kcode-k1-access-profile-sqlite 0.1.0

Exact SQLite persistence leaf for K1 saved access profiles
Documentation
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use std::{
    fs,
    path::{Path, PathBuf},
    sync::Mutex,
    time::Duration,
};

use kcode_k1_access_profile_wire::{decode_profile, encode_profile};
use rusqlite::{
    Connection, ErrorCode, OpenFlags, OptionalExtension, Row, TransactionBehavior, params,
};

pub use kcode_k1_access_profile_values::{
    AuthorizationProfile, ProfileId, ProfileRevision, TxId, UserId,
};

const DATABASE_FILE: &str = "profiles.sqlite3";
const METADATA_SQL: &str = "CREATE TABLE metadata(schema_version INTEGER NOT NULL CHECK(schema_version=1), last_applied_txid BLOB CHECK(last_applied_txid IS NULL OR (typeof(last_applied_txid)='blob' AND length(last_applied_txid)=12)))";
const PROFILES_SQL: &str = "CREATE TABLE profiles(profile_id BLOB PRIMARY KEY NOT NULL CHECK(typeof(profile_id)='blob' AND length(profile_id)=12), owner BLOB NOT NULL CHECK(typeof(owner)='blob' AND length(owner)=12), revision BLOB NOT NULL CHECK(typeof(revision)='blob' AND length(revision)=12), profile BLOB NOT NULL CHECK(typeof(profile)='blob')) WITHOUT ROWID";
const OWNER_INDEX_SQL: &str = "CREATE INDEX profiles_owner ON profiles(owner)";
const CREATE_SCHEMA: &str = "BEGIN IMMEDIATE;
CREATE TABLE metadata(schema_version INTEGER NOT NULL CHECK(schema_version=1), last_applied_txid BLOB CHECK(last_applied_txid IS NULL OR (typeof(last_applied_txid)='blob' AND length(last_applied_txid)=12)));
CREATE TABLE profiles(profile_id BLOB PRIMARY KEY NOT NULL CHECK(typeof(profile_id)='blob' AND length(profile_id)=12), owner BLOB NOT NULL CHECK(typeof(owner)='blob' AND length(owner)=12), revision BLOB NOT NULL CHECK(typeof(revision)='blob' AND length(revision)=12), profile BLOB NOT NULL CHECK(typeof(profile)='blob')) WITHOUT ROWID;
CREATE INDEX profiles_owner ON profiles(owner);
INSERT INTO metadata(schema_version, last_applied_txid) VALUES(1, NULL);
COMMIT;";

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SavedProfile {
    profile_id: ProfileId,
    owner: UserId,
    revision: ProfileRevision,
    profile: AuthorizationProfile,
}

impl SavedProfile {
    pub const fn profile_id(&self) -> ProfileId {
        self.profile_id
    }

    pub const fn owner(&self) -> UserId {
        self.owner
    }

    pub const fn revision(&self) -> ProfileRevision {
        self.revision
    }

    pub fn profile(&self) -> &AuthorizationProfile {
        &self.profile
    }
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ProfileAction {
    Create {
        owner: UserId,
        profile: AuthorizationProfile,
    },
    Replace {
        profile_id: ProfileId,
        actor: UserId,
        profile: AuthorizationProfile,
    },
    Delete {
        profile_id: ProfileId,
        actor: UserId,
    },
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum ApplyOutcome {
    Applied(ProfileRevision),
    Unchanged(ProfileRevision),
    Rejected(String),
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Snapshot {
    cursor: Option<TxId>,
    profiles: Vec<SavedProfile>,
}

impl Snapshot {
    pub const fn cursor(&self) -> Option<TxId> {
        self.cursor
    }

    pub fn profiles(&self) -> &[SavedProfile] {
        &self.profiles
    }
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum OpenError {
    Rebuildable,
    Fatal(String),
}

