drk/
walletdb.rs

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/* This file is part of DarkFi (https://dark.fi)
 *
 * Copyright (C) 2020-2025 Dyne.org foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

use std::{
    path::PathBuf,
    sync::{Arc, Mutex},
};

use darkfi_sdk::{
    crypto::{
        pasta_prelude::PrimeField,
        smt::{PoseidonFp, SparseMerkleTree, StorageAdapter, SMT_FP_DEPTH},
    },
    error::{ContractError, ContractResult},
    pasta::pallas,
};
use log::{debug, error};
use num_bigint::BigUint;
use rusqlite::{
    types::{ToSql, Value},
    Connection,
};

use crate::error::{WalletDbError, WalletDbResult};

pub type WalletPtr = Arc<WalletDb>;

/// Structure representing base wallet database operations.
pub struct WalletDb {
    /// Connection to the SQLite database.
    pub conn: Mutex<Connection>,
    /// Inverse queries cache, in case we want to rollback
    /// executed queries, stored as raw SQL strings.
    inverse_cache: Mutex<Vec<String>>,
}

impl WalletDb {
    /// Create a new wallet database handler. If `path` is `None`, create it in memory.
    pub fn new(path: Option<PathBuf>, password: Option<&str>) -> WalletDbResult<WalletPtr> {
        let Ok(conn) = (match path.clone() {
            Some(p) => Connection::open(p),
            None => Connection::open_in_memory(),
        }) else {
            return Err(WalletDbError::ConnectionFailed);
        };

        if let Some(password) = password {
            if let Err(e) = conn.pragma_update(None, "key", password) {
                error!(target: "walletdb::new", "[WalletDb] Pragma update failed: {e}");
                return Err(WalletDbError::PragmaUpdateError);
            };
        }
        if let Err(e) = conn.pragma_update(None, "foreign_keys", "ON") {
            error!(target: "walletdb::new", "[WalletDb] Pragma update failed: {e}");
            return Err(WalletDbError::PragmaUpdateError);
        };

        debug!(target: "walletdb::new", "[WalletDb] Opened Sqlite connection at \"{path:?}\"");
        Ok(Arc::new(Self { conn: Mutex::new(conn), inverse_cache: Mutex::new(vec![]) }))
    }

    /// This function executes a given SQL query that contains multiple SQL statements,
    /// that don't contain any parameters.
    pub fn exec_batch_sql(&self, query: &str) -> WalletDbResult<()> {
        debug!(target: "walletdb::exec_batch_sql", "[WalletDb] Executing batch SQL query:\n{query}");
        let Ok(conn) = self.conn.lock() else { return Err(WalletDbError::FailedToAquireLock) };
        if let Err(e) = conn.execute_batch(query) {
            error!(target: "walletdb::exec_batch_sql", "[WalletDb] Query failed: {e}");
            return Err(WalletDbError::QueryExecutionFailed)
        };

        Ok(())
    }

    /// This function executes a given SQL query, but isn't able to return anything.
    /// Therefore it's best to use it for initializing a table or similar things.
    pub fn exec_sql(&self, query: &str, params: &[&dyn ToSql]) -> WalletDbResult<()> {
        debug!(target: "walletdb::exec_sql", "[WalletDb] Executing SQL query:\n{query}");
        let Ok(conn) = self.conn.lock() else { return Err(WalletDbError::FailedToAquireLock) };

        // If no params are provided, execute directly
        if params.is_empty() {
            if let Err(e) = conn.execute(query, ()) {
                error!(target: "walletdb::exec_sql", "[WalletDb] Query failed: {e}");
                return Err(WalletDbError::QueryExecutionFailed)
            };
            return Ok(())
        }

        // First we prepare the query
        let Ok(mut stmt) = conn.prepare(query) else {
            return Err(WalletDbError::QueryPreparationFailed)
        };

        // Execute the query using provided params
        if let Err(e) = stmt.execute(params) {
            error!(target: "walletdb::exec_sql", "[WalletDb] Query failed: {e}");
            return Err(WalletDbError::QueryExecutionFailed)
        };

