1 00:00:00,690 --> 00:00:01,970 Hello, welcome back. 2 00:00:02,060 --> 00:00:04,590 It's a lesson we should talk about, queue management. 3 00:00:06,010 --> 00:00:13,840 Right, so Q's are used as Pfeifle buffers, where data is inserted at the back and removed from the 4 00:00:13,840 --> 00:00:18,880 front, Kyuss can hold a finite number of fixed data items. 5 00:00:19,420 --> 00:00:24,630 The maximum number of items AQ can hold is called the length of the queue. 6 00:00:25,780 --> 00:00:27,300 OK, parsing data. 7 00:00:27,670 --> 00:00:28,720 We have two options. 8 00:00:28,720 --> 00:00:31,750 We can pass the data by value or pass by reference. 9 00:00:32,020 --> 00:00:37,200 When we see pass by value, we simply insert that data into the queue, the actual data. 10 00:00:37,570 --> 00:00:44,080 But when we say pass by reference, this involves using Qs to transfer pointers to the data rather than 11 00:00:44,080 --> 00:00:48,220 copy the data itself into and out of the Q bite by bite. 12 00:00:48,640 --> 00:00:55,090 This is the preferred way when we are passing large data to the Q and this saves memory. 13 00:00:56,610 --> 00:01:03,660 So let's talk about Blockin with regards to Q When we're dealing with cuz we're going to be right into 14 00:01:03,660 --> 00:01:05,580 the Q or reading from the Q. 15 00:01:07,130 --> 00:01:09,740 When a task attempts to read from a Q. 16 00:01:10,630 --> 00:01:13,580 It can optionally specify a block time. 17 00:01:14,140 --> 00:01:20,140 This is the time the task will be kept in the blocked states to wait for data to be available from the 18 00:01:20,140 --> 00:01:22,170 queue if the queue is empty. 19 00:01:23,220 --> 00:01:28,980 And as soon as that data becomes available, the task automatically moves to the red state. 20 00:01:30,690 --> 00:01:37,540 The same way with regards to writing, the task is placed in the blocked state if the queue is full. 21 00:01:37,560 --> 00:01:41,130 If the queue is full, the task cannot write to the queue. 22 00:01:41,460 --> 00:01:46,750 So it is placed in the blocked state as soon as space becomes available in the queue. 23 00:01:47,130 --> 00:01:49,440 The task is moved to the ready state. 24 00:01:51,040 --> 00:01:51,610 OK. 25 00:01:52,750 --> 00:02:00,010 So let's see some commonly used APIs, we have this one called Excuse and the variations of it, we 26 00:02:00,010 --> 00:02:06,550 have the excuse and we have sent to France into back, but we'll simply be using excuse and to represent 27 00:02:06,550 --> 00:02:07,420 all of these tweets. 28 00:02:07,630 --> 00:02:10,440 And each day this takes three arguments. 29 00:02:10,810 --> 00:02:12,610 The first is the handle of the Q. 30 00:02:13,620 --> 00:02:15,720 The second is the. 31 00:02:17,090 --> 00:02:17,840 The. 32 00:02:19,120 --> 00:02:25,570 They pointed to the buffer, we want to send all the variable, we want to send its address, and then 33 00:02:25,570 --> 00:02:29,470 this is the block time, how much time we want to indicate to wait for this. 34 00:02:30,990 --> 00:02:39,270 Right, we have the Q receive this is the handle of the Q where we want to receive where we want to 35 00:02:39,270 --> 00:02:46,320 store the received data and then the amount of block time we want to wait for this. 36 00:02:47,200 --> 00:02:52,840 OK, and then we have the execute you create, this is used to create the queue, the first argument 37 00:02:52,840 --> 00:02:57,070 is the length of the queue, how many items that is going to hold. 38 00:02:57,370 --> 00:03:01,360 And then the second argument is the size of the items. 39 00:03:02,020 --> 00:03:10,540 OK, now let's see cuz it's cuz it's allow a task to receive data from more than one Q without a task 40 00:03:10,540 --> 00:03:13,210 pool HQ in turn to determine if. 41 00:03:14,340 --> 00:03:22,080 Any of the if any of the tasks, if any, of the queues as new data, so when we use queues, it's the 42 00:03:22,080 --> 00:03:28,930 task automatically receive notification that one of the queues in the queue set has new data. 43 00:03:29,490 --> 00:03:36,690 The task would need to always check is a queue one queue to walk you through with the new data that 44 00:03:37,200 --> 00:03:42,660 is not required when using queues it so queues that allow a task to receive data from more than one 45 00:03:42,660 --> 00:03:47,910 queue without the task polling HQ to determine which one contains the new data. 46 00:03:47,940 --> 00:03:55,860 So if we want to use this, we have to go to our free Arktos config file and set the config use queue 47 00:03:55,860 --> 00:03:56,730 set to one. 48 00:03:58,680 --> 00:04:04,020 Commonly use apps with regards to Cusato is the one for creating a Q set itself is called the X. 49 00:04:04,030 --> 00:04:10,170 Q Great function and this simply takes to the length of the Q. 50 00:04:11,380 --> 00:04:17,440 The length of the queue set and the length of the queue said basically dictate how many queues the queue 51 00:04:17,440 --> 00:04:22,880 sets can hold and then we have the queue to set. 52 00:04:23,110 --> 00:04:28,300 This allows us to add a queue to the queues it and we can also add semaphores to accuse it. 53 00:04:28,450 --> 00:04:32,120 So that is why the first argument is excuse or semaphore. 54 00:04:32,920 --> 00:04:35,320 So the first argument is the queue or SEMAFO. 55 00:04:35,320 --> 00:04:40,270 You want to add to the queue sits and then the second argument is the handle of the queue sits. 56 00:04:40,780 --> 00:04:45,580 The handle of the queue or semaphore you want to add is the first argument and the second argument is 57 00:04:45,580 --> 00:04:47,020 the handle of the queue set. 58 00:04:47,900 --> 00:04:54,560 OK, so that's all there is, so we shall go to our idea and see how this works practically. 59 00:04:54,770 --> 00:04:55,660 I'll see you later.