Merge remote-tracking branch 'jgallagher/master' into vtab

.travis.yml

@@ -1,10 +1,6 @@
 language: rust
 sudo: false
 
-env:
-    global:
-        secure: "FyGzHF0AIYdBcuM/2qIoABotx3MbNAlaHDzxPbbeUlVg64bnuib9G9K/qWve0a1BWCgv+8e/SbXZb7gt3JlUNE27aE4RZG4FEdtEpLYQp87Dc9d9HX0FwpUeFK3binsrtYl4WEBnIjQ3ICnUVey0E6GHEdkM+t5bWyJO5c4dJ30="
-
 script:
     - cargo build
     - cargo test

Cargo.toml

@@ -24,6 +24,7 @@ csvtab = ["csv"]
 [dependencies]
 time = "~0.1.0"
 bitflags = "0.7"
+lru-cache = "0.0.7"
 libc = "~0.2"
 clippy = {version = "~0.0.58", optional = true}
 chrono = { version = "~0.2", optional = true }

Changelog.md

@@ -1,5 +1,19 @@
 # Version UPCOMING (...)
 
+* BREAKING CHANGE: Creating transactions from a `Connection` or savepoints from a `Transaction`
+  now take `&mut self` instead of `&self` to correctly represent that transactions within a
+  connection are inherently nested. While a transaction is alive, the parent connection or
+  transaction is unusable, so `Transaction` now implements `Deref<Target=Connection>`, giving
+  access to `Connection`'s methods via the `Transaction` itself.
+* BREAKING CHANGE: `Transaction::set_commit` and `Transaction::set_rollback` have been replaced
+  by `Transaction::set_drop_behavior`.
+* BREAKING CHANGE: `Transaction::savepoint()` now returns a `Savepoint` instead of another
+  `Transaction`. Unlike `Transaction`, `Savepoint`s can be rolled back while keeping the current
+  savepoint active.
+* Adds `Connection::prepare_cached`. `Connection` now keeps an internal cache of any statements
+  prepared via this method. The size of this cache defaults to 16 (`prepare_cached` will always
+  work but may re-prepare statements if more are prepared than the cache holds), and can be
+  controlled via `Connection::set_prepared_statement_cache_capacity`.
 * Adds `insert` convenience method to `Statement` which returns the row ID of an inserted row.
 * Adds `exists` convenience method returning whether a query finds one or more rows.
 * Adds support for serializing types from the `serde_json` crate. Requires the `serde_json` feature.

benches/lib.rs

@@ -0,0 +1,23 @@
+#![feature(test)]
+extern crate test;
+
+extern crate rusqlite;
+
+use rusqlite::Connection;
+use rusqlite::cache::StatementCache;
+use test::Bencher;
+
+#[bench]
+fn bench_no_cache(b: &mut Bencher) {
+    let db = Connection::open_in_memory().unwrap();
+    let sql = "SELECT 1, 'test', 3.14 UNION SELECT 2, 'exp', 2.71";
+    b.iter(|| db.prepare(sql).unwrap());
+}
+
+#[bench]
+fn bench_cache(b: &mut Bencher) {
+    let db = Connection::open_in_memory().unwrap();
+    let cache = StatementCache::new(&db, 15);
+    let sql = "SELECT 1, 'test', 3.14 UNION SELECT 2, 'exp', 2.71";
+    b.iter(|| cache.get(sql).unwrap());
+}

publish-ghp-docs.sh

@@ -8,7 +8,7 @@ fi
 
 cd $(git rev-parse --show-toplevel)
 rm -rf target/doc/
-multirust run nightly cargo doc --no-deps --features "load_extension trace"
+multirust run nightly cargo doc --no-deps --features "backup cache functions load_extension trace blob"
 echo '<meta http-equiv=refresh content=0;url=rusqlite/index.html>' > target/doc/index.html
 ghp-import target/doc
 git push origin gh-pages:gh-pages