        // Finalize query and drop connection lock
        if let Err(e) = stmt.finalize() {
            error!(target: "walletdb::exec_sql", "[WalletDb] Query finalization failed: {e}");
            return Err(WalletDbError::QueryFinalizationFailed)
        };
        drop(conn);

        Ok(())
    }

    /// Generate a new statement for provided query and bind the provided params,
    /// returning the raw SQL query as a string.
    pub fn create_prepared_statement(
        &self,
        query: &str,
        params: &[&dyn ToSql],
    ) -> WalletDbResult<String> {
        debug!(target: "walletdb::create_prepared_statement", "[WalletDb] Preparing statement for SQL query:\n{query}");
        let Ok(conn) = self.conn.lock() else { return Err(WalletDbError::FailedToAquireLock) };

        // First we prepare the query
        let Ok(mut stmt) = conn.prepare(query) else {
            return Err(WalletDbError::QueryPreparationFailed)
        };

        // Bind all provided params
        for (index, param) in params.iter().enumerate() {
            if stmt.raw_bind_parameter(index + 1, param).is_err() {
                return Err(WalletDbError::QueryPreparationFailed)
            };
        }

        // Grab the raw SQL
        let query = stmt.expanded_sql().unwrap();

        // Drop statement and the connection lock
        drop(stmt);
        drop(conn);

        Ok(query)
    }

    /// Generate a `SELECT` query for provided table from selected column names and
    /// provided `WHERE` clauses. Named parameters are supported in the `WHERE` clauses,
    /// assuming they follow the normal formatting ":{column_name}".
    fn generate_select_query(
        &self,
        table: &str,
        col_names: &[&str],
        params: &[(&str, &dyn ToSql)],
    ) -> String {
        let mut query = if col_names.is_empty() {
            format!("SELECT * FROM {}", table)
        } else {
            format!("SELECT {} FROM {}", col_names.join(", "), table)
        };
        if params.is_empty() {
            return query
        }

        let mut where_str = Vec::with_capacity(params.len());
        for (k, _) in params {
            let col = &k[1..];
            where_str.push(format!("{col} = {k}"));
        }
        query.push_str(&format!(" WHERE {}", where_str.join(" AND ")));

        query
    }

    /// Query provided table from selected column names and provided `WHERE` clauses,
    /// for a single row.
    pub fn query_single(
        &self,
        table: &str,
        col_names: &[&str],
        params: &[(&str, &dyn ToSql)],
    ) -> WalletDbResult<Vec<Value>> {
        // Generate `SELECT` query
        let query = self.generate_select_query(table, col_names, params);
        debug!(target: "walletdb::query_single", "[WalletDb] Executing SQL query:\n{query}");

        // First we prepare the query
        let Ok(conn) = self.conn.lock() else { return Err(WalletDbError::FailedToAquireLock) };

        let Ok(mut stmt) = conn.prepare(&query) else {
            return Err(WalletDbError::QueryPreparationFailed)
        };

        // Execute the query using provided params
        let Ok(mut rows) = stmt.query(params) else {
            return Err(WalletDbError::QueryExecutionFailed)
        };

        // Check if row exists
        let Ok(next) = rows.next() else { return Err(WalletDbError::QueryExecutionFailed) };
        let row = match next {
            Some(row_result) => row_result,
            None => return Err(WalletDbError::RowNotFound),
        };

        // Grab returned values
        let mut result = vec![];
        if col_names.is_empty() {
            let mut idx = 0;
            loop {
                let Ok(value) = row.get(idx) else { break };
                result.push(value);
                idx += 1;
            }
        } else {
            for col in col_names {
                let Ok(value) = row.get(*col) else {
                    return Err(WalletDbError::ParseColumnValueError)
                };
                result.push(value);
            }
        }

