1 /* 2 * Copyright (C) 2016 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 CHRE_CORE_EVENT_LOOP_H_ 18 #define CHRE_CORE_EVENT_LOOP_H_ 19 20 #include "chre/core/event.h" 21 #include "chre/core/nanoapp.h" 22 #include "chre/core/timer_pool.h" 23 #include "chre/platform/mutex.h" 24 #include "chre/platform/platform_nanoapp.h" 25 #include "chre/util/dynamic_vector.h" 26 #include "chre/util/fixed_size_blocking_queue.h" 27 #include "chre/util/non_copyable.h" 28 #include "chre/util/synchronized_memory_pool.h" 29 #include "chre/util/unique_ptr.h" 30 31 namespace chre { 32 33 /** 34 * The EventLoop represents a single thread of execution that is shared among 35 * zero or more nanoapps. As the name implies, the EventLoop is built around a 36 * loop that delivers events to the nanoapps managed within for processing. 37 */ 38 class EventLoop : public NonCopyable { 39 public: 40 /** 41 * Setup the event loop. 42 */ 43 EventLoop(); 44 45 /** 46 * Synchronous callback used with forEachNanoapp 47 */ 48 typedef void (NanoappCallbackFunction)(const Nanoapp *nanoapp, void *data); 49 50 /** 51 * Searches the set of nanoapps managed by this EventLoop for one with the 52 * given app ID. If found, provides its instance ID, which can be used to send 53 * events to the app. 54 * 55 * This function is safe to call from any thread. 56 * 57 * @param appId The nanoapp identifier to search for. 58 * @param instanceId If this function returns true, will be populated with the 59 * instanceId associated with the given appId; otherwise unmodified. 60 * Must not be null. 61 * @return true if the given app ID was found and instanceId was populated 62 */ 63 bool findNanoappInstanceIdByAppId(uint64_t appId, uint32_t *instanceId); 64 65 /** 66 * Iterates over the list of Nanoapps managed by this EventLoop, and invokes 67 * the supplied callback for each one. This holds a lock if necessary, so it 68 * is safe to call from any thread. 69 * 70 * @param callback Function to invoke on each Nanoapp (synchronously) 71 * @param data Arbitrary data to pass to the callback 72 */ 73 void forEachNanoapp(NanoappCallbackFunction *callback, void *data); 74 75 /** 76 * Invokes the Nanoapp's start callback, and if successful, adds it to the 77 * set of Nanoapps managed by this EventLoop. This function must only be 78 * called from the context of the thread that runs this event loop (i.e. from 79 * the same thread that will call run() or from a callback invoked within 80 * run()). 81 * 82 * @param nanoapp The nanoapp that will be started. Upon success, this 83 * UniquePtr will become invalid, as the underlying Nanoapp instance 84 * will have been transferred to be managed by this EventLoop. 85 * @return true if the app was started successfully 86 */ 87 bool startNanoapp(UniquePtr<Nanoapp>& nanoapp); 88 89 /** 90 * Stops a nanoapp by invoking the stop entry point. The nanoapp passed in 91 * must have been previously started by the startNanoapp method. After this 92 * function returns, all references to the Nanoapp are invalid. 93 * 94 * @param nanoapp A pointer to the nanoapp to stop. 95 */ 96 void stopNanoapp(Nanoapp *nanoapp); 97 98 /** 99 * Executes the loop that blocks on the event queue and delivers received 100 * events to nanoapps. Only returns after stop() is called (from another 101 * context). 102 */ 103 void run(); 104 105 /** 106 * Signals the event loop currently executing in run() to exit gracefully at 107 * the next available opportunity. This function is thread-safe. 108 */ 109 void stop(); 110 111 /** 112 * Posts an event to a nanoapp that is currently running (or all nanoapps if 113 * the target instance ID is kBroadcastInstanceId). 114 * 115 * This function is safe to call from any thread. 116 * 117 * @param eventType The type of data being posted. 118 * @param eventData The data being posted. 119 * @param freeCallback The callback to invoke when the event is no longer 120 * needed. 121 * @param senderInstanceId The instance ID of the sender of this event. 122 * @param targetInstanceId The instance ID of the destination of this event. 