src/cache.rs

@@ -0,0 +1,269 @@
+//! Prepared statements cache for faster execution.
+
+use std::cell::RefCell;
+use std::ops::{Deref, DerefMut};
+use lru_cache::LruCache;
+use {Result, Connection, Statement};
+use raw_statement::RawStatement;
+
+impl Connection {
+    /// Prepare a SQL statement for execution, returning a previously prepared (but
+    /// not currently in-use) statement if one is available. The returned statement
+    /// will be cached for reuse by future calls to `prepare_cached` once it is
+    /// dropped.
+    ///
+    /// ```rust,no_run
+    /// # use rusqlite::{Connection, Result};
+    /// fn insert_new_people(conn: &Connection) -> Result<()> {
+    ///     {
+    ///         let mut stmt = try!(conn.prepare_cached("INSERT INTO People (name) VALUES (?)"));
+    ///         try!(stmt.execute(&[&"Joe Smith"]));
+    ///     }
+    ///     {
+    ///         // This will return the same underlying SQLite statement handle without
+    ///         // having to prepare it again.
+    ///         let mut stmt = try!(conn.prepare_cached("INSERT INTO People (name) VALUES (?)"));
+    ///         try!(stmt.execute(&[&"Bob Jones"]));
+    ///     }
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `sql` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite call fails.
+    pub fn prepare_cached<'a>(&'a self, sql: &str) -> Result<CachedStatement<'a>> {
+        self.cache.get(&self, sql)
+    }
+
+    /// Set the maximum number of cached prepared statements this connection will hold.
+    /// By default, a connection will hold a relatively small number of cached statements.
+    /// If you need more, or know that you will not use cached statements, you can set
+    /// the capacity manually using this method.
+    pub fn set_prepared_statement_cache_capacity(&self, capacity: usize) {
+        self.cache.set_capacity(capacity)
+    }
+}
+
+/// Prepared statements LRU cache.
+#[derive(Debug)]
+pub struct StatementCache(RefCell<LruCache<String, RawStatement>>);
+
+/// Cacheable statement.
+///
+/// Statement will return automatically to the cache by default.
+/// If you want the statement to be discarded, call `discard()` on it.
+pub struct CachedStatement<'conn> {
+    stmt: Option<Statement<'conn>>,
+    cache: &'conn StatementCache,
+}
+
+impl<'conn> Deref for CachedStatement<'conn> {
+    type Target = Statement<'conn>;
+
+    fn deref(&self) -> &Statement<'conn> {
+        self.stmt.as_ref().unwrap()
+    }
+}
+
+impl<'conn> DerefMut for CachedStatement<'conn> {
+    fn deref_mut(&mut self) -> &mut Statement<'conn> {
+        self.stmt.as_mut().unwrap()
+    }
+}
+
+impl<'conn> Drop for CachedStatement<'conn> {
+    #[allow(unused_must_use)]
+    fn drop(&mut self) {
+        if let Some(stmt) = self.stmt.take() {
+            self.cache.cache_stmt(stmt.into());
+        }
+    }
+}
+
+impl<'conn> CachedStatement<'conn> {
+    fn new(stmt: Statement<'conn>, cache: &'conn StatementCache) -> CachedStatement<'conn> {
+        CachedStatement {
+            stmt: Some(stmt),
+            cache: cache,
+        }
+    }
+
+    pub fn discard(mut self) {
+        self.stmt = None;
+    }
+}
+
+impl StatementCache {
+    /// Create a statement cache.
+    pub fn with_capacity(capacity: usize) -> StatementCache {
+        StatementCache(RefCell::new(LruCache::new(capacity)))
+    }
+
+    fn set_capacity(&self, capacity: usize) {
+        self.0.borrow_mut().set_capacity(capacity)
+    }
+
+    // Search the cache for a prepared-statement object that implements `sql`.
+    // If no such prepared-statement can be found, allocate and prepare a new one.
+    //
+    // # Failure
+    //
+    // Will return `Err` if no cached statement can be found and the underlying SQLite prepare
+    // call fails.
+    fn get<'conn>(&'conn self,
+                  conn: &'conn Connection,
+                  sql: &str)
+                  -> Result<CachedStatement<'conn>> {
+        let mut cache = self.0.borrow_mut();
+        let stmt = match cache.remove(sql) {
+            Some(raw_stmt) => Ok(Statement::new(conn, raw_stmt)),
+            None => conn.prepare(sql),
+        };
+        stmt.map(|stmt| CachedStatement::new(stmt, self))
+    }
+
+    // Return a statement to the cache.
+    fn cache_stmt(&self, stmt: RawStatement) {
+        let mut cache = self.0.borrow_mut();
+        stmt.clear_bindings();
+        let sql = String::from_utf8_lossy(stmt.sql().to_bytes()).to_string();
+        cache.insert(sql, stmt);
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use Connection;
+    use super::StatementCache;
+
+    impl StatementCache {
+        fn clear(&self) {
+            self.0.borrow_mut().clear();
+        }
+
+        fn len(&self) -> usize {
+            self.0.borrow().len()
+        }
+
+        fn capacity(&self) -> usize {
+            self.0.borrow().capacity()
+        }
+    }
+
+    #[test]
+    fn test_cache() {
+        let db = Connection::open_in_memory().unwrap();
+        let cache = &db.cache;
+        let initial_capacity = cache.capacity();
+        assert_eq!(0, cache.len());
+        assert!(initial_capacity > 0);
+
+        let sql = "PRAGMA schema_version";
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(0, cache.len());
+            assert_eq!(0,
+                       stmt.query(&[]).unwrap().get_expected_row().unwrap().get::<i32, i64>(0));
+        }
+        assert_eq!(1, cache.len());
+
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(0, cache.len());
+            assert_eq!(0,
+                       stmt.query(&[]).unwrap().get_expected_row().unwrap().get::<i32, i64>(0));
+        }
+        assert_eq!(1, cache.len());
+
+        cache.clear();
+        assert_eq!(0, cache.len());
+        assert_eq!(initial_capacity, cache.capacity());
+    }
+
+    #[test]
+    fn test_set_capacity() {
+        let db = Connection::open_in_memory().unwrap();
+        let cache = &db.cache;
+
+        let sql = "PRAGMA schema_version";
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(0, cache.len());
+            assert_eq!(0,
+                       stmt.query(&[]).unwrap().get_expected_row().unwrap().get::<i32, i64>(0));
+        }
+        assert_eq!(1, cache.len());
+
+        db.set_prepared_statement_cache_capacity(0);
+        assert_eq!(0, cache.len());
+
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(0, cache.len());
+            assert_eq!(0,
+                       stmt.query(&[]).unwrap().get_expected_row().unwrap().get::<i32, i64>(0));
+        }
+        assert_eq!(0, cache.len());
+
+        db.set_prepared_statement_cache_capacity(8);
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(0, cache.len());
+            assert_eq!(0,
+                       stmt.query(&[]).unwrap().get_expected_row().unwrap().get::<i32, i64>(0));
+        }
+        assert_eq!(1, cache.len());
+    }
+
+    #[test]
+    fn test_discard() {
+        let db = Connection::open_in_memory().unwrap();
+        let cache = &db.cache;
+
+        let sql = "PRAGMA schema_version";
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(0, cache.len());
+            assert_eq!(0,
+                       stmt.query(&[]).unwrap().get_expected_row().unwrap().get::<i32, i64>(0));
+            stmt.discard();
+        }
+        assert_eq!(0, cache.len());
+    }
+
+    #[test]
+    fn test_ddl() {
+        let db = Connection::open_in_memory().unwrap();
+        db.execute_batch(r#"
+            CREATE TABLE foo (x INT);
+            INSERT INTO foo VALUES (1);
+        "#)
+            .unwrap();
+
+        let sql = "SELECT * FROM foo";
+
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!(1i32,
+                       stmt.query_map(&[], |r| r.get(0)).unwrap().next().unwrap().unwrap());
+        }
+
+        db.execute_batch(r#"
+            ALTER TABLE foo ADD COLUMN y INT;
+            UPDATE foo SET y = 2;
+        "#)
+            .unwrap();
+
+        {
+            let mut stmt = db.prepare_cached(sql).unwrap();
+            assert_eq!((1i32, 2i32),
+                       stmt.query_map(&[], |r| (r.get(0), r.get(1)))
+                           .unwrap()
+                           .next()
+                           .unwrap()
+                           .unwrap());
+        }
+    }
+}

src/lib.rs

@@ -55,6 +55,7 @@
 
 extern crate libc;
 extern crate libsqlite3_sys as ffi;
+extern crate lru_cache;
 #[macro_use]
 extern crate bitflags;
 #[cfg(test)]
@@ -76,18 +77,23 @@ use libc::{c_int, c_char};
 
 use types::{ToSql, FromSql};
 use error::{error_from_sqlite_code, error_from_handle};
+use raw_statement::RawStatement;
+use cache::StatementCache;
 
 pub use transaction::{SqliteTransaction, Transaction, TransactionBehavior};
 pub use error::{SqliteError, Error};
+pub use cache::CachedStatement;
 