        Ok(result)
    }

    /// Query provided table from selected column names and provided `WHERE` clauses,
    /// for multiple rows.
    pub fn query_multiple(
        &self,
        table: &str,
        col_names: &[&str],
        params: &[(&str, &dyn ToSql)],
    ) -> WalletDbResult<Vec<Vec<Value>>> {
        // Generate `SELECT` query
        let query = self.generate_select_query(table, col_names, params);
        debug!(target: "walletdb::query_multiple", "[WalletDb] Executing SQL query:\n{query}");

        // First we prepare the query
        let Ok(conn) = self.conn.lock() else { return Err(WalletDbError::FailedToAquireLock) };
        let Ok(mut stmt) = conn.prepare(&query) else {
            return Err(WalletDbError::QueryPreparationFailed)
        };

        // Execute the query using provided converted params
        let Ok(mut rows) = stmt.query(params) else {
            return Err(WalletDbError::QueryExecutionFailed)
        };

        // Loop over returned rows and parse them
        let mut result = vec![];
        loop {
            // Check if an error occured
            let row = match rows.next() {
                Ok(r) => r,
                Err(_) => return Err(WalletDbError::QueryExecutionFailed),
            };

            // Check if no row was returned
            let row = match row {
                Some(r) => r,
                None => break,
            };

            // Grab row returned values
            let mut row_values = vec![];
            if col_names.is_empty() {
                let mut idx = 0;
                loop {
                    let Ok(value) = row.get(idx) else { break };
                    row_values.push(value);
                    idx += 1;
                }
            } else {
                for col in col_names {
                    let Ok(value) = row.get(*col) else {
                        return Err(WalletDbError::ParseColumnValueError)
                    };
                    row_values.push(value);
                }
            }
            result.push(row_values);
        }

        Ok(result)
    }

    /// Query provided table using provided query for multiple rows.
    pub fn query_custom(
        &self,
        query: &str,
        params: &[&dyn ToSql],
    ) -> WalletDbResult<Vec<Vec<Value>>> {
        debug!(target: "walletdb::query_custom", "[WalletDb] Executing SQL query:\n{query}");

        // First we prepare the query
        let Ok(conn) = self.conn.lock() else { return Err(WalletDbError::FailedToAquireLock) };
        let Ok(mut stmt) = conn.prepare(query) else {
            return Err(WalletDbError::QueryPreparationFailed)
        };

        // Execute the query using provided converted params
        let Ok(mut rows) = stmt.query(params) else {
            return Err(WalletDbError::QueryExecutionFailed)
        };

        // Loop over returned rows and parse them
        let mut result = vec![];
        loop {
            // Check if an error occured
            let row = match rows.next() {
                Ok(r) => r,
                Err(_) => return Err(WalletDbError::QueryExecutionFailed),
            };

            // Check if no row was returned
            let row = match row {
                Some(r) => r,
                None => break,
            };

            // Grab row returned values
            let mut row_values = vec![];
            let mut idx = 0;
            loop {
                let Ok(value) = row.get(idx) else { break };
                row_values.push(value);
                idx += 1;
            }
            result.push(row_values);
        }

        Ok(result)
    }

    /// Auxiliary function to store provided inverse query into our cache.
    pub fn cache_inverse(&self, query: String) -> WalletDbResult<()> {
        debug!(target: "walletdb::cache_inverse", "[WalletDb] Storing query:\n{query}");
        let Ok(mut cache) = self.inverse_cache.lock() else {
            return Err(WalletDbError::FailedToAquireLock)
        };

        // Push the query into the cache
        cache.push(query);

        // Drop cache lock
        drop(cache);

        Ok(())
    }

    /// Auxiliary function to retrieve cached inverse queries into a single SQL execution block.
    /// The final query will contain the queries in reverse order, and cache is cleared afterwards.
    pub fn grab_inverse_cache_block(&self) -> WalletDbResult<String> {
        // Grab cache lock
        debug!(target: "walletdb::grab_inverse_block", "[WalletDb] Grabbing cached inverse queries");
        let Ok(cache) = self.inverse_cache.lock() else {
            return Err(WalletDbError::FailedToAquireLock)
        };

