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CPI Example

This example contract shows how to perform a cross-program invocation (CPI) of the ORAO VRF contract.

Contract

This contract implements a trivial single-player Russian Roulette. The outcome of a round is based on the randomness, requested from ORAO VRF contract via CPI. The contract have only one instruction called "SpinAndPullTheTrigger { force }" (see programs/russian-roulette/src/lib.rs). This instruction asserts that the player is able to play and invokes ORAO VRF via CPI. The "force" value (generated randomly) is used as a VRF seed.

Round outcome is derived lazily from the fulfilled VRF randomness.

The contract logic

There are three possible player states:

  • alive – last round outcome shows that the player is still alive (5/6 chance) or is not yet played. Player is able to play again.
  • dead – last round outcome shows that the player is dead (1/6 chance). Player can't play anymore.
  • playing – another round was started but the randomness is not yet fulfilled by VRF authorities (indicated as "spinning cylinder"). Player is not able to play at the moment.

How to play

Tests shows the contract logic in action.

Also there are a simple CLI for this contract (it is published on devnet):

# The `state` subcommand shows the current player state:
$ cargo run -q --package roulette-cli -- state
-- Using RPC https://api.devnet.solana.com, keypair /tmp/id.json
-- ------
Player 56HnAmFGyM9QcuNM51WvX88cXX76aMVQivc53aHuAHxK is alive after 10 round(s)

# The `play` subcommand runs a single round:
$ cargo run -q --package roulette-cli -- play
-- Using RPC https://api.devnet.solana.com, keypair /tmp/id.json
-- ------
Loading a bullet and spinning the cylinder..
CLICK! Player 56HnAmFGyM9QcuNM51WvX88cXX76aMVQivc53aHuAHxK is alive after 11 round(s)

How to deploy the contract

Requirements:

Note: these instructions assume you have a working solana-cli, rust, anchor installation (v0.29) and that all env and paths are set. The contract is already deployed on both the devnet and mainnet, however you can change it's ID and deploy to another address:

# Generete a new keypair
$ solana-keygen new -o /tmp/new_keypair.json

# Update contract ID with the public key of the new keypair
vim programs/russian-roulette/src/lib.rs # update `declare_id!` macro value
vim Anchor.toml # update `programs.localnet.russian_roulette` address

# Build the contract, from the ./rust/examples/cpi directory
$ anchor build

# Deploy on the new address (add more funds to your wallet in case of 0x1 error)
anchor deploy --program-keypair /tmp/new_keypair.json --program-name russian-roulette