 #[cfg(feature = "load_extension")]
 pub use load_extension_guard::{SqliteLoadExtensionGuard, LoadExtensionGuard};
 
 pub mod types;
 mod transaction;
+mod cache;
 mod named_params;
 mod error;
 mod convenient;
+mod raw_statement;
 #[cfg(feature = "load_extension")]mod load_extension_guard;
 #[cfg(feature = "trace")]pub mod trace;
 #[cfg(feature = "backup")]pub mod backup;
@@ -95,6 +101,9 @@ mod convenient;
 #[cfg(feature = "blob")]pub mod blob;
 #[cfg(all(feature = "vtab", feature = "functions"))]pub mod vtab;
 
+// Number of cached prepared statements we'll hold on to.
+const STATEMENT_CACHE_DEFAULT_CAPACITY: usize = 16;
+
 /// Old name for `Result`. `SqliteResult` is deprecated.
 pub type SqliteResult<T> = Result<T>;
 
@@ -147,6 +156,7 @@ pub type SqliteConnection = Connection;
 /// A connection to a SQLite database.
 pub struct Connection {
     db: RefCell<InnerConnection>,
+    cache: StatementCache,
     path: Option<PathBuf>,
 }
 
@@ -191,6 +201,7 @@ impl Connection {
         InnerConnection::open_with_flags(&c_path, flags).map(|db| {
             Connection {
                 db: RefCell::new(db),
+                cache: StatementCache::with_capacity(STATEMENT_CACHE_DEFAULT_CAPACITY),
                 path: Some(path.as_ref().to_path_buf()),
             }
         })
@@ -209,50 +220,12 @@ impl Connection {
         InnerConnection::open_with_flags(&c_memory, flags).map(|db| {
             Connection {
                 db: RefCell::new(db),
+                cache: StatementCache::with_capacity(STATEMENT_CACHE_DEFAULT_CAPACITY),
                 path: None,
             }
         })
     }
 
-    /// Begin a new transaction with the default behavior (DEFERRED).
-    ///
-    /// The transaction defaults to rolling back when it is dropped. If you want the transaction to
-    /// commit, you must call `commit` or `set_commit`.
-    ///
-    /// ## Example
-    ///
-    /// ```rust,no_run
-    /// # use rusqlite::{Connection, Result};
-    /// # fn do_queries_part_1(conn: &Connection) -> Result<()> { Ok(()) }
-    /// # fn do_queries_part_2(conn: &Connection) -> Result<()> { Ok(()) }
-    /// fn perform_queries(conn: &Connection) -> Result<()> {
-    ///     let tx = try!(conn.transaction());
-    ///
-    ///     try!(do_queries_part_1(conn)); // tx causes rollback if this fails
-    ///     try!(do_queries_part_2(conn)); // tx causes rollback if this fails
-    ///
-    ///     tx.commit()
-    /// }
-    /// ```
-    ///
-    /// # Failure
-    ///
-    /// Will return `Err` if the underlying SQLite call fails.
-    pub fn transaction(&self) -> Result<Transaction> {
-        Transaction::new(self, TransactionBehavior::Deferred)
-    }
-
-    /// Begin a new transaction with a specified behavior.
-    ///
-    /// See `transaction`.
-    ///
-    /// # Failure
-    ///
-    /// Will return `Err` if the underlying SQLite call fails.
-    pub fn transaction_with_behavior(&self, behavior: TransactionBehavior) -> Result<Transaction> {
-        Transaction::new(self, behavior)
-    }
-
     /// Convenience method to run multiple SQL statements (that cannot take any parameters).
     ///
     /// Uses [sqlite3_exec](http://www.sqlite.org/c3ref/exec.html) under the hood.
@@ -687,7 +660,7 @@ impl InnerConnection {
                                     &mut c_stmt,
                                     ptr::null_mut())
         };
-        self.decode_result(r).map(|_| Statement::new(conn, c_stmt))
+        self.decode_result(r).map(|_| Statement::new(conn, RawStatement::new(c_stmt)))
     }
 
     fn changes(&mut self) -> c_int {
@@ -708,25 +681,23 @@ pub type SqliteStatement<'conn> = Statement<'conn>;
 /// A prepared statement.
 pub struct Statement<'conn> {
     conn: &'conn Connection,
-    stmt: *mut ffi::sqlite3_stmt,
+    stmt: RawStatement,
-    column_count: c_int,
 }
 
 impl<'conn> Statement<'conn> {
-    fn new(conn: &Connection, stmt: *mut ffi::sqlite3_stmt) -> Statement {
+    fn new(conn: &Connection, stmt: RawStatement) -> Statement {
         Statement {
             conn: conn,
             stmt: stmt,
-            column_count: unsafe { ffi::sqlite3_column_count(stmt) },
         }
     }
 
     /// Get all the column names in the result set of the prepared statement.
     pub fn column_names(&self) -> Vec<&str> {
-        let n = self.column_count;
+        let n = self.column_count();
         let mut cols = Vec::with_capacity(n as usize);
         for i in 0..n {
-            let slice = unsafe { CStr::from_ptr(ffi::sqlite3_column_name(self.stmt, i)) };
+            let slice = self.stmt.column_name(i);
             let s = str::from_utf8(slice.to_bytes()).unwrap();
             cols.push(s);
         }
@@ -735,7 +706,7 @@ impl<'conn> Statement<'conn> {
 
     /// Return the number of columns in the result set returned by the prepared statement.
     pub fn column_count(&self) -> i32 {
-        self.column_count
+        self.stmt.column_count()
     }
 
