SHOW:
|
|
- or go back to the newest paste.
| 1 | #include <stdio.h> | |
| 2 | #include <stdlib.h> | |
| 3 | #include "pthread.h" | |
| 4 | #include "semaphore.h" | |
| 5 | ||
| 6 | typedef struct GlobalState {
| |
| 7 | pthread_mutex_t ActMutex; | |
| 8 | int iFanPerType[2]; | |
| 9 | int MustJoinCaptain; | |
| 10 | int FansRemaining; | |
| 11 | pthread_t aFanCarThread[4]; | |
| 12 | pthread_mutex_t BeginNewCar; | |
| 13 | pthread_barrier_t JoinTheCar; | |
| 14 | sem_t DoneSemaphore; | |
| 15 | } GlobalState; | |
| 16 | ||
| 17 | GlobalState g_tState; | |
| 18 | ||
| 19 | void *FanThread(void *arg) {
| |
| 20 | int n, iFan = (int)arg, iFansInCar; | |
| 21 | pthread_t tid = pthread_self(); | |
| 22 | ||
| 23 | //show the looking for message right after thread creation | |
| 24 | pthread_mutex_lock(&g_tState.ActMutex); | |
| 25 | printf("Thread ID: %lli, Team: %c, I am looking for a car\n",tid,'A'+iFan);
| |
| 26 | pthread_mutex_unlock(&g_tState.ActMutex); | |
| 27 | ||
| 28 | while (1) {
| |
| 29 | pthread_mutex_lock(&g_tState.ActMutex); | |
| 30 | //clean up last captain thread if any | |
| 31 | if (g_tState.MustJoinCaptain) {
| |
| 32 | pthread_join(g_tState.aFanCarThread[3], NULL ); | |
| 33 | g_tState.MustJoinCaptain = 0; | |
| 34 | } | |
| 35 | //number of fans on car is #A + #B | |
| 36 | iFansInCar = g_tState.iFanPerType[0]+g_tState.iFanPerType[1]; | |
| 37 | //allowed combinatios are 2:2 or 4:0 | |
| 38 | if ((iFansInCar < 3) || (g_tState.iFanPerType[iFan] & 1)) {
| |
| 39 | //set the TID for this fan on a car slot (so we can wait & cleanup) | |
| 40 | g_tState.aFanCarThread[iFansInCar] = tid; | |
| 41 | g_tState.iFanPerType[iFan]++; | |
| 42 | ||
| 43 | //printf("Thread ID: %lli, Team: %c, I am looking for a car\n",tid,'A'+iFan);
| |
| 44 | ||
| 45 | // wait for 4 compatible fans to arrive before entering the car | |
| 46 | pthread_mutex_unlock(&g_tState.ActMutex); | |
| 47 | pthread_barrier_wait( &g_tState.JoinTheCar ); | |
| 48 | pthread_mutex_trylock(&g_tState.BeginNewCar); | |
| 49 | pthread_mutex_lock(&g_tState.ActMutex); | |
| 50 | ||
| 51 | printf("Thread ID: %lli, Team: %c, I have found a spot in a car\n",tid,'A'+iFan);
| |
| 52 | pthread_mutex_unlock(&g_tState.ActMutex); | |
| 53 | //if this fan will fill a car, then it becomes the captain and a car is finished | |
| 54 | if (iFansInCar==3) {
| |
| 55 | //so then we can "join" the previous 3 fan threads that finished (thread cleanup) | |
| 56 | for (n=0 ; n<iFansInCar ; n++) {
| |
| 57 | pthread_join(g_tState.aFanCarThread[n], NULL ); | |
| 58 | } | |
| 59 | pthread_mutex_lock(&g_tState.ActMutex); | |
| 60 | printf("Thread ID: %lli, Team: %c, I am the captain and driving the car\n",tid,'A'+iFan);
| |
| 61 | g_tState.iFanPerType[0] = g_tState.iFanPerType[1] = 0; | |
| 62 | g_tState.MustJoinCaptain = 1; | |
