hawdb-storage 0.12.0

// Copyright 2026 Nowledge
// Licensed under the Apache License, Version 2.0.

//! Exhaustive pinned baseline input, separate from retained change history.
use super::*;
use crate::relational::{
    RelationalHydrationBudget, RelationalKey, RelationalRowPageProjectedRange,
    RelationalRowPageProjectedRangeFields, RelationalRowPageSnapshotReadError,
    RelationalRowPageSnapshotReadLimits, RelationalRowPageSnapshotReader,
};
use std::num::NonZeroUsize;
use std::ops::Bound;

#[derive(Debug, Clone, Copy)]
pub struct ProjectionFullSourceLimits {
    pub max_tables: NonZeroUsize,
    /// Estimated cursor, table-name directory and two retained key slots.
    /// Existing snapshot/cache/row-reader ownership has its separate admission.
    pub metadata_bytes: NonZeroUsize,
    pub key_bytes: NonZeroUsize,
    pub row_reads: RelationalRowPageSnapshotReadLimits,
}
impl Default for ProjectionFullSourceLimits {
    fn default() -> Self {
        Self {
            max_tables: NonZeroUsize::new(1024).unwrap(),
            metadata_bytes: NonZeroUsize::new(256 * 1024).unwrap(),
            key_bytes: NonZeroUsize::new(4096).unwrap(),
            row_reads: RelationalRowPageSnapshotReadLimits::default(),
        }
    }
}

/// Graph candidates include allocation holes and deleted IDs. Hydration against
/// the same snapshot determines presence; every attempted ID consumes admission.
/// Every canonical relational table is announced, including empty tables.
#[derive(Debug, Clone, Copy)]
pub enum ProjectionFullSourceItem<'a> {
    GraphNodeCandidate {
        node_id: u64,
    },
    RelationalTable {
        table: &'a str,
    },
    RelationalKey {
        table: &'a str,
        key: &'a RelationalKey,
    },
    End {
        source_epoch: u64,
    },
}

/// Owns an immutable source/history pin and private resume state. Completion
/// proves enumeration only, never the correctness or coverage of staged output.
#[derive(Debug)]
pub struct ProjectionFullSourceCursor {
    source: Box<GraphStore>,
    rows: Option<RelationalRowPageSnapshotReader>,
    tables: Vec<String>,
    node: u64,
    table: usize,
    announced: bool,
    last: Option<RelationalKey>,
    pending: Option<(RelationalKey, usize)>,
    table_rows: usize,
    ended: bool,
    failed: bool,
    total: ProjectionFeedLimits,
    limits: ProjectionFullSourceLimits,
    used: ProjectionFeedUsage,
    task: RuntimeTaskContext,
}

impl GraphStore {
    #[doc(hidden)]
    pub fn capture_full_projection_source(
        &self,
        total: ProjectionFeedLimits,
        limits: ProjectionFullSourceLimits,
        task: RuntimeTaskContext,
    ) -> std::result::Result<ProjectionFullSourceCursor, ProjectionFeedError> {
        self.ensure_usable().map_err(ProjectionFeedError::Source)?;
        task.checkpoint()
            .map_err(|e| ProjectionFeedError::Source(HawDBError::Execution(e.to_string())))?;
        let mut bytes = std::mem::size_of::<ProjectionFullSourceCursor>()
            .saturating_add(std::mem::size_of::<GraphStore>())
            .saturating_add(limits.key_bytes.get().saturating_mul(2));
        let mut count = 0usize;
        for schema in self.relational_state.table_schemas() {
            count += 1;
            bytes = bytes
                .saturating_add(schema.name.len())
                .saturating_add(std::mem::size_of::<String>());
            if count > limits.max_tables.get() || bytes > limits.metadata_bytes.get() {
                return Err(ProjectionFeedError::BudgetExceeded(
                    ProjectionFeedResource::Bytes,
                ));
            }
            if schema.primary_key.is_empty() || schema.primary_key.len() > 32 {
                return Err(ProjectionFeedError::Source(HawDBError::Execution(
                    "full projection source requires bounded canonical primary keys".into(),
                )));
            }
        }
        if bytes > limits.metadata_bytes.get() {
            return Err(ProjectionFeedError::BudgetExceeded(
                ProjectionFeedResource::Bytes,
            ));
        }
        let rows = if self.relational_state.canonical_row_metadata_only() {
            Some(
                self.open_relational_row_snapshot_reader()
                    .map_err(ProjectionFeedError::Source)?
                    .ok_or_else(|| {
                        ProjectionFeedError::Source(HawDBError::StorageIntegrity(
                            "full projection source has no canonical row reader".into(),
                        ))
                    })?,
            )
        } else {
            self.relational_state
                .require_materialized_rows("full projection source")
                .map_err(|e| ProjectionFeedError::Source(HawDBError::Storage(e.to_string())))?;
            None
        };
        let tables = self
            .relational_state
            .table_schemas()
            .map(|s| s.name.clone())
            .collect();
        Ok(ProjectionFullSourceCursor {
            source: Box::new(self.snapshot_for_read()),
            rows,
            tables,
            node: 0,
            table: 0,
            announced: false,
            last: None,
            pending: None,
            table_rows: 0,
            ended: false,
            failed: false,
            total,
            limits,
            used: ProjectionFeedUsage::default(),
            task,
        })
    }
}