     /// Returns the column index in the result set for a given column name.
@@ -745,10 +716,9 @@ impl<'conn> Statement<'conn> {
     /// Will return an `Error::InvalidColumnName` when there is no column with the specified `name`.
     pub fn column_index(&self, name: &str) -> Result<i32> {
         let bytes = name.as_bytes();
-        let n = self.column_count;
+        let n = self.column_count();
         for i in 0..n {
-            let slice = unsafe { CStr::from_ptr(ffi::sqlite3_column_name(self.stmt, i)) };
+            if bytes == self.stmt.column_name(i).to_bytes() {
-            if bytes == slice.to_bytes() {
                 return Ok(i);
             }
         }
@@ -779,18 +749,16 @@ impl<'conn> Statement<'conn> {
     /// Will return `Err` if binding parameters fails, the executed statement returns rows (in
     /// which case `query` should be used instead), or the underling SQLite call fails.
     pub fn execute(&mut self, params: &[&ToSql]) -> Result<c_int> {
-        unsafe {
         try!(self.bind_parameters(params));
         self.execute_()
     }
-    }
 
-    unsafe fn execute_(&mut self) -> Result<c_int> {
+    fn execute_(&mut self) -> Result<c_int> {
-        let r = ffi::sqlite3_step(self.stmt);
+        let r = self.stmt.step();
-        ffi::sqlite3_reset(self.stmt);
+        self.stmt.reset();
         match r {
             ffi::SQLITE_DONE => {
-                if self.column_count == 0 {
+                if self.column_count() == 0 {
                     Ok(self.conn.changes())
                 } else {
                     Err(Error::ExecuteReturnedResults)
@@ -825,10 +793,7 @@ impl<'conn> Statement<'conn> {
     ///
     /// Will return `Err` if binding parameters fails.
     pub fn query<'a>(&'a mut self, params: &[&ToSql]) -> Result<Rows<'a>> {
-        unsafe {
         try!(self.bind_parameters(params));
-        }
-
         Ok(Rows::new(self))
     }
 
@@ -889,32 +854,39 @@ impl<'conn> Statement<'conn> {
         self.finalize_()
     }
 
-    unsafe fn bind_parameters(&mut self, params: &[&ToSql]) -> Result<()> {
+    fn bind_parameters(&mut self, params: &[&ToSql]) -> Result<()> {
-        assert!(params.len() as c_int == ffi::sqlite3_bind_parameter_count(self.stmt),
+        assert!(params.len() as c_int == self.stmt.bind_parameter_count(),
                 "incorrect number of parameters to query(): expected {}, got {}",
-                ffi::sqlite3_bind_parameter_count(self.stmt),
+                self.stmt.bind_parameter_count(),
                 params.len());
 
         for (i, p) in params.iter().enumerate() {
-            try!(self.conn.decode_result(p.bind_parameter(self.stmt, (i + 1) as c_int)));
+            try!(unsafe {
+                self.conn.decode_result(p.bind_parameter(self.stmt.ptr(), (i + 1) as c_int))
+            });
         }
 
         Ok(())
     }
 
     fn finalize_(&mut self) -> Result<()> {
-        let r = unsafe { ffi::sqlite3_finalize(self.stmt) };
+        let mut stmt = RawStatement::new(ptr::null_mut());
-        self.stmt = ptr::null_mut();
+        mem::swap(&mut stmt, &mut self.stmt);
-        self.conn.decode_result(r)
+        self.conn.decode_result(stmt.finalize())
+    }
+}
+
+impl<'conn> Into<RawStatement> for Statement<'conn> {
+    fn into(mut self) -> RawStatement {
+        let mut stmt = RawStatement::new(ptr::null_mut());
+        mem::swap(&mut stmt, &mut self.stmt);
+        stmt
     }
 }
 
 impl<'conn> fmt::Debug for Statement<'conn> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let sql = unsafe {
+        let sql = str::from_utf8(self.stmt.sql().to_bytes());
-            let c_slice = CStr::from_ptr(ffi::sqlite3_sql(self.stmt)).to_bytes();
-            str::from_utf8(c_slice)
-        };
         f.debug_struct("Statement")
             .field("conn", self.conn)
             .field("stmt", &self.stmt)
@@ -1024,9 +996,7 @@ impl<'stmt> Rows<'stmt> {
 
     fn reset(&mut self) {
         if let Some(stmt) = self.stmt.take() {
-            unsafe {
+            stmt.stmt.reset();
-                ffi::sqlite3_reset(stmt.stmt);
-            }
         }
     }
 }
@@ -1036,7 +1006,7 @@ impl<'stmt> Iterator for Rows<'stmt> {
 
     fn next(&mut self) -> Option<Result<Row<'stmt>>> {
         self.stmt.and_then(|stmt| {
-            match unsafe { ffi::sqlite3_step(stmt.stmt) } {
+            match stmt.stmt.step() {
                 ffi::SQLITE_ROW => {
                     let current_row = self.current_row.get() + 1;
                     self.current_row.set(current_row);
@@ -1131,8 +1101,8 @@ impl<'stmt> Row<'stmt> {
         unsafe {
             let idx = try!(idx.idx(self.stmt));
 
-            match T::column_has_valid_sqlite_type(self.stmt.stmt, idx) {
+            match T::column_has_valid_sqlite_type(self.stmt.stmt.ptr(), idx) {
-                Ok(()) => FromSql::column_result(self.stmt.stmt, idx),
+                Ok(()) => FromSql::column_result(self.stmt.stmt.ptr(), idx),
                 Err(e) => Err(e),
             }
         }
@@ -1154,7 +1124,7 @@ pub trait RowIndex {
 impl RowIndex for i32 {
     #[inline]
     fn idx(&self, stmt: &Statement) -> Result<i32> {
-        if *self < 0 || *self >= stmt.column_count {
+        if *self < 0 || *self >= stmt.column_count() {
             Err(Error::InvalidColumnIndex(*self))
         } else {
             Ok(*self)

src/named_params.rs

@@ -1,7 +1,5 @@
 use libc::c_int;
 
-use super::ffi;
-
 use {Result, Error, Connection, Statement, Rows, Row, str_to_cstring};
 use types::ToSql;
 
