WEBVTT 00:00.440 --> 00:06.200 So guys, now let us discuss the example program that we will going to discuss in order to understand 00:06.200 --> 00:07.440 thread cancellation. 00:07.460 --> 00:14.000 So the program file is present in this path that is Multithreading Bible slash thread basics slash thread 00:14.000 --> 00:18.110 cancellation and the name of the file is master underscore slave one dot c. 00:18.290 --> 00:18.970 Right. 00:18.980 --> 00:25.280 So I have implemented a very basic multithreaded program and the program is all about to create five 00:25.310 --> 00:27.770 threads and all the five threads. 00:27.770 --> 00:32.540 Write a string into a file thread x dot txt where x is a thread id. 00:32.570 --> 00:33.320 Right. 00:33.440 --> 00:36.710 So just assign some thread id to each of these five threads. 00:36.710 --> 00:38.690 Let's say 012, three four. 00:38.780 --> 00:39.530 Right. 00:39.530 --> 00:47.180 And then each of these threads create a file thread x dot txt where x is the thread id and then each 00:47.180 --> 00:49.790 of these threads write a very simple string. 00:49.790 --> 00:53.420 I am thread and thread id into their respective files. 00:53.420 --> 00:54.110 Right. 00:54.110 --> 00:59.360 So you can see that all the five threads write a string into their respective text file. 00:59.360 --> 01:02.460 And this is what this program does, right? 01:02.670 --> 01:09.720 So I'm in the file master slave one dot c and you can go through this file implementation. 01:09.720 --> 01:16.590 It is very simple and you can simply compile this program using shell script, which I have written, 01:16.590 --> 01:25.140 and it will create an executable master slave one dot x simply execute and then simply execute this 01:25.140 --> 01:26.100 executable. 01:26.100 --> 01:26.850 Right? 01:27.730 --> 01:32.500 Now, when you run this executable, it will show you only one choice to select, which is cancel the 01:32.500 --> 01:33.220 thread. 01:33.250 --> 01:34.090 Right. 01:34.210 --> 01:41.440 So you can see that in the main program I have implemented a main menu kind of approach and the choice 01:41.440 --> 01:44.170 number one says that cancel the thread. 01:44.170 --> 01:50.350 Right now, the thread which needs to be canceled is identified by taking an input from the user. 01:50.380 --> 01:53.980 That input is nothing, but it is a thread ID, right. 01:54.160 --> 01:57.070 So you can see that as soon as the program starts. 01:57.070 --> 01:59.650 I am just creating five threads here. 01:59.650 --> 02:03.340 This macro and slaves is equated to five. 02:03.340 --> 02:03.970 Right. 02:04.000 --> 02:07.740 You can change this number to any value as per your choice. 02:07.750 --> 02:14.170 So here you can see that I am creating a loop and creating five threads, passing the respective thread 02:14.200 --> 02:15.550 ID as an argument. 02:15.550 --> 02:16.300 Right. 02:16.600 --> 02:22.690 So if you go into this function right into file, you will find that each of the thread is iterating 02:22.690 --> 02:25.660 into an infinite loop with a sleep value one. 02:25.660 --> 02:26.410 Right. 02:26.410 --> 02:32.110 And each thread is simply writing a text string into its respective text file. 02:32.120 --> 02:35.960 The name of the text file can be derived using as print function. 02:35.960 --> 02:36.650 Right. 02:37.700 --> 02:43.700 Using a sprinter function, you can cook up the file name using thread ID, and then you can open the 02:43.700 --> 02:45.680 file with that name in the right mode. 02:45.680 --> 02:46.400 Right. 02:46.400 --> 02:53.030 And then your thread can enter into an infinite loop writing a text string into its respective text 02:53.030 --> 02:53.540 file. 02:53.540 --> 02:54.260 Right. 02:55.070 --> 02:59.860 So now in the another window, you can see that I had already executed the executable. 02:59.870 --> 03:06.130 It simply means that each of the five threads must be writing a string into their files. 03:06.140 --> 03:11.690 So if you look into this directory, you can see that corresponding to each of the five threads, their 03:11.690 --> 03:13.910 respective text files have been created. 03:13.910 --> 03:14.690 Right? 03:14.780 --> 03:22.520 So using tail minus F command, you can check any of these file and see whether the thread is writing 03:22.520 --> 03:24.470 the content into this file or not. 03:24.470 --> 03:25.250 Right. 03:25.250 --> 03:31.370 So you can check any of these text files and you will find that each of the thread is writing this string 03:31.370 --> 03:32.540 into their file. 03:33.140 --> 03:39.320 So I expect you that you go through this very short program which is only 90 lines of code. 03:39.350 --> 03:40.820 Understand this program. 03:40.820 --> 03:46.010 And then in the next lecture video we will see how we can implement thread cancellation. 03:46.010 --> 03:46.730 Right? 03:47.150 --> 03:50.300 Basically, we need to implement this case, number one. 03:50.330 --> 03:54.320 That is, we need to cancel the thread based on the user input here. 03:54.320 --> 03:58.650 The user input is nothing, but it is the thread ID, right. 03:59.610 --> 04:05.130 So if the user provides an input, say three, we will going to cancel the thread with thread ID three. 04:05.160 --> 04:09.490 Here, thread id simply will be the index of this array. 04:09.510 --> 04:14.250 This is the array which I have taken in order to represent the five threads writing the content into 04:14.250 --> 04:15.130 a text file. 04:15.150 --> 04:15.900 Right. 04:15.930 --> 04:21.680 This is the array of thread handles and at the time of creation of the thread it is. 04:21.690 --> 04:27.000 I obtained the thread handle from that array in order to pass as a first argument to this thread. 04:27.030 --> 04:28.380 Underscore create API. 04:28.590 --> 04:29.340 Right. 04:30.590 --> 04:36.440 So basically in this program you have all the thread handles stored in this global array so that you 04:36.440 --> 04:42.590 have access to all the thread handles and we will see that how we can make use of this global array 04:42.710 --> 04:49.930 storing thread handles in order to cancel the threads whose ID has been entered or asked from the user. 04:49.940 --> 04:50.660 Right.