Anchor Token Swap Program

Overview

This token-swap project is rewritten using Anchor, forked from solana-program-library/token-swap.

Advantages of using anchor

1. Unpack & Pack:

   Using macros like #[account] and #[derive(AnchorSerialize, AnchorDeserialize)] can simply implement the unpack and pack methods, which can reduce chunky of boliplate code.

2. Configuable Constraints:

   The configurable validations are a great enhancement compared to the original code using lots of comparasion. Below is an example:

    #[account(
        token::token_program = token_swap.token_program_id,
        token::mint = pool_mint.key(),
        constraint = host_fee_account.owner != authority.key() @ SwapError::InvalidOwner
    )]
    pub host_fee_account: Option<InterfaceAccount<'info, TokenAccount>>, 

3. Client friendly:

   It automatically generates client types & even methods for typescript client.

4. Other features:

   • init can combine create the account via system CPI and initialize the account in one step.
   • #[derive(InitSpace)] can measure the initial size of the account.
   • seeds Configurable PDA support
   • CpiContext Strongly typed for CPI calling.

Noticeable Changes

Javascript is the default client language, unfortunately, it's power is not well utilized in some partss the original code. Below are the notable changes (tracked here: #2):

1. Misuse of async javascript

   • It's a rather common misconception that main typescript client executes the transaction one after another (sequentially). In fact, that can be perfectly submitted in batches. You know the reason why solana is faster is because it supports parallel processing.

   • sleep shouldn't be used, as javascript is event-driven, there is always an async way to be informed when a transaction is done, using sleep to wait for a fixed-period of time can make the execution much ineffective, because the actual time of transaction execution can be vary for different traffic.

2. Fix a bug onaccount validation

   I detected an business logic issue, details are here: #3

3. Pre-commit hooks

This project uses pre-commit to format the code before each commits #4.

How to run

• build: anchor build
• unit test & proptest: cargo test
• integration test: anchor test (make sure yarn install has been executed to ensure all javascript/typescript dependencies are installed)
• run two above tests in one go: yarn test

Todo

• Add tests on curves including constant_price and offset
• Add tests on both spl-token and spl-token-2022, all the mints can use each of the token programs.
• Add tests related to bpf-upgradeable

License

This project is licensed under the MIT License. See the LICENSE file for details.