mono/utils/mono-threads-coop.c

   1  /*
   2  * mono-threads.c: Coop threading
   3  *
   4  * Author:
   5  *      Rodrigo Kumpera (kumpera@gmail.com)
   6  *
   7  * Copyright 2015 Xamarin, Inc (http://www.xamarin.com)
   8  */
   9
  10 #include <config.h>
  11
  12 /* enable pthread extensions */
  13 #ifdef TARGET_MACH
  14 #define _DARWIN_C_SOURCE
  15 #endif
  16
  17 #include <mono/utils/mono-compiler.h>
  18 #include <mono/utils/mono-semaphore.h>
  19 #include <mono/utils/mono-threads.h>
  20 #include <mono/utils/mono-tls.h>
  21 #include <mono/utils/hazard-pointer.h>
  22 #include <mono/utils/mono-memory-model.h>
  23 #include <mono/utils/mono-mmap.h>
  24 #include <mono/utils/atomic.h>
  25 #include <mono/utils/mono-time.h>
  26 #include <mono/utils/mono-counters.h>
  27
  28 #ifdef TARGET_OSX
  29 #include <mono/utils/mach-support.h>
  30 #endif
  31
  32 #ifdef USE_COOP_BACKEND
  33
  34 volatile size_t mono_polling_required;
  35
  36 static int coop_reset_blocking_count, coop_try_blocking_count, coop_do_blocking_count, coop_do_polling_count, coop_save_count;
  37
  38 void
  39 mono_threads_state_poll (void)
  40 {
  41         MonoThreadInfo *info;
  42         ++coop_do_polling_count;
  43
  44         info = mono_thread_info_current_unchecked ();
  45         if (!info)
  46                 return;
  47         THREADS_SUSPEND_DEBUG ("FINISH SELF SUSPEND OF %p\n", mono_thread_info_get_tid (info));
  48
  49         /* Fast check for pending suspend requests */
  50         if (!(info->thread_state & (STATE_ASYNC_SUSPEND_REQUESTED | STATE_SELF_SUSPEND_REQUESTED)))
  51                 return;
  52
  53         ++coop_save_count;
  54         mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
  55
  56         /* commit the saved state and notify others if needed */
  57         switch (mono_threads_transition_state_poll (info)) {
  58         case SelfSuspendResumed:
  59                 return;
  60         case SelfSuspendWait:
  61                 mono_thread_info_wait_for_resume (info);
  62                 break;
  63         case SelfSuspendNotifyAndWait:
  64                 mono_threads_notify_initiator_of_suspend (info);
  65                 mono_thread_info_wait_for_resume (info);
  66                 break;
  67         }
  68 }
  69
  70 void*
  71 mono_threads_prepare_blocking (void)
  72 {
  73         MonoThreadInfo *info;
  74         ++coop_do_blocking_count;
  75
  76         info = mono_thread_info_current_unchecked ();
  77         /* If the thread is not attached, it doesn't make sense prepare for suspend. */
  78         if (!info || !mono_thread_info_is_live (info)) {
  79                 THREADS_SUSPEND_DEBUG ("PREPARE-BLOCKING failed %p\n", mono_thread_info_get_tid (info));
  80                 return NULL;
  81         }
  82
  83 retry:
  84         ++coop_save_count;
  85         mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
  86
  87         switch (mono_threads_transition_do_blocking (info)) {
  88         case DoBlockingContinue:
  89                 break;
  90         case DoBlockingPollAndRetry:
  91                 mono_threads_state_poll ();
  92                 goto retry;
  93         }
  94
  95         return info;
  96 }
  97
  98 void
  99 mono_threads_finish_blocking (void *cookie)
 100 {
 101         static gboolean warned_about_bad_transition;
 102         MonoThreadInfo *info = cookie;
 103
 104         if (!info)
 105                 return;
 106
 107         g_assert (info == mono_thread_info_current_unchecked ());
 108
 109         switch (mono_threads_transition_done_blocking (info)) {
 110         case DoneBlockingAborted:
 111                 if (!warned_about_bad_transition) {
 112                         warned_about_bad_transition = TRUE;
 113                         g_warning ("[%p] Blocking call ended in running state for, this might lead to unbound GC pauses.", mono_thread_info_get_tid (info));
 114                 }
 115                 mono_threads_state_poll ();
 116                 break;
 117         case DoneBlockingOk:
 118                 info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
 119                 break;
 120         case DoneBlockingWait:
 121                 THREADS_SUSPEND_DEBUG ("state polling done, notifying of resume\n");
 122                 mono_thread_info_wait_for_resume (info);
 123                 break;
 124         default:
 125                 g_error ("Unknown thread state");
 126         }
 127 }
 128
 129
 130 void*
 131 mono_threads_reset_blocking_start (void)
 132 {
 133         MonoThreadInfo *info = mono_thread_info_current_unchecked ();
 134         ++coop_reset_blocking_count;
 135
 136         /* If the thread is not attached, it doesn't make sense prepare for suspend. */
 137         if (!info || !mono_thread_info_is_live (info))
 138                 return NULL;
 139
 140         switch (mono_threads_transition_abort_blocking (info)) {
