Struct Memo 

pub struct Memo<T> { /* private fields */ }

A value derived from one generation of the repository, kept until that generation ends.

The OpenAPI document, the MCP tool and resource listings and the resolved web surfaces are all expensive functions of the index and the registry, and all of them used to be OnceLocks — right while the index was immutable for the life of a process, and a second frozen picture the moment it was not. A memo answers from the generation it was built for and rebuilds for the next one.

use majordomus_cli::live::Memo;

let memo: Memo<String> = Memo::default();
let a = memo.get_or_init(0, || "built once".to_string());
let b = memo.get_or_init(0, || panic!("the same generation must not rebuild"));
assert_eq!(*a, *b);
let c = memo.get_or_init(1, || "built again".to_string());
assert_eq!(*c, "built again", "a new generation is a new value");

Implementations

impl<T> Memo<T>

pub fn get_or_init(&self, generation: u64, build: impl FnOnce() -> T) -> Arc<T>

The value for generation, building it once when this memo does not hold it.

The lock is held across build, so two threads that arrive together on a new generation do the work once rather than twice.

use majordomus_cli::live::Memo;

let memo: Memo<Vec<u8>> = Memo::default();
let first = memo.get_or_init(3, || vec![1, 2, 3]);
let again = memo.get_or_init(3, || unreachable!("the same generation is not rebuilt"));
assert!(std::sync::Arc::ptr_eq(&first, &again));
assert_eq!(*memo.get_or_init(4, Vec::new), Vec::<u8>::new(), "a new generation rebuilds");

Trait Implementations

impl<T: Debug> Debug for Memo<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Default for Memo<T>

fn default() -> Self

Returns the “default value” for a type.