bench.sh: rearrange order again
[model-checker-benchmarks.git] / ms-queue / my_queue.c
1 #include <threads.h>
2 #include <stdlib.h>
3 #include "librace.h"
4 #include "model-assert.h"
5
6 #include "my_queue.h"
7
8 #define relaxed memory_order_relaxed
9 #define release memory_order_release
10 #define acquire memory_order_acquire
11
12 #define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
13 #define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
14
15 #define POISON_IDX 0x666
16
17 static unsigned int (*free_lists)[MAX_FREELIST];
18
19 /* Search this thread's free list for a "new" node */
20 static unsigned int new_node()
21 {
22         int i;
23         int t = get_thread_num();
24         for (i = 0; i < MAX_FREELIST; i++) {
25                 unsigned int node = load_32(&free_lists[t][i]);
26                 if (node) {
27                         store_32(&free_lists[t][i], 0);
28                         return node;
29                 }
30         }
31         /* free_list is empty? */
32         MODEL_ASSERT(0);
33         return 0;
34 }
35
36 /* Place this node index back on this thread's free list */
37 static void reclaim(unsigned int node)
38 {
39         int i;
40         int t = get_thread_num();
41
42         /* Don't reclaim NULL node */
43         MODEL_ASSERT(node);
44
45         for (i = 0; i < MAX_FREELIST; i++) {
46                 /* Should never race with our own thread here */
47                 unsigned int idx = load_32(&free_lists[t][i]);
48
49                 /* Found empty spot in free list */
50                 if (idx == 0) {
51                         store_32(&free_lists[t][i], node);
52                         return;
53                 }
54         }
55         /* free list is full? */
56         MODEL_ASSERT(0);
57 }
58
59 void init_queue(queue_t *q, int num_threads)
60 {
61         int i, j;
62
63         /* Initialize each thread's free list with INITIAL_FREE pointers */
64         /* The actual nodes are initialized with poison indexes */
65         free_lists = malloc(num_threads * sizeof(*free_lists));
66         for (i = 0; i < num_threads; i++) {
67                 for (j = 0; j < INITIAL_FREE; j++) {
68                         free_lists[i][j] = 2 + i * MAX_FREELIST + j;
69                         atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
70                 }
71         }
72
73         /* initialize queue */
74         atomic_init(&q->head, MAKE_POINTER(1, 0));
75         atomic_init(&q->tail, MAKE_POINTER(1, 0));
76         atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
77 }
78
79 void enqueue(queue_t *q, unsigned int val)
80 {
81         int success = 0;
82         unsigned int node;
83         pointer tail;
84         pointer next;
85         pointer tmp;
86
87         node = new_node();
88         store_32(&q->nodes[node].value, val);
89         tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
90         set_ptr(&tmp, 0); // NULL
91         atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
92
93         while (!success) {
94                 tail = atomic_load_explicit(&q->tail, acquire);
95                 next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
96                 if (tail == atomic_load_explicit(&q->tail, relaxed)) {
97
98                         /* Check for uninitialized 'next' */
99                         MODEL_ASSERT(get_ptr(next) != POISON_IDX);
100
101                         if (get_ptr(next) == 0) { // == NULL
102                                 pointer value = MAKE_POINTER(node, get_count(next) + 1);
103                                 success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
104                                                 &next, value, release, release);
105                         }
106                         if (!success) {
107                                 unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
108                                 pointer value = MAKE_POINTER(ptr,
109                                                 get_count(tail) + 1);
110                                 atomic_compare_exchange_strong_explicit(&q->tail,
111                                                 &tail, value,
112                                                 release, release);
113                                 thrd_yield();
114                         }
115                 }
116         }
117         atomic_compare_exchange_strong_explicit(&q->tail,
118                         &tail,
119                         MAKE_POINTER(node, get_count(tail) + 1),
120                         release, release);
121 }
122
123 unsigned int dequeue(queue_t *q)
124 {
125         unsigned int value;
126         int success = 0;
127         pointer head;
128         pointer tail;
129         pointer next;
130
131         while (!success) {
132                 head = atomic_load_explicit(&q->head, acquire);
133                 tail = atomic_load_explicit(&q->tail, relaxed);
134                 next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
135                 if (atomic_load_explicit(&q->head, relaxed) == head) {
136                         if (get_ptr(head) == get_ptr(tail)) {
137
138                                 /* Check for uninitialized 'next' */
139                                 MODEL_ASSERT(get_ptr(next) != POISON_IDX);
140
141                                 if (get_ptr(next) == 0) { // NULL
142                                         return 0; // NULL
143                                 }
144                                 atomic_compare_exchange_strong_explicit(&q->tail,
145                                                 &tail,
146                                                 MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
147                                                 release, release);
148                                 thrd_yield();
149                         } else {
150                                 value = load_32(&q->nodes[get_ptr(next)].value);
151                                 success = atomic_compare_exchange_strong_explicit(&q->head,
152                                                 &head,
153                                                 MAKE_POINTER(get_ptr(next), get_count(head) + 1),
154                                                 release, release);
155                                 if (!success)
156                                         thrd_yield();
157                         }
158                 }
159         }
160         reclaim(get_ptr(head));
161         return value;
162 }