fd32919e9d415cf32c791c0eb23a8bd8aedae243
[ghc.git] / includes / rts / storage / TSO.h
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team, 1998-2009
4 *
5 * The definitions for Thread State Objects.
6 *
7 * ---------------------------------------------------------------------------*/
8
9 #ifndef RTS_STORAGE_TSO_H
10 #define RTS_STORAGE_TSO_H
11
12 /*
13 * PROFILING info in a TSO
14 */
15 typedef struct {
16 CostCentreStack *cccs; /* thread's current CCS */
17 } StgTSOProfInfo;
18
19 /*
20 * There is no TICKY info in a TSO at this time.
21 */
22
23 /*
24 * Thread IDs are 32 bits.
25 */
26 typedef StgWord32 StgThreadID;
27
28 #define tsoLocked(tso) ((tso)->flags & TSO_LOCKED)
29
30 /*
31 * Type returned after running a thread. Values of this type
32 * include HeapOverflow, StackOverflow etc. See Constants.h for the
33 * full list.
34 */
35 typedef unsigned int StgThreadReturnCode;
36
37 #if defined(mingw32_HOST_OS)
38 /* results from an async I/O request + its request ID. */
39 typedef struct {
40 unsigned int reqID;
41 int len;
42 int errCode;
43 } StgAsyncIOResult;
44 #endif
45
46 /* Reason for thread being blocked. See comment above struct StgTso_. */
47 typedef union {
48 StgClosure *closure;
49 StgTSO *prev; // a back-link when the TSO is on the run queue (NotBlocked)
50 struct MessageBlackHole_ *bh;
51 struct MessageThrowTo_ *throwto;
52 struct MessageWakeup_ *wakeup;
53 StgInt fd; /* StgInt instead of int, so that it's the same size as the ptrs */
54 #if defined(mingw32_HOST_OS)
55 StgAsyncIOResult *async_result;
56 #endif
57 #if !defined(THREADED_RTS)
58 StgWord target;
59 // Only for the non-threaded RTS: the target time for a thread
60 // blocked in threadDelay, in units of 1ms. This is a
61 // compromise: we don't want to take up much space in the TSO. If
62 // you want better resolution for threadDelay, use -threaded.
63 #endif
64 } StgTSOBlockInfo;
65
66
67 /*
68 * TSOs live on the heap, and therefore look just like heap objects.
69 * Large TSOs will live in their own "block group" allocated by the
70 * storage manager, and won't be copied during garbage collection.
71 */
72
73 /*
74 * Threads may be blocked for several reasons. A blocked thread will
75 * have the reason in the why_blocked field of the TSO, and some
76 * further info (such as the closure the thread is blocked on, or the
77 * file descriptor if the thread is waiting on I/O) in the block_info
78 * field.
79 */
80
81 typedef struct StgTSO_ {
82 StgHeader header;
83
84 /* The link field, for linking threads together in lists (e.g. the
85 run queue on a Capability.
86 */
87 struct StgTSO_* _link;
88 /*
89 Currently used for linking TSOs on:
90 * cap->run_queue_{hd,tl}
91 * (non-THREADED_RTS); the blocked_queue
92 * and pointing to the next chunk for a ThreadOldStack
93
94 NOTE!!! do not modify _link directly, it is subject to
95 a write barrier for generational GC. Instead use the
96 setTSOLink() function. Exceptions to this rule are:
97
98 * setting the link field to END_TSO_QUEUE
99 * setting the link field of the currently running TSO, as it
100 will already be dirty.
101 */
102
103 struct StgTSO_* global_link; // Links threads on the
104 // generation->threads lists
105
106 /*
107 * The thread's stack
108 */
109 struct StgStack_ *stackobj;
110
111 /*
112 * The tso->dirty flag indicates that this TSO's stack should be
113 * scanned during garbage collection. It also indicates that this
114 * TSO is on the mutable list.
115 *
116 * NB. The dirty flag gets a word to itself, so that it can be set
117 * safely by multiple threads simultaneously (the flags field is
118 * not safe for this purpose; see #3429). It is harmless for the
119 * TSO to be on the mutable list multiple times.
120 *
121 * tso->dirty is set by dirty_TSO(), and unset by the garbage
122 * collector (only).
123 */
124
125 StgWord16 what_next; // Values defined in Constants.h
126 StgWord16 why_blocked; // Values defined in Constants.h
127 StgWord32 flags; // Values defined in Constants.h
128 StgTSOBlockInfo block_info;
129 StgThreadID id;
130 StgWord32 saved_errno;
131 StgWord32 dirty; /* non-zero => dirty */
132 struct InCall_* bound;
133 struct Capability_* cap;
134
135 struct StgTRecHeader_ * trec; /* STM transaction record */
136
137 /*
138 * A list of threads blocked on this TSO waiting to throw exceptions.
