Merge branch 'master' of https://github.com/jgallagher/rusqlite into stmt-cache

CONTRIBUTORS.md

@@ -8,3 +8,5 @@ rusqlite contributors (sorted alphabetically)
 * [Huon Wilson](https://github.com/huonw)
 * [Patrick Fernie](https://github.com/pfernie)
 * [Steve Klabnik](https://github.com/steveklabnik)
+* [krdln](https://github.com/krdln)
+* [Ben Striegel](https://github.com/bstrie)

Cargo.toml

@@ -15,14 +15,16 @@ name = "rusqlite"
 [features]
 load_extension = ["libsqlite3-sys/load_extension"]
 cache = ["lru-cache"]
+trace = []
 
 [dependencies]
 time = "~0.1.0"
 bitflags = "~0.1"
-libc = "~0.1"
+libc = "~0.2"
 
 [dev-dependencies]
 tempdir = "~0.3.4"
+lazy_static = "~0.1"
 
 [dependencies.libsqlite3-sys]
 path = "libsqlite3-sys"
@@ -30,4 +32,8 @@ version = "0.2.0"
 
 [dependencies.lru-cache]
 version = "~0.0.4"
-optional = true
+optional = true
+
+[[test]]
+name = "config_log"
+harness = false

Changelog.md

@@ -1,3 +1,11 @@
+# Version UPCOMING (TBD)
+
+* Adds `trace` feature that allows the use of SQLite's logging, tracing, and profiling hooks.
+* Slight change to the closure types passed to `query_map` and `query_and_then`:
+    * Remove the `'static` requirement on the closure's output type.
+    * Give the closure a `&SqliteRow` instead of a `SqliteRow`.
+* Add more documentation for failure modes of functions that return `SqliteResult`s.
+
 # Version 0.4.0 (2015-11-03)
 
 * Adds `Sized` bound to `FromSql` trait as required by RFC 1214.

README.md

@@ -91,7 +91,7 @@ There are other, less obvious things that may result in a panic as well, such as
 `collect()` on a `SqliteRows` and then trying to use the collected rows.
 
 Strongly consider using the method `query_map()` instead, if you can.
-`query_map()` returns an iterator over rows-mapped-to-some-`'static`-type. This
+`query_map()` returns an iterator over rows-mapped-to-some-type. This
 iterator does not have any of the above issues with panics due to attempting to
 access stale rows.
 

libsqlite3-sys/Cargo.toml

@@ -15,4 +15,4 @@ load_extension = []
 pkg-config = "~0.3"
 
 [dependencies]
-libc = "~0.1"
+libc = "~0.2"

libsqlite3-sys/src/lib.rs

@@ -92,3 +92,5 @@ pub fn code_to_str(code: c_int) -> &'static str {
         _                => "Unknown error code",
     }
 }
+
+pub const SQLITE_CONFIG_LOG  : c_int = 16;

src/lib.rs

@@ -53,6 +53,7 @@
 extern crate libc;
 extern crate libsqlite3_sys as ffi;
 #[macro_use] extern crate bitflags;
+#[cfg(test)] #[macro_use] extern crate lazy_static;
 
 use std::default::Default;
 use std::convert;
@@ -81,6 +82,7 @@ pub mod types;
 mod transaction;
 #[cfg(feature = "load_extension")] mod load_extension_guard;
 #[cfg(feature = "cache")] pub mod cache;
+#[cfg(feature = "trace")] pub mod trace;
 
 /// A typedef of the result returned by many methods.
 pub type SqliteResult<T> = Result<T, SqliteError>;
@@ -129,28 +131,19 @@ impl SqliteError {
 fn str_to_cstring(s: &str) -> SqliteResult<CString> {
     CString::new(s).map_err(|_| SqliteError{
         code: ffi::SQLITE_MISUSE,
-        message: "Could not convert path to C-combatible string".to_string()
+        message: format!("Could not convert string {} to C-combatible string", s),
     })
 }
 
 fn path_to_cstring(p: &Path) -> SqliteResult<CString> {
     let s = try!(p.to_str().ok_or(SqliteError{
         code: ffi::SQLITE_MISUSE,
-        message: "Could not convert path to UTF-8 string".to_string()
+        message: format!("Could not convert path {} to UTF-8 string", p.to_string_lossy()),
     }));
     str_to_cstring(s)
 }
 
