Add a write barrier to the TSO link field (#1589)
[ghc.git] / rts / Schedule.h
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team 1998-2005
4 *
5 * Prototypes for functions in Schedule.c
6 * (RTS internal scheduler interface)
7 *
8 * -------------------------------------------------------------------------*/
9
10 #ifndef SCHEDULE_H
11 #define SCHEDULE_H
12
13 #include "OSThreads.h"
14 #include "Capability.h"
15
16 /* initScheduler(), exitScheduler()
17 * Called from STG : no
18 * Locks assumed : none
19 */
20 void initScheduler (void);
21 void exitScheduler (rtsBool wait_foreign);
22 void freeScheduler (void);
23
24 // Place a new thread on the run queue of the current Capability
25 void scheduleThread (Capability *cap, StgTSO *tso);
26
27 // Place a new thread on the run queue of a specified Capability
28 // (cap is the currently owned Capability, cpu is the number of
29 // the desired Capability).
30 void scheduleThreadOn(Capability *cap, StgWord cpu, StgTSO *tso);
31
32 /* awakenBlockedQueue()
33 *
34 * Takes a pointer to the beginning of a blocked TSO queue, and
35 * wakes up the entire queue.
36 * Called from STG : yes
37 * Locks assumed : none
38 */
39 #if defined(GRAN)
40 void awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node);
41 #elif defined(PAR)
42 void awakenBlockedQueue(StgBlockingQueueElement *q, StgClosure *node);
43 #else
44 void awakenBlockedQueue (Capability *cap, StgTSO *tso);
45 #endif
46
47 /* wakeUpRts()
48 *
49 * Causes an OS thread to wake up and run the scheduler, if necessary.
50 */
51 void wakeUpRts(void);
52
53 /* unblockOne()
54 *
55 * Put the specified thread on the run queue of the given Capability.
56 * Called from STG : yes
57 * Locks assumed : we own the Capability.
58 */
59 StgTSO * unblockOne (Capability *cap, StgTSO *tso);
60
61 /* raiseExceptionHelper */
62 StgWord raiseExceptionHelper (StgRegTable *reg, StgTSO *tso, StgClosure *exception);
63
64 /* findRetryFrameHelper */
65 StgWord findRetryFrameHelper (StgTSO *tso);
66
67 /* workerStart()
68 *
69 * Entry point for a new worker task.
70 * Called from STG : NO
71 * Locks assumed : none
72 */
73 void workerStart(Task *task);
74
75 #if defined(GRAN)
76 void awaken_blocked_queue(StgBlockingQueueElement *q, StgClosure *node);
77 void unlink_from_bq(StgTSO* tso, StgClosure* node);
78 void initThread(StgTSO *tso, nat stack_size, StgInt pri);
79 #elif defined(PAR)
80 nat run_queue_len(void);
81 void awaken_blocked_queue(StgBlockingQueueElement *q, StgClosure *node);
82 void initThread(StgTSO *tso, nat stack_size);
83 #else
84 char *info_type(StgClosure *closure); // dummy
85 char *info_type_by_ip(StgInfoTable *ip); // dummy
86 void awaken_blocked_queue(StgTSO *q);
87 void initThread(StgTSO *tso, nat stack_size);
88 #endif
89
90 /* Context switch flag.
91 * Locks required : none (conflicts are harmless)
92 */
93 extern int RTS_VAR(context_switch);
94
95 /* The state of the scheduler. This is used to control the sequence
96 * of events during shutdown, and when the runtime is interrupted
97 * using ^C.
98 */
99 #define SCHED_RUNNING 0 /* running as normal */
100 #define SCHED_INTERRUPTING 1 /* ^C detected, before threads are deleted */
101 #define SCHED_SHUTTING_DOWN 2 /* final shutdown */
102
103 extern rtsBool RTS_VAR(sched_state);
104
105 /*
106 * flag that tracks whether we have done any execution in this time slice.
107 */
108 #define ACTIVITY_YES 0 /* there has been activity in the current slice */
109 #define ACTIVITY_MAYBE_NO 1 /* no activity in the current slice */
110 #define ACTIVITY_INACTIVE 2 /* a complete slice has passed with no activity */
111 #define ACTIVITY_DONE_GC 3 /* like 2, but we've done a GC too */
112
113 /* Recent activity flag.
114 * Locks required : Transition from MAYBE_NO to INACTIVE
115 * happens in the timer signal, so it is atomic. Trnasition from
116 * INACTIVE to DONE_GC happens under sched_mutex. No lock required
117 * to set it to ACTIVITY_YES.
118 */
119 extern nat recent_activity;
120
121 /* Thread queues.
122 * Locks required : sched_mutex
123 *
124 * In GranSim we have one run/blocked_queue per PE.
125 */
126 #if defined(GRAN)
127 // run_queue_hds defined in GranSim.h
128 #else
129 extern StgTSO *RTS_VAR(blackhole_queue);
130 #if !defined(THREADED_RTS)
131 extern StgTSO *RTS_VAR(blocked_queue_hd), *RTS_VAR(blocked_queue_tl);
132 extern StgTSO *RTS_VAR(sleeping_queue);
133 #endif
134 #endif
135
136 /* Linked list of all threads.
137 * Locks required : sched_mutex
138 */
139 extern StgTSO *RTS_VAR(all_threads);
140
141 /* Set to rtsTrue if there are threads on the blackhole_queue, and
142 * it is possible that one or more of them may be available to run.
