2 * Copyright (C) 2013-2019 Red Hat Inc.
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40 /* Note that the plugin's thread model cannot change after being
41 * loaded, so caching it here is safe.
43 static int thread_model
= -1;
45 static pthread_mutex_t connection_lock
= PTHREAD_MUTEX_INITIALIZER
;
46 static pthread_mutex_t all_requests_lock
= PTHREAD_MUTEX_INITIALIZER
;
47 static pthread_rwlock_t unload_prevention_lock
= PTHREAD_RWLOCK_INITIALIZER
;
49 /* Map thread model to string; use only from single-threaded context */
51 name_of_thread_model (int model
)
53 static char buf
[] = "-2147483648 # unknown thread model!";
56 case NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS
:
57 return "serialize_connections";
58 case NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS
:
59 return "serialize_all_requests";
60 case NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS
:
61 return "serialize_requests";
62 case NBDKIT_THREAD_MODEL_PARALLEL
:
65 snprintf (buf
, sizeof buf
, "%d # unknown thread model!", model
);
70 lock_init_thread_model (void)
72 thread_model
= backend
->thread_model (backend
);
73 debug ("using thread model: %s", name_of_thread_model (thread_model
));
77 lock_connection (void)
79 assert (thread_model
>= 0);
80 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS
&&
81 pthread_mutex_lock (&connection_lock
))
86 unlock_connection (void)
88 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_CONNECTIONS
&&
89 pthread_mutex_unlock (&connection_lock
))
94 lock_request (struct connection
*conn
)
96 assert (thread_model
>= 0);
97 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS
&&
98 pthread_mutex_lock (&all_requests_lock
))
101 if (conn
&& thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS
&&
102 pthread_mutex_lock (&conn
->request_lock
))
105 if (pthread_rwlock_rdlock (&unload_prevention_lock
))
110 unlock_request (struct connection
*conn
)
112 if (pthread_rwlock_unlock (&unload_prevention_lock
))
115 if (conn
&& thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_REQUESTS
&&
116 pthread_mutex_unlock (&conn
->request_lock
))
119 if (thread_model
<= NBDKIT_THREAD_MODEL_SERIALIZE_ALL_REQUESTS
&&
120 pthread_mutex_unlock (&all_requests_lock
))
127 if (pthread_rwlock_wrlock (&unload_prevention_lock
))
134 if (pthread_rwlock_unlock (&unload_prevention_lock
))