WEBVTT 00:05.040 --> 00:11.100 So guys, now let us discuss what are the data structures that we need to declare in order to solve 00:11.100 --> 00:12.780 our dining philosopher problem. 00:12.780 --> 00:17.940 So in the dining philosopher problem, you can see that there are usually two types of objects which 00:17.970 --> 00:19.440 interact with each other. 00:19.650 --> 00:23.000 The objects are the philosophers and the spoons. 00:23.010 --> 00:29.610 So it simply means that we need to define the data structures which represents philosophers and which 00:29.610 --> 00:31.800 represent spoons, right? 00:32.700 --> 00:39.810 So in the header file dining philosophers, we have declared or defined the data structures, philosophers 00:39.810 --> 00:41.240 and the data structure. 00:41.250 --> 00:42.060 Spoons. 00:42.060 --> 00:42.840 Right. 00:45.000 --> 00:50.340 Now let us discuss the fields of each of these data structures and what is the use of those fields one 00:50.340 --> 00:51.090 by one. 00:51.330 --> 00:56.190 So if you notice that the philosopher data structure has a philosopher ID. 00:56.580 --> 01:02.970 So in the diagram on the right hand side, you can see that I am addressing the philosophers as th zero 01:02.970 --> 01:05.790 PS1, PS2, PS3, etcetera. 01:05.790 --> 01:06.540 Right. 01:06.570 --> 01:12.690 So it simply means that each philosopher has been given a unique ID 0123 up to N. 01:13.020 --> 01:13.860 Right. 01:14.070 --> 01:18.360 So it is this philosopher ID which uniquely identifies the philosopher. 01:18.510 --> 01:22.440 And we also discussed that philosophers are nothing but they are threads. 01:22.470 --> 01:26.970 Therefore, philosopher data structure needs to have a thread handle right. 01:27.360 --> 01:33.450 And the third member usually do not contribute towards the solution of a dining philosopher problem. 01:33.570 --> 01:42.330 The eat count is a member which keeps a track regarding how many times a philosopher is able to grab 01:42.330 --> 01:46.290 an access to both the spoons and enjoy the cake. 01:46.300 --> 01:47.140 Right? 01:47.260 --> 01:53.920 So every time a philosopher is able to grab an access to both of his spoons, we will going to increment 01:53.920 --> 01:56.140 the eat count variable of that philosopher. 01:56.290 --> 02:00.250 So this is the data structure which represents the philosopher. 02:00.250 --> 02:03.310 And the second data structure is the spoon. 02:03.430 --> 02:06.220 And again, the spoon will have a spoon ID. 02:06.550 --> 02:13.030 So you can see on the diagram on the right hand side, spoons are given names such as SP zero, SP1, 02:13.120 --> 02:14.440 SP2, etcetera. 02:14.620 --> 02:18.220 So every spoon is given an ID, which is an spoon ID. 02:18.670 --> 02:24.250 Now the second variable of the spoon is a boolean variable, which is either true or false. 02:24.280 --> 02:32.080 So as the name suggests, if the spoon is being used by any philosopher, then that particular spoon 02:32.080 --> 02:38.440 is said to be being used and we will set is used flag for that spoon to true. 02:38.620 --> 02:39.430 Right. 02:39.430 --> 02:45.970 And since that spoon is being used by some philosopher, therefore the third member that is this philosopher 02:45.970 --> 02:52.120 pointer will be set to point to that philosopher which has got an access to the spoon. 02:52.360 --> 02:53.140 Right? 02:53.140 --> 02:59.170 So basically here we are keeping a track that if the spoon is being used, then which philosopher is 02:59.170 --> 03:00.430 using that spoon? 03:00.520 --> 03:01.390 Right? 03:01.390 --> 03:08.170 And if the philosopher released the spoon then is used, member of the spoon will be set to false. 03:08.170 --> 03:14.560 And since there is no philosopher who is using that spoon, therefore this philosopher pointer will 03:14.560 --> 03:15.850 be reset to null. 03:16.060 --> 03:16.900 Right. 03:17.470 --> 03:24.730 And in this dining philosopher problem, the spoon is a resource for which the philosophers are competing. 03:24.730 --> 03:25.480 Right? 03:25.510 --> 03:32.080 Therefore, therefore spoon as a resource will have its own mutex and a condition variable. 03:32.080 --> 03:32.860 Right? 03:33.190 --> 03:38.350 So both of these two data structures have been defined in the fine dining philosopher dot H. 03:38.440 --> 03:46.440 So if you take a look at the header file, you can see that I'm in the file dining philosopher dot h. 03:46.450 --> 03:49.960 And both these data structures have been defined already. 03:49.960 --> 03:56.350 Right now you understand what is the meaning of these two data structures and what each field of these 03:56.350 --> 03:58.240 data structure is used for. 03:58.480 --> 04:02.950 Now, in the next lecture video, we will going to set up our assignment program.