1 /* -----------------------------------------------------------------------------
2 * $Id: TSO.h,v 1.7 1999/05/11 16:47:42 keithw Exp $
4 * (c) The GHC Team, 1998-1999
6 * The definitions for Thread State Objects.
8 * ---------------------------------------------------------------------------*/
13 #if defined(PROFILING)
15 CostCentreStack *CCCS; /* thread's current CCS */
17 #else /* !PROFILING */
20 #endif /* PROFILING */
30 #if defined(TICKY_TICKY)
33 #else /* !TICKY_TICKY */
36 #endif /* TICKY_TICKY */
52 * We are completely paranoid and make thread IDs 64 bits to avoid
53 * having to worry about overflow. A little calculation shows that
54 * even doing 10^6 forks per second would take 35 million years to
55 * overflow a 64 bit thread ID :-)
58 typedef StgWord32 StgThreadID;
61 * This type is returned to the scheduler by a thread that has
62 * stopped for one reason or another.
66 HeapOverflow, /* might also be StackOverflow */
71 } StgThreadReturnCode;
74 * TSOs live on the heap, and therefore look just like heap objects.
75 * Large TSOs will live in their own "block group" allocated by the
76 * storage manager, and won't be copied during garbage collection.
79 typedef struct StgTSO_ {
82 StgMutClosure * mut_link; /* TSO's are mutable of course! */
83 StgTSOWhatNext whatNext;
84 StgClosure * blocked_on;
86 StgTSOTickyInfo ticky;
91 /* The thread stack... */
92 StgWord stack_size; /* stack size in *words* */
93 StgWord max_stack_size; /* maximum stack size in *words* */
101 extern DLL_IMPORT_RTS StgTSO *CurrentTSO;
103 /* -----------------------------------------------------------------------------
106 An active thread has the following properties:
108 tso->stack < tso->sp < tso->stack+tso->stack_size
109 tso->stack_size <= tso->max_stack_size
110 tso->splim == tso->stack + RESERVED_STACK_WORDS;
112 RESERVED_STACK_WORDS is large enough for any heap-check or
115 The size of the TSO struct plus the stack is either
116 (a) smaller than a block, or
117 (b) a multiple of BLOCK_SIZE
120 == END_TSO_QUEUE , iff the thread is currently running.
121 == (StgTSO *) , otherwise, and it is linked onto either:
123 - the runnable_queue tso->blocked_on == END_TSO_QUEUE
124 - the blocked_queue tso->blocked_on == END_TSO_QUEUE
125 - a BLACKHOLE_BQ, tso->blocked_on == the BLACKHOLE_BQ
126 - an MVAR, tso->blocked_on == the MVAR
128 A zombie thread has the following properties:
130 tso->whatNext == ThreadComplete or ThreadKilled
131 tso->link == (could be on some queue somewhere)
132 tso->su == tso->stack + tso->stack_size
133 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
134 tso->sp[0] == return value of thread, if whatNext == ThreadComplete,
135 exception , if whatNext == ThreadKilled
137 (tso->sp is left pointing at the top word on the stack so that
138 the return value or exception will be retained by a GC).
140 ---------------------------------------------------------------------------- */
142 /* Workaround for a bug/quirk in gcc on certain architectures.
143 * symptom is that (&tso->stack - &tso->header) /= sizeof(StgTSO)
144 * in other words, gcc pads the structure at the end.
147 extern StgTSO dummy_tso;
149 #define TSO_STRUCT_SIZE \
150 ((int)&(dummy_tso).stack - (int)&(dummy_tso).header)
152 #define TSO_STRUCT_SIZEW (TSO_STRUCT_SIZE / sizeof(W_))