event_loop.h revision 4788193c974230e6f1813b20773bb2370d109179
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/platform/power_control_manager.h" 26#include "chre/util/dynamic_vector.h" 27#include "chre/util/fixed_size_blocking_queue.h" 28#include "chre/util/non_copyable.h" 29#include "chre/util/synchronized_memory_pool.h" 30#include "chre/util/unique_ptr.h" 31#include "chre_api/chre/event.h" 32 33namespace chre { 34 35/** 36 * The EventLoop represents a single thread of execution that is shared among 37 * zero or more nanoapps. As the name implies, the EventLoop is built around a 38 * loop that delivers events to the nanoapps managed within for processing. 39 */ 40class EventLoop : public NonCopyable { 41 public: 42 /** 43 * Synchronous callback used with forEachNanoapp 44 */ 45 typedef void (NanoappCallbackFunction)(const Nanoapp *nanoapp, void *data); 46 47 /** 48 * Searches the set of nanoapps managed by this EventLoop for one with the 49 * given app ID. If found, provides its instance ID, which can be used to send 50 * events to the app. 51 * 52 * This function is safe to call from any thread. 53 * 54 * @param appId The nanoapp identifier to search for. 55 * @param instanceId If this function returns true, will be populated with the 56 * instanceId associated with the given appId; otherwise unmodified. 57 * Must not be null. 58 * @return true if the given app ID was found and instanceId was populated 59 */ 60 bool findNanoappInstanceIdByAppId(uint64_t appId, uint32_t *instanceId) const; 61 62 /** 63 * Iterates over the list of Nanoapps managed by this EventLoop, and invokes 64 * the supplied callback for each one. This holds a lock if necessary, so it 65 * is safe to call from any thread. 66 * 67 * @param callback Function to invoke on each Nanoapp (synchronously) 68 * @param data Arbitrary data to pass to the callback 69 */ 70 void forEachNanoapp(NanoappCallbackFunction *callback, void *data); 71 72 /** 73 * Invokes a message to host free callback supplied by the given nanoapp 74 * (identified by app ID). Ensures that the calling context is updated 75 * appropriately. 76 * 77 * @param appId Identifies the nanoapp that sent this message and supplied the 78 * free callback 79 * @param freeFunction The non-null message free callback given by the nanoapp 80 * @param message Pointer to the message data 81 * @param messageSize Size of the message 82 */ 83 void invokeMessageFreeFunction( 84 uint64_t appId, chreMessageFreeFunction *freeFunction, void *message, 85 size_t messageSize); 86 87 /** 88 * Invokes the Nanoapp's start callback, and if successful, adds it to the 89 * set of Nanoapps managed by this EventLoop. This function must only be 90 * called from the context of the thread that runs this event loop (i.e. from 91 * the same thread that will call run() or from a callback invoked within 92 * run()). 93 * 94 * @param nanoapp The nanoapp that will be started. Upon success, this 95 * UniquePtr will become invalid, as the underlying Nanoapp instance 96 * will have been transferred to be managed by this EventLoop. 97 * @return true if the app was started successfully 98 */ 99 bool startNanoapp(UniquePtr<Nanoapp>& nanoapp); 100 101 /** 102 * Stops and unloads a nanoapp identified by its instance ID. The end entry 103 * point will be invoked, and the chre::Nanoapp instance will be destroyed. 104 * After this function returns, all references to the Nanoapp instance are 105 * invalidated. 106 * 107 * @param instanceId The nanoapp's unique instance identifier 108 * @param allowSystemNanoappUnload If false, this function will reject 109 * attempts to unload a system nanoapp 110 * 111 * @return true if the nanoapp with the given instance ID was found & unloaded 112 */ 113 bool unloadNanoapp(uint32_t instanceId, bool allowSystemNanoappUnload); 114 115 /** 116 * Executes the loop that blocks on the event queue and delivers received 117 * events to nanoapps. Only returns after stop() is called (from another 118 * context). 119 */ 120 void run(); 121 122 /** 123 * Signals the event loop currently executing in run() to exit gracefully at 124 * the next available opportunity. This function is thread-safe. 125 */ 126 void stop(); 127 128 /** 129 * Posts an event to a nanoapp that is currently running (or all nanoapps if 130 * the target instance ID is kBroadcastInstanceId). 131 * 132 * This function is safe to call from any thread. 133 * 134 * @param eventType The type of data being posted. 