123 * 124 * @return true if the event was successfully added to the queue 125 * 126 * @see chreSendEvent 127 */ 128 bool postEvent(uint16_t eventType, void *eventData, 129 chreEventCompleteFunction *freeCallback, 130 uint32_t senderInstanceId = kSystemInstanceId, 131 uint32_t targetInstanceId = kBroadcastInstanceId); 132 133 /** 134 * Returns a pointer to the currently executing Nanoapp, or nullptr if none is 135 * currently executing. Must only be called from within the thread context 136 * associated with this EventLoop. 137 * 138 * @return the currently executing nanoapp, or nullptr 139 */ 140 Nanoapp *getCurrentNanoapp() const; 141 142 /** 143 * Gets the number of nanoapps currently associated with this event loop. Must 144 * only be called within the context of this EventLoop. 145 * 146 * @return The number of nanoapps managed by this event loop 147 */ 148 size_t getNanoappCount() const; 149 150 /** 151 * Obtains the TimerPool associated with this event loop. 152 * 153 * @return The timer pool owned by this event loop. 154 */ 155 TimerPool& getTimerPool(); 156 157 /** 158 * Searches the set of nanoapps managed by this EventLoop for one with the 159 * given instance ID. 160 * 161 * This function is safe to call from any thread. 162 * 163 * @param instanceId The nanoapp instance ID to search for. 164 * @return a pointer to the found nanoapp or nullptr if no match was found. 165 */ 166 Nanoapp *findNanoappByInstanceId(uint32_t instanceId); 167 168 private: 169 //! The maximum number of events that can be active in the system. 170 static constexpr size_t kMaxEventCount = 1024; 171 172 //! The maximum number of events that are awaiting to be scheduled. These 173 //! events are in a queue to be distributed to apps. 174 static constexpr size_t kMaxUnscheduledEventCount = 1024; 175 176 //! The memory pool to allocate incoming events from. 177 SynchronizedMemoryPool<Event, kMaxEventCount> mEventPool; 178 179 //! The timer used schedule timed events for tasks running in this event loop. 180 TimerPool mTimerPool; 181 182 //! The list of nanoapps managed by this event loop. 183 DynamicVector<UniquePtr<Nanoapp>> mNanoapps; 184 185 //! This lock *must* be held whenever we: 186 //! (1) make changes to the mNanoapps vector, or 187 //! (2) read the mNanoapps vector from a thread other than the one 188 //! associated with this EventLoop 189 //! It is not necessary to acquire the lock when reading mNanoapps from within 190 //! the thread context of this EventLoop. 191 Mutex mNanoappsLock; 192 193 //! The blocking queue of incoming events from the system that have not been 194 //! distributed out to apps yet. 195 FixedSizeBlockingQueue<Event *, kMaxUnscheduledEventCount> mEvents; 196 197 // TODO: should probably be atomic to be fully correct 198 volatile bool mRunning = false; 199 200 Nanoapp *mCurrentApp = nullptr; 201 202 /** 203 * Delivers the next event pending in the Nanoapp's queue, and takes care of 204 * freeing events once they have been delivered to all nanoapps. Must only be 205 * called after confirming that the app has at least 1 pending event. 206 * 207 * @return true if the nanoapp has another event pending in its queue 208 */ 209 bool deliverNextEvent(const UniquePtr<Nanoapp>& app); 210 211 /** 212 * Call after when an Event has been delivered to all intended recipients. 213 * Invokes the event's free callback (if given) and releases resources. 214 * 215 * @param event The event to be freed 216 */ 217 void freeEvent(Event *event); 218 219 /** 220 * Finds a Nanoapp with the given instanceId. 221 * 222 * Only safe to call within this EventLoop's thread. 223 * 224 * @param instanceId Nanoapp instance identifier 225 * @return Nanoapp with the given instanceId, or nullptr if not found 226 */ 227 Nanoapp *lookupAppByInstanceId(uint32_t instanceId); 228 229 /** 230 * Stops the Nanoapp at the given index in mNanoapps 231 */ 232 void stopNanoapp(size_t index); 233 }; 234 235 } // namespace chre 236 237 #endif // CHRE_CORE_EVENT_LOOP_H_ 238