41 // struct to store queue information.
43   // type of data in the queue.
45   // flavor of the queue (sync or unsync).
47   // pointer to the actual queue object.
51 // A fast message queue class that manages all fast message queues created
53 // into the queue.
71   // Constructor to initialize a Fast Message Queue (FMQ) manager.
80   // Creates a brand new FMQ, i.e. the "first message queue object".
82   // @param data_type  type of data in the queue. This information is stored
84   // @param queue_size number of elements in the queue.
85   // @param blocking   whether to enable blocking within the queue.
87   // @return message queue object id associated with the caller on success,
92   // Creates a new FMQ object based on an existing message queue
95   // @param data_type      type of data in the queue. This information is stored
97   // @param queue_id       identifies the message queue object.
100   // @return message queue object id associated with the caller on success,
106   // Creates a new FMQ object based on an existing message queue
107   // (Using queue descriptor.).
108   // This method will reset read/write pointers in the new queue object.
110   // @param data_type        type of data in the queue. This information is
112   // @param queue_descriptor pointer to descriptor of an existing queue.
114   // @return message queue object id associated with the caller on success,
121   // @param data_type type of data in the queue. This information is verified
123   // @param queue_id  identifies the message queue object.
136   // message queue object" of the FMQ.
138   // @param data_type      type of data in the queue. This information is
140   // @param queue_id       identifies the message queue object.
153   // @param data_type          type of data in the queue. This information is
156   // @param queue_id           identifies the message queue object.
175   // @param data_type type of data in the queue. This information is verified
177   // @param queue_id  identifies the message queue object.
188   // the queue.
190   // message queue object" of the FMQ.
192   // @param data_type      type of data in the queue. This information is
195   // @param queue_id       identifies the message queue object.
208   // @param data_type          type of data in the queue. This information is
211   // @param queue_id           identifies the message queue object.
228   // Gets space available to write in the queue.
230   // @param data_type type of data in the queue. This information is
232   // @param queue_id  identifies the message queue object.
234   //                  the return value signals if the queue is found correctly.
236   // @return true if queue is found and type matches, and puts actual result in
243   // Gets number of items available to read in the queue.
245   // @param data_type type of data in the queue. This information is
247   // @param queue_id  identifies the message queue object.
249   //                  the return value signals if the queue is found correctly.
251   // @return true if queue is found and type matches, and puts actual result in
258   // Gets size of item in the queue.
260   // @param data_type type of data in the queue. This information is
262   // @param queue_id  identifies the message queue object.
264   //                  the return value signals if the queue is found correctly.
266   // @return true if queue is found and type matches, and puts actual result in
273   // Gets number of items that fit in the queue.
275   // @param data_type type of data in the queue. This information is
277   // @param queue_id  identifies the message queue object.
279   //                  the return value signals if the queue is found correctly.
281   // @return true if queue is found and type matches, and puts actual result in
288   // Checks if the queue associated with queue_id is valid.
290   // @param data_type type of data in the queue. This information is
292   // @param queue_id  identifies the message queue object.
294   // @return true if the queue object is valid, false otherwise.
298   // Gets event flag word of the queue, which allows multiple queues
303   // @param data_type type of data in the queue. This information is
305   // @param queue_id  identifies the message queue object.
307   //                  the return value signals if the queue is found correctly.
309   // @return true if queue is found and type matches, and puts actual result in
316   // Gets the address of queue descriptor in memory. This function is called by
319   // @param data_type type of data in the queue. This information is
321   // @param queue_id  identifies the message queue object.
324   // @return true if queue is found, and type matches, and puts actual result in
332   // Finds the queue in the map based on the input queue ID.
334   // @param data_type type of data in the queue. This function verifies this
336   // @param queue_id  identifies the message queue object.
338   // @return the pointer to message queue object,
339   //         nullptr if queue ID is invalid or queue type is misspecified.
343   // Inserts a FMQ object into the map, along with its type of data and queue
344   // flavor. This function ensures only one thread is inserting queue into the
347   // @param data_type    type of data in the queue. This information is stored
351   // @return id associated with the queue.
357   // The key of the hashtable is the queue ID.
358   // The value of the hashtable is a smart pointer to message queue object
359   // information struct associated with the queue ID.
383                << "Fast Message Queue with ID " << queue_id << ".";  in CreateFmq()
421                << "unsynchronized queue.";  in ReadFmqBlocking()
440                << "unsynchronized queue.";  in ReadFmqBlocking()
477                << "unsynchronized queue.";  in WriteFmqBlocking()
496                << "unsynchronized queue.";  in WriteFmqBlocking()
591   if (iterator == fmq_map_.end()) {  // queue not found  in FindQueue()
592     LOG(ERROR) << "FMQ Driver: cannot find Fast Message Queue with ID "  in FindQueue()
598   if (queue_info->queue_data_type != data_type) {  // queue data type incorrect  in FindQueue()
605   if (queue_info->queue_flavor != flavor) {  // queue flavor incorrect  in FindQueue()
607                << "doesn't match with the stored queue flavor "  in FindQueue()
612   // type check passes, extract queue from the struct  in FindQueue()
628   // Create a struct to store queue object, type of data, and  in InsertQueue()
629   // queue flavor.  in InsertQueue()