Ensure connection can be safely returned to a pool (#353)

* Add binding to sqlite3_get_autocommit.
* Add binding to sqlite3_stmt_busy.
* Disable test_is_busy by default

src/lib.rs

@@ -573,6 +573,18 @@ impl Connection {
     fn changes(&self) -> c_int {
         self.db.borrow_mut().changes()
     }
+
+    /// Test for auto-commit mode.
+    /// Autocommit mode is on by default.
+    pub fn is_autocommit(&self) -> bool {
+        self.db.borrow().is_autocommit()
+    }
+
+    /// Determine if all associated prepared statements have been reset.
+    #[cfg(feature = "bundled")]
+    pub fn is_busy(&self) -> bool {
+        self.db.borrow().is_busy()
+    }
 }
 
 impl fmt::Debug for Connection {
@@ -903,6 +915,25 @@ impl InnerConnection {
         unsafe { ffi::sqlite3_changes(self.db()) }
     }
 
+    fn is_autocommit(&self) -> bool {
+        unsafe { ffi::sqlite3_get_autocommit(self.db()) != 0 }
+    }
+
+    #[cfg(feature = "bundled")] // 3.8.6
+    fn is_busy(&self) -> bool {
+        let db = self.db();
+        unsafe {
+            let mut stmt = ffi::sqlite3_next_stmt(db, ptr::null_mut());
+            while !stmt.is_null() {
+                if ffi::sqlite3_stmt_busy(stmt) != 0 {
+                    return true;
+                }
+                stmt = ffi::sqlite3_next_stmt(db, stmt);
+            }
+        }
+        return false;
+    }
+
     #[cfg(not(feature = "hooks"))]
     fn remove_hooks(&mut self) {
     }
@@ -1223,6 +1254,30 @@ mod test {
         assert_eq!(db.last_insert_rowid(), 10);
     }
 
+    #[test]
+    fn test_is_autocommit() {
+        let db = checked_memory_handle();
+        assert!(db.is_autocommit(),
+                "autocommit expected to be active by default");
+    }
+
+    #[test]
+    #[cfg(feature = "bundled")]
+    fn test_is_busy() {
+        let db = checked_memory_handle();
+        assert!(!db.is_busy());
+        let mut stmt = db.prepare("PRAGMA schema_version").unwrap();
+        assert!(!db.is_busy());
+        {
+            let mut rows = stmt.query(&[]).unwrap();
+            assert!(!db.is_busy());
+            let row = rows.next();
+            assert!(db.is_busy());
+            assert!(row.is_some());
+        }
+        assert!(!db.is_busy());
+    }
+
     #[test]
     fn test_statement_debugging() {
         let db = checked_memory_handle();