 /// A connection to a SQLite database.
-///
-/// ## Warning
-///
-/// Note that despite the fact that most `SqliteConnection` methods take an immutable reference to
-/// `self`, `SqliteConnection` is NOT threadsafe, and using it from multiple threads may result in
-/// runtime panics or data races. The SQLite connection handle has at least two pieces of internal
-/// state (the last insertion ID and the last error message) that rusqlite uses, but wrapping these
-/// APIs in a safe way from Rust would be too restrictive (for example, you would not be able to
-/// prepare multiple statements at the same time).
 pub struct SqliteConnection {
     db: RefCell<InnerSqliteConnection>,
     path: Option<PathBuf>,
@@ -163,12 +156,21 @@ impl SqliteConnection {
     ///
     /// `SqliteConnection::open(path)` is equivalent to `SqliteConnection::open_with_flags(path,
     /// SQLITE_OPEN_READ_WRITE | SQLITE_OPEN_CREATE)`.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `path` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite open call fails.
     pub fn open<P: AsRef<Path>>(path: P) -> SqliteResult<SqliteConnection> {
         let flags = Default::default();
         SqliteConnection::open_with_flags(path, flags)
     }
 
     /// Open a new connection to an in-memory SQLite database.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite open call fails.
     pub fn open_in_memory() -> SqliteResult<SqliteConnection> {
         let flags = Default::default();
         SqliteConnection::open_in_memory_with_flags(flags)
@@ -178,6 +180,11 @@ impl SqliteConnection {
     ///
     /// Database Connection](http://www.sqlite.org/c3ref/open.html) for a description of valid
     /// flag combinations.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `path` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite open call fails.
     pub fn open_with_flags<P: AsRef<Path>>(path: P, flags: SqliteOpenFlags)
             -> SqliteResult<SqliteConnection> {
         let c_path = try!(path_to_cstring(path.as_ref()));
@@ -190,6 +197,10 @@ impl SqliteConnection {
     ///
     /// Database Connection](http://www.sqlite.org/c3ref/open.html) for a description of valid
     /// flag combinations.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite open call fails.
     pub fn open_in_memory_with_flags(flags: SqliteOpenFlags) -> SqliteResult<SqliteConnection> {
         let c_memory = try!(str_to_cstring(":memory:"));
         InnerSqliteConnection::open_with_flags(&c_memory, flags).map(|db| {
@@ -217,6 +228,10 @@ impl SqliteConnection {
     ///     tx.commit()
     /// }
     /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
     pub fn transaction<'a>(&'a self) -> SqliteResult<SqliteTransaction<'a>> {
         SqliteTransaction::new(self, SqliteTransactionDeferred)
     }
@@ -224,6 +239,10 @@ impl SqliteConnection {
     /// 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<'a>(&'a self, behavior: SqliteTransactionBehavior)
             -> SqliteResult<SqliteTransaction<'a>> {
         SqliteTransaction::new(self, behavior)
@@ -244,6 +263,11 @@ impl SqliteConnection {
     ///                         COMMIT;")
     /// }
     /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `sql` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite call fails.
     pub fn execute_batch(&self, sql: &str) -> SqliteResult<()> {
         self.db.borrow_mut().execute_batch(sql)
     }
@@ -264,6 +288,11 @@ impl SqliteConnection {
     ///     }
     /// }
     /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `sql` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite call fails.
     pub fn execute(&self, sql: &str, params: &[&ToSql]) -> SqliteResult<c_int> {
         self.prepare(sql).and_then(|mut stmt| stmt.execute(params))
     }
@@ -290,6 +319,11 @@ impl SqliteConnection {
     /// ```
     ///
     /// If the query returns more than one row, all rows except the first are ignored.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `sql` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite call fails.