pub struct ProfileDatabase {
    database: PathBuf,
    apply_connection: Mutex<Connection>,
}

impl ProfileDatabase {
    pub fn open(root: &Path) -> Result<(Self, Snapshot), OpenError> {
        fs::create_dir_all(root)
            .map_err(|error| OpenError::Fatal(format!("profile root is unavailable: {error}")))?;
        let database = root.join(DATABASE_FILE);
        let (connection, snapshot) = load_database(&database)?;
        Ok((
            Self {
                database,
                apply_connection: Mutex::new(connection),
            },
            snapshot,
        ))
    }

    pub fn rebuild(root: &Path) -> Result<(Self, Snapshot), String> {
        remove_database(root)?;
        match Self::open(root) {
            Ok(value) => Ok(value),
            Err(OpenError::Fatal(error)) => Err(error),
            Err(OpenError::Rebuildable) => Err("profile database rebuild failed".to_owned()),
        }
    }

    pub fn apply(
        &self,
        callback_txid: TxId,
        action: ProfileAction,
    ) -> Result<ApplyOutcome, String> {
        let encoded = match &action {
            ProfileAction::Create { profile, .. } | ProfileAction::Replace { profile, .. } => {
                Some(encode_profile(profile)?)
            }
            ProfileAction::Delete { .. } => None,
        };
        let mut connection = self
            .apply_connection
            .lock()
            .map_err(|_| "profile apply lane is unavailable".to_owned())?;
        let transaction = connection
            .transaction_with_behavior(TransactionBehavior::Immediate)
            .map_err(persistence_error)?;
        let outcome = apply_action(&transaction, callback_txid, action, encoded)?;
        transaction.commit().map_err(persistence_error)?;
        Ok(outcome)
    }

    pub fn get_for_user(
        &self,
        user: UserId,
        profile_id: ProfileId,
    ) -> Result<Option<SavedProfile>, String> {
        query_profile(&self.database, user, profile_id)
    }

    pub fn list_for_user(&self, user: UserId) -> Result<Vec<SavedProfile>, String> {
        query_profiles(&self.database, user)
    }

    pub fn clear(&self) -> Result<(), String> {
        let mut connection = self
            .apply_connection
            .lock()
            .map_err(|_| "profile apply lane is unavailable".to_owned())?;
        let transaction = connection
            .transaction_with_behavior(TransactionBehavior::Immediate)
            .map_err(persistence_error)?;
        transaction
            .execute("DELETE FROM profiles", [])
            .map_err(persistence_error)?;
        changed_one(transaction.execute("UPDATE metadata SET last_applied_txid=NULL", []))?;
        transaction.commit().map_err(persistence_error)
    }
}