        // Build the full SQL block query
        let mut inverse_batch = String::from("BEGIN;");
        for query in cache.iter().rev() {
            inverse_batch += query;
        }
        inverse_batch += "END;";

        // Drop the lock
        drop(cache);

        Ok(inverse_batch)
    }

    /// Auxiliary function to clear inverse queries cache.
    pub fn clear_inverse_cache(&self) -> WalletDbResult<()> {
        // Grab cache lock
        let Ok(mut cache) = self.inverse_cache.lock() else {
            return Err(WalletDbError::FailedToAquireLock)
        };

        // Clear cache
        *cache = vec![];

        // Drop the lock
        drop(cache);

        Ok(())
    }
}

/// Custom implementation of rusqlite::named_params! to use `expr` instead of `literal` as `$param_name`,
/// and append the ":" named parameters prefix.
#[macro_export]
macro_rules! convert_named_params {
    () => {
        &[] as &[(&str, &dyn rusqlite::types::ToSql)]
    };
    ($(($param_name:expr, $param_val:expr)),+ $(,)?) => {
        &[$((format!(":{}", $param_name).as_str(), &$param_val as &dyn rusqlite::types::ToSql)),+] as &[(&str, &dyn rusqlite::types::ToSql)]
    };
}

/// Wallet SMT definition
pub type WalletSmt<'a> = SparseMerkleTree<
    'static,
    SMT_FP_DEPTH,
    { SMT_FP_DEPTH + 1 },
    pallas::Base,
    PoseidonFp,
    WalletStorage<'a>,
>;

/// An SMT adapter for wallet SQLite database storage.
pub struct WalletStorage<'a> {
    wallet: &'a WalletPtr,
    table: &'a str,
    key_col: &'a str,
    value_col: &'a str,
}

impl<'a> WalletStorage<'a> {
    pub fn new(
        wallet: &'a WalletPtr,
        table: &'a str,
        key_col: &'a str,
        value_col: &'a str,
    ) -> Self {
        Self { wallet, table, key_col, value_col }
    }
}

impl StorageAdapter for WalletStorage<'_> {
    type Value = pallas::Base;

    fn put(&mut self, key: BigUint, value: pallas::Base) -> ContractResult {
        // Check if record already exists to create the corresponding query,
        // its param and its inverse.
        let (query, params, inverse) = match self.get(&key) {
            Some(v) => {
                // Create an SQL `UPDATE` query
                let q = format!(
                    "UPDATE {} SET {} = ?1 WHERE {} = ?2;",
                    self.table, self.value_col, self.key_col
                );

                // Create its inverse query
                let i = match self.wallet.create_prepared_statement(
                    &format!(
                        "UPDATE {} SET {} = ?1 WHERE {} = ?2;",
                        self.table, self.value_col, self.key_col
                    ),
                    rusqlite::params![v.to_repr(), key.to_bytes_le()],
                ) {
                    Ok(i) => i,
                    Err(e) => {
                        error!(target: "walletdb::StorageAdapter::put", "Creating inverse query for key {key:?} failed: {e:?}");
                        return Err(ContractError::SmtPutFailed)
                    }
                };

                (q, rusqlite::params![value.to_repr(), key.to_bytes_le()], i)
            }
            None => {
                // Create an SQL `INSERT` query
                let q = format!(
                    "INSERT INTO {} ({}, {}) VALUES (?1, ?2);",
                    self.table, self.key_col, self.value_col
                );

                // Create its inverse query
                let i = match self.wallet.create_prepared_statement(
                    &format!("DELETE FROM {} WHERE {} = ?1;", self.table, self.key_col),
                    rusqlite::params![key.to_bytes_le()],
                ) {
                    Ok(i) => i,
                    Err(e) => {
                        error!(target: "walletdb::StorageAdapter::put", "Creating inverse query for key {key:?} failed: {e:?}");
                        return Err(ContractError::SmtPutFailed)
                    }
                };

                (q, rusqlite::params![key.to_bytes_le(), value.to_repr()], i)
            }
        };

