wifi/1.4/default/hidl_callback_util.h

/*
 * Copyright (C) 2017 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.
 */

#ifndef HIDL_CALLBACK_UTIL_H_
#define HIDL_CALLBACK_UTIL_H_

#include <set>

#include <hidl/HidlSupport.h>

namespace {
// Type of callback invoked by the death handler.
using on_death_cb_function = std::function<void(uint64_t)>;

// Private class used to keep track of death of individual
// callbacks stored in HidlCallbackHandler.
template <typename CallbackType>
class HidlDeathHandler : public android::hardware::hidl_death_recipient {
   public:
    HidlDeathHandler(const on_death_cb_function& user_cb_function)
        : cb_function_(user_cb_function) {}
    ~HidlDeathHandler() = default;

    // Death notification for callbacks.
    void serviceDied(
        uint64_t cookie,
        const android::wp<android::hidl::base::V1_0::IBase>& /* who */)
        override {
        cb_function_(cookie);
    }

   private:
    on_death_cb_function cb_function_;

    DISALLOW_COPY_AND_ASSIGN(HidlDeathHandler);
};
}  // namespace

namespace android {
namespace hardware {
namespace wifi {
namespace V1_4 {
namespace implementation {
namespace hidl_callback_util {
template <typename CallbackType>
// Provides a class to manage callbacks for the various HIDL interfaces and
// handle the death of the process hosting each callback.
class HidlCallbackHandler {
   public:
    HidlCallbackHandler()
        : death_handler_(new HidlDeathHandler<CallbackType>(
              std::bind(&HidlCallbackHandler::onObjectDeath, this,
                        std::placeholders::_1))) {}
    ~HidlCallbackHandler() = default;

    bool addCallback(const sp<CallbackType>& cb) {
        // TODO(b/33818800): Can't compare proxies yet. So, use the cookie
        // (callback proxy's raw pointer) to track the death of individual
        // clients.
        uint64_t cookie = reinterpret_cast<uint64_t>(cb.get());
        if (cb_set_.find(cb) != cb_set_.end()) {
            LOG(WARNING) << "Duplicate death notification registration";
            return true;
        }
        if (!cb->linkToDeath(death_handler_, cookie)) {
            LOG(ERROR) << "Failed to register death notification";
            return false;
        }
        cb_set_.insert(cb);
        return true;
    }

    const std::set<android::sp<CallbackType>>& getCallbacks() {
        return cb_set_;
    }

    // Death notification for callbacks.
    void onObjectDeath(uint64_t cookie) {
        CallbackType* cb = reinterpret_cast<CallbackType*>(cookie);
        const auto& iter = cb_set_.find(cb);
        if (iter == cb_set_.end()) {
            LOG(ERROR) << "Unknown callback death notification received";
            return;
        }
        cb_set_.erase(iter);
        LOG(DEBUG) << "Dead callback removed from list";
    }

    void invalidate() {
        for (const sp<CallbackType>& cb : cb_set_) {
            if (!cb->unlinkToDeath(death_handler_)) {
                LOG(ERROR) << "Failed to deregister death notification";
            }
        }
        cb_set_.clear();
    }

   private:
    std::set<sp<CallbackType>> cb_set_;
    sp<HidlDeathHandler<CallbackType>> death_handler_;

    DISALLOW_COPY_AND_ASSIGN(HidlCallbackHandler);
};

}  // namespace hidl_callback_util
}  // namespace implementation
}  // namespace V1_4
}  // namespace wifi
}  // namespace hardware
}  // namespace android
#endif  // HIDL_CALLBACK_UTIL_H_