fn key_bytes(key: &RelationalKey, limit: usize) -> std::result::Result<usize, ProjectionFeedError> {
    let mut bytes = std::mem::size_of::<RelationalKey>();
    if key.0.len() > 32 {
        return Err(ProjectionFeedError::BudgetExceeded(
            ProjectionFeedResource::Bytes,
        ));
    }
    for value in &key.0 {
        bytes = bytes
            .saturating_add(std::mem::size_of_val(value))
            .saturating_add(value.estimated_payload_bytes());
        if bytes > limit {
            return Err(ProjectionFeedError::BudgetExceeded(
                ProjectionFeedResource::Bytes,
            ));
        }
    }
    Ok(bytes)
}

impl ProjectionFullSourceCursor {
    pub fn source_epoch(&self) -> u64 {
        self.source.commit_epoch
    }
    pub fn usage(&self) -> ProjectionFeedUsage {
        self.used
    }
    pub fn is_complete(&self) -> bool {
        self.ended && !self.failed
    }

    pub fn finish(self) -> std::result::Result<ProjectionFeedUsage, ProjectionFeedError> {
        if self.failed {
            return Err(ProjectionFeedError::Failed);
        }
        if !self.ended {
            return Err(ProjectionFeedError::Incomplete);
        }
        self.source
            .ensure_usable()
            .map_err(ProjectionFeedError::Source)?;
        self.task
            .checkpoint()
            .map_err(|e| ProjectionFeedError::Source(HawDBError::Execution(e.to_string())))?;
        Ok(self.used)
    }

    fn integrity(&self, message: &str) -> ProjectionFeedError {
        let result = Err::<(), _>(HawDBError::StorageIntegrity(message.into()));
        self.source.poison_on_storage_error(&result);
        let Err(error) = result else {
            unreachable!("integrity result is always an error")
        };
        ProjectionFeedError::Source(error)
    }

    fn charge(
        &mut self,
        step: ProjectionFeedLimits,
        now: &mut ProjectionFeedUsage,
        work: usize,
        items: usize,
        bytes: usize,
    ) -> std::result::Result<bool, ProjectionFeedError> {
        let amounts = [
            (
                ProjectionFeedResource::Work,
                work,
                self.used.work,
                self.total.work.get(),
                now.work,
                step.work.get(),
            ),
            (
                ProjectionFeedResource::Items,
                items,
                self.used.items,
                self.total.items.get(),
                now.items,
                step.items.get(),
            ),
            (
                ProjectionFeedResource::Bytes,
                bytes,
                self.used.bytes,
                self.total.bytes.get(),
                now.bytes,
                step.bytes.get(),
            ),
        ];
        for (resource, n, used, total, _, _) in amounts {
            if n > total.saturating_sub(used) {
                return Err(ProjectionFeedError::BudgetExceeded(resource));
            }
        }
        for (resource, n, _, _, used, cap) in amounts {
            if n > cap {
                return Err(ProjectionFeedError::StepTooSmall(resource));
            }
            if n > cap - used {
                return Ok(false);
            }
        }
        self.used.work += work;
        self.used.items += items;
        self.used.bytes += bytes;
        now.work += work;
        now.items += items;
        now.bytes += bytes;
        Ok(true)
    }

    fn next_key(&self) -> std::result::Result<Option<(RelationalKey, usize)>, ProjectionFeedError> {
        let table = &self.tables[self.table];
        if let Some(reader) = &self.rows {
            let mut found = None;
            let mut error = None;
            let result = reader.visit_projected_range_fields_resolving_ref(
                RelationalRowPageProjectedRangeFields {
                    range: RelationalRowPageProjectedRange {
                        table,
                        lower: self.last.as_ref().map_or(Bound::Unbounded, Bound::Excluded),
                        upper: Bound::Unbounded,
                        requested_fields: &[],
                    },
                    hydration_fields: &[],
                },
                self.limits.row_reads,
                &mut RelationalHydrationBudget::default(),
                &self.task,
                |_, _, _| Ok(()),
                |row, _| {
                    let key = row.primary_key();
                    match key_bytes(key, self.limits.key_bytes.get()) {
                        Ok(bytes) => found = Some((key.clone(), bytes)),
                        Err(e) => error = Some(e),
                    }
                    false
                },
            );
            let result = result.map_err(|e| match e {
                RelationalRowPageSnapshotReadError::Corrupt(_)
                | RelationalRowPageSnapshotReadError::MissingTable(_) => {
                    HawDBError::StorageIntegrity(e.to_string())
                }
                RelationalRowPageSnapshotReadError::Stopped(_) => {
                    HawDBError::Execution(e.to_string())
                }
                RelationalRowPageSnapshotReadError::FileDescriptors(e) => {
                    HawDBError::FileDescriptors(e)
                }
                _ => HawDBError::Storage(e.to_string()),
            });
            self.source.poison_on_storage_error(&result);
            result.map_err(ProjectionFeedError::Source)?;
            if let Some(e) = error {
                return Err(e);
            }
            Ok(found)
        } else {
            let key = self
                .source
                .relational_state
                .first_primary_key_after(table, self.last.as_ref())
                .map_err(|e| ProjectionFeedError::Source(HawDBError::Storage(e.to_string())))?;
            key.map(|key| {
                key_bytes(key, self.limits.key_bytes.get()).map(|bytes| (key.clone(), bytes))
            })
            .transpose()
        }
    }

