Feature sqlite3_{log,trace,profile}.

Cargo.toml

@@ -14,6 +14,7 @@ name = "rusqlite"
 
 [features]
 load_extension = ["libsqlite3-sys/load_extension"]
+trace_extension = []
 
 [dependencies]
 time = "~0.1.0"

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

@@ -50,6 +50,7 @@
 //!     }
 //! }
 //! ```
+#![cfg_attr(test, feature(duration))]
 extern crate libc;
 extern crate libsqlite3_sys as ffi;
 #[macro_use] extern crate bitflags;
@@ -79,6 +80,7 @@ pub use transaction::{SqliteTransactionBehavior,
 pub mod types;
 mod transaction;
 #[cfg(feature = "load_extension")] mod load_extension_guard;
+#[cfg(feature = "trace_extension")] pub mod trace_extension;
 
 /// A typedef of the result returned by many methods.
 pub type SqliteResult<T> = Result<T, SqliteError>;
@@ -664,7 +666,7 @@ impl<'conn> SqliteStatement<'conn> {
     }
 
     /// Executes the prepared statement and maps a function over the resulting
-    /// rows. 
+    /// rows.
     ///
     /// Unlike the iterator produced by `query`, the returned iterator does not expose the possibility
     /// for accessing stale rows.

src/trace_extension.rs

@@ -0,0 +1,98 @@
+use libc::{c_char, c_int, c_void};
+use std::ffi::CString;
+use std::ptr;
+
+use super::ffi;
+use {SqliteError, SqliteResult, SqliteConnection};
+
+pub type LogCallback =
+    Option<extern "C" fn (udp: *mut c_void, err: c_int, msg: *const c_char)>;
+
+/// Set up the error logging callback
+///
+/// cf [The Error And Warning Log](http://sqlite.org/errlog.html).
+pub fn config_log(cb: LogCallback) -> SqliteResult<()> {
+    let rc = unsafe {
+        let p_arg: *mut c_void = ptr::null_mut();
+        ffi::sqlite3_config(ffi::SQLITE_CONFIG_LOG, cb, p_arg)
+    };
+    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).unwrap();
+    unsafe {
+        ffi::sqlite3_log(err_code, msg.as_ptr());
+    }
+}
+
+pub type TraceCallback =
+    Option<extern "C" fn (p_arg: *mut c_void, z_sql: *const c_char)>;
+pub type ProfileCallback =
+    Option<extern "C" fn (p_arg: *mut c_void, z_sql: *const c_char, nanoseconds: u64)>;
+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, x_trace: TraceCallback) {
+        let c = self.db.borrow_mut();
+        unsafe { ffi::sqlite3_trace(c.db(), x_trace, 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, x_profile: ProfileCallback) {
+        let c = self.db.borrow_mut();
+        unsafe { ffi::sqlite3_profile(c.db(), x_profile, ptr::null_mut()); }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use libc::{c_char, c_int, c_void};
+    use std::ffi::CStr;
+    use std::io::Write;
+    use std::str;
+
+    use ffi;
+    use SqliteConnection;
+
+    extern "C" fn log_callback(_: *mut c_void, err: c_int, msg: *const c_char) {
+        unsafe {
+            let c_slice = CStr::from_ptr(msg).to_bytes();
+            let _ = writeln!(::std::io::stderr(), "{}: {:?}", err, str::from_utf8(c_slice));
+        }
+    }
+
+    #[test]
+    fn test_log() {
+        if true { // To avoid freezing tests
+            return
+        }
+        unsafe { ffi::sqlite3_shutdown() };
+        super::config_log(Some(log_callback)).unwrap();
+        //super::log(ffi::SQLITE_NOTICE, "message from rusqlite");
+        super::config_log(None).unwrap();
+    }
+
+    extern "C" fn profile_callback(_: *mut ::libc::c_void, sql: *const ::libc::c_char, nanoseconds: u64) {
+        use std::time::Duration;
+        unsafe {
+            let c_slice = ::std::ffi::CStr::from_ptr(sql).to_bytes();
+            let d = Duration::from_millis(nanoseconds / 1_000_000);
+            let _ = writeln!(::std::io::stderr(), "PROFILE: {:?} ({})", ::std::str::from_utf8(c_slice), d);
+        }
+    }
+
+    #[test]
+    fn test_profile() {
+        let mut db = SqliteConnection::open_in_memory().unwrap();
+        db.profile(Some(profile_callback));
+        db.execute_batch("PRAGMA application_id = 1").unwrap();
+    }
+}