        // Execute the query
        if let Err(e) = self.wallet.exec_sql(&query, params) {
            error!(target: "walletdb::StorageAdapter::put", "Inserting key {key:?}, value {value:?} into DB failed: {e:?}");
            return Err(ContractError::SmtPutFailed)
        }

        // Store its inverse
        if let Err(e) = self.wallet.cache_inverse(inverse) {
            error!(target: "walletdb::StorageAdapter::put", "Inserting inverse query into cache failed: {e:?}");
            return Err(ContractError::SmtPutFailed)
        }

        Ok(())
    }

    fn get(&self, key: &BigUint) -> Option<pallas::Base> {
        let row = match self.wallet.query_single(
            self.table,
            &[self.value_col],
            convert_named_params! {(self.key_col, key.to_bytes_le())},
        ) {
            Ok(r) => r,
            Err(WalletDbError::RowNotFound) => return None,
            Err(e) => {
                error!(target: "walletdb::StorageAdapter::get", "Fetching key {key:?} from DB failed: {e:?}");
                return None
            }
        };

        let Value::Blob(ref value_bytes) = row[0] else {
            error!(target: "walletdb::StorageAdapter::get", "Parsing key {key:?} value bytes");
            return None
        };

        let mut repr = [0; 32];
        repr.copy_from_slice(value_bytes);

        pallas::Base::from_repr(repr).into()
    }

    fn del(&mut self, key: &BigUint) -> ContractResult {
        // Check if record already exists to create the corresponding query,
        // its param and its inverse.
        let (query, params, inverse) = match self.get(key) {
            Some(value) => {
                // Create an SQL `DELETE` query
                let q = format!("DELETE FROM {} WHERE {} = ?1;", self.table, self.key_col);

                // Create its inverse query
                let i = match self.wallet.create_prepared_statement(
                    &format!(
                        "INSERT INTO {} ({}, {}) VALUES (?1, ?2);",
                        self.table, self.key_col, self.value_col
                    ),
                    rusqlite::params![key.to_bytes_le(), value.to_repr()],
                ) {
                    Ok(i) => i,
                    Err(e) => {
                        error!(target: "walletdb::StorageAdapter::del", "Creating inverse query for key {key:?} failed: {e:?}");
                        return Err(ContractError::SmtDelFailed)
                    }
                };

                (q, rusqlite::params![key.to_bytes_le()], i)
            }
            None => {
                // If record doesn't exist do nothing
                return Ok(())
            }
        };

        // Execute the query
        if let Err(e) = self.wallet.exec_sql(&query, params) {
            error!(target: "walletdb::StorageAdapter::del", "Removing key {key:?} from DB failed: {e:?}");
            return Err(ContractError::SmtDelFailed)
        }

        // Store its inverse
        if let Err(e) = self.wallet.cache_inverse(inverse) {
            error!(target: "walletdb::StorageAdapter::del", "Inserting inverse query into cache failed: {e:?}");
            return Err(ContractError::SmtDelFailed)
        }

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use darkfi::zk::halo2::Field;
    use darkfi_sdk::{
        crypto::smt::{gen_empty_nodes, util::FieldHasher, PoseidonFp, SparseMerkleTree},
        pasta::pallas,
    };
    use rand::rngs::OsRng;
    use rusqlite::types::Value;

    use crate::walletdb::{WalletDb, WalletStorage};

    #[test]
    fn test_mem_wallet() {
        let wallet = WalletDb::new(None, Some("foobar")).unwrap();
        wallet
            .exec_batch_sql(
                "CREATE TABLE mista ( numba INTEGER ); INSERT INTO mista ( numba ) VALUES ( 42 );",
            )
            .unwrap();

        let ret = wallet.query_single("mista", &["numba"], &[]).unwrap();
        assert_eq!(ret.len(), 1);
        let numba: i64 = if let Value::Integer(numba) = ret[0] { numba } else { -1 };
        assert_eq!(numba, 42);

        let ret = wallet.query_custom("SELECT numba FROM mista;", &[]).unwrap();
        assert_eq!(ret.len(), 1);
        assert_eq!(ret[0].len(), 1);
        let numba: i64 = if let Value::Integer(numba) = ret[0][0] { numba } else { -1 };
        assert_eq!(numba, 42);
    }