@@ -56,11 +54,7 @@ impl<'conn> Statement<'conn> {
     /// is valid but not a bound parameter of this statement.
     pub fn parameter_index(&self, name: &str) -> Result<Option<i32>> {
         let c_name = try!(str_to_cstring(name));
-        let c_index = unsafe { ffi::sqlite3_bind_parameter_index(self.stmt, c_name.as_ptr()) };
+        Ok(self.stmt.bind_parameter_index(&c_name))
-        Ok(match c_index {
-            0 => None, // A zero is returned if no matching parameter is found.
-            n => Some(n),
-        })
     }
 
     /// Execute the prepared statement with named parameter(s). If any parameters
@@ -87,7 +81,7 @@ impl<'conn> Statement<'conn> {
     /// which case `query` should be used instead), or the underling SQLite call fails.
     pub fn execute_named(&mut self, params: &[(&str, &ToSql)]) -> Result<c_int> {
         try!(self.bind_parameters_named(params));
-        unsafe { self.execute_() }
+        self.execute_()
     }
 
     /// Execute the prepared statement with named parameter(s), returning an iterator over the
@@ -120,7 +114,7 @@ impl<'conn> Statement<'conn> {
     fn bind_parameters_named(&mut self, params: &[(&str, &ToSql)]) -> Result<()> {
         for &(name, value) in params {
             if let Some(i) = try!(self.parameter_index(name)) {
-                try!(self.conn.decode_result(unsafe { value.bind_parameter(self.stmt, i) }));
+                try!(self.conn.decode_result(unsafe { value.bind_parameter(self.stmt.ptr(), i) }));
             } else {
                 return Err(Error::InvalidParameterName(name.into()));
             }

src/raw_statement.rs

@@ -0,0 +1,70 @@
+use std::ffi::CStr;
+use std::ptr;
+use libc::c_int;
+use super::ffi;
+
+// Private newtype for raw sqlite3_stmts that finalize themselves when dropped.
+#[derive(Debug)]
+pub struct RawStatement(*mut ffi::sqlite3_stmt);
+
+impl RawStatement {
+    pub fn new(stmt: *mut ffi::sqlite3_stmt) -> RawStatement {
+        RawStatement(stmt)
+    }
+
+    pub unsafe fn ptr(&self) -> *mut ffi::sqlite3_stmt {
+        self.0
+    }
+
+    pub fn column_count(&self) -> c_int {
+        unsafe { ffi::sqlite3_column_count(self.0) }
+    }
+
+    pub fn column_name(&self, idx: c_int) -> &CStr {
+        unsafe { CStr::from_ptr(ffi::sqlite3_column_name(self.0, idx)) }
+    }
+
+    pub fn step(&self) -> c_int {
+        unsafe { ffi::sqlite3_step(self.0) }
+    }
+
+    pub fn reset(&self) -> c_int {
+        unsafe { ffi::sqlite3_reset(self.0) }
+    }
+
+    pub fn bind_parameter_count(&self) -> c_int {
+        unsafe { ffi::sqlite3_bind_parameter_count(self.0) }
+    }
+
+    pub fn bind_parameter_index(&self, name: &CStr) -> Option<c_int> {
+        let r = unsafe { ffi::sqlite3_bind_parameter_index(self.0, name.as_ptr()) };
+        match r {
+            0 => None,
+            i => Some(i),
+        }
+    }
+
+    pub fn clear_bindings(&self) -> c_int {
+        unsafe { ffi::sqlite3_clear_bindings(self.0) }
+    }
+
+    pub fn sql(&self) -> &CStr {
+        unsafe { CStr::from_ptr(ffi::sqlite3_sql(self.0)) }
+    }
+
+    pub fn finalize(mut self) -> c_int {
+        self.finalize_()
+    }
+
+    fn finalize_(&mut self) -> c_int {
+        let r = unsafe { ffi::sqlite3_finalize(self.0) };
+        self.0 = ptr::null_mut();
+        r
+    }
+}
+
+impl Drop for RawStatement {
+    fn drop(&mut self) {
+        self.finalize_();
+    }
+}

src/transaction.rs

@@ -1,3 +1,4 @@
+use std::ops::Deref;
 use {Result, Connection};
 
 /// Old name for `TransactionBehavior`. `SqliteTransactionBehavior` is deprecated.
@@ -12,16 +13,30 @@ pub enum TransactionBehavior {
     Exclusive,
 }
 
+/// Options for how a Transaction or Savepoint should behave when it is dropped.
+#[derive(Copy,Clone,PartialEq,Eq)]
+pub enum DropBehavior {
+    /// Roll back the changes. This is the default.
+    Rollback,
+
+    /// Commit the changes.
+    Commit,
+
+    /// Do not commit or roll back changes - this will leave the transaction or savepoint
+    /// open, so should be used with care.
+    Ignore,
+}
+
 /// Old name for `Transaction`. `SqliteTransaction` is deprecated.
 pub type SqliteTransaction<'conn> = Transaction<'conn>;
 
-///
 /// Represents a transaction on a database connection.
 ///
 /// ## Note
 ///
-/// Transactions will roll back by default. Use the `set_commit` or `commit` methods to commit the
+/// Transactions will roll back by default. Use `commit` method to explicitly commit the
-/// transaction.
+/// transaction, or use `set_drop_behavior` to change what happens when the transaction
+/// is dropped.
 ///
 /// ## Example
 ///
@@ -40,25 +55,54 @@ pub type SqliteTransaction<'conn> = Transaction<'conn>;
 /// ```
 pub struct Transaction<'conn> {
     conn: &'conn Connection,
+    drop_behavior: DropBehavior,
+    committed: bool,
+}
+
+/// Represents a savepoint on a database connection.
+///
+/// ## Note
+///
+/// Savepoints will roll back by default. Use `commit` method to explicitly commit the
+/// savepoint, or use `set_drop_behavior` to change what happens when the savepoint
+/// is dropped.
+///
+/// ## Example
+///
+/// ```rust,no_run
+/// # use rusqlite::{Connection, Result};
+/// # fn do_queries_part_1(conn: &Connection) -> Result<()> { Ok(()) }
+/// # fn do_queries_part_2(conn: &Connection) -> Result<()> { Ok(()) }
+/// fn perform_queries(conn: &Connection) -> Result<()> {
+///     let sp = try!(conn.savepoint());
+///
+///     try!(do_queries_part_1(conn)); // sp causes rollback if this fails
+///     try!(do_queries_part_2(conn)); // sp causes rollback if this fails
+///
+///     sp.commit()
+/// }
+/// ```
+pub struct Savepoint<'conn> {
+    conn: &'conn Connection,
+    name: String,
     depth: u32,
-    commit: bool,
+    drop_behavior: DropBehavior,
-    finished: bool,
+    committed: bool,
 }
 
