1 /* -----------------------------------------------------------------------------
2 * $Id: TSO.h,v 1.11 2000/01/22 18:00:03 simonmar Exp $
4 * (c) The GHC Team, 1998-1999
6 * The definitions for Thread State Objects.
8 * ---------------------------------------------------------------------------*/
13 #if defined(GRAN) || defined(PAR)
14 // magic marker for TSOs; debugging only
15 #define TSO_MAGIC 4321
37 #if defined(PROFILING)
39 CostCentreStack *CCCS; /* thread's current CCS */
41 #else /* !PROFILING */
44 #endif /* PROFILING */
47 typedef StgTSOStatBuf StgTSOParInfo;
54 typedef StgTSOStatBuf StgTSOGranInfo;
64 #else /* !TICKY_TICKY */
67 #endif /* TICKY_TICKY */
75 * The whatNext field of a TSO indicates how the thread is to be run.
78 ThreadEnterGHC, /* enter top thunk on stack */
79 ThreadRunGHC, /* return to address on top of stack */
80 ThreadEnterHugs, /* enter top thunk on stack (w/ interpreter) */
81 ThreadKilled, /* thread has died, don't run it */
82 ThreadRelocated, /* thread has moved, link points to new locn */
83 ThreadComplete /* thread has finished */
87 * We are completely paranoid and make thread IDs 64 bits to avoid
88 * having to worry about overflow. A little calculation shows that
89 * even doing 10^6 forks per second would take 35 million years to
90 * overflow a 64 bit thread ID :-)
93 typedef StgWord32 StgThreadID;
96 * This type is returned to the scheduler by a thread that has
97 * stopped for one reason or another.
101 HeapOverflow, /* might also be StackOverflow */
106 } StgThreadReturnCode;
109 * Threads may be blocked for several reasons. A blocked thread will
110 * have the reason in the why_blocked field of the TSO, and some
111 * further info (such as the closure the thread is blocked on, or the
112 * file descriptor if the thread is waiting on I/O) in the block_info
125 , BlockedOnGA // blocked on a remote closure represented by a Global Address
140 * TSOs live on the heap, and therefore look just like heap objects.
141 * Large TSOs will live in their own "block group" allocated by the
142 * storage manager, and won't be copied during garbage collection.
145 typedef struct StgTSO_ {
147 struct StgTSO_* link;
148 /* SDM and HWL agree that it would be cool to have a list of all TSOs */
149 StgMutClosure * mut_link; /* TSO's are mutable of course! */
150 StgTSOWhatNext whatNext;
151 StgTSOBlockReason why_blocked;
152 StgTSOBlockInfo block_info;
153 struct StgTSO_* blocked_exceptions;
155 StgTSOTickyInfo ticky;
160 /* The thread stack... */
161 StgWord stack_size; /* stack size in *words* */
162 StgWord max_stack_size; /* maximum stack size in *words* */
170 /* -----------------------------------------------------------------------------
173 An active thread has the following properties:
175 tso->stack < tso->sp < tso->stack+tso->stack_size
176 tso->stack_size <= tso->max_stack_size
177 tso->splim == tso->stack + RESERVED_STACK_WORDS;
179 RESERVED_STACK_WORDS is large enough for any heap-check or
182 The size of the TSO struct plus the stack is either
183 (a) smaller than a block, or
184 (b) a multiple of BLOCK_SIZE
186 tso->block_reason tso->block_info location
187 ----------------------------------------------------------------------
188 NotBlocked NULL runnable_queue, or running
190 BlockedOnBlackHole the BLACKHOLE_BQ the BLACKHOLE_BQ's queue
192 BlockedOnMVar the MVAR the MVAR's queue
194 BlockedOnException the TSO TSO->blocked_exception
196 BlockedOnRead NULL blocked_queue
197 BlockedOnWrite NULL blocked_queue
198 BlockedOnDelay NULL blocked_queue
200 tso->link == END_TSO_QUEUE, if the thread is currently running.
202 A zombie thread has the following properties:
204 tso->whatNext == ThreadComplete or ThreadKilled
205 tso->link == (could be on some queue somewhere)
206 tso->su == tso->stack + tso->stack_size
207 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
208 tso->sp[0] == return value of thread, if whatNext == ThreadComplete,
209 exception , if whatNext == ThreadKilled
211 (tso->sp is left pointing at the top word on the stack so that
212 the return value or exception will be retained by a GC).
214 tso->blocked_exceptions is either:
216 NULL if async exceptions are unblocked.
218 END_TSO_QUEUE if async exceptions are blocked, but no threads
219 are currently waiting to deliver.
221 (StgTSO *)tso if threads are currently awaiting delivery of
222 exceptions to this thread.
224 ---------------------------------------------------------------------------- */
226 /* Workaround for a bug/quirk in gcc on certain architectures.
227 * symptom is that (&tso->stack - &tso->header) /= sizeof(StgTSO)
228 * in other words, gcc pads the structure at the end.
231 extern StgTSO dummy_tso;
233 #define TSO_STRUCT_SIZE \
234 ((int)&(dummy_tso).stack - (int)&(dummy_tso).header)
236 #define TSO_STRUCT_SIZEW (TSO_STRUCT_SIZE / sizeof(W_))