1 /* 2 * Copyright (C) 2024 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ANDROID_SERVERS_CAMERA_UTILS_H 18 #define ANDROID_SERVERS_CAMERA_UTILS_H 19 20 #include <sched.h> 21 #include <unistd.h> 22 #include <type_traits> 23 24 #include <camera/CameraMetadata.h> 25 26 namespace android { 27 28 /** 29 * Magically convert an enum to its underlying integer type, mostly so they can be 30 * printed with printf-style formatters without warnings. 31 * Backport of C++23 std::to_underlying() 32 */ 33 template<typename Enum> eToI(Enum val)34constexpr std::underlying_type_t<Enum> eToI(Enum val) { 35 return static_cast<std::underlying_type_t<Enum>>(val); 36 } 37 38 /** 39 * Helper function for getting the current VNDK version. 40 * 41 * If the current VNDK version cannot be determined, this function returns 42 * __ANDROID_API_FUTURE__. 43 */ 44 int getVNDKVersion(); 45 46 /** 47 * Returns the deviceId for the given camera metadata. For any virtual camera, this is the id 48 * of the virtual device owning the camera. For any real camera, this is kDefaultDeviceId. 49 */ 50 int32_t getDeviceId(const CameraMetadata& cameraInfo); 51 52 /** 53 * An instance of this class will raise the scheduling policy of a given 54 * given thread to real time and keep it this way throughout the lifetime 55 * of the object. The thread scheduling policy will revert back to its original 56 * state after the instances is released. By default the implementation will 57 * raise the priority of the current thread unless clients explicitly specify 58 * another thread id. 59 * Client must avoid: 60 * - Keeping an instance of this class for extended and long running operations. 61 * This is only intended for short/temporarily priority bumps that mitigate 62 * scheduling delays within critical camera paths. 63 * - Allocating instances of this class on the memory heap unless clients have 64 * complete control over the object lifetime. It is preferable to allocate 65 * instances of this class on the stack instead. 66 * - Nesting multiple instances of this class using the same default or same thread id. 67 */ 68 class RunThreadWithRealtimePriority final { 69 public: 70 RunThreadWithRealtimePriority(int tid = gettid()); 71 ~RunThreadWithRealtimePriority(); 72 73 RunThreadWithRealtimePriority(const RunThreadWithRealtimePriority&) = delete; 74 RunThreadWithRealtimePriority& operator=(const RunThreadWithRealtimePriority&) = delete; 75 76 // SCHED_FIFO priority for request submission thread in HFR mode 77 static const int kRequestThreadPriority = 1; 78 79 private: 80 int mTid; 81 int mPreviousPolicy; 82 bool mPolicyBumped = false; 83 struct sched_param mPreviousParams; 84 }; 85 86 } // namespace android 87 88 #endif //ANDROID_SERVERS_CAMERA_UTILS_H 89