    pub fn visit_next(
        &mut self,
        step: ProjectionFeedLimits,
        mut visitor: impl FnMut(ProjectionFullSourceItem<'_>) -> Result<()>,
    ) -> std::result::Result<ProjectionFeedStep, ProjectionFeedError> {
        if self.failed {
            return Err(ProjectionFeedError::Failed);
        }
        if self.ended {
            return Ok(ProjectionFeedStep {
                usage: ProjectionFeedUsage::default(),
                complete: true,
            });
        }
        self.failed = true;
        let result = self.advance(step, &mut visitor);
        if result.is_ok() {
            self.failed = false;
        }
        result
    }

    fn advance(
        &mut self,
        step: ProjectionFeedLimits,
        visitor: &mut impl FnMut(ProjectionFullSourceItem<'_>) -> Result<()>,
    ) -> std::result::Result<ProjectionFeedStep, ProjectionFeedError> {
        let mut used = ProjectionFeedUsage::default();
        loop {
            self.source
                .ensure_usable()
                .map_err(ProjectionFeedError::Source)?;
            self.task
                .checkpoint()
                .map_err(|e| ProjectionFeedError::Source(HawDBError::Execution(e.to_string())))?;
            if self.node < self.source.next_node_id {
                if !self.charge(step, &mut used, 1, 1, 8)? {
                    break;
                }
                visitor(ProjectionFullSourceItem::GraphNodeCandidate { node_id: self.node })
                    .map_err(ProjectionFeedError::Callback)?;
                self.node += 1;
            } else if self.table < self.tables.len() {
                if !self.announced {
                    let bytes = self.tables[self.table].len();
                    if !self.charge(step, &mut used, 1, 1, bytes)? {
                        break;
                    }
                    visitor(ProjectionFullSourceItem::RelationalTable {
                        table: &self.tables[self.table],
                    })
                    .map_err(ProjectionFeedError::Callback)?;
                    self.announced = true;
                } else if let Some((_, bytes)) = self.pending.as_ref() {
                    let bytes = bytes.saturating_add(self.tables[self.table].len());
                    if !self.charge(step, &mut used, 1, 1, bytes)? {
                        break;
                    }
                    let (key, _) = self.pending.take().expect("pending key");
                    visitor(ProjectionFullSourceItem::RelationalKey {
                        table: &self.tables[self.table],
                        key: &key,
                    })
                    .map_err(ProjectionFeedError::Callback)?;
                    self.last = Some(key);
                    self.table_rows += 1;
                } else {
                    let table = &self.tables[self.table];
                    let count = self.source.relational_state.row_count(table);
                    let columns = self
                        .source
                        .relational_state
                        .table_schema(table)
                        .expect("pinned schema")
                        .primary_key
                        .len();
                    let work = 1 + (usize::BITS - count.leading_zeros()) as usize + columns;
                    if !self.charge(step, &mut used, work, 0, 0)? {
                        break;
                    }
                    self.pending = self.next_key()?;
                    if let Some((key, _)) = &self.pending {
                        if self.last.as_ref().is_some_and(|last| key <= last) {
                            return Err(self.integrity("full source key order regressed"));
                        }
                    } else {
                        if self.table_rows != count {
                            return Err(self
                                .integrity("full source row count differs from pinned metadata"));
                        }
                        self.table += 1;
                        self.last = None;
                        self.announced = false;
                        self.table_rows = 0;
                    }
                }
            } else {
                if !self.charge(step, &mut used, 1, 1, 8)? {
                    break;
                }
                visitor(ProjectionFullSourceItem::End {
                    source_epoch: self.source_epoch(),
                })
                .map_err(ProjectionFeedError::Callback)?;
                self.source
                    .ensure_usable()
                    .map_err(ProjectionFeedError::Source)?;
                self.task.checkpoint().map_err(|e| {
                    ProjectionFeedError::Source(HawDBError::Execution(e.to_string()))
                })?;
                self.ended = true;
                break;
            }
        }
        Ok(ProjectionFeedStep {
            usage: used,
            complete: self.ended,
        })
    }
}