     pub fn query_row<T, F>(&self, sql: &str, params: &[&ToSql], f: F) -> SqliteResult<T>
                            where F: FnOnce(SqliteRow) -> T {
         let mut stmt = try!(self.prepare(sql));
@@ -320,6 +354,11 @@ impl SqliteConnection {
     /// ```
     ///
     /// If the query returns more than one row, all rows except the first are ignored.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if `sql` cannot be converted to a C-compatible string or if the
+    /// underlying SQLite call fails.
     pub fn query_row_and_then<T, E, F>(&self, sql: &str, params: &[&ToSql], f: F) -> Result<T, E>
                            where F: FnOnce(SqliteRow) -> Result<T, E>,
                                  E: convert::From<SqliteError> {
@@ -372,6 +411,11 @@ impl SqliteConnection {
     ///     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<'a>(&'a self, sql: &str) -> SqliteResult<SqliteStatement<'a>> {
         self.db.borrow_mut().prepare(self, sql)
     }
@@ -380,6 +424,10 @@ impl SqliteConnection {
     ///
     /// This is functionally equivalent to the `Drop` implementation for `SqliteConnection` except
     /// that it returns any error encountered to the caller.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
     pub fn close(self) -> SqliteResult<()> {
         let mut db = self.db.borrow_mut();
         db.close()
@@ -399,6 +447,10 @@ impl SqliteConnection {
     ///     conn.load_extension_disable()
     /// }
     /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
     #[cfg(feature = "load_extension")]
     pub fn load_extension_enable(&self) -> SqliteResult<()> {
         self.db.borrow_mut().enable_load_extension(1)
@@ -407,6 +459,10 @@ impl SqliteConnection {
     /// Disable loading of SQLite extensions.
     ///
     /// See `load_extension_enable` for an example.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
     #[cfg(feature = "load_extension")]
     pub fn load_extension_disable(&self) -> SqliteResult<()> {
         self.db.borrow_mut().enable_load_extension(0)
@@ -429,6 +485,10 @@ impl SqliteConnection {
     ///
     ///     conn.load_extension("my_sqlite_extension", None)
     /// }
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
     #[cfg(feature = "load_extension")]
     pub fn load_extension<P: AsRef<Path>>(&self, dylib_path: P, entry_point: Option<&str>) -> SqliteResult<()> {
         self.db.borrow_mut().load_extension(dylib_path, entry_point)
@@ -445,7 +505,9 @@ impl SqliteConnection {
 
 impl fmt::Debug for SqliteConnection {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "SqliteConnection( path: {:?} )", &self.path)
+        f.debug_struct("SqliteConnection")
+            .field("path", &self.path)
+            .finish()
     }
 }
 
@@ -652,6 +714,11 @@ impl<'conn> SqliteStatement<'conn> {
     ///     Ok(())
     /// }
     /// ```
+    ///
+    /// # Failure
+    ///
+    /// 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]) -> SqliteResult<c_int> {
         unsafe {
             try!(self.bind_parameters(params));
@@ -693,6 +760,10 @@ impl<'conn> SqliteStatement<'conn> {
     ///     Ok(names)
     /// }
     /// ```
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if binding parameters fails.
     pub fn query<'a>(&'a mut self, params: &[&ToSql]) -> SqliteResult<SqliteRows<'a>> {
         self.reset_if_needed();
 
@@ -709,10 +780,13 @@ impl<'conn> SqliteStatement<'conn> {
     ///
     /// Unlike the iterator produced by `query`, the returned iterator does not expose the possibility
     /// for accessing stale rows.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if binding parameters fails.
     pub fn query_map<'a, T, F>(&'a mut self, params: &[&ToSql], f: F)
                                      -> SqliteResult<MappedRows<'a, F>>
-                                     where T: 'static,
+                                     where F: FnMut(&SqliteRow) -> T {
-                                           F: FnMut(SqliteRow) -> T {
         let row_iter = try!(self.query(params));
 
