Register resource observer and handle resource lost.

bug: 168307955
bug: 154733526
Change-Id: I2d5e39ce23bc873dd3bac090e3f7aa1124d0a579
diff --git a/media/libmediatranscoding/TranscodingResourcePolicy.cpp b/media/libmediatranscoding/TranscodingResourcePolicy.cpp
new file mode 100644
index 0000000..4fd8338
--- /dev/null
+++ b/media/libmediatranscoding/TranscodingResourcePolicy.cpp
@@ -0,0 +1,169 @@
+/*
+ * Copyright (C) 2020 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_NDEBUG 0
+#define LOG_TAG "TranscodingResourcePolicy"
+
+#include <aidl/android/media/BnResourceObserver.h>
+#include <aidl/android/media/IResourceObserverService.h>
+#include <android/binder_manager.h>
+#include <android/binder_process.h>
+#include <binder/IServiceManager.h>
+#include <media/TranscodingResourcePolicy.h>
+#include <utils/Log.h>
+
+namespace android {
+
+using Status = ::ndk::ScopedAStatus;
+using ::aidl::android::media::BnResourceObserver;
+using ::aidl::android::media::IResourceObserverService;
+using ::aidl::android::media::MediaObservableEvent;
+using ::aidl::android::media::MediaObservableFilter;
+using ::aidl::android::media::MediaObservableParcel;
+using ::aidl::android::media::MediaObservableType;
+
+static std::string toString(const MediaObservableParcel& observable) {
+    return "{" + ::aidl::android::media::toString(observable.type) + ", " +
+           std::to_string(observable.value) + "}";
+}
+
+struct TranscodingResourcePolicy::ResourceObserver : public BnResourceObserver {
+    explicit ResourceObserver(TranscodingResourcePolicy* owner) : mOwner(owner), mPid(getpid()) {}
+
+    // IResourceObserver
+    ::ndk::ScopedAStatus onStatusChanged(
+            MediaObservableEvent event, int32_t uid, int32_t pid,
+            const std::vector<MediaObservableParcel>& observables) override {
+        ALOGD("%s: %s, uid %d, pid %d, %s", __FUNCTION__,
+              ::aidl::android::media::toString(event).c_str(), uid, pid,
+              toString(observables[0]).c_str());
+
+        // Only report kIdle event for codec resources from other processes.
+        if (((uint64_t)event & (uint64_t)MediaObservableEvent::kIdle) != 0 && (pid != mPid)) {
+            for (auto& observable : observables) {
+                if (observable.type == MediaObservableType::kVideoSecureCodec ||
+                    observable.type == MediaObservableType::kVideoNonSecureCodec) {
+                    mOwner->onResourceAvailable();
+                    break;
+                }
+            }
+        }
+        return ::ndk::ScopedAStatus::ok();
+    }
+
+    TranscodingResourcePolicy* mOwner;
+    const pid_t mPid;
+};
+
+// static
+void TranscodingResourcePolicy::BinderDiedCallback(void* cookie) {
+    TranscodingResourcePolicy* owner = reinterpret_cast<TranscodingResourcePolicy*>(cookie);
+    if (owner != nullptr) {
+        owner->unregisterSelf();
+    }
+    // TODO(chz): retry to connecting to IResourceObserverService after failure.
+    // Also need to have back-up logic if IResourceObserverService is offline for
+    // Prolonged period of time. A possible alternative could be, during period where
+    // IResourceObserverService is not available, trigger onResourceAvailable() everytime
+    // when top uid changes (in hope that'll free up some codec instances that we could
+    // reclaim).
+}
+
+TranscodingResourcePolicy::TranscodingResourcePolicy()
+      : mRegistered(false), mDeathRecipient(AIBinder_DeathRecipient_new(BinderDiedCallback)) {
+    registerSelf();
+}
+
+TranscodingResourcePolicy::~TranscodingResourcePolicy() {
+    unregisterSelf();
+}
+
+void TranscodingResourcePolicy::registerSelf() {
+    ALOGI("TranscodingResourcePolicy: registerSelf");
+
+    ::ndk::SpAIBinder binder(AServiceManager_getService("media.resource_observer"));
+
+    std::scoped_lock lock{mRegisteredLock};
+
+    if (mRegistered) {
+        return;
+    }
+
+    // TODO(chz): retry to connecting to IResourceObserverService after failure.
+    mService = IResourceObserverService::fromBinder(binder);
+    if (mService == nullptr) {
+        ALOGE("Failed to get IResourceObserverService");
+        return;
+    }
+
+    // Only register filters for codec resource available.
+    mObserver = ::ndk::SharedRefBase::make<ResourceObserver>(this);
+    std::vector<MediaObservableFilter> filters = {
+            {MediaObservableType::kVideoSecureCodec, MediaObservableEvent::kIdle},
+            {MediaObservableType::kVideoNonSecureCodec, MediaObservableEvent::kIdle}};
+
+    Status status = mService->registerObserver(mObserver, filters);
+    if (!status.isOk()) {
+        ALOGE("failed to register: error %d", status.getServiceSpecificError());
+        mService = nullptr;
+        mObserver = nullptr;
+        return;
+    }
+
+    AIBinder_linkToDeath(binder.get(), mDeathRecipient.get(), reinterpret_cast<void*>(this));
+
+    ALOGD("@@@ registered observer");
+    mRegistered = true;
+}
+
+void TranscodingResourcePolicy::unregisterSelf() {
+    ALOGI("TranscodingResourcePolicy: unregisterSelf");
+
+    std::scoped_lock lock{mRegisteredLock};
+
+    if (!mRegistered) {
+        return;
+    }
+
+    ::ndk::SpAIBinder binder = mService->asBinder();
+    if (binder.get() != nullptr) {
+        Status status = mService->unregisterObserver(mObserver);
+        AIBinder_unlinkToDeath(binder.get(), mDeathRecipient.get(), reinterpret_cast<void*>(this));
+    }
+
+    mService = nullptr;
+    mObserver = nullptr;
+    mRegistered = false;
+}
+
+void TranscodingResourcePolicy::setCallback(
+        const std::shared_ptr<ResourcePolicyCallbackInterface>& cb) {
+    std::scoped_lock lock{mCallbackLock};
+    mResourcePolicyCallback = cb;
+}
+
+void TranscodingResourcePolicy::onResourceAvailable() {
+    std::shared_ptr<ResourcePolicyCallbackInterface> cb;
+    {
+        std::scoped_lock lock{mCallbackLock};
+        cb = mResourcePolicyCallback.lock();
+    }
+
+    if (cb != nullptr) {
+        cb->onResourceAvailable();
+    }
+}
+}  // namespace android