icydb-core 0.211.2

//! Module: db::schema::mutation::budget
//! Responsibility: own shared resource limits for complete schema-transition work.
//! Does not own: operation-specific derived-state or publication accounting.
//! Boundary: schema mutation controllers consume canonical limits and resource identities.

use crate::error::SchemaTransitionBudgetResource;

const MAX_SOURCE_ROWS: usize = 65_536;
const MAX_SOURCE_ROW_BYTES: usize = 256 * 1024 * 1024;
pub(in crate::db) const MAX_SCHEMA_PROJECTION_ENTRIES: usize = 131_072;
pub(in crate::db) const MAX_SCHEMA_PROJECTION_WORK_UNITS: usize = 262_144;
pub(in crate::db) const MAX_SCHEMA_STAGED_RAW_BYTES: usize = 256 * 1024 * 1024;

///
/// SchemaTransitionSourceBudget
///
/// Incremental exact source-domain budget shared by complete schema operations.
/// Schema mutation owns its counters; operation-specific stages only consume it.
///

pub(in crate::db) struct SchemaTransitionSourceBudget {
    source_row_bytes: usize,
    source_rows: usize,
}

impl SchemaTransitionSourceBudget {
    /// Build the maintained complete-domain source budget.
    #[must_use]
    pub(in crate::db) const fn standard() -> Self {
        Self {
            source_row_bytes: 0,
            source_rows: 0,
        }
    }

    /// Consume one authoritative row before operation-specific work begins.
    pub(in crate::db) fn consume_source_row(
        &mut self,
        encoded_row_bytes: usize,
    ) -> Result<(), SchemaTransitionBudgetResource> {
        self.source_rows = self
            .source_rows
            .checked_add(1)
            .ok_or(SchemaTransitionBudgetResource::SourceRows)?;
        if self.source_rows > MAX_SOURCE_ROWS {
            return Err(SchemaTransitionBudgetResource::SourceRows);
        }

        self.source_row_bytes = self
            .source_row_bytes
            .checked_add(encoded_row_bytes)
            .ok_or(SchemaTransitionBudgetResource::SourceRowBytes)?;
        if self.source_row_bytes > MAX_SOURCE_ROW_BYTES {
            return Err(SchemaTransitionBudgetResource::SourceRowBytes);
        }

        Ok(())
    }

    /// Return the exact number of source rows consumed so far.
    #[must_use]
    pub(in crate::db) const fn source_rows(&self) -> usize {
        self.source_rows
    }

    /// Return the exact cumulative source-row bytes consumed so far.
    #[must_use]
    pub(in crate::db) const fn source_row_bytes(&self) -> usize {
        self.source_row_bytes
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn source_budget_matches_the_maintained_complete_domain_caps() {
        let mut rows = SchemaTransitionSourceBudget::standard();
        for _ in 0..MAX_SOURCE_ROWS {
            rows.consume_source_row(0)
                .expect("rows through the exact cap should admit");
        }
        assert_eq!(
            rows.consume_source_row(0),
            Err(SchemaTransitionBudgetResource::SourceRows),
        );

        let mut bytes = SchemaTransitionSourceBudget::standard();
        assert_eq!(
            bytes.consume_source_row(MAX_SOURCE_ROW_BYTES + 1),
            Err(SchemaTransitionBudgetResource::SourceRowBytes),
        );
    }
}