 141         case AbortBlockingIgnore:
 142                 info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
 143                 return NULL;
 144         case AbortBlockingIgnoreAndPoll:
 145                 mono_threads_state_poll ();
 146                 return NULL;
 147         case AbortBlockingOk:
 148                 info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
 149                 return info;
 150         case AbortBlockingOkAndPool:
 151                 mono_threads_state_poll ();
 152                 return info;
 153         default:
 154                 g_error ("Unknown thread state");
 155         }
 156 }
 157
 158 void
 159 mono_threads_reset_blocking_end (void *cookie)
 160 {
 161         MonoThreadInfo *info = cookie;
 162
 163         if (!info)
 164                 return;
 165
 166         g_assert (info == mono_thread_info_current_unchecked ());
 167         mono_threads_prepare_blocking ();
 168 }
 169
 170 void*
 171 mono_threads_try_prepare_blocking (void)
 172 {
 173         MonoThreadInfo *info;
 174         ++coop_try_blocking_count;
 175
 176         info = mono_thread_info_current_unchecked ();
 177         /* If the thread is not attached, it doesn't make sense prepare for suspend. */
 178         if (!info || !mono_thread_info_is_live (info) || mono_thread_info_current_state (info) == STATE_BLOCKING) {
 179                 THREADS_SUSPEND_DEBUG ("PREPARE-TRY-BLOCKING failed %p\n", mono_thread_info_get_tid (info));
 180                 return NULL;
 181         }
 182
 183 retry:
 184         ++coop_save_count;
 185         mono_threads_get_runtime_callbacks ()->thread_state_init (&info->thread_saved_state [SELF_SUSPEND_STATE_INDEX]);
 186
 187         switch (mono_threads_transition_do_blocking (info)) {
 188         case DoBlockingContinue:
 189                 break;
 190         case DoBlockingPollAndRetry:
 191                 mono_threads_state_poll ();
 192                 goto retry;
 193         }
 194
 195         return info;
 196 }
 197
 198 void
 199 mono_threads_finish_try_blocking (void* cookie)
 200 {
 201         mono_threads_finish_blocking (cookie);
 202 }
 203
 204 gboolean
 205 mono_threads_core_begin_async_resume (MonoThreadInfo *info)
 206 {
 207         g_error ("FIXME");
 208         return FALSE;
 209 }
 210
 211 gboolean
 212 mono_threads_core_begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
 213 {
 214         mono_threads_add_to_pending_operation_set (info);
 215         /* There's nothing else to do after we async request the thread to suspend */
 216         return TRUE;
 217 }
 218
 219 gboolean
 220 mono_threads_core_check_suspend_result (MonoThreadInfo *info)
 221 {
 222         /* Async suspend can't async fail on coop */
 223         return TRUE;
 224 }
 225
 226 void
 227 mono_threads_init_platform (void)
 228 {
 229         mono_counters_register ("Coop Reset Blocking", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_reset_blocking_count);
 230         mono_counters_register ("Coop Try Blocking", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_try_blocking_count);
 231         mono_counters_register ("Coop Do Blocking", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_do_blocking_count);
 232         mono_counters_register ("Coop Do Polling", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_do_polling_count);
 233         mono_counters_register ("Coop Save Count", MONO_COUNTER_GC | MONO_COUNTER_INT, &coop_save_count);
 234         //See the above for what's wrong here.
 235 }
 236
 237 void
 238 mono_threads_platform_free (MonoThreadInfo *info)
 239 {
 240 #ifdef TARGET_MACH
 241         mach_port_deallocate (current_task (), info->native_handle);
 242 #endif
 243
 244         //See the above for what's wrong here.
 245 }
 246
 247 void
 248 mono_threads_platform_register (MonoThreadInfo *info)
 249 {
 250 #ifdef TARGET_MACH
 251         char thread_name [64];
 252
 253         info->native_handle = mach_thread_self ();
 254         snprintf (thread_name, 64, "tid_%x", (int)info->native_handle);
 255         pthread_setname_np (thread_name);
 256 #endif
 257
 258         //See the above for what's wrong here.
 259 }
 260
 261 void
 262 mono_threads_core_begin_global_suspend (void)
 263 {
 264         mono_polling_required = 1;
 265 }
 266
 267 void
 268 mono_threads_core_end_global_suspend (void)
 269 {
 270         mono_polling_required = 0;
 271 }
 272
 273 void*
 274 mono_threads_enter_gc_unsafe_region (void)
 275 {
 276         return mono_threads_reset_blocking_start ();
 277 }
 278
 279 void
 280 mono_threads_exit_gc_unsafe_region (void *regions_cookie)
 281 {
 282         mono_threads_reset_blocking_end (regions_cookie);
 283 }
 284
 285 #else
 286
 287 void*
 288 mono_threads_enter_gc_unsafe_region (void)
 289 {
 290         return NULL;
 291 }
 292
 293 void
 294 mono_threads_exit_gc_unsafe_region (void *regions_cookie)
 295 {
 296 }
 297
 298 #endif