 impl<'conn> Transaction<'conn> {
     /// Begin a new transaction. Cannot be nested; see `savepoint` for nested transactions.
-    pub fn new(conn: &Connection, behavior: TransactionBehavior) -> Result<Transaction> {
+    pub fn new(conn: &mut Connection, behavior: TransactionBehavior) -> Result<Transaction> {
         let query = match behavior {
             TransactionBehavior::Deferred => "BEGIN DEFERRED",
             TransactionBehavior::Immediate => "BEGIN IMMEDIATE",
             TransactionBehavior::Exclusive => "BEGIN EXCLUSIVE",
         };
-        conn.execute_batch(query).map(|_| {
+        conn.execute_batch(query).map(move |_| {
             Transaction {
                 conn: conn,
-                depth: 0,
+                drop_behavior: DropBehavior::Rollback,
-                commit: false,
+                committed: false,
-                finished: false,
             }
         })
     }
@@ -89,35 +133,23 @@ impl<'conn> Transaction<'conn> {
     ///     tx.commit()
     /// }
     /// ```
-    pub fn savepoint(&self) -> Result<Transaction> {
+    pub fn savepoint(&mut self) -> Result<Savepoint> {
-        self.conn.execute_batch("SAVEPOINT sp").map(|_| {
+        Savepoint::with_depth(self.conn, 1)
-            Transaction {
-                conn: self.conn,
-                depth: self.depth + 1,
-                commit: false,
-                finished: false,
-            }
-        })
     }
 
-    /// Returns whether or not the transaction is currently set to commit.
+    /// Create a new savepoint with a custom savepoint name. See `savepoint()`.
-    pub fn will_commit(&self) -> bool {
+    pub fn savepoint_with_name<T: Into<String>>(&mut self, name: T) -> Result<Savepoint> {
-        self.commit
+        Savepoint::with_depth_and_name(self.conn, 1, name)
     }
 
-    /// Returns whether or not the transaction is currently set to rollback.
+    /// Get the current setting for what happens to the transaction when it is dropped.
-    pub fn will_rollback(&self) -> bool {
+    pub fn drop_behavior(&self) -> DropBehavior {
-        !self.commit
+        self.drop_behavior
     }
 
-    /// Set the transaction to commit at its completion.
+    /// Configure the transaction to perform the specified action when it is dropped.
-    pub fn set_commit(&mut self) {
+    pub fn set_drop_behavior(&mut self, drop_behavior: DropBehavior) {
-        self.commit = true
+        self.drop_behavior = drop_behavior
-    }
-
-    /// Set the transaction to rollback at its completion.
-    pub fn set_rollback(&mut self) {
-        self.commit = false
     }
 
     /// A convenience method which consumes and commits a transaction.
@@ -126,12 +158,8 @@ impl<'conn> Transaction<'conn> {
     }
 
     fn commit_(&mut self) -> Result<()> {
-        self.finished = true;
+        self.committed = true;
-        self.conn.execute_batch(if self.depth == 0 {
+        self.conn.execute_batch("COMMIT")
-            "COMMIT"
-        } else {
-            "RELEASE sp"
-        })
     }
 
     /// A convenience method which consumes and rolls back a transaction.
@@ -140,16 +168,12 @@ impl<'conn> Transaction<'conn> {
     }
 
     fn rollback_(&mut self) -> Result<()> {
-        self.finished = true;
+        self.committed = true;
-        self.conn.execute_batch(if self.depth == 0 {
+        self.conn.execute_batch("ROLLBACK")
-            "ROLLBACK"
-        } else {
-            "ROLLBACK TO sp"
-        })
     }
 
     /// Consumes the transaction, committing or rolling back according to the current setting
-    /// (see `will_commit`, `will_rollback`).
+    /// (see `drop_behavior`).
     ///
     /// Functionally equivalent to the `Drop` implementation, but allows callers to see any
     /// errors that occur.
@@ -158,11 +182,22 @@ impl<'conn> Transaction<'conn> {
     }
 
     fn finish_(&mut self) -> Result<()> {
-        match (self.finished, self.commit) {
+        if self.committed {
-            (true, _) => Ok(()),
+            return Ok(());
-            (false, true) => self.commit_(),
-            (false, false) => self.rollback_(),
         }
+        match self.drop_behavior() {
+            DropBehavior::Commit => self.commit_(),
+            DropBehavior::Rollback => self.rollback_(),
+            DropBehavior::Ignore => Ok(()),
+        }
+    }
+}
+
+impl<'conn> Deref for Transaction<'conn> {
+    type Target = Connection;
+
+    fn deref(&self) -> &Connection {
+        self.conn
     }
 }
 
