add thread safety predicate to SQLite3

Author: tenderlove

ext/sqlite3/sqlite3.c

@@ -65,6 +65,14 @@ static VALUE libversion(VALUE UNUSED(klass))
   return INT2NUM(sqlite3_libversion_number());
 }
 
+/* Returns the compile time setting of the SQLITE_THREADSAFE flag.
+ * See: https://www.sqlite.org/c3ref/threadsafe.html
+ */
+static VALUE threadsafe_p(VALUE UNUSED(klass))
+{
+  return INT2NUM(sqlite3_threadsafe());
+}
+
 void Init_sqlite3_native()
 {
   /*
@@ -92,6 +100,7 @@ void Init_sqlite3_native()
 #endif
 
   rb_define_singleton_method(mSqlite3, "libversion", libversion, 0);
+  rb_define_singleton_method(mSqlite3, "threadsafe", threadsafe_p, 0);
   rb_define_const(mSqlite3, "SQLITE_VERSION", rb_str_new2(SQLITE_VERSION));
   rb_define_const(mSqlite3, "SQLITE_VERSION_NUMBER", INT2FIX(SQLITE_VERSION_NUMBER));
 }

lib/sqlite3.rb

@@ -8,3 +8,8 @@
 
 require 'sqlite3/database'
 require 'sqlite3/version'
+
+module SQLite3
+  # Was sqlite3 compiled with thread safety on?
+  def self.threadsafe?; threadsafe > 0; end
+end

test/test_sqlite3.rb

@@ -5,5 +5,17 @@ class TestSQLite3 < SQLite3::TestCase
     def test_libversion
       assert_not_nil SQLite3.libversion
     end
+
+    def test_threadsafe
+      assert_not_nil SQLite3.threadsafe
+    end
+
+    def test_threadsafe?
+      if SQLite3.threadsafe > 0
+        assert SQLite3.threadsafe?
+      else
+        refute SQLite3.threadsafe?
+      end
+    end
   end
 end