    #[test]
    fn test_query_single() {
        let wallet = WalletDb::new(None, None).unwrap();
        wallet
            .exec_batch_sql("CREATE TABLE mista ( why INTEGER, are TEXT, you INTEGER, gae BLOB );")
            .unwrap();

        let why = 42;
        let are = "are".to_string();
        let you = 69;
        let gae = vec![42u8; 32];

        wallet
            .exec_sql(
                "INSERT INTO mista ( why, are, you, gae ) VALUES (?1, ?2, ?3, ?4);",
                rusqlite::params![why, are, you, gae],
            )
            .unwrap();

        let ret = wallet.query_single("mista", &["why", "are", "you", "gae"], &[]).unwrap();
        assert_eq!(ret.len(), 4);
        assert_eq!(ret[0], Value::Integer(why));
        assert_eq!(ret[1], Value::Text(are.clone()));
        assert_eq!(ret[2], Value::Integer(you));
        assert_eq!(ret[3], Value::Blob(gae.clone()));
        let ret = wallet.query_custom("SELECT why, are, you, gae FROM mista;", &[]).unwrap();
        assert_eq!(ret.len(), 1);
        assert_eq!(ret[0].len(), 4);
        assert_eq!(ret[0][0], Value::Integer(why));
        assert_eq!(ret[0][1], Value::Text(are.clone()));
        assert_eq!(ret[0][2], Value::Integer(you));
        assert_eq!(ret[0][3], Value::Blob(gae.clone()));

        let ret = wallet
            .query_single(
                "mista",
                &["gae"],
                rusqlite::named_params! {":why": why, ":are": are, ":you": you},
            )
            .unwrap();
        assert_eq!(ret.len(), 1);
        assert_eq!(ret[0], Value::Blob(gae.clone()));
        let ret = wallet
            .query_custom(
                "SELECT gae FROM mista WHERE why = ?1 AND are = ?2 AND you = ?3;",
                rusqlite::params![why, are, you],
            )
            .unwrap();
        assert_eq!(ret.len(), 1);
        assert_eq!(ret[0].len(), 1);
        assert_eq!(ret[0][0], Value::Blob(gae));
    }

    #[test]
    fn test_query_multi() {
        let wallet = WalletDb::new(None, None).unwrap();
        wallet
            .exec_batch_sql("CREATE TABLE mista ( why INTEGER, are TEXT, you INTEGER, gae BLOB );")
            .unwrap();

        let why = 42;
        let are = "are".to_string();
        let you = 69;
        let gae = vec![42u8; 32];

        wallet
            .exec_sql(
                "INSERT INTO mista ( why, are, you, gae ) VALUES (?1, ?2, ?3, ?4);",
                rusqlite::params![why, are, you, gae],
            )
            .unwrap();
        wallet
            .exec_sql(
                "INSERT INTO mista ( why, are, you, gae ) VALUES (?1, ?2, ?3, ?4);",
                rusqlite::params![why, are, you, gae],
            )
            .unwrap();

        let ret = wallet.query_multiple("mista", &[], &[]).unwrap();
        assert_eq!(ret.len(), 2);
        for row in ret {
            assert_eq!(row.len(), 4);
            assert_eq!(row[0], Value::Integer(why));
            assert_eq!(row[1], Value::Text(are.clone()));
            assert_eq!(row[2], Value::Integer(you));
            assert_eq!(row[3], Value::Blob(gae.clone()));
        }
        let ret = wallet.query_custom("SELECT * FROM mista;", &[]).unwrap();
        assert_eq!(ret.len(), 2);
        for row in ret {
            assert_eq!(row.len(), 4);
            assert_eq!(row[0], Value::Integer(why));
            assert_eq!(row[1], Value::Text(are.clone()));
            assert_eq!(row[2], Value::Integer(you));
            assert_eq!(row[3], Value::Blob(gae.clone()));
        }

