MediaUtils: Use delayed / lazy library loading
Postpone loading libutilscallstack until needed
to save memory.
Test: atest library_tests
Test: adb shell 'showmap $(pgrep mediametrics)'
Bug: 227536784
Change-Id: I3d4c9e9b6d854b013185e18fc20d4bec320df14e
diff --git a/media/utils/tests/library_tests.cpp b/media/utils/tests/library_tests.cpp
new file mode 100644
index 0000000..c5c500c
--- /dev/null
+++ b/media/utils/tests/library_tests.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "library_tests"
+#include <utils/Log.h>
+
+#include <mediautils/Library.h>
+
+#include <android-base/file.h>
+#include <gtest/gtest.h>
+
+using namespace android::mediautils;
+
+namespace {
+
+static int32_t here = 0; // accessed on same thread.
+
+TEST(library_tests, basic) {
+ std::string path = android::base::GetExecutableDirectory() + "/libsharedtest.so";
+ // The flags to loadLibrary should not include RTLD_GLOBAL or RTLD_NODELETE
+ // which prevent unloading.
+ std::shared_ptr<void> library = loadLibrary(path.c_str(), RTLD_LAZY);
+ ASSERT_TRUE(library);
+ ASSERT_EQ(1, library.use_count());
+
+ std::shared_ptr<int32_t*> ptr = getObjectFromLibrary<int32_t*>("gPtr", library);
+ ASSERT_TRUE(ptr);
+ ASSERT_EQ(2, library.use_count());
+
+ ASSERT_EQ(nullptr, *ptr); // original contents are nullptr.
+
+ // There is a static object destructor in libsharedtest.so that will set the
+ // contents of the integer pointer (if non-null) to 1 when called.
+ // This is used to detect that the library is unloaded.
+ *ptr = &here;
+
+ ptr.reset(); // Note: this shared pointer uses library's refcount.
+ ASSERT_EQ(1, library.use_count()); // Verify library's refcount goes down by 1.
+ ASSERT_EQ(0, here); // the shared library's object destructor hasn't been called.
+
+ // use weak_ptr to investigate whether the library is gone.
+ std::weak_ptr<void> wlibrary = library;
+ ASSERT_EQ(1, wlibrary.use_count());
+ library.reset();
+
+ // we should have released the last reference.
+ ASSERT_EQ(0, wlibrary.use_count());
+
+ // The library should unload and the global object destroyed.
+ // Note on Android, specifying RTLD_GLOBAL or RTLD_NODELETE in the flags
+ // will prevent unloading libraries.
+ ASSERT_EQ(1, here);
+}
+
+TEST(library_tests, sad_library) {
+ std::string path = android::base::GetExecutableDirectory()
+ + "/something_random_library_that_doesn't_exit.so";
+
+ std::shared_ptr<void> library = loadLibrary(path.c_str(), RTLD_LAZY);
+ // We shouldn't crash on an invalid library path, just return an empty shared pointer.
+ // Check the logcat for any error details.
+ ASSERT_FALSE(library);
+}
+
+} // namespace