fn apply_action(
    tx: &rusqlite::Transaction<'_>,
    callback: TxId,
    action: ProfileAction,
    encoded: Option<Vec<u8>>,
) -> Result<ApplyOutcome, String> {
    let outcome = match action {
        ProfileAction::Create { owner, .. } => {
            let id = ProfileId::new(callback);
            if load_saved(tx, id)?.is_some() {
                ApplyOutcome::Rejected("profile already exists".to_owned())
            } else {
                let profile = encoded
                    .as_deref()
                    .ok_or("profile encoding is unavailable")?;
                let id_bytes = callback.into_bytes();
                let owner_bytes = owner.as_tx_id().into_bytes();
                changed_one(tx.execute(
                    "INSERT INTO profiles(profile_id, owner, revision, profile) VALUES(?1, ?2, ?3, ?4)",
                    params![
                        id_bytes.as_slice(),
                        owner_bytes.as_slice(),
                        id_bytes.as_slice(),
                        profile
                    ],
                ))?;
                ApplyOutcome::Applied(ProfileRevision::new(id, callback))
            }
        }
        ProfileAction::Replace {
            profile_id,
            actor,
            profile,
        } => match load_saved(tx, profile_id)? {
            Some(current) if current.owner() == actor => {
                if current.profile() == &profile {
                    ApplyOutcome::Unchanged(current.revision())
                } else {
                    let blob = encoded
                        .as_deref()
                        .ok_or("profile encoding is unavailable")?;
                    let id = profile_id.txid().into_bytes();
                    let revision = callback.into_bytes();
                    changed_one(tx.execute(
                        "UPDATE profiles SET revision=?1, profile=?2 WHERE profile_id=?3",
                        params![revision.as_slice(), blob, id.as_slice()],
                    ))?;
                    ApplyOutcome::Applied(ProfileRevision::new(profile_id, callback))
                }
            }
            _ => ApplyOutcome::Rejected("profile is unavailable".to_owned()),
        },
        ProfileAction::Delete { profile_id, actor } => match load_saved(tx, profile_id)? {
            Some(current) if current.owner() == actor => {
                let id = profile_id.txid().into_bytes();
                changed_one(tx.execute(
                    "DELETE FROM profiles WHERE profile_id=?1",
                    params![id.as_slice()],
                ))?;
                ApplyOutcome::Applied(ProfileRevision::new(profile_id, callback))
            }
            _ => ApplyOutcome::Rejected("profile is unavailable".to_owned()),
        },
    };
    let cursor = callback.into_bytes();
    changed_one(tx.execute(
        "UPDATE metadata SET last_applied_txid=?1",
        params![cursor.as_slice()],
    ))?;
    Ok(outcome)
}

fn changed_one(result: rusqlite::Result<usize>) -> Result<(), String> {
    match result.map_err(persistence_error)? {
        1 => Ok(()),
        _ => Err("profile persistence contradiction".to_owned()),
    }
}

fn persistence_error(error: rusqlite::Error) -> String {
    format!("profile persistence failed: {error}")
}

fn load_saved(
    tx: &rusqlite::Transaction<'_>,
    id: ProfileId,
) -> Result<Option<SavedProfile>, String> {
    let bytes = id.txid().into_bytes();
    let raw = tx
        .query_row(
            "SELECT profile_id, owner, revision, profile FROM profiles WHERE profile_id=?1",
            params![bytes.as_slice()],
            raw_profile,
        )
        .optional()
        .map_err(persistence_error)?;
    raw.map(decode_saved).transpose()
}

fn query_profile(
    database: &Path,
    user: UserId,
    id: ProfileId,
) -> Result<Option<SavedProfile>, String> {
    let connection = open_query(database)?;
    let owner = user.as_tx_id().into_bytes();
    let profile = id.txid().into_bytes();
    let raw = connection
        .query_row(
            "SELECT profile_id, owner, revision, profile FROM profiles WHERE profile_id=?1 AND owner=?2",
            params![profile.as_slice(), owner.as_slice()],
            raw_profile,
        )
        .optional()
        .map_err(query_error)?;
    raw.map(decode_saved).transpose()
}

fn query_profiles(database: &Path, user: UserId) -> Result<Vec<SavedProfile>, String> {
    let connection = open_query(database)?;
    let owner = user.as_tx_id().into_bytes();
    let mut statement = connection
        .prepare("SELECT profile_id, owner, revision, profile FROM profiles WHERE owner=?1")
        .map_err(query_error)?;
    let mut rows = statement
        .query(params![owner.as_slice()])
        .map_err(query_error)?;
    let mut profiles = Vec::new();
    while let Some(row) = rows.next().map_err(query_error)? {
        profiles.push(decode_saved(raw_profile(row).map_err(query_error)?)?);
    }
    Ok(profiles)
}

fn open_query(database: &Path) -> Result<Connection, String> {
    let flags = OpenFlags::SQLITE_OPEN_READ_ONLY | OpenFlags::SQLITE_OPEN_NO_MUTEX;
    let connection = Connection::open_with_flags(database, flags).map_err(query_error)?;
    connection
        .busy_timeout(Duration::ZERO)
        .map_err(query_error)?;
    Ok(connection)
}

