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/*
* Copyright (C) 2021 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 android_hardware_automotive_vehicle_aidl_impl_vhal_include_PendingRequestPool_H_
#define android_hardware_automotive_vehicle_aidl_impl_vhal_include_PendingRequestPool_H_
#include <VehicleUtils.h>
#include <android-base/result.h>
#include <android-base/thread_annotations.h>
#include <atomic>
#include <list>
#include <mutex>
#include <thread>
#include <unordered_map>
#include <unordered_set>
namespace android {
namespace hardware {
namespace automotive {
namespace vehicle {
// A thread-safe pending request pool that tracks whether each request has timed-out.
class PendingRequestPool final {
public:
using TimeoutCallbackFunc = std::function<void(const std::unordered_set<int64_t>&)>;
explicit PendingRequestPool(int64_t timeoutInNano);
~PendingRequestPool();
// Adds a list of requests to the request pool.
// The clientId is the key for all the requests. It could be a number or an address to a data
// structure that represents a client. The caller must maintain this data structure.
// All the request IDs must be unique for one client, if any of the requestIds is duplicate with
// any pending request IDs for the client, this function returns error and no requests would be
// added. Otherwise, they would be added to the request pool.
// The callback would be called if requests are not finished within {@code mTimeoutInNano}
// seconds.
VhalResult<void> addRequests(const void* clientId,
const std::unordered_set<int64_t>& requestIds,
std::shared_ptr<const TimeoutCallbackFunc> callback);
// Checks whether the request is currently pending.
bool isRequestPending(const void* clientId, int64_t requestId) const;
// Tries to mark the requests as finished and remove them from the pool if the request is
// currently pending. Returns the list of request that is pending and has been finished
// successfully. This function would try to finish any valid requestIds even though some of the
// requestIds are not valid.
std::unordered_set<int64_t> tryFinishRequests(const void* clientId,
const std::unordered_set<int64_t>& requestIds);
// Returns how many pending requests in the pool, for testing purpose.
size_t countPendingRequests(const void* clientId) const;
size_t countPendingRequests() const;
private:
// The maximum number of pending requests allowed per client. If exceeds this number, adding
// more requests would fail. This is to prevent spamming from client.
static constexpr size_t MAX_PENDING_REQUEST_PER_CLIENT = 10000;
struct PendingRequest {
std::unordered_set<int64_t> requestIds;
int64_t timeoutTimestamp;
std::shared_ptr<const TimeoutCallbackFunc> callback;
};
int64_t mTimeoutInNano;
mutable std::mutex mLock;
std::unordered_map<const void*, std::list<PendingRequest>> mPendingRequestsByClient
GUARDED_BY(mLock);
std::thread mThread;
std::atomic<bool> mThreadStop = false;
std::condition_variable mCv;
std::mutex mCvLock;
bool isRequestPendingLocked(const void* clientId, int64_t requestId) const REQUIRES(mLock);
// Checks whether the requests in the pool has timed-out, run periodically in a separate thread.
void checkTimeout();
};
} // namespace vehicle
} // namespace automotive
} // namespace hardware
} // namespace android
#endif // android_hardware_automotive_vehicle_aidl_impl_vhal_include_PendingRequestPool_H_
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