         Ok(MappedRows{
@@ -727,11 +801,14 @@ impl<'conn> SqliteStatement<'conn> {
     ///
     /// Unlike the iterator produced by `query`, the returned iterator does not expose the possibility
     /// for accessing stale rows.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if binding parameters fails.
     pub fn query_and_then<'a, T, E, F>(&'a mut self, params: &[&ToSql], f: F)
                                      -> SqliteResult<AndThenRows<'a, F>>
-                                     where T: 'static,
+                                     where E: convert::From<SqliteError>,
-                                           E: convert::From<SqliteError>,
+                                           F: FnMut(&SqliteRow) -> Result<T, E> {
-                                           F: FnMut(SqliteRow) -> Result<T, E> {
         let row_iter = try!(self.query(params));
 
         Ok(AndThenRows{
@@ -744,6 +821,10 @@ impl<'conn> SqliteStatement<'conn> {
     ///
     /// Functionally equivalent to the `Drop` implementation, but allows callers to see any errors
     /// that occur.
+    ///
+    /// # Failure
+    ///
+    /// Will return `Err` if the underlying SQLite call fails.
     pub fn finalize(mut self) -> SqliteResult<()> {
         self.finalize_()
     }
@@ -789,7 +870,11 @@ impl<'conn> fmt::Debug for SqliteStatement<'conn> {
             let c_slice = CStr::from_ptr(ffi::sqlite3_sql(self.stmt)).to_bytes();
             str::from_utf8(c_slice)
         };
-        write!(f, "SqliteStatement( conn: {:?}, stmt: {:?}, sql: {:?} )", self.conn, self.stmt, sql)
+        f.debug_struct("SqliteStatement")
+            .field("conn", self.conn)
+            .field("stmt", &self.stmt)
+            .field("sql", &sql)
+            .finish()
     }
 }
 
@@ -807,12 +892,11 @@ pub struct MappedRows<'stmt, F> {
 }
 
 impl<'stmt, T, F> Iterator for MappedRows<'stmt, F>
-                        where T: 'static,
+                        where F: FnMut(&SqliteRow) -> T {
-                              F: FnMut(SqliteRow) -> T {
     type Item = SqliteResult<T>;
 
     fn next(&mut self) -> Option<SqliteResult<T>> {
-        self.rows.next().map(|row_result| row_result.map(|row| (self.map)(row)))
+        self.rows.next().map(|row_result| row_result.map(|row| (self.map)(&row)))
     }
 }
 
@@ -824,15 +908,14 @@ pub struct AndThenRows<'stmt, F> {
 }
 
 impl<'stmt, T, E, F> Iterator for AndThenRows<'stmt, F>
-                        where T: 'static,
+                        where E: convert::From<SqliteError>,
-                              E: convert::From<SqliteError>,
+                              F: FnMut(&SqliteRow) -> Result<T, E> {
-                              F: FnMut(SqliteRow) -> Result<T, E> {
     type Item = Result<T, E>;
 
     fn next(&mut self) -> Option<Self::Item> {
         self.rows.next().map(|row_result| row_result
                              .map_err(E::from)
-                             .and_then(|row| (self.map)(row)))
+                             .and_then(|row| (self.map)(&row)))
     }
 }
 

