Lazily create a linked list of context items (#1833)

This approach has the benefit that it does not require any *a priori*
initialization, and that each context pointer is identified by the way
in which it was created. Additionally, retrieving the context pointer
now requires that the entity responsible for creating/destroying it
(the manager) be given. Since managers are stored in global static
const structures, they should not normally be visible across source
files, and thus there should be no danger that a context item will be
retrieved by the wrong manager and thus cast into the wrong data type.

Since the items are stored in a linked list, their number will be
limited to exactly as many as are needed for a given context, with the
caveat that storing too many on a context will cause slow retrieval.

Thanks @mhdawson for the idea!

Fixes https://github.com/jerryscript-project/jerryscript/issues/1845

JerryScript-DCO-1.0-Signed-off-by: Gabriel Schulhof gabriel.schulhof@intel.com

tests/unit-core/test-context-data.c

@@ -0,0 +1,95 @@
+/* Copyright JS Foundation and other contributors, http://js.foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "config.h"
+#include "jerryscript.h"
+#include "test-common.h"
+
+static bool test_context_data1_new_called = false;
+static bool test_context_data2_new_called = false;
+static bool test_context_data1_free_called = false;
+static bool test_context_data2_free_called = false;
+
+/* Context item 1 */
+const char *string1 = "item1";
+
+static void
+test_context_data1_new (void *user_data_p)
+{
+  test_context_data1_new_called = true;
+  *((const char **) user_data_p) = string1;
+} /* test_context_data1_new */
+
+static void
+test_context_data1_free (void *user_data_p)
+{
+  test_context_data1_free_called = true;
+  TEST_ASSERT ((*(const char **) user_data_p) == string1);
+} /* test_context_data1_free */
+
+static const jerry_context_data_manager_t manager1 =
+{
+  .init_cb = test_context_data1_new,
+  .deinit_cb = test_context_data1_free,
+  .bytes_needed = sizeof (const char *)
+};
+
+/* Context item 2 */
+const char *string2 = "item2";
+
+static void
+test_context_data2_new (void *user_data_p)
+{
+  test_context_data2_new_called = true;
+  *((const char **) user_data_p) = string2;
+} /* test_context_data2_new */
+
+static void
+test_context_data2_free (void *user_data_p)
+{
+  test_context_data2_free_called = true;
+  TEST_ASSERT ((*(const char **) user_data_p) == string2);
+} /* test_context_data2_free */
+
+static const jerry_context_data_manager_t manager2 =
+{
+  .init_cb = test_context_data2_new,
+  .deinit_cb = test_context_data2_free,
+  .bytes_needed = sizeof (const char *)
+};
+
+int
+main (void)
+{
+  TEST_INIT ();
+
+  jerry_init (JERRY_INIT_EMPTY);
+
+  TEST_ASSERT (!strcmp (*((const char **) jerry_get_context_data (&manager1)), "item1"));
+  TEST_ASSERT (!strcmp (*((const char **) jerry_get_context_data (&manager2)), "item2"));
+
+  TEST_ASSERT (test_context_data1_new_called);
+  TEST_ASSERT (test_context_data2_new_called);
+
+  TEST_ASSERT (!test_context_data1_free_called);
+  TEST_ASSERT (!test_context_data2_free_called);
+
+  jerry_cleanup ();
+
+  TEST_ASSERT (test_context_data1_free_called);
+  TEST_ASSERT (test_context_data2_free_called);
+
+  return 0;
+} /* main */

tests/unit-core/test-user-context.c

@@ -1,53 +0,0 @@
-/* Copyright JS Foundation and other contributors, http://js.foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include "config.h"
-#include "jerryscript.h"
-#include "test-common.h"
-
-static const char *identifying_string = "identifying string";
-static bool user_context_new_was_called = false;
-static bool user_context_free_was_called = false;
-
-static void *
-user_context_new (void)
-{
-  user_context_new_was_called = true;
-  return (void *) identifying_string;
-} /* user_context_new */
-
-static void
-user_context_free (void *user_context_p)
-{
-  user_context_free_was_called = true;
-  TEST_ASSERT (((const char *) user_context_p) == identifying_string);
-} /* user_context_free */
-
-int
-main (void)
-{
-  TEST_INIT ();
-
-  jerry_init_with_user_context (JERRY_INIT_EMPTY, user_context_new, user_context_free);
-
-  TEST_ASSERT ((((const char *)(jerry_get_user_context ()))) == identifying_string);
-
-  jerry_cleanup ();
-
-  TEST_ASSERT (user_context_new_was_called);
-  TEST_ASSERT (user_context_free_was_called);
-
-  return 0;
-} /* main */