16: Lock-based Concurrent Data Structures

typedef struct __counter_t { int value; pthread_mutex_t lock; } counter_t; void init(counter_t *c) { c->value = 0; pthread_mutex_init(&c->lock, NULL); }

void increment(counter_t *c) { pthread_mutex_lock(&c->lock); c->value++; pthread_mutex_unlock(&c->lock); } void decrement(counter_t *c) { pthread_mutex_lock(&c->lock); c->value--; pthread_mutex_unlock(&c->lock); } int get(counter_t *c) { pthread_mutex_lock(&c->lock); int rc = c->value; pthread_mutex_unlock(&c->lock); return rc; }

typedef struct __node_t { int key; struct __node_t *next; } node_t; typedef struct __list_t { node_t *head; pthread_mutex_t lock; } list_t; void List_Init(list_t *L) { L->head = NULL; pthread_mutex_init(&L->lock, NULL); }

int List_Insert(list_t *L, int key) { pthread_mutex_lock(&L->lock); node_t *new = malloc(sizeof(node_t)); if (new == NULL) { perror("malloc"); pthread_mutex_unlock(&L->lock); return -1; // fail } new->key = key; new->next = L->head; L->head = new; pthread_mutex_unlock(&L->lock); return 0; // success }

int List_Lookup(list_t *L, int key) { pthread_mutex_lock(&L->lock); node_t *curr = L->head; while (curr) { if (curr->key == key) { pthread_mutex_unlock(&L->lock); return 0; // success } curr = curr->next; } pthread_mutex_unlock(&L->lock); return -1; // failure }