@@ -173,10 +208,196 @@ impl<'conn> Drop for Transaction<'conn> {
     }
 }
 
+impl<'conn> Savepoint<'conn> {
+    fn with_depth_and_name<T: Into<String>>(conn: &Connection, depth: u32, name: T) -> Result<Savepoint> {
+        let name = name.into();
+        conn.execute_batch(&format!("SAVEPOINT {}", name)).map(|_| {
+            Savepoint {
+                conn: conn,
+                name: name,
+                depth: depth,
+                drop_behavior: DropBehavior::Rollback,
+                committed: false,
+            }
+        })
+    }
+
+    fn with_depth(conn: &Connection, depth: u32) -> Result<Savepoint> {
+        let name = format!("_rusqlite_sp_{}", depth);
+        Savepoint::with_depth_and_name(conn, depth, name)
+    }
+
+    /// Begin a new savepoint. Can be nested.
+    pub fn new(conn: &mut Connection) -> Result<Savepoint> {
+        Savepoint::with_depth(conn, 0)
+    }
+
+    /// Begin a new savepoint with a user-provided savepoint name.
+    pub fn with_name<T: Into<String>>(conn: &mut Connection, name: T) -> Result<Savepoint> {
+        Savepoint::with_depth_and_name(conn, 0, name)
+    }
+
+    /// Begin a nested savepoint.
+    pub fn savepoint(&mut self) -> Result<Savepoint> {
+        Savepoint::with_depth(self.conn, self.depth + 1)
+    }
+
+    /// Begin a nested savepoint with a user-provided savepoint name.
+    pub fn savepoint_with_name<T: Into<String>>(&mut self, name: T) -> Result<Savepoint> {
+        Savepoint::with_depth_and_name(self.conn, self.depth + 1, name)
+    }
+
+    /// Get the current setting for what happens to the savepoint when it is dropped.
+    pub fn drop_behavior(&self) -> DropBehavior {
+        self.drop_behavior
+    }
+
+    /// Configure the savepoint to perform the specified action when it is dropped.
+    pub fn set_drop_behavior(&mut self, drop_behavior: DropBehavior) {
+        self.drop_behavior = drop_behavior
+    }
+
+    /// A convenience method which consumes and commits a savepoint.
+    pub fn commit(mut self) -> Result<()> {
+        self.commit_()
+    }
+
+    fn commit_(&mut self) -> Result<()> {
+        self.committed = true;
+        self.conn.execute_batch(&format!("RELEASE {}", self.name))
+    }
+
+    /// A convenience method which rolls back a savepoint.
+    ///
+    /// ## Note
+    ///
+    /// Unlike `Transaction`s, savepoints remain active after they have been rolled back,
+    /// and can be rolled back again or committed.
+    pub fn rollback(&mut self) -> Result<()> {
+        self.conn.execute_batch(&format!("ROLLBACK TO {}", self.name))
+    }
+
+    /// Consumes the savepoint, committing or rolling back according to the current setting
+    /// (see `drop_behavior`).
+    ///
+    /// Functionally equivalent to the `Drop` implementation, but allows callers to see any
+    /// errors that occur.
+    pub fn finish(mut self) -> Result<()> {
+        self.finish_()
+    }
+
+    fn finish_(&mut self) -> Result<()> {
+        if self.committed {
+            return Ok(());
+        }
+        match self.drop_behavior() {
+            DropBehavior::Commit => self.commit_(),
+            DropBehavior::Rollback => self.rollback(),
+            DropBehavior::Ignore => Ok(()),
+        }
+    }
+}
+
+impl<'conn> Deref for Savepoint<'conn> {
+    type Target = Connection;
+
+    fn deref(&self) -> &Connection {
+        self.conn
+    }
+}
+
+#[allow(unused_must_use)]
+impl<'conn> Drop for Savepoint<'conn> {
+    fn drop(&mut self) {
+        self.finish_();
+    }
+}
+
+impl Connection {
+    /// Begin a new transaction with the default behavior (DEFERRED).
+    ///
+    /// The transaction defaults to rolling back when it is dropped. If you want the transaction to
+    /// commit, you must call `commit` or `set_drop_behavior(DropBehavior::Commit)`.
+    ///
+    /// ## Example
+    ///
+    /// ```rust,no_run
+    /// # use rusqlite::{Connection, Result};
+    /// # fn do_queries_part_1(conn: &Connection) -> Result<()> { Ok(()) }
+    /// # fn do_queries_part_2(conn: &Connection) -> Result<()> { Ok(()) }
+    /// fn perform_queries(conn: &Connection) -> Result<()> {
+    ///     let tx = try!(conn.transaction());
+    ///
+    ///     try!(do_queries_part_1(conn)); // tx causes rollback if this fails
+    ///     try!(do_queries_part_2(conn)); // tx causes rollback if this fails
+    ///
+    ///     tx.commit()
+    /// }
+    /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
+    pub fn transaction(&mut self) -> Result<Transaction> {
+        Transaction::new(self, TransactionBehavior::Deferred)
+    }
+
+    /// Begin a new transaction with a specified behavior.
+    ///
+    /// See `transaction`.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
+    pub fn transaction_with_behavior(&mut self, behavior: TransactionBehavior) -> Result<Transaction> {
+        Transaction::new(self, behavior)
+    }
+
+    /// Begin a new savepoint with the default behavior (DEFERRED).
+    ///
+    /// The savepoint defaults to rolling back when it is dropped. If you want the savepoint to
+    /// commit, you must call `commit` or `set_drop_behavior(DropBehavior::Commit)`.
+    ///
+    /// ## Example
+    ///
+    /// ```rust,no_run
+    /// # use rusqlite::{Connection, Result};
+    /// # fn do_queries_part_1(conn: &Connection) -> Result<()> { Ok(()) }
+    /// # fn do_queries_part_2(conn: &Connection) -> Result<()> { Ok(()) }
+    /// fn perform_queries(conn: &Connection) -> Result<()> {
+    ///     let sp = try!(conn.savepoint());
+    ///
+    ///     try!(do_queries_part_1(conn)); // sp causes rollback if this fails
+    ///     try!(do_queries_part_2(conn)); // sp causes rollback if this fails
+    ///
+    ///     sp.commit()
+    /// }
+    /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
+    pub fn savepoint(&mut self) -> Result<Savepoint> {
+        Savepoint::new(self)
+    }
+
+    /// Begin a new savepoint with a specified name.
+    ///
+    /// See `savepoint`.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
+    pub fn savepoint_with_name<T: Into<String>>(&mut self, name: T) -> Result<Savepoint> {
+        Savepoint::with_name(self, name)
+    }
+}
+
 #[cfg(test)]
 #[cfg_attr(feature="clippy", allow(similar_names))]
 mod test {
     use Connection;
+    use super::DropBehavior;
 
     fn checked_memory_handle() -> Connection {
         let db = Connection::open_in_memory().unwrap();
@@ -186,69 +407,141 @@ mod test {
 