135 * @param eventData The data being posted. 136 * @param freeCallback The callback to invoke when the event is no longer 137 * needed. 138 * @param senderInstanceId The instance ID of the sender of this event. 139 * @param targetInstanceId The instance ID of the destination of this event. 140 * 141 * @return true if the event was successfully added to the queue. Note that 142 * unlike chreSendEvent, this does *not* invoke the free callback if 143 * it failed to post the event. 144 * 145 * @see chreSendEvent 146 */ 147 bool postEvent(uint16_t eventType, void *eventData, 148 chreEventCompleteFunction *freeCallback, 149 uint32_t senderInstanceId = kSystemInstanceId, 150 uint32_t targetInstanceId = kBroadcastInstanceId); 151 152 /** 153 * Returns a pointer to the currently executing Nanoapp, or nullptr if none is 154 * currently executing. Must only be called from within the thread context 155 * associated with this EventLoop. 156 * 157 * @return the currently executing nanoapp, or nullptr 158 */ 159 Nanoapp *getCurrentNanoapp() const { 160 return mCurrentApp; 161 } 162 163 /** 164 * Gets the number of nanoapps currently associated with this event loop. Must 165 * only be called within the context of this EventLoop. 166 * 167 * @return The number of nanoapps managed by this event loop 168 */ 169 size_t getNanoappCount() const { 170 return mNanoapps.size(); 171 } 172 173 /** 174 * Obtains the TimerPool associated with this event loop. 175 * 176 * @return The timer pool owned by this event loop. 177 */ 178 TimerPool& getTimerPool() { 179 return mTimerPool; 180 } 181 182 /** 183 * Searches the set of nanoapps managed by this EventLoop for one with the 184 * given instance ID. 185 * 186 * This function is safe to call from any thread. 187 * 188 * @param instanceId The nanoapp instance ID to search for. 189 * @return a pointer to the found nanoapp or nullptr if no match was found. 190 */ 191 Nanoapp *findNanoappByInstanceId(uint32_t instanceId) const; 192 193 /** 194 * Looks for an app with the given ID and if found, populates info with its 195 * metadata. Safe to call from any thread. 196 * 197 * @see chreGetNanoappInfoByAppId 198 */ 199 bool populateNanoappInfoForAppId(uint64_t appId, 200 struct chreNanoappInfo *info) const; 201 202 /** 203 * Looks for an app with the given instance ID and if found, populates info 204 * with its metadata. Safe to call from any thread. 205 * 206 * @see chreGetNanoappInfoByInstanceId 207 */ 208 bool populateNanoappInfoForInstanceId(uint32_t instanceId, 209 struct chreNanoappInfo *info) const; 210 211 /** 212 * @return true if the current Nanoapp (or entire CHRE) is being unloaded, and 213 * therefore it should not be allowed to send events or messages, etc. 214 */ 215 bool currentNanoappIsStopping() const; 216 217 /** 218 * Prints state in a string buffer. Must only be called from the context of 219 * the main CHRE thread. 220 * 221 * @param buffer Pointer to the start of the buffer. 222 * @param bufferPos Pointer to buffer position to start the print (in-out). 223 * @param size Size of the buffer in bytes. 224 * 225 * @return true if entire log printed, false if overflow or error. 226 */ 227 bool logStateToBuffer(char *buffer, size_t *bufferPos, 228 size_t bufferSize) const; 229 230 231 /** 232 * Returns a reference to the power control manager. This allows power 233 * controls from subsystems outside the event loops. 234 */ 235 PowerControlManager& getPowerControlManager() { 236 return mPowerControlManager; 237 } 238 239 private: 240 //! The maximum number of events that can be active in the system. 241 static constexpr size_t kMaxEventCount = 96; 242 243 //! The maximum number of events that are awaiting to be scheduled. These 244 //! events are in a queue to be distributed to apps. 245 static constexpr size_t kMaxUnscheduledEventCount = 96; 246 247 //! The memory pool to allocate incoming events from. 248 SynchronizedMemoryPool<Event, kMaxEventCount> mEventPool; 249 250 //! The timer used schedule timed events for tasks running in this event loop. 251 TimerPool mTimerPool; 252 253 //! The list of nanoapps managed by this event loop. 254 DynamicVector<UniquePtr<Nanoapp>> mNanoapps; 255 256 //! This lock *must* be held whenever we: 257 //! (1) make changes to the mNanoapps vector, or 258 //! (2) read the mNanoapps vector from a thread other than the one 259 //! associated with this EventLoop 260 //! It is not necessary to acquire the lock when reading mNanoapps from within 261 //! the thread context of this EventLoop. 