, which requires making a dedicated program instruction - is this common?

2. If I close the entire Solana program, will all the program-owned accounts also be closed at the same time? If so who will receive all the account fees - the upgrade auth?

Answer 1

To close a program account, you'll need dedicated instruction in your program as you mentioned.

If you're using Anchor here's a basic reference that you can add additional constraints to: https://github.com/coral-xyz/sealevel-attacks/blob/master/programs/9-closing-accounts/recommended/src/lib.rs

use anchor_lang::prelude::*;

declare_id!("Fg6PaFpoGXkYsidMpWTK6W2BeZ7FEfcYkg476zPFsLnS");

#[program]
pub mod closing_accounts_recommended {
    use super::*;

    pub fn close(ctx: Context<Close>) -> ProgramResult {
        Ok(())
    }
}

#[derive(Accounts)]
pub struct Close<'info> {
    #[account(mut, close = destination)]
    account: Account<'info, Data>,
    #[account(mut)]
    destination: AccountInfo<'info>,
}

#[account]
pub struct Data {
    data: u64,
}

If you close the program, I don't think any of the existing program accounts get closed.