ic-memory 0.48.1

Durable stable-memory allocation governance for Internet Computer canisters
Documentation 
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use super::{AllocationLedger, AllocationRecord};
use crate::declaration::AllocationDeclaration;
use crate::slot::MemoryManagerSlot;

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum ClaimOutcome {
    Existing,
    New,
}

///
/// ClaimConflict
///
/// Internal claim failure carrying the historical record needed for error
/// projection. Existing bindings never require ledger mutation.
///

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum ClaimConflict<'ledger> {
    StableKeyMoved { record: &'ledger AllocationRecord },
    SlotReused { record: &'ledger AllocationRecord },
}

pub fn validate_declaration_claim<'ledger>(
    ledger: &'ledger AllocationLedger,
    declaration: &AllocationDeclaration,
) -> Result<ClaimOutcome, ClaimConflict<'ledger>> {
    if let Some(record) = ledger
        .records()
        .iter()
        .find(|record| record.stable_key == declaration.stable_key)
    {
        if record.slot != declaration.slot {
            return Err(ClaimConflict::StableKeyMoved { record });
        }
        return Ok(ClaimOutcome::Existing);
    }

    validate_new_claim(ledger, &declaration.slot)
}

pub fn validate_new_claim<'ledger>(
    ledger: &'ledger AllocationLedger,
    slot: &MemoryManagerSlot,
) -> Result<ClaimOutcome, ClaimConflict<'ledger>> {
    if let Some(record) = ledger.records().iter().find(|record| &record.slot == slot) {
        return Err(ClaimConflict::SlotReused { record });
    }
    Ok(ClaimOutcome::New)
}