262 mutable Mutex mNanoappsLock; 263 264 //! The blocking queue of incoming events from the system that have not been 265 //! distributed out to apps yet. 266 FixedSizeBlockingQueue<Event *, kMaxUnscheduledEventCount> mEvents; 267 268 // TODO: should probably be atomic to be fully correct 269 volatile bool mRunning = true; 270 271 //! The nanoapp that is currently executing - must be set any time we call 272 //! into the nanoapp's entry points or callbacks 273 Nanoapp *mCurrentApp = nullptr; 274 275 //! Set to the nanoapp we are in the process of unloading in unloadNanoapp() 276 Nanoapp *mStoppingNanoapp = nullptr; 277 278 //! The object which manages power related controls. 279 PowerControlManager mPowerControlManager; 280 281 //! The maximum number of events ever waiting in the event pool. 282 size_t mMaxEventPoolUsage = 0; 283 284 /** 285 * Do one round of Nanoapp event delivery, only considering events in 286 * Nanoapps' own queues (not mEvents). 287 * 288 * @return true if there are more events pending in Nanoapps' own queues 289 */ 290 bool deliverEvents(); 291 292 /** 293 * Delivers the next event pending in the Nanoapp's queue, and takes care of 294 * freeing events once they have been delivered to all nanoapps. Must only be 295 * called after confirming that the app has at least 1 pending event. 296 * 297 * @return true if the nanoapp has another event pending in its queue 298 */ 299 bool deliverNextEvent(const UniquePtr<Nanoapp>& app); 300 301 /** 302 * Given an event pulled from the main incoming event queue (mEvents), deliver 303 * it to all Nanoapps that should receive the event, or free the event if 304 * there are no valid recipients. 305 * 306 * @param event The Event to distribute to Nanoapps 307 */ 308 void distributeEvent(Event *event); 309 310 /** 311 * Distribute all events pending in the inbound event queue. Note that this 312 * function only guarantees that any events in the inbound queue at the time 313 * it is called will be distributed to Nanoapp event queues - new events may 314 * still be posted during or after this function call from other threads as 315 * long as postEvent() will accept them. 316 */ 317 void flushInboundEventQueue(); 318 319 /** 320 * Delivers events pending in Nanoapps' own queues until they are all empty. 321 */ 322 void flushNanoappEventQueues(); 323 324 /** 325 * Call after when an Event has been delivered to all intended recipients. 326 * Invokes the event's free callback (if given) and releases resources. 327 * 328 * @param event The event to be freed 329 */ 330 void freeEvent(Event *event); 331 332 /** 333 * Finds a Nanoapp with the given 64-bit appId. 334 * 335 * Only safe to call within this EventLoop's thread, or if mNanoappsLock is 336 * held. 337 * 338 * @param appId Nanoapp ID 339 * @return Pointer to Nanoapp instance in this EventLoop with the given app 340 * ID, or nullptr if not found 341 */ 342 Nanoapp *lookupAppByAppId(uint64_t appId) const; 343 344 /** 345 * Finds a Nanoapp with the given instanceId. 346 * 347 * Only safe to call within this EventLoop's thread, or if mNanoappsLock is 348 * held. 349 * 350 * @param instanceId Nanoapp instance identifier 351 * @return Nanoapp with the given instanceId, or nullptr if not found 352 */ 353 Nanoapp *lookupAppByInstanceId(uint32_t instanceId) const; 354 355 /** 356 * Sends an event with payload struct chreNanoappInfo populated from the given 357 * Nanoapp instance to inform other nanoapps about it starting/stopping. 358 * 359 * @param eventType Should be one of CHRE_EVENT_NANOAPP_{STARTED, STOPPED} 360 * @param nanoapp The nanoapp instance whose status has changed 361 */ 362 void notifyAppStatusChange(uint16_t eventType, const Nanoapp& nanoapp); 363 364 /** 365 * Stops and unloads the Nanoapp at the given index in mNanoapps. 366 * 367 * IMPORTANT: prior to calling this function, the event queues must be in a 368 * safe condition for removal of this nanoapp. This means that there must not 369 * be any pending events in this nanoapp's queue, and there must not be any 370 * outstanding events sent by this nanoapp, as they may reference the 371 * nanoapp's own memory (even if there is no free callback). 372 */ 373 void unloadNanoappAtIndex(size_t index); 374}; 375 376} // namespace chre 377 378#endif // CHRE_CORE_EVENT_LOOP_H_ 379