fn query_error(error: rusqlite::Error) -> String {
    format!("profile query failed: {error}")
}

struct RawProfile {
    profile_id: Vec<u8>,
    owner: Vec<u8>,
    revision: Vec<u8>,
    profile: Vec<u8>,
}

fn raw_profile(row: &Row<'_>) -> rusqlite::Result<RawProfile> {
    Ok(RawProfile {
        profile_id: row.get(0)?,
        owner: row.get(1)?,
        revision: row.get(2)?,
        profile: row.get(3)?,
    })
}

fn decode_saved(raw: RawProfile) -> Result<SavedProfile, String> {
    let profile_id = ProfileId::new(TxId::from_bytes(bytes_12(raw.profile_id)?));
    let owner = UserId::from_tx_id(TxId::from_bytes(bytes_12(raw.owner)?));
    let revision = TxId::from_bytes(bytes_12(raw.revision)?);
    let profile = decode_profile(&raw.profile).map_err(|_| "profile persistence contradiction")?;
    if encode_profile(&profile).map_err(|_| "profile persistence contradiction")? != raw.profile {
        return Err("profile persistence contradiction".to_owned());
    }
    Ok(SavedProfile {
        profile_id,
        owner,
        revision: ProfileRevision::new(profile_id, revision),
        profile,
    })
}

fn bytes_12(bytes: Vec<u8>) -> Result<[u8; 12], String> {
    bytes
        .try_into()
        .map_err(|_| "profile persistence contradiction".to_owned())
}

fn load_database(database: &Path) -> Result<(Connection, Snapshot), OpenError> {
    let connection = connect(database)?;
    let count: i64 = connection
        .query_row(
            "SELECT count(*) FROM sqlite_schema WHERE name NOT LIKE 'sqlite_%'",
            [],
            |row| row.get(0),
        )
        .map_err(sql_issue)?;
    if count == 0 {
        connection.execute_batch(CREATE_SCHEMA).map_err(sql_issue)?;
    }
    validate_schema(&connection)?;
    let snapshot = validate_rows(&connection)?;
    Ok((connection, snapshot))
}

fn connect(database: &Path) -> Result<Connection, OpenError> {
    let connection = Connection::open(database).map_err(sql_issue)?;
    connection.busy_timeout(Duration::ZERO).map_err(sql_issue)?;
    let journal: String = connection
        .query_row("PRAGMA journal_mode=WAL", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if !journal.eq_ignore_ascii_case("wal") {
        return Err(OpenError::Fatal("SQLite WAL is unavailable".to_owned()));
    }
    connection
        .execute_batch("PRAGMA synchronous=FULL;")
        .map_err(sql_issue)?;
    let synchronous: i64 = connection
        .query_row("PRAGMA synchronous", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if synchronous != 2 {
        return Err(OpenError::Fatal(
            "SQLite FULL synchronization is unavailable".to_owned(),
        ));
    }
    Ok(connection)
}

fn validate_schema(connection: &Connection) -> Result<(), OpenError> {
    let integrity: String = connection
        .query_row("PRAGMA integrity_check", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if integrity != "ok" {
        return Err(OpenError::Rebuildable);
    }
    let mut statement = connection
        .prepare("SELECT name, sql FROM sqlite_schema WHERE name NOT LIKE 'sqlite_%'")
        .map_err(sql_issue)?;
    let mut rows = statement.query([]).map_err(sql_issue)?;
    let mut found = 0;
    while let Some(row) = rows.next().map_err(sql_issue)? {
        let name: String = row.get(0).map_err(|_| OpenError::Rebuildable)?;
        let sql: String = row.get(1).map_err(|_| OpenError::Rebuildable)?;
        match (name.as_str(), sql.as_str()) {
            ("metadata", METADATA_SQL)
            | ("profiles", PROFILES_SQL)
            | ("profiles_owner", OWNER_INDEX_SQL) => found += 1,
            _ => return Err(OpenError::Rebuildable),
        }
    }
    (found == 3).then_some(()).ok_or(OpenError::Rebuildable)
}

