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_. */
50 StgInt fd; /* StgInt instead of int, so that it's the same size as the ptrs */
51 #if defined(mingw32_HOST_OS)
52 StgAsyncIOResult *async_result;
59 * TSOs live on the heap, and therefore look just like heap objects.
60 * Large TSOs will live in their own "block group" allocated by the
61 * storage manager, and won't be copied during garbage collection.
65 * Threads may be blocked for several reasons. A blocked thread will
66 * have the reason in the why_blocked field of the TSO, and some
67 * further info (such as the closure the thread is blocked on, or the
68 * file descriptor if the thread is waiting on I/O) in the block_info
72 typedef struct StgTSO_ {
75 /* The link field, for linking threads together in lists (e.g. the
76 run queue on a Capability.
78 struct StgTSO_* _link;
80 NOTE!!! do not modify _link directly, it is subject to
81 a write barrier for generational GC. Instead use the
82 setTSOLink() function. Exceptions to this rule are:
84 * setting the link field to END_TSO_QUEUE
85 * putting a TSO on the blackhole_queue
86 * setting the link field of the currently running TSO, as it
87 will already be dirty.
90 struct StgTSO_* global_link; /* Links all threads together */
92 StgWord dirty; /* non-zero => dirty */
94 * The tso->dirty flag indicates that this TSO's stack should be
95 * scanned during garbage collection. It also indicates that this
96 * TSO is on the mutable list.
98 * NB. The dirty flag gets a word to itself, so that it can be set
99 * safely by multiple threads simultaneously (the flags field is
100 * not safe for this purpose; see #3429). It is harmless for the
101 * TSO to be on the mutable list multiple times.
103 * tso->dirty is set by dirty_TSO(), and unset by the garbage
106 * The link field has a separate dirty bit of its own, namely the
107 * bit TSO_LINK_DIRTY in the tso->flags field, set by
111 StgWord16 what_next; /* Values defined in Constants.h */
112 StgWord16 why_blocked; /* Values defined in Constants.h */
114 StgTSOBlockInfo block_info;
118 struct Capability_* cap;
119 struct StgTRecHeader_ * trec; /* STM transaction record */
122 A list of threads blocked on this TSO waiting to throw
123 exceptions. In order to access this field, the TSO must be
124 locked using lockClosure/unlockClosure (see SMP.h).
126 struct StgTSO_ * blocked_exceptions;
129 /* TICKY-specific stuff would go here. */
134 #ifdef mingw32_HOST_OS
135 StgWord32 saved_winerror;
138 /* The thread stack... */
139 StgWord32 stack_size; /* stack size in *words* */
140 StgWord32 max_stack_size; /* maximum stack size in *words* */
143 StgWord stack[FLEXIBLE_ARRAY];
146 /* -----------------------------------------------------------------------------
148 -------------------------------------------------------------------------- */
150 void dirty_TSO (Capability *cap, StgTSO *tso);
151 void setTSOLink (Capability *cap, StgTSO *tso, StgTSO *target);
153 /* -----------------------------------------------------------------------------
156 An active thread has the following properties:
158 tso->stack < tso->sp < tso->stack+tso->stack_size
159 tso->stack_size <= tso->max_stack_size
161 RESERVED_STACK_WORDS is large enough for any heap-check or
164 The size of the TSO struct plus the stack is either
165 (a) smaller than a block, or
166 (b) a multiple of BLOCK_SIZE
168 tso->why_blocked tso->block_info location
169 ----------------------------------------------------------------------
170 NotBlocked NULL runnable_queue, or running
172 BlockedOnBlackHole the BLACKHOLE blackhole_queue
174 BlockedOnMVar the MVAR the MVAR's queue
176 BlockedOnSTM END_TSO_QUEUE STM wait queue(s)
178 BlockedOnException the TSO TSO->blocked_exception
180 BlockedOnRead NULL blocked_queue
181 BlockedOnWrite NULL blocked_queue
182 BlockedOnDelay NULL blocked_queue
183 BlockedOnGA closure TSO blocks on BQ of that closure
184 BlockedOnGA_NoSend closure TSO blocks on BQ of that closure
186 tso->link == END_TSO_QUEUE, if the thread is currently running.
188 A zombie thread has the following properties:
190 tso->what_next == ThreadComplete or ThreadKilled
191 tso->link == (could be on some queue somewhere)
192 tso->su == tso->stack + tso->stack_size
193 tso->sp == tso->stack + tso->stack_size - 1 (i.e. top stack word)
194 tso->sp[0] == return value of thread, if what_next == ThreadComplete,
195 exception , if what_next == ThreadKilled
197 (tso->sp is left pointing at the top word on the stack so that
198 the return value or exception will be retained by a GC).
200 The 2 cases BlockedOnGA and BlockedOnGA_NoSend are needed in a GUM
201 setup only. They mark a TSO that has entered a FETCH_ME or
202 FETCH_ME_BQ closure, respectively; only the first TSO hitting the
203 closure will send a Fetch message.
204 Currently we have no separate code for blocking on an RBH; we use the
205 BlockedOnBlackHole case for that. -- HWL
207 ---------------------------------------------------------------------------- */
209 /* Workaround for a bug/quirk in gcc on certain architectures.
210 * symptom is that (&tso->stack - &tso->header) /= sizeof(StgTSO)
211 * in other words, gcc pads the structure at the end.
214 extern StgTSO dummy_tso;
216 #define TSO_STRUCT_SIZE \
217 ((char *)&dummy_tso.stack - (char *)&dummy_tso.header)
219 #define TSO_STRUCT_SIZEW (TSO_STRUCT_SIZE / sizeof(W_))
221 /* this is the NIL ptr for a TSO queue (e.g. runnable queue) */
222 #define END_TSO_QUEUE ((StgTSO *)(void*)&stg_END_TSO_QUEUE_closure)
224 #endif /* RTS_STORAGE_TSO_H */