1 /* -----------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2009
5 * The definitions for Thread State Objects.
7 * ---------------------------------------------------------------------------*/
9 #ifndef RTS_STORAGE_TSO_H
10 #define RTS_STORAGE_TSO_H
13 * PROFILING info in a TSO
16 CostCentreStack *CCCS; /* thread's current CCS */
20 * There is no TICKY info in a TSO at this time.
24 * Thread IDs are 32 bits.
26 typedef StgWord32 StgThreadID;
28 #define tsoLocked(tso) ((tso)->flags & TSO_LOCKED)
31 * Type returned after running a thread. Values of this type
32 * include HeapOverflow, StackOverflow etc. See Constants.h for the
35 typedef unsigned int StgThreadReturnCode;
37 #if defined(mingw32_HOST_OS)
38 /* results from an async I/O request + its request ID. */
46 /* Reason for thread being blocked. See comment above struct StgTso_. */
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;
62 * TSOs live on the heap, and therefore look just like heap objects.
63 * Large TSOs will live in their own "block group" allocated by the
64 * storage manager, and won't be copied during garbage collection.
68 * Threads may be blocked for several reasons. A blocked thread will
69 * have the reason in the why_blocked field of the TSO, and some
70 * further info (such as the closure the thread is blocked on, or the
71 * file descriptor if the thread is waiting on I/O) in the block_info
75 typedef struct StgTSO_ {
78 /* The link field, for linking threads together in lists (e.g. the
79 run queue on a Capability.
81 struct StgTSO_* _link;
83 Currently used for linking TSOs on:
84 * cap->run_queue_{hd,tl}
85 * (non-THREADED_RTS); the blocked_queue
86 * and pointing to the next chunk for a ThreadOldStack
88 NOTE!!! do not modify _link directly, it is subject to
89 a write barrier for generational GC. Instead use the
90 setTSOLink() function. Exceptions to this rule are:
92 * setting the link field to END_TSO_QUEUE
93 * setting the link field of the currently running TSO, as it
94 will already be dirty.
97 struct StgTSO_* global_link; // Links threads on the
98 // generation->threads lists
103 struct StgStack_ *stackobj;
106 * The tso->dirty flag indicates that this TSO's stack should be
107 * scanned during garbage collection. It also indicates that this
108 * TSO is on the mutable list.
110 * NB. The dirty flag gets a word to itself, so that it can be set
111 * safely by multiple threads simultaneously (the flags field is
112 * not safe for this purpose; see #3429). It is harmless for the
113 * TSO to be on the mutable list multiple times.
115 * tso->dirty is set by dirty_TSO(), and unset by the garbage
119 StgWord16 what_next; // Values defined in Constants.h
120 StgWord16 why_blocked; // Values defined in Constants.h
121 StgWord32 flags; // Values defined in Constants.h
122 StgTSOBlockInfo block_info;
124 StgWord32 saved_errno;
125 StgWord32 dirty; /* non-zero => dirty */
126 struct InCall_* bound;
127 struct Capability_* cap;
129 struct StgTRecHeader_ * trec; /* STM transaction record */
132 * A list of threads blocked on this TSO waiting to throw exceptions.
134 struct MessageThrowTo_ * blocked_exceptions;
137 * A list of StgBlockingQueue objects, representing threads
138 * blocked on thunks that are under evaluation by this thread.
140 struct StgBlockingQueue_ *bq;
143 /* TICKY-specific stuff would go here. */
148 #ifdef mingw32_HOST_OS
149 StgWord32 saved_winerror;
153 * sum of the sizes of all stack chunks (in words), used to decide
154 * whether to throw the StackOverflow exception when the stack
155 * overflows, or whether to just chain on another stack chunk.
157 * Note that this overestimates the real stack size, because each
158 * chunk will have a gap at the end, of +RTS -kb<size> words.
159 * This means stack overflows are not entirely accurate, because
160 * the more gaps there are, the sooner the stack will run into the
161 * hard +RTS -K<size> limit.
163 StgWord32 tot_stack_size;
167 typedef struct StgStack_ {
169 StgWord32 stack_size; // stack size in *words*
170 StgWord32 dirty; // non-zero => dirty
171 StgPtr sp; // current stack pointer
172 StgWord stack[FLEXIBLE_ARRAY];
175 // Calculate SpLim from a TSO (reads tso->stackobj, but no fields from
176 // the stackobj itself).
177 INLINE_HEADER StgPtr tso_SpLim (StgTSO* tso)
179 return tso->stackobj->stack + RESERVED_STACK_WORDS;
182 /* -----------------------------------------------------------------------------
184 -------------------------------------------------------------------------- */
186 void dirty_TSO (Capability *cap, StgTSO *tso);
187 void setTSOLink (Capability *cap, StgTSO *tso, StgTSO *target);
188 void setTSOPrev (Capability *cap, StgTSO *tso, StgTSO *target);
190 void dirty_STACK (Capability *cap, StgStack *stack);
192 /* -----------------------------------------------------------------------------
195 An active thread has the following properties:
197 tso->stack < tso->sp < tso->stack+tso->stack_size
198 tso->stack_size <= tso->max_stack_size
200 RESERVED_STACK_WORDS is large enough for any heap-check or
203 The size of the TSO struct plus the stack is either
204 (a) smaller than a block, or
205 (b) a multiple of BLOCK_SIZE
207 tso->why_blocked tso->block_info location
208 ----------------------------------------------------------------------
209 NotBlocked END_TSO_QUEUE runnable_queue, or running
211 BlockedOnBlackHole the BLACKHOLE blackhole_queue
213 BlockedOnMVar the MVAR the MVAR's queue
215 BlockedOnSTM END_TSO_QUEUE STM wait queue(s)
217 BlockedOnMsgThrowTo MessageThrowTo * TSO->blocked_exception
219 BlockedOnRead NULL blocked_queue
220 BlockedOnWrite NULL blocked_queue
221 BlockedOnDelay NULL blocked_queue
222 BlockedOnGA closure TSO blocks on BQ of that closure
223 BlockedOnGA_NoSend closure TSO blocks on BQ of that closure
225 tso->link == END_TSO_QUEUE, if the thread is currently running.
227 A zombie thread has the following properties:
229 tso->what_next == ThreadComplete or ThreadKilled
230 tso->link == (could be on some queue somewhere)
231 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
232 tso->sp[0] == return value of thread, if what_next == ThreadComplete,
233 exception , if what_next == ThreadKilled
235 (tso->sp is left pointing at the top word on the stack so that
236 the return value or exception will be retained by a GC).
238 The 2 cases BlockedOnGA and BlockedOnGA_NoSend are needed in a GUM
239 setup only. They mark a TSO that has entered a FETCH_ME or
240 FETCH_ME_BQ closure, respectively; only the first TSO hitting the
241 closure will send a Fetch message.
242 Currently we have no separate code for blocking on an RBH; we use the
243 BlockedOnBlackHole case for that. -- HWL
245 ---------------------------------------------------------------------------- */
247 /* this is the NIL ptr for a TSO queue (e.g. runnable queue) */
248 #define END_TSO_QUEUE ((StgTSO *)(void*)&stg_END_TSO_QUEUE_closure)
250 #endif /* RTS_STORAGE_TSO_H */