139 */
140 struct MessageThrowTo_ * blocked_exceptions;
141
142 /*
143 * A list of StgBlockingQueue objects, representing threads
144 * blocked on thunks that are under evaluation by this thread.
145 */
146 struct StgBlockingQueue_ *bq;
147
148 /*
149 * The allocation limit for this thread, which is updated as the
150 * thread allocates. If the value drops below zero, and
151 * TSO_ALLOC_LIMIT is set in flags, we raise an exception in the
152 * thread, and give the thread a little more space to handle the
153 * exception before we raise the exception again.
154 *
155 * This is an integer, because we might update it in a place where
156 * it isn't convenient to raise the exception, so we want it to
157 * stay negative until we get around to checking it.
158 *
159 * Use only PK_Int64/ASSIGN_Int64 macros to get/set the value of alloc_limit
160 * in C code otherwise you will cause alignment issues on SPARC
161 */
162 StgInt64 alloc_limit; /* in bytes */
163
164 /*
165 * sum of the sizes of all stack chunks (in words), used to decide
166 * whether to throw the StackOverflow exception when the stack
167 * overflows, or whether to just chain on another stack chunk.
168 *
169 * Note that this overestimates the real stack size, because each
170 * chunk will have a gap at the end, of +RTS -kb<size> words.
171 * This means stack overflows are not entirely accurate, because
172 * the more gaps there are, the sooner the stack will run into the
173 * hard +RTS -K<size> limit.
174 */
175 StgWord32 tot_stack_size;
176
177 #ifdef TICKY_TICKY
178 /* TICKY-specific stuff would go here. */
179 #endif
180 #ifdef PROFILING
181 StgTSOProfInfo prof;
182 #endif
183 #ifdef mingw32_HOST_OS
184 StgWord32 saved_winerror;
185 #endif
186
187 } *StgTSOPtr; // StgTSO defined in rts/Types.h
188
189 typedef struct StgStack_ {
190 StgHeader header;
191 StgWord32 stack_size; // stack size in *words*
192 StgWord32 dirty; // non-zero => dirty
193 StgPtr sp; // current stack pointer
194 StgWord stack[];
195 } StgStack;
196
197 // Calculate SpLim from a TSO (reads tso->stackobj, but no fields from
198 // the stackobj itself).
199 INLINE_HEADER StgPtr tso_SpLim (StgTSO* tso)
200 {
201 return tso->stackobj->stack + RESERVED_STACK_WORDS;
202 }
203
204 /* -----------------------------------------------------------------------------
205 functions
206 -------------------------------------------------------------------------- */
207
208 void dirty_TSO (Capability *cap, StgTSO *tso);
209 void setTSOLink (Capability *cap, StgTSO *tso, StgTSO *target);
210 void setTSOPrev (Capability *cap, StgTSO *tso, StgTSO *target);
211
212 void dirty_STACK (Capability *cap, StgStack *stack);
213
214 /* -----------------------------------------------------------------------------
215 Invariants:
216
217 An active thread has the following properties:
218
219 tso->stack < tso->sp < tso->stack+tso->stack_size
220 tso->stack_size <= tso->max_stack_size
221
222 RESERVED_STACK_WORDS is large enough for any heap-check or
223 stack-check failure.
224
225 The size of the TSO struct plus the stack is either
226 (a) smaller than a block, or
227 (b) a multiple of BLOCK_SIZE
228
229 tso->why_blocked tso->block_info location
230 ----------------------------------------------------------------------
231 NotBlocked END_TSO_QUEUE runnable_queue, or running
232
233 BlockedOnBlackHole MessageBlackHole * TSO->bq
234
235 BlockedOnMVar the MVAR the MVAR's queue
236
237 BlockedOnSTM END_TSO_QUEUE STM wait queue(s)
238 BlockedOnSTM STM_AWOKEN run queue
239
240 BlockedOnMsgThrowTo MessageThrowTo * TSO->blocked_exception
241
242 BlockedOnRead NULL blocked_queue
243 BlockedOnWrite NULL blocked_queue
244 BlockedOnDelay NULL blocked_queue
245
246 tso->link == END_TSO_QUEUE, if the thread is currently running.
247
248 A zombie thread has the following properties:
249
250 tso->what_next == ThreadComplete or ThreadKilled
251 tso->link == (could be on some queue somewhere)
252 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
253 tso->sp[0] == return value of thread, if what_next == ThreadComplete,
254 exception , if what_next == ThreadKilled
255
256 (tso->sp is left pointing at the top word on the stack so that
257 the return value or exception will be retained by a GC).
258
259 ---------------------------------------------------------------------------- */
260
261 /* this is the NIL ptr for a TSO queue (e.g. runnable queue) */
262 #define END_TSO_QUEUE ((StgTSO *)(void*)&stg_END_TSO_QUEUE_closure)
263
264 #endif /* RTS_STORAGE_TSO_H */