fn validate_rows(connection: &Connection) -> Result<Snapshot, OpenError> {
    let count: i64 = connection
        .query_row("SELECT count(*) FROM metadata", [], |row| row.get(0))
        .map_err(sql_issue)?;
    if count != 1 {
        return Err(OpenError::Rebuildable);
    }
    let (version, cursor): (i64, Option<Vec<u8>>) = connection
        .query_row(
            "SELECT schema_version, last_applied_txid FROM metadata",
            [],
            |row| Ok((row.get(0)?, row.get(1)?)),
        )
        .map_err(|_| OpenError::Rebuildable)?;
    if version != 1 {
        return Err(OpenError::Rebuildable);
    }
    let cursor = cursor
        .map(|bytes| bytes_12(bytes).map(TxId::from_bytes))
        .transpose()
        .map_err(|_| OpenError::Rebuildable)?;
    let mut statement = connection
        .prepare("SELECT profile_id, owner, revision, profile FROM profiles")
        .map_err(sql_issue)?;
    let mut rows = statement.query([]).map_err(sql_issue)?;
    let mut profiles = Vec::new();
    while let Some(row) = rows.next().map_err(sql_issue)? {
        let raw = raw_profile(row).map_err(|_| OpenError::Rebuildable)?;
        profiles.push(decode_saved(raw).map_err(|_| OpenError::Rebuildable)?);
    }
    if !profiles.is_empty() && cursor.is_none() {
        return Err(OpenError::Rebuildable);
    }
    Ok(Snapshot { cursor, profiles })
}

fn sql_issue(error: rusqlite::Error) -> OpenError {
    match error.sqlite_error_code() {
        Some(ErrorCode::DatabaseCorrupt | ErrorCode::NotADatabase) => OpenError::Rebuildable,
        _ => OpenError::Fatal(format!("SQLite is unavailable: {error}")),
    }
}

fn remove_database(root: &Path) -> Result<(), String> {
    for file in [
        "profiles.sqlite3-wal",
        "profiles.sqlite3-shm",
        DATABASE_FILE,
    ] {
        match fs::remove_file(root.join(file)) {
            Ok(()) => (),
            Err(error) if error.kind() == std::io::ErrorKind::NotFound => (),
            Err(error) => return Err(format!("profile database cannot be rebuilt: {error}")),
        }
    }
    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::time::{SystemTime, UNIX_EPOCH};

    #[test]
    fn rejected_delete_cursor_survives_reopen_and_clear_resets_it() {
        let nonce = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap()
            .as_nanos();
        let root = std::env::temp_dir().join(format!("profile-sqlite-test-{nonce}"));
        let tx = |byte| TxId::from_bytes([byte; 12]);
        let (database, _) = ProfileDatabase::open(&root).unwrap();
        let action = ProfileAction::Delete {
            profile_id: ProfileId::new(tx(1)),
            actor: UserId::from_tx_id(tx(2)),
        };
        let outcome = database.apply(tx(3), action).unwrap();
        let rejected = ApplyOutcome::Rejected("profile is unavailable".to_owned());
        assert_eq!(outcome, rejected);
        drop(database);

        let (database, snapshot) = ProfileDatabase::open(&root).unwrap();
        assert_eq!(snapshot.cursor(), Some(tx(3)));
        assert!(snapshot.profiles().is_empty());
        database.clear().unwrap();
        drop(database);

        let (database, snapshot) = ProfileDatabase::open(&root).unwrap();
        assert_eq!(snapshot.cursor(), None);
        assert!(snapshot.profiles().is_empty());
        drop(database);
        fs::remove_dir_all(root).unwrap();
    }
}