| 63 | g_tState.FansRemaining -= 4; | |
| 64 | if (!g_tState.FansRemaining) { sem_post( &g_tState.DoneSemaphore ); }
| |
| 65 | pthread_mutex_unlock(&g_tState.ActMutex); | |
| 66 | pthread_mutex_unlock(&g_tState.BeginNewCar); | |
| 67 | //when finishing a car a new one can start... | |
| 68 | } | |
| 69 | //fan is inside a car so exit the thread | |
| 70 | break; | |
| 71 | } else {
| |
| 72 | //printf("Thread ID: %lli, Team: %c, waiting for a new car...\n",tid,'A'+iFan);
| |
| 73 | pthread_mutex_unlock(&g_tState.ActMutex); | |
| 74 | //wait for a new car | |
| 75 | pthread_mutex_lock(&g_tState.BeginNewCar); | |
| 76 | pthread_mutex_unlock(&g_tState.BeginNewCar); | |
| 77 | - | sem_post( &g_tState.DoneSemaphore ); |
| 77 | + | |
| 78 | } | |
| 79 | ||
| 80 | } | |
| 81 | ||
| 82 | void ManageThreads(int iNumA,int iNumB) {
| |
| 83 | ||
| 84 | int i; | |
| 85 | pthread_t tid; | |
| 86 | ||
| 87 | //number of fans on each group must be even | |
| 88 | if ((iNumA & 1) || (iNumB & 1)) return; | |
| 89 | //total number must be a multiple of 4 | |
| 90 | if ((iNumA+iNumB) & 3) return; | |
| 91 | ||
| 92 | //initialize global state | |
| 93 | g_tState.FansRemaining = iNumA+iNumB; | |
| 94 | g_tState.MustJoinCaptain = 0; | |
| 95 | pthread_mutex_init(&g_tState.ActMutex, NULL); | |
| 96 | pthread_mutex_init(&g_tState.BeginNewCar, NULL); | |
| 97 | //pthread_mutex_lock(&g_tState.BeginNewCar); | |
| 98 | pthread_barrier_init(&g_tState.JoinTheCar, NULL, 4); | |
| 99 | sem_init(&g_tState.DoneSemaphore, 0, 0); | |
| 100 | ||
| 101 | // creating threads | |
| 102 | for ( i=0 ; i<iNumA ; i++ ) {
| |
| 103 | pthread_create(&tid, NULL, &FanThread, (void*)0); | |
| 104 | } | |
| 105 | ||
| 106 | for ( i=0 ; i<iNumB ; i++ ) {
| |
| 107 | pthread_create(&tid, NULL, &FanThread, (void*)1); | |
| 108 | } | |
| 109 | - | for ( i=0 ; i<(iNumA+iNumB) ; i++ ) {
|
| 109 | + | |
| 110 | - | sem_wait( &g_tState.DoneSemaphore ); |
| 110 | + | |
| 111 | sem_wait( &g_tState.DoneSemaphore ); | |
| 112 | //waiting for last thread to finish | |
| 113 | pthread_join(g_tState.aFanCarThread[3], NULL ); | |
| 114 | ||
| 115 | //free resources | |
| 116 | pthread_barrier_destroy(&g_tState.JoinTheCar); | |
| 117 | sem_destroy(&g_tState.DoneSemaphore); | |
| 118 | pthread_mutex_destroy(&g_tState.ActMutex); | |
| 119 | pthread_mutex_destroy(&g_tState.BeginNewCar); | |
| 120 | } | |
| 121 | ||
| 122 | int main(int argc, char *argv[]) {
| |
| 123 | int iNumA,iNumB; | |
| 124 | ||
| 125 | //number of arguments must be 3... | |
| 126 | //ProgramName , FansA , FansB | |
| 127 | if (argc == 3) {
| |
| 128 | //fans of different members | |
| 129 | iNumA = atoi(argv[1]); | |
| 130 | iNumB = atoi(argv[2]); | |
| 131 | ManageThreads( iNumA , iNumB ); | |
| 132 | } | |
| 133 | ||
| 134 | puts("main terminates");
| |
| 135 | return 0; | |
| 136 | } | |
| 137 |