audiopolicy: Load the engine library dynamically
Android provides 2 audio policy engines:
libaudiopolicyenginedefault and
libaudiopolicyengineconfigurable. This change makes the engine
to be loaded dynamically based on the configuration (currently
the engine name is hardcoded into AudioPolicyConfig). Dynamic
loading allows building and installing of both libraries without
any conflicts.
Technical changes:
- AudioPolicyManagerInterface renamed to EngineInterface
for clarity;
- For the purpose of dynamic loading, APM does not depend
anymore on the EngineInstance class. The class got removed
from the default AP engine, but left in the configurable engine
because it is also used by its plugins;
- Added EngineLibrary class to encapsulate dynamic loading
of the AP engine. The class name EngineInstance is repurposed
for a smart pointer to EngineInterface;
- services/audiopolicy/managerdefault/Android.mk converted
into Android.bp;
- Added engine loading failure test;
Bug: 132639720
Test: sanity tests for audio; audiopolicy_tests
Change-Id: I0581569a172f810e030aec879225e817bfa7851a
Merged-In: I0581569a172f810e030aec879225e817bfa7851a
diff --git a/services/audiopolicy/managerdefault/EngineLibrary.cpp b/services/audiopolicy/managerdefault/EngineLibrary.cpp
new file mode 100644
index 0000000..ef699aa
--- /dev/null
+++ b/services/audiopolicy/managerdefault/EngineLibrary.cpp
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2019 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 "APM_EngineLoader"
+
+#include <dlfcn.h>
+#include <utils/Log.h>
+
+#include "EngineLibrary.h"
+
+namespace android {
+
+// static
+std::shared_ptr<EngineLibrary> EngineLibrary::load(std::string libraryPath)
+{
+ std::shared_ptr<EngineLibrary> engLib(new EngineLibrary());
+ return engLib->init(std::move(libraryPath)) ? engLib : nullptr;
+}
+
+EngineLibrary::~EngineLibrary()
+{
+ close();
+}
+
+bool EngineLibrary::init(std::string libraryPath)
+{
+ mLibraryHandle = dlopen(libraryPath.c_str(), 0);
+ if (mLibraryHandle == nullptr) {
+ ALOGE("Could not dlopen %s: %s", libraryPath.c_str(), dlerror());
+ return false;
+ }
+ mCreateEngineInstance = (EngineInterface* (*)())dlsym(mLibraryHandle, "createEngineInstance");
+ mDestroyEngineInstance = (void (*)(EngineInterface*))dlsym(
+ mLibraryHandle, "destroyEngineInstance");
+ if (mCreateEngineInstance == nullptr || mDestroyEngineInstance == nullptr) {
+ ALOGE("Could not find engine interface functions in %s", libraryPath.c_str());
+ close();
+ return false;
+ }
+ ALOGD("Loaded engine from %s", libraryPath.c_str());
+ return true;
+}
+
+EngineInstance EngineLibrary::createEngine()
+{
+ if (mCreateEngineInstance == nullptr || mDestroyEngineInstance == nullptr) {
+ return EngineInstance();
+ }
+ return EngineInstance(mCreateEngineInstance(),
+ [lib = shared_from_this(), destroy = mDestroyEngineInstance] (EngineInterface* e) {
+ destroy(e);
+ });
+}
+
+void EngineLibrary::close()
+{
+ if (mLibraryHandle != nullptr) {
+ dlclose(mLibraryHandle);
+ }
+ mLibraryHandle = nullptr;
+ mCreateEngineInstance = nullptr;
+ mDestroyEngineInstance = nullptr;
+}
+
+} // namespace android