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 relocated version of a ThreadRelocated
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
100 StgWord dirty; /* non-zero => dirty */
102 * The tso->dirty flag indicates that this TSO's stack should be
103 * scanned during garbage collection. It also indicates that this
104 * TSO is on the mutable list.
106 * NB. The dirty flag gets a word to itself, so that it can be set
107 * safely by multiple threads simultaneously (the flags field is
108 * not safe for this purpose; see #3429). It is harmless for the
109 * TSO to be on the mutable list multiple times.
111 * tso->dirty is set by dirty_TSO(), and unset by the garbage
114 * The link field has a separate dirty bit of its own, namely the
115 * bit TSO_LINK_DIRTY in the tso->flags field, set by
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;
125 struct InCall_* bound;
126 struct Capability_* cap;
127 struct StgTRecHeader_ * trec; /* STM transaction record */
130 A list of threads blocked on this TSO waiting to throw
131 exceptions. In order to access this field, the TSO must be
132 locked using lockClosure/unlockClosure (see SMP.h).
134 struct MessageThrowTo_ * blocked_exceptions;
137 A list of StgBlockingQueue objects, representing threads blocked
138 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;
152 /* The thread stack... */
153 StgWord32 stack_size; /* stack size in *words* */
154 StgWord32 max_stack_size; /* maximum stack size in *words* */
157 StgWord stack[FLEXIBLE_ARRAY];
160 /* -----------------------------------------------------------------------------
162 -------------------------------------------------------------------------- */
164 void dirty_TSO (Capability *cap, StgTSO *tso);
165 void setTSOLink (Capability *cap, StgTSO *tso, StgTSO *target);
166 void setTSOPrev (Capability *cap, StgTSO *tso, StgTSO *target);
168 // Apply to a TSO before looking at it if you are not sure whether it
169 // might be ThreadRelocated or not (basically, that's most of the time
170 // unless the TSO is the current TSO).
172 INLINE_HEADER StgTSO * deRefTSO(StgTSO *tso)
174 while (tso->what_next == ThreadRelocated) {
180 /* -----------------------------------------------------------------------------
183 An active thread has the following properties:
185 tso->stack < tso->sp < tso->stack+tso->stack_size
186 tso->stack_size <= tso->max_stack_size
188 RESERVED_STACK_WORDS is large enough for any heap-check or
191 The size of the TSO struct plus the stack is either
192 (a) smaller than a block, or
193 (b) a multiple of BLOCK_SIZE
195 tso->why_blocked tso->block_info location
196 ----------------------------------------------------------------------
197 NotBlocked END_TSO_QUEUE runnable_queue, or running
199 BlockedOnBlackHole the BLACKHOLE blackhole_queue
201 BlockedOnMVar the MVAR the MVAR's queue
203 BlockedOnSTM END_TSO_QUEUE STM wait queue(s)
205 BlockedOnMsgThrowTo MessageThrowTo * TSO->blocked_exception
207 BlockedOnRead NULL blocked_queue
208 BlockedOnWrite NULL blocked_queue
209 BlockedOnDelay NULL blocked_queue
210 BlockedOnGA closure TSO blocks on BQ of that closure
211 BlockedOnGA_NoSend closure TSO blocks on BQ of that closure
213 tso->link == END_TSO_QUEUE, if the thread is currently running.
215 A zombie thread has the following properties:
217 tso->what_next == ThreadComplete or ThreadKilled
218 tso->link == (could be on some queue somewhere)
219 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
220 tso->sp[0] == return value of thread, if what_next == ThreadComplete,
221 exception , if what_next == ThreadKilled
223 (tso->sp is left pointing at the top word on the stack so that
224 the return value or exception will be retained by a GC).
226 The 2 cases BlockedOnGA and BlockedOnGA_NoSend are needed in a GUM
227 setup only. They mark a TSO that has entered a FETCH_ME or
228 FETCH_ME_BQ closure, respectively; only the first TSO hitting the
229 closure will send a Fetch message.
230 Currently we have no separate code for blocking on an RBH; we use the
231 BlockedOnBlackHole case for that. -- HWL
233 ---------------------------------------------------------------------------- */
235 /* Workaround for a bug/quirk in gcc on certain architectures.
236 * symptom is that (&tso->stack - &tso->header) /= sizeof(StgTSO)
237 * in other words, gcc pads the structure at the end.
240 extern StgTSO dummy_tso;
242 #define TSO_STRUCT_SIZE \
243 ((char *)&dummy_tso.stack - (char *)&dummy_tso.header)
245 #define TSO_STRUCT_SIZEW (TSO_STRUCT_SIZE / sizeof(W_))
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 */