src/trace.rs

@@ -0,0 +1,162 @@
+//! Tracing and profiling functions. Error and warning log.
+
+use libc::{c_char, c_int, c_void};
+use std::ffi::{CStr, CString};
+use std::mem;
+use std::ptr;
+use std::str;
+use std::time::Duration;
+
+use super::ffi;
+use {SqliteError, SqliteResult, SqliteConnection};
+
+/// Set up the process-wide SQLite error logging callback.
+/// This function is marked unsafe for two reasons:
+///
+/// * The function is not threadsafe. No other SQLite calls may be made while
+///   `config_log` is running, and multiple threads may not call `config_log`
+///   simultaneously.
+/// * The provided `callback` itself function has two requirements:
+///     * It must not invoke any SQLite calls.
+///     * It must be threadsafe if SQLite is used in a multithreaded way.
+///
+/// cf [The Error And Warning Log](http://sqlite.org/errlog.html).
+pub unsafe fn config_log(callback: Option<fn(c_int, &str)>) -> SqliteResult<()> {
+    extern "C" fn log_callback(p_arg: *mut c_void, err: c_int, msg: *const c_char) {
+        let c_slice = unsafe { CStr::from_ptr(msg).to_bytes() };
+        let callback: fn(c_int, &str) = unsafe { mem::transmute(p_arg) };
+
+        if let Ok(s) = str::from_utf8(c_slice) {
+            callback(err, s);
+        }
+    }
+
+    let rc = match callback {
+        Some(f) => {
+            let p_arg: *mut c_void = mem::transmute(f);
+            ffi::sqlite3_config(ffi::SQLITE_CONFIG_LOG, Some(log_callback), p_arg)
+        },
+        None => {
+            let nullptr: *mut c_void = ptr::null_mut();
+            ffi::sqlite3_config(ffi::SQLITE_CONFIG_LOG, nullptr, nullptr)
+        }
+    };
+
+    if rc != ffi::SQLITE_OK {
+        return Err(SqliteError{ code: rc, message: "sqlite3_config(SQLITE_CONFIG_LOG, ...)".to_string() });
+    }
+
+    Ok(())
+}
+
+/// Write a message into the error log established by `config_log`.
+pub fn log(err_code: c_int, msg: &str) {
+    let msg = CString::new(msg).expect("SQLite log messages cannot contain embedded zeroes");
+    unsafe {
+        ffi::sqlite3_log(err_code, msg.as_ptr());
+    }
+}
+
+impl SqliteConnection {
+    /// Register or clear a callback function that can be used for tracing the execution of SQL statements.
+    ///
+    /// Prepared statement placeholders are replaced/logged with their assigned values.
+    /// There can only be a single tracer defined for each database connection.
+    /// Setting a new tracer clears the old one.
+    pub fn trace(&mut self, trace_fn: Option<fn(&str)>) {
+        extern "C" fn trace_callback (p_arg: *mut c_void, z_sql: *const c_char) {
+            let trace_fn: fn(&str) = unsafe { mem::transmute(p_arg) };
+            let c_slice = unsafe { CStr::from_ptr(z_sql).to_bytes() };
+            if let Ok(s) = str::from_utf8(c_slice) {
+                trace_fn(s);
+            }
+        }
+
+        let c = self.db.borrow_mut();
+        match trace_fn {
+            Some(f) => unsafe { ffi::sqlite3_trace(c.db(), Some(trace_callback), mem::transmute(f)); },
+            None    => unsafe { ffi::sqlite3_trace(c.db(), None, ptr::null_mut()); },
+        }
+    }
+
+    /// Register or clear a callback function that can be used for profiling the execution of SQL statements.
+    ///
+    /// There can only be a single profiler defined for each database connection.
+    /// Setting a new profiler clears the old one.
+    pub fn profile(&mut self, profile_fn: Option<fn(&str, Duration)>) {
+        extern "C" fn profile_callback(p_arg: *mut c_void, z_sql: *const c_char, nanoseconds: u64) {
+            let profile_fn: fn(&str, Duration) = unsafe { mem::transmute(p_arg) };
+            let c_slice = unsafe { CStr::from_ptr(z_sql).to_bytes() };
+            if let Ok(s) = str::from_utf8(c_slice) {
+                const NANOS_PER_SEC: u64 = 1_000_000_000;
+
+                let duration = Duration::new(nanoseconds / NANOS_PER_SEC,
+                                             (nanoseconds % NANOS_PER_SEC) as u32);
+                profile_fn(s, duration);
+            }
+        }
+
+        let c = self.db.borrow_mut();
+        match profile_fn {
+            Some(f) => unsafe { ffi::sqlite3_profile(c.db(), Some(profile_callback), mem::transmute(f)) },
+            None    => unsafe { ffi::sqlite3_profile(c.db(), None, ptr::null_mut()) },
+        };
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use std::sync::Mutex;
+    use std::time::Duration;
+
+    use SqliteConnection;
+
+    #[test]
+    fn test_trace() {
+        lazy_static! {
+            static ref TRACED_STMTS: Mutex<Vec<String>> = Mutex::new(Vec::new());
+        }
+        fn tracer(s: &str) {
+            let mut traced_stmts = TRACED_STMTS.lock().unwrap();
+            traced_stmts.push(s.to_owned());
+        }
+
+        let mut db = SqliteConnection::open_in_memory().unwrap();
+        db.trace(Some(tracer));
+        {
+            let _ = db.query_row("SELECT ?", &[&1i32], |_| {});
+            let _ = db.query_row("SELECT ?", &[&"hello"], |_| {});
+        }
+        db.trace(None);
+        {
+            let _ = db.query_row("SELECT ?", &[&2i32], |_| {});
+            let _ = db.query_row("SELECT ?", &[&"goodbye"], |_| {});
+        }
+
+        let traced_stmts = TRACED_STMTS.lock().unwrap();
+        assert_eq!(traced_stmts.len(), 2);
+        assert_eq!(traced_stmts[0], "SELECT 1");
+        assert_eq!(traced_stmts[1], "SELECT 'hello'");
+    }
+
+    #[test]
+    fn test_profile() {
+        lazy_static! {
+            static ref PROFILED: Mutex<Vec<(String, Duration)>> = Mutex::new(Vec::new());
+        }
+        fn profiler(s: &str, d: Duration) {
+            let mut profiled = PROFILED.lock().unwrap();
+            profiled.push((s.to_owned(), d));
+        }
+
+        let mut db = SqliteConnection::open_in_memory().unwrap();
+        db.profile(Some(profiler));
+        db.execute_batch("PRAGMA application_id = 1").unwrap();
+        db.profile(None);
+        db.execute_batch("PRAGMA application_id = 2").unwrap();
+
+        let profiled = PROFILED.lock().unwrap();
+        assert_eq!(profiled.len(), 1);
+        assert_eq!(profiled[0].0, "PRAGMA application_id = 1");
+    }
+}

