neuralnetworks/1.0/utils/src/ProtectCallback.cpp

/*
 * 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.
 */

#include "ProtectCallback.h"

#include <android-base/logging.h>
#include <android-base/scopeguard.h>
#include <android-base/thread_annotations.h>
#include <android/hidl/base/1.0/IBase.h>
#include <hidl/HidlSupport.h>
#include <nnapi/Result.h>

#include "HandleError.h"

#include <algorithm>
#include <functional>
#include <mutex>
#include <vector>

namespace android::hardware::neuralnetworks::utils {

void DeathRecipient::serviceDied(uint64_t /*cookie*/, const wp<hidl::base::V1_0::IBase>& /*who*/) {
    std::lock_guard guard(mMutex);
    std::for_each(mObjects.begin(), mObjects.end(),
                  [](IProtectedCallback* killable) { killable->notifyAsDeadObject(); });
    mObjects.clear();
    mIsDeadObject = true;
}

void DeathRecipient::add(IProtectedCallback* killable) const {
    CHECK(killable != nullptr);
    std::lock_guard guard(mMutex);
    if (mIsDeadObject) {
        killable->notifyAsDeadObject();
    } else {
        mObjects.push_back(killable);
    }
}

void DeathRecipient::remove(IProtectedCallback* killable) const {
    CHECK(killable != nullptr);
    std::lock_guard guard(mMutex);
    const auto newEnd = std::remove(mObjects.begin(), mObjects.end(), killable);
    mObjects.erase(newEnd, mObjects.end());
}

nn::GeneralResult<DeathHandler> DeathHandler::create(sp<hidl::base::V1_0::IBase> object) {
    if (object == nullptr) {
        return NN_ERROR(nn::ErrorStatus::INVALID_ARGUMENT)
               << "utils::DeathHandler::create must have non-null object";
    }
    auto deathRecipient = sp<DeathRecipient>::make();

    const auto ret = object->linkToDeath(deathRecipient, /*cookie=*/0);
    const bool success = HANDLE_TRANSPORT_FAILURE(ret);
    if (!success) {
        return NN_ERROR(nn::ErrorStatus::GENERAL_FAILURE) << "IBase::linkToDeath returned false";
    }

    return DeathHandler(std::move(object), std::move(deathRecipient));
}

DeathHandler::DeathHandler(sp<hidl::base::V1_0::IBase> object, sp<DeathRecipient> deathRecipient)
    : mObject(std::move(object)), mDeathRecipient(std::move(deathRecipient)) {
    CHECK(mObject != nullptr);
    CHECK(mDeathRecipient != nullptr);
}

DeathHandler::~DeathHandler() {
    if (mObject != nullptr && mDeathRecipient != nullptr) {
        const auto successful = mObject->unlinkToDeath(mDeathRecipient).isOk();
        if (!successful) {
            LOG(ERROR) << "IBase::linkToDeath failed";
        }
    }
}

[[nodiscard]] base::ScopeGuard<DeathHandler::Cleanup> DeathHandler::protectCallback(
        IProtectedCallback* killable) const {
    CHECK(killable != nullptr);
    mDeathRecipient->add(killable);
    return base::make_scope_guard(
            [deathRecipient = mDeathRecipient, killable] { deathRecipient->remove(killable); });
}

void DeathHandler::protectCallbackForLifetimeOfDeathHandler(IProtectedCallback* killable) const {
    CHECK(killable != nullptr);
    mDeathRecipient->add(killable);
}

}  // namespace android::hardware::neuralnetworks::utils