     #[test]
     fn test_drop() {
-        let db = checked_memory_handle();
+        let mut db = checked_memory_handle();
         {
-            let _tx = db.transaction().unwrap();
+            let tx = db.transaction().unwrap();
-            db.execute_batch("INSERT INTO foo VALUES(1)").unwrap();
+            tx.execute_batch("INSERT INTO foo VALUES(1)").unwrap();
             // default: rollback
         }
         {
             let mut tx = db.transaction().unwrap();
-            db.execute_batch("INSERT INTO foo VALUES(2)").unwrap();
+            tx.execute_batch("INSERT INTO foo VALUES(2)").unwrap();
-            tx.set_commit()
+            tx.set_drop_behavior(DropBehavior::Commit)
         }
         {
-            let _tx = db.transaction().unwrap();
+            let tx = db.transaction().unwrap();
             assert_eq!(2i32,
-                       db.query_row("SELECT SUM(x) FROM foo", &[], |r| r.get(0)).unwrap());
+                       tx.query_row("SELECT SUM(x) FROM foo", &[], |r| r.get(0)).unwrap());
         }
     }
 
     #[test]
     fn test_explicit_rollback_commit() {
-        let db = checked_memory_handle();
+        let mut db = checked_memory_handle();
         {
-            let tx = db.transaction().unwrap();
+            let mut tx = db.transaction().unwrap();
-            db.execute_batch("INSERT INTO foo VALUES(1)").unwrap();
+            {
-            tx.rollback().unwrap();
+                let mut sp = tx.savepoint().unwrap();
+                sp.execute_batch("INSERT INTO foo VALUES(1)").unwrap();
+                sp.rollback().unwrap();
+                sp.execute_batch("INSERT INTO foo VALUES(2)").unwrap();
+                sp.commit().unwrap();
             }
-        {
-            let tx = db.transaction().unwrap();
-            db.execute_batch("INSERT INTO foo VALUES(2)").unwrap();
             tx.commit().unwrap();
         }
         {
-            let _tx = db.transaction().unwrap();
+            let tx = db.transaction().unwrap();
-            assert_eq!(2i32,
+            tx.execute_batch("INSERT INTO foo VALUES(4)").unwrap();
-                       db.query_row("SELECT SUM(x) FROM foo", &[], |r| r.get(0)).unwrap());
+            tx.commit().unwrap();
+        }
+        {
+            let tx = db.transaction().unwrap();
+            assert_eq!(6i32,
+                       tx.query_row("SELECT SUM(x) FROM foo", &[], |r| r.get(0)).unwrap());
         }
     }
 
     #[test]
     fn test_savepoint() {
-        let db = checked_memory_handle();
+        let mut db = checked_memory_handle();
         {
             let mut tx = db.transaction().unwrap();
-            db.execute_batch("INSERT INTO foo VALUES(1)").unwrap();
+            tx.execute_batch("INSERT INTO foo VALUES(1)").unwrap();
-            tx.set_commit();
+            assert_current_sum(1, &tx);
+            tx.set_drop_behavior(DropBehavior::Commit);
             {
                 let mut sp1 = tx.savepoint().unwrap();
-                db.execute_batch("INSERT INTO foo VALUES(2)").unwrap();
+                sp1.execute_batch("INSERT INTO foo VALUES(2)").unwrap();
-                sp1.set_commit();
+                assert_current_sum(3, &sp1);
+                // will rollback sp1
                 {
-                    let sp2 = sp1.savepoint().unwrap();
+                    let mut sp2 = sp1.savepoint().unwrap();
-                    db.execute_batch("INSERT INTO foo VALUES(4)").unwrap();
+                    sp2.execute_batch("INSERT INTO foo VALUES(4)").unwrap();
+                    assert_current_sum(7, &sp2);
                     // will rollback sp2
                     {
                         let sp3 = sp2.savepoint().unwrap();
-                        db.execute_batch("INSERT INTO foo VALUES(8)").unwrap();
+                        sp3.execute_batch("INSERT INTO foo VALUES(8)").unwrap();
+                        assert_current_sum(15, &sp3);
                         sp3.commit().unwrap();
                         // committed sp3, but will be erased by sp2 rollback
                     }
-                }
+                    assert_current_sum(15, &sp2);
-            }
+                }
-        }
+                assert_current_sum(3, &sp1);
-        assert_eq!(3i32,
+            }
-                   db.query_row("SELECT SUM(x) FROM foo", &[], |r| r.get(0)).unwrap());
+            assert_current_sum(1, &tx);
+        }
+        assert_current_sum(1, &db);
+    }
+
+    #[test]
+    fn test_ignore_drop_behavior() {
+        let mut db = checked_memory_handle();
+
+        let mut tx = db.transaction().unwrap();
+        {
+            let mut sp1 = tx.savepoint().unwrap();
+            insert(1, &sp1);
+            sp1.rollback().unwrap();
+            insert(2, &sp1);
+            {
+                let mut sp2 = sp1.savepoint().unwrap();
+                sp2.set_drop_behavior(DropBehavior::Ignore);
+                insert(4, &sp2);
+            }
+            assert_current_sum(6, &sp1);
+            sp1.commit().unwrap();
+        }
+        assert_current_sum(6, &tx);
+    }
+
+    #[test]
+    fn test_savepoint_names() {
+        let mut db = checked_memory_handle();
+
+        {
+            let mut sp1 = db.savepoint_with_name("my_sp").unwrap();
+            insert(1, &sp1);
+            assert_current_sum(1, &sp1);
+            {
+                let mut sp2 = sp1.savepoint_with_name("my_sp").unwrap();
+                sp2.set_drop_behavior(DropBehavior::Commit);
+                insert(2, &sp2);
+                assert_current_sum(3, &sp2);
+                sp2.rollback().unwrap();
+                assert_current_sum(1, &sp2);
+                insert(4, &sp2);
+            }
+            assert_current_sum(5, &sp1);
+            sp1.rollback().unwrap();
+            {
+                let mut sp2 = sp1.savepoint_with_name("my_sp").unwrap();
+                sp2.set_drop_behavior(DropBehavior::Ignore);
+                insert(8, &sp2);
+            }
+            assert_current_sum(8, &sp1);
+            sp1.commit().unwrap();
+        }
+        assert_current_sum(8, &db);
+    }
+
+    fn insert(x: i32, conn: &Connection) {
+        conn.execute("INSERT INTO foo VALUES(?)", &[&x]).unwrap();
+    }
+
+    fn assert_current_sum(x: i32, conn: &Connection) {
+        let i = conn.query_row("SELECT SUM(x) FROM foo", &[], |r| r.get(0)).unwrap();
+        assert_eq!(x, i);
     }
 }