tests/config_log.rs

@@ -0,0 +1,36 @@
+//! This file contains unit tests for rusqlite::trace::config_log. This function affects
+//! SQLite process-wide and so is not safe to run as a normal #[test] in the library.
+
+#[macro_use] extern crate lazy_static;
+extern crate libc;
+extern crate rusqlite;
+
+#[cfg(feature = "trace")]
+fn main() {
+    use libc::c_int;
+    use std::sync::Mutex;
+
+    lazy_static! {
+        static ref LOGS_RECEIVED: Mutex<Vec<(c_int, String)>> = Mutex::new(Vec::new());
+    }
+
+    fn log_handler(err: c_int, message: &str) {
+        let mut logs_received = LOGS_RECEIVED.lock().unwrap();
+        logs_received.push((err, message.to_owned()));
+    }
+
+    use rusqlite::trace;
+
+    unsafe { trace::config_log(Some(log_handler)) }.unwrap();
+    trace::log(10, "First message from rusqlite");
+    unsafe { trace::config_log(None) }.unwrap();
+    trace::log(11, "Second message from rusqlite");
+
+    let logs_received = LOGS_RECEIVED.lock().unwrap();
+    assert_eq!(logs_received.len(), 1);
+    assert_eq!(logs_received[0].0, 10);
+    assert_eq!(logs_received[0].1, "First message from rusqlite");
+}
+
+#[cfg(not(feature = "trace"))]
+fn main() {}