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/Library.cpp b/media/utils/Library.cpp
new file mode 100644
index 0000000..c1e22bf
--- /dev/null
+++ b/media/utils/Library.cpp
@@ -0,0 +1,72 @@
+/*
+ * 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"
+#include <utils/Log.h>
+#include <mediautils/Library.h>
+
+namespace {
+
+std::string dlerrorIfPresent() {
+ const char *dlerr = dlerror();
+ if (dlerr == nullptr) return "dlerror: none";
+ return std::string("dlerror: '").append(dlerr).append("'");
+}
+
+}
+namespace android::mediautils {
+
+std::shared_ptr<void> loadLibrary(const char *libraryName, int flags) {
+ std::shared_ptr<void> library{
+ dlopen(libraryName, flags),
+ [](void *lib) {
+ if (lib != nullptr) {
+ const int ret = dlclose(lib);
+ ALOGW_IF(ret !=0, "%s: dlclose(%p) == %d, %s",
+ __func__, lib, ret, dlerrorIfPresent().c_str());
+ }
+ }
+ };
+
+ if (!library) {
+ ALOGW("%s: cannot load libraryName %s, %s",
+ __func__, libraryName, dlerrorIfPresent().c_str());
+ return {};
+ }
+ return library;
+}
+
+std::shared_ptr<void> getUntypedObjectFromLibrary(
+ const char *objectName, const std::shared_ptr<void>& library) {
+ if (!library) {
+ ALOGW("%s: null library, cannot load objectName %s", __func__, objectName);
+ return {};
+ }
+ void *ptr = dlsym(library.get(), objectName);
+ if (ptr == nullptr) {
+ ALOGW("%s: cannot load objectName %s, %s",
+ __func__, objectName, dlerrorIfPresent().c_str());
+ return {};
+ }
+
+ // Note: we use the "aliasing" constructor of the std:shared_ptr.
+ //
+ // https://en.cppreference.com/w/cpp/memory/shared_ptr/shared_ptr
+ //
+ return { library, ptr }; // returns shared_ptr to ptr, but ref counted on library.
+}
+
+} // namespace android::mediautils