1 #ifndef JEMALLOC_INTERNAL_MUTEX_POOL_H
2 #define JEMALLOC_INTERNAL_MUTEX_POOL_H
3 
4 #include "jemalloc/internal/hash.h"
5 #include "jemalloc/internal/mutex.h"
6 #include "jemalloc/internal/witness.h"
7 
8 /* We do mod reductions by this value, so it should be kept a power of 2. */
9 #define MUTEX_POOL_SIZE 256
10 
11 typedef struct mutex_pool_s mutex_pool_t;
12 struct mutex_pool_s {
13 	malloc_mutex_t mutexes[MUTEX_POOL_SIZE];
14 };
15 
16 bool mutex_pool_init(mutex_pool_t *pool, const char *name, witness_rank_t rank);
17 
18 /* Internal helper - not meant to be called outside this module. */
19 static inline malloc_mutex_t *
mutex_pool_mutex(mutex_pool_t * pool,uintptr_t key)20 mutex_pool_mutex(mutex_pool_t *pool, uintptr_t key) {
21 	size_t hash_result[2];
22 	hash(&key, sizeof(key), 0xd50dcc1b, hash_result);
23 	return &pool->mutexes[hash_result[0] % MUTEX_POOL_SIZE];
24 }
25 
26 static inline void
mutex_pool_assert_not_held(tsdn_t * tsdn,mutex_pool_t * pool)27 mutex_pool_assert_not_held(tsdn_t *tsdn, mutex_pool_t *pool) {
28 	for (int i = 0; i < MUTEX_POOL_SIZE; i++) {
29 		malloc_mutex_assert_not_owner(tsdn, &pool->mutexes[i]);
30 	}
31 }
32 
33 /*
34  * Note that a mutex pool doesn't work exactly the way an embdedded mutex would.
35  * You're not allowed to acquire mutexes in the pool one at a time.  You have to
36  * acquire all the mutexes you'll need in a single function call, and then
37  * release them all in a single function call.
38  */
39 
40 static inline void
mutex_pool_lock(tsdn_t * tsdn,mutex_pool_t * pool,uintptr_t key)41 mutex_pool_lock(tsdn_t *tsdn, mutex_pool_t *pool, uintptr_t key) {
42 	mutex_pool_assert_not_held(tsdn, pool);
43 
44 	malloc_mutex_t *mutex = mutex_pool_mutex(pool, key);
45 	malloc_mutex_lock(tsdn, mutex);
46 }
47 
48 static inline void
mutex_pool_unlock(tsdn_t * tsdn,mutex_pool_t * pool,uintptr_t key)49 mutex_pool_unlock(tsdn_t *tsdn, mutex_pool_t *pool, uintptr_t key) {
50 	malloc_mutex_t *mutex = mutex_pool_mutex(pool, key);
51 	malloc_mutex_unlock(tsdn, mutex);
52 
53 	mutex_pool_assert_not_held(tsdn, pool);
54 }
55 
56 static inline void
mutex_pool_lock2(tsdn_t * tsdn,mutex_pool_t * pool,uintptr_t key1,uintptr_t key2)57 mutex_pool_lock2(tsdn_t *tsdn, mutex_pool_t *pool, uintptr_t key1,
58     uintptr_t key2) {
59 	mutex_pool_assert_not_held(tsdn, pool);
60 
61 	malloc_mutex_t *mutex1 = mutex_pool_mutex(pool, key1);
62 	malloc_mutex_t *mutex2 = mutex_pool_mutex(pool, key2);
63 	if ((uintptr_t)mutex1 < (uintptr_t)mutex2) {
64 		malloc_mutex_lock(tsdn, mutex1);
65 		malloc_mutex_lock(tsdn, mutex2);
66 	} else if ((uintptr_t)mutex1 == (uintptr_t)mutex2) {
67 		malloc_mutex_lock(tsdn, mutex1);
68 	} else {
69 		malloc_mutex_lock(tsdn, mutex2);
70 		malloc_mutex_lock(tsdn, mutex1);
71 	}
72 }
73 
74 static inline void
mutex_pool_unlock2(tsdn_t * tsdn,mutex_pool_t * pool,uintptr_t key1,uintptr_t key2)75 mutex_pool_unlock2(tsdn_t *tsdn, mutex_pool_t *pool, uintptr_t key1,
76     uintptr_t key2) {
77 	malloc_mutex_t *mutex1 = mutex_pool_mutex(pool, key1);
78 	malloc_mutex_t *mutex2 = mutex_pool_mutex(pool, key2);
79 	if (mutex1 == mutex2) {
80 		malloc_mutex_unlock(tsdn, mutex1);
81 	} else {
82 		malloc_mutex_unlock(tsdn, mutex1);
83 		malloc_mutex_unlock(tsdn, mutex2);
84 	}
85 
86 	mutex_pool_assert_not_held(tsdn, pool);
87 }
88 
89 static inline void
mutex_pool_assert_owner(tsdn_t * tsdn,mutex_pool_t * pool,uintptr_t key)90 mutex_pool_assert_owner(tsdn_t *tsdn, mutex_pool_t *pool, uintptr_t key) {
91 	malloc_mutex_assert_owner(tsdn, mutex_pool_mutex(pool, key));
92 }
93 
94 #endif /* JEMALLOC_INTERNAL_MUTEX_POOL_H */
95