143 * This flag is set to rtsFalse after we've checked the queue, and
144 * set to rtsTrue just before we run some Haskell code. It is used
145 * to decide whether we should yield the Capability or not.
146 * Locks required : none (see scheduleCheckBlackHoles()).
147 */
148 extern rtsBool blackholes_need_checking;
149
150 #if defined(THREADED_RTS)
151 extern Mutex RTS_VAR(sched_mutex);
152 #endif
153
154 SchedulerStatus rts_mainLazyIO(HaskellObj p, /*out*/HaskellObj *ret);
155
156 /* Called by shutdown_handler(). */
157 void interruptStgRts (void);
158
159 nat run_queue_len (void);
160
161 void resurrectThreads (StgTSO *);
162
163 void printAllThreads(void);
164
165 /* debugging only
166 */
167 #ifdef DEBUG
168 void print_bq (StgClosure *node);
169 #endif
170 #if defined(PAR)
171 void print_bqe (StgBlockingQueueElement *bqe);
172 #endif
173
174 /* -----------------------------------------------------------------------------
175 * Some convenient macros/inline functions...
176 */
177
178 #if !IN_STG_CODE
179
180 /* END_TSO_QUEUE and friends now defined in includes/StgMiscClosures.h */
181
182 /* Add a thread to the end of the run queue.
183 * NOTE: tso->link should be END_TSO_QUEUE before calling this macro.
184 * ASSUMES: cap->running_task is the current task.
185 */
186 INLINE_HEADER void
187 appendToRunQueue (Capability *cap, StgTSO *tso)
188 {
189 ASSERT(tso->_link == END_TSO_QUEUE);
190 if (cap->run_queue_hd == END_TSO_QUEUE) {
191 cap->run_queue_hd = tso;
192 } else {
193 setTSOLink(cap, cap->run_queue_tl, tso);
194 }
195 cap->run_queue_tl = tso;
196 }
197
198 /* Push a thread on the beginning of the run queue. Used for
199 * newly awakened threads, so they get run as soon as possible.
200 * ASSUMES: cap->running_task is the current task.
201 */
202 INLINE_HEADER void
203 pushOnRunQueue (Capability *cap, StgTSO *tso)
204 {
205 setTSOLink(cap, tso, cap->run_queue_hd);
206 cap->run_queue_hd = tso;
207 if (cap->run_queue_tl == END_TSO_QUEUE) {
208 cap->run_queue_tl = tso;
209 }
210 }
211
212 /* Pop the first thread off the runnable queue.
213 */
214 INLINE_HEADER StgTSO *
215 popRunQueue (Capability *cap)
216 {
217 StgTSO *t = cap->run_queue_hd;
218 ASSERT(t != END_TSO_QUEUE);
219 cap->run_queue_hd = t->_link;
220 t->_link = END_TSO_QUEUE; // no write barrier req'd
221 if (cap->run_queue_hd == END_TSO_QUEUE) {
222 cap->run_queue_tl = END_TSO_QUEUE;
223 }
224 return t;
225 }
226
227 /* Add a thread to the end of the blocked queue.
228 */
229 #if !defined(THREADED_RTS)
230 INLINE_HEADER void
231 appendToBlockedQueue(StgTSO *tso)
232 {
233 ASSERT(tso->_link == END_TSO_QUEUE);
234 if (blocked_queue_hd == END_TSO_QUEUE) {
235 blocked_queue_hd = tso;
236 } else {
237 setTSOLink(&MainCapability, blocked_queue_tl, tso);
238 }
239 blocked_queue_tl = tso;
240 }
241 #endif
242
243 #if defined(THREADED_RTS)
244 INLINE_HEADER void
245 appendToWakeupQueue (Capability *cap, StgTSO *tso)
246 {
247 ASSERT(tso->_link == END_TSO_QUEUE);
248 if (cap->wakeup_queue_hd == END_TSO_QUEUE) {
249 cap->wakeup_queue_hd = tso;
250 } else {
251 setTSOLink(cap, cap->wakeup_queue_tl, tso);
252 }
253 cap->wakeup_queue_tl = tso;
254 }
255 #endif
256
257 /* Check whether various thread queues are empty
258 */
259 INLINE_HEADER rtsBool
260 emptyQueue (StgTSO *q)
261 {
262 return (q == END_TSO_QUEUE);
263 }
264
265 INLINE_HEADER rtsBool
266 emptyRunQueue(Capability *cap)
267 {
268 return emptyQueue(cap->run_queue_hd);
269 }
270
271 #if defined(THREADED_RTS)
272 INLINE_HEADER rtsBool
273 emptyWakeupQueue(Capability *cap)
274 {
275 return emptyQueue(cap->wakeup_queue_hd);
276 }
277 #endif
278
279 #if !defined(THREADED_RTS)
280 #define EMPTY_BLOCKED_QUEUE() (emptyQueue(blocked_queue_hd))
281 #define EMPTY_SLEEPING_QUEUE() (emptyQueue(sleeping_queue))
282 #endif
283
284 INLINE_HEADER rtsBool
285 emptyThreadQueues(Capability *cap)
286 {
287 return emptyRunQueue(cap)
288 #if !defined(THREADED_RTS)
289 && EMPTY_BLOCKED_QUEUE() && EMPTY_SLEEPING_QUEUE()
290 #endif
291 ;
292 }
293
294 #endif /* !IN_STG_CODE */
295
296 #endif /* SCHEDULE_H */
297