1 /* -----------------------------------------------------------------------------
2 * $Id: TSO.h,v 1.21 2001/04/02 07:24:12 qrczak Exp $
4 * (c) The GHC Team, 1998-1999
6 * The definitions for Thread State Objects.
8 * ---------------------------------------------------------------------------*/
13 #if defined(GRAN) || defined(PAR)
16 #define TSO_MAGIC 4321
39 #if defined(PROFILING)
41 CostCentreStack *CCCS; /* thread's current CCS */
43 #else /* !PROFILING */
46 #endif /* PROFILING */
49 typedef StgTSOStatBuf StgTSOParInfo;
57 StgThreadPriority priority;
58 StgInt revalTid; /* ToDo: merge both into 1 word */
67 typedef StgTSOStatBuf StgTSOGranInfo;
77 #else /* !TICKY_TICKY */
80 #endif /* TICKY_TICKY */
88 * The what_next field of a TSO indicates how the thread is to be run.
91 ThreadEnterGHC, /* enter top thunk on stack */
92 ThreadRunGHC, /* return to address on top of stack */
93 ThreadEnterInterp, /* enter top thunk on stack (w/ interpreter) */
94 ThreadKilled, /* thread has died, don't run it */
95 ThreadRelocated, /* thread has moved, link points to new locn */
96 ThreadComplete /* thread has finished */
100 * We are completely paranoid and make thread IDs 64 bits to avoid
101 * having to worry about overflow. A little calculation shows that
102 * even doing 10^6 forks per second would take 35 million years to
103 * overflow a 64 bit thread ID :-)
106 typedef StgWord32 StgThreadID;
109 * This type is returned to the scheduler by a thread that has
110 * stopped for one reason or another.
114 HeapOverflow, /* might also be StackOverflow */
119 } StgThreadReturnCode;
122 * We distinguish between the various classes of threads in the system.
132 * Threads may be blocked for several reasons. A blocked thread will
133 * have the reason in the why_blocked field of the TSO, and some
134 * further info (such as the closure the thread is blocked on, or the
135 * file descriptor if the thread is waiting on I/O) in the block_info
148 , BlockedOnGA // blocked on a remote closure represented by a Global Address
149 , BlockedOnGA_NoSend // same as above but without sending a Fetch message
161 * TSOs live on the heap, and therefore look just like heap objects.
162 * Large TSOs will live in their own "block group" allocated by the
163 * storage manager, and won't be copied during garbage collection.
167 * ToDo: make this structure sensible on a non-32-bit arch.
170 typedef struct StgTSO_ {
173 struct StgTSO_* link; /* Links threads onto blocking queues */
174 StgMutClosure * mut_link; /* TSO's are mutable of course! */
175 struct StgTSO_* global_link; /* Links all threads together */
177 StgTSOWhatNext what_next : 16;
178 StgTSOBlockReason why_blocked : 16;
179 StgTSOBlockInfo block_info;
180 struct StgTSO_* blocked_exceptions;
183 StgTSOTickyInfo ticky;
189 /* The thread stack... */
190 StgWord stack_size; /* stack size in *words* */
191 StgWord max_stack_size; /* maximum stack size in *words* */
198 /* -----------------------------------------------------------------------------
201 An active thread has the following properties:
203 tso->stack < tso->sp < tso->stack+tso->stack_size
204 tso->stack_size <= tso->max_stack_size
206 RESERVED_STACK_WORDS is large enough for any heap-check or
209 The size of the TSO struct plus the stack is either
210 (a) smaller than a block, or
211 (b) a multiple of BLOCK_SIZE
213 tso->why_blocked tso->block_info location
214 ----------------------------------------------------------------------
215 NotBlocked NULL runnable_queue, or running
217 BlockedOnBlackHole the BLACKHOLE_BQ the BLACKHOLE_BQ's queue
219 BlockedOnMVar the MVAR the MVAR's queue
221 BlockedOnException the TSO TSO->blocked_exception
223 BlockedOnRead NULL blocked_queue
224 BlockedOnWrite NULL blocked_queue
225 BlockedOnDelay NULL blocked_queue
226 BlockedOnGA closure TSO blocks on BQ of that closure
227 BlockedOnGA_NoSend closure TSO blocks on BQ of that closure
229 tso->link == END_TSO_QUEUE, if the thread is currently running.
231 A zombie thread has the following properties:
233 tso->what_next == ThreadComplete or ThreadKilled
234 tso->link == (could be on some queue somewhere)
235 tso->su == tso->stack + tso->stack_size
236 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
237 tso->sp[0] == return value of thread, if what_next == ThreadComplete,
238 exception , if what_next == ThreadKilled
240 (tso->sp is left pointing at the top word on the stack so that
241 the return value or exception will be retained by a GC).
243 tso->blocked_exceptions is either:
245 NULL if async exceptions are unblocked.
247 END_TSO_QUEUE if async exceptions are blocked, but no threads
248 are currently waiting to deliver.
250 (StgTSO *)tso if threads are currently awaiting delivery of
251 exceptions to this thread.
253 The 2 cases BlockedOnGA and BlockedOnGA_NoSend are needed in a GUM
254 setup only. They mark a TSO that has entered a FETCH_ME or
255 FETCH_ME_BQ closure, respectively; only the first TSO hitting the
256 closure will send a Fetch message.
257 Currently we have no separate code for blocking on an RBH; we use the
258 BlockedOnBlackHole case for that. -- HWL
260 ---------------------------------------------------------------------------- */
262 /* Workaround for a bug/quirk in gcc on certain architectures.
263 * symptom is that (&tso->stack - &tso->header) /= sizeof(StgTSO)
264 * in other words, gcc pads the structure at the end.
267 extern StgTSO dummy_tso;
269 #define TSO_STRUCT_SIZE \
270 ((char *)&dummy_tso.stack - (char *)&dummy_tso.header)
272 #define TSO_STRUCT_SIZEW (TSO_STRUCT_SIZE / sizeof(W_))