        let ret = wallet
            .query_multiple(
                "mista",
                &["gae"],
                convert_named_params! {("why", why), ("are", are), ("you", you)},
            )
            .unwrap();
        assert_eq!(ret.len(), 2);
        for row in ret {
            assert_eq!(row.len(), 1);
            assert_eq!(row[0], Value::Blob(gae.clone()));
        }
        let ret = wallet
            .query_custom(
                "SELECT gae FROM mista WHERE why = ?1 AND are = ?2 AND you = ?3;",
                rusqlite::params![why, are, you],
            )
            .unwrap();
        assert_eq!(ret.len(), 2);
        for row in ret {
            assert_eq!(row.len(), 1);
            assert_eq!(row[0], Value::Blob(gae.clone()));
        }
    }

    #[test]
    fn test_sqlite_smt() {
        // Setup SQLite database
        let table = &"smt";
        let key_col = &"smt_key";
        let value_col = &"smt_value";
        let wallet = WalletDb::new(None, None).unwrap();
        wallet.exec_batch_sql(&format!("CREATE TABLE {table} ( {key_col} BLOB INTEGER PRIMARY KEY NOT NULL, {value_col} BLOB NOT NULL);")).unwrap();

        // Setup SMT
        const HEIGHT: usize = 3;
        let hasher = PoseidonFp::new();
        let empty_leaf = pallas::Base::ZERO;
        let empty_nodes = gen_empty_nodes::<{ HEIGHT + 1 }, _, _>(&hasher, empty_leaf);
        let store = WalletStorage::new(&wallet, table, key_col, value_col);
        let mut smt = SparseMerkleTree::<HEIGHT, { HEIGHT + 1 }, _, _, _>::new(
            store,
            hasher.clone(),
            &empty_nodes,
        );

        // Verify database is empty
        let rows = wallet.query_multiple(table, &[key_col], &[]).unwrap();
        assert!(rows.is_empty());

        let leaves = vec![
            (pallas::Base::from(1), pallas::Base::random(&mut OsRng)),
            (pallas::Base::from(2), pallas::Base::random(&mut OsRng)),
            (pallas::Base::from(3), pallas::Base::random(&mut OsRng)),
        ];
        smt.insert_batch(leaves.clone()).unwrap();

        let hash1 = leaves[0].1;
        let hash2 = leaves[1].1;
        let hash3 = leaves[2].1;

        let hash = |l, r| hasher.hash([l, r]);

        let hash01 = hash(empty_nodes[3], hash1);
        let hash23 = hash(hash2, hash3);

        let hash0123 = hash(hash01, hash23);
        let root = hash(hash0123, empty_nodes[1]);
        assert_eq!(root, smt.root());

        // Now try to construct a membership proof for leaf 3
        let pos = leaves[2].0;
        let path = smt.prove_membership(&pos);
        assert_eq!(path.path[0], empty_nodes[1]);
        assert_eq!(path.path[1], hash01);
        assert_eq!(path.path[2], hash2);

        assert_eq!(hash23, hash(path.path[2], hash3));
        assert_eq!(hash0123, hash(path.path[1], hash(path.path[2], hash3)));
        assert_eq!(root, hash(hash(path.path[1], hash(path.path[2], hash3)), path.path[0]));

        assert!(path.verify(&root, &hash3, &pos));

        // Verify database contains keys
        let rows = wallet.query_multiple(table, &[key_col], &[]).unwrap();
        assert!(!rows.is_empty());

        // We are now going to rollback the wallet changes
        let rollback_query = wallet.grab_inverse_cache_block().unwrap();
        wallet.exec_batch_sql(&rollback_query).unwrap();

        // Clear cache
        wallet.clear_inverse_cache().unwrap();

        // Verify database is empty again
        let rows = wallet.query_multiple(table, &[key_col], &[]).unwrap();
        assert!(rows.is_empty());
    }
}
drk/walletdb.rs

drk/
walletdb.rs
