solana_program/
feature.rs

1//! Runtime features.
2//!
3//! Runtime features provide a mechanism for features to be simultaneously activated across the
4//! network. Since validators may choose when to upgrade, features must remain dormant until a
5//! sufficient majority of the network is running a version that would support a given feature.
6//!
7//! Feature activation is accomplished by:
8//! 1. Activation is requested by the feature authority, who issues a transaction to create the
9//!    feature account. The newly created feature account will have the value of
10//!    `Feature::default()`
11//! 2. When the next epoch is entered the runtime will check for new activation requests and
12//!    active them.  When this occurs, the activation slot is recorded in the feature account
13
14use {
15    crate::{
16        account_info::AccountInfo, instruction::Instruction, program_error::ProgramError,
17        pubkey::Pubkey, rent::Rent, system_instruction,
18    },
19    solana_clock::Slot,
20};
21
22crate::declare_id!("Feature111111111111111111111111111111111111");
23
24#[derive(Default, Debug, Serialize, Deserialize, PartialEq, Eq)]
25pub struct Feature {
26    pub activated_at: Option<Slot>,
27}
28
29impl Feature {
30    pub const fn size_of() -> usize {
31        9 // see test_feature_size_of.
32    }
33
34    pub fn from_account_info(account_info: &AccountInfo) -> Result<Self, ProgramError> {
35        if *account_info.owner != id() {
36            return Err(ProgramError::InvalidAccountOwner);
37        }
38        bincode::deserialize(&account_info.data.borrow())
39            .map_err(|_| ProgramError::InvalidAccountData)
40    }
41}
42
43/// Activate a feature
44pub fn activate(feature_id: &Pubkey, funding_address: &Pubkey, rent: &Rent) -> Vec<Instruction> {
45    activate_with_lamports(
46        feature_id,
47        funding_address,
48        rent.minimum_balance(Feature::size_of()),
49    )
50}
51
52pub fn activate_with_lamports(
53    feature_id: &Pubkey,
54    funding_address: &Pubkey,
55    lamports: u64,
56) -> Vec<Instruction> {
57    vec![
58        system_instruction::transfer(funding_address, feature_id, lamports),
59        system_instruction::allocate(feature_id, Feature::size_of() as u64),
60        system_instruction::assign(feature_id, &id()),
61    ]
62}
63
64#[cfg(test)]
65mod test {
66    use super::*;
67
68    #[test]
69    fn test_feature_size_of() {
70        assert_eq!(Feature::size_of() as u64, {
71            let feature = Feature {
72                activated_at: Some(0),
73            };
74            bincode::serialized_size(&feature).unwrap()
75        });
76        assert!(
77            Feature::size_of() >= bincode::serialized_size(&Feature::default()).unwrap() as usize
78        );
79        assert_eq!(Feature::default(), Feature { activated_at: None });
80
81        let features = [
82            Feature {
83                activated_at: Some(0),
84            },
85            Feature {
86                activated_at: Some(Slot::MAX),
87            },
88        ];
89        for feature in &features {
90            assert_eq!(
91                Feature::size_of(),
92                bincode::serialized_size(feature).unwrap() as usize
93            );
94        }
95    }
96}
solana_program/feature.rs

solana_program/
feature.rs
