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Remove redundent coroutines guard
jonroach 29 Dec 2025 16:08
1 contributor
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1#include "coroutine.h"
2#include <assert.h>
3#include <setjmp.h>
4#include <stdbool.h>
5#include <stddef.h>
6#include <stdio.h>
7#include "cor_platform.h"
8
9// see CPython again, this time from ctypes.h
10#if (defined (__SVR4) && defined (__sun)) || defined(COROUTINE_HAVE_ALLOCA_H)
11# include <alloca.h>
12#elif defined(MS_WIN32)
13# include <malloc.h>
14#endif
15
16/* If the system does not define alloca(), we have to hope for a compiler builtin. */
17#ifndef alloca
18# if defined __GNUC__ || (__clang_major__ >= 4)
19# define alloca __builtin_alloca
20# else
21# error "Could not define alloca() on your platform."
22# endif
23#endif
24
25static void Coroutine_RunNext(void);
26static void _Coroutine_Continue(Coroutine *cor, void *value, bool early);
27static unsigned char *StackTopNow(void);
28
29///////////////////////////////////////////////////////////////////////////////
30// 2-way linked lists...
31//
32// Brought inline here to avoid namespace polution
33///////////////////////////////////////////////////////////////////////////////
34
35typedef struct List_Link List_Link;
36struct List_Link {
37 List_Link *next;
38 List_Link *prev;
39};
40
41typedef struct List_Head List_Head;
42struct List_Head {
43 union {
44 struct {
45 List_Link link;
46 List_Link *filler;
47 } fwd;
48 struct {
49 List_Link *filler;
50 List_Link link;
51 } back;
52 };
53};
54
55
56static inline bool List_IsEmpty(
57 const List_Head *list
58){
59 return list->fwd.link.next == &list->back.link;
60}
61
62
63static inline List_Link *List_GetHead(
64 const List_Head *list
65){
66 return List_IsEmpty(list) ? NULL : list->fwd.link.next;
67}
68
69
70static inline List_Link *List_Begin(
71 const List_Head *list
72){
73 return list->fwd.link.next;
74}
75
76
77static inline bool Link_NextIsLink(
78 const List_Link *link
79){
80 return link->next != NULL;
81}
82
83
84static inline List_Link *Link_Next(
85 List_Link *link
86){
87 return link->next;
88}
89
90
91static inline bool Link_PrevIsLink(
92 const List_Link *link
93){
94 return link->prev != NULL;
95}
96
97
98static inline List_Link *Link_Prev(
99 List_Link *link
100){
101 return link->prev;
102}
103
104static inline List_Link *List_GetTail(
105 const List_Head *list
106){
107 return List_IsEmpty(list) ? NULL : list->back.link.prev;
108}
109
110
111#define OFFSETOF(Container, Field) ((char *)&((Container *)4)->Field - (char *)(Container *)4)
112#define List_Link_Container(Container, Link, link) ((Container *)((char *)(link) - OFFSETOF(Container, Link)))
113
114
115static inline void List_Init(
116 List_Head *list
117){
118 list->fwd.link.next = &list->back.link;
119 list->fwd.link.prev = NULL;
120 list->back.link.prev = &list->fwd.link;
121}
122
123
124static inline void Link_AddAfter(
125 List_Link *link,
126 List_Link *after
127){
128 link->next = after->next;
129 link->prev = after;
130 after->next->prev = link;
131 after->next = link;
132}
133
134
135static inline void List_AddHead(
136 List_Head *list,
137 List_Link *link
138){
139 Link_AddAfter(link, &list->fwd.link);
140}
141
142
143static inline void Link_AddBefore(
144 List_Link *link,
145 List_Link *before
146){
147 link->prev = before->prev;
148 link->next = before;
149 before->prev->next = link;
150 before->prev = link;
151}
152
153
154static inline void List_AddTail(
155 List_Head *list,
156 List_Link *link
157){
158 Link_AddBefore(link, &list->back.link);
159}
160
161
162static inline void Link_Remove(
163 List_Link *link
164){
165 link->prev->next = link->next;
166 link->next->prev = link->prev;
167}
168
169///////////////////////////////////////////////////////////////////////////////
170// ...2-way linked lists
171///////////////////////////////////////////////////////////////////////////////
172
173typedef struct Coroutines Coroutines;
174
175enum {
176 Coroutines_Starting,
177 Coroutines_Started,
178 Coroutines_Active,
179 Coroutines_Stopping
180};
181
182enum {
183 Chunk_Initial,
184 Chunk_Create,
185 Chunk_Split,
186 Chunk_Enter
187};
188
189typedef enum Coroutine_State {
190 Coroutine_Free,
191 Coroutine_Idle,
192 Coroutine_Running,
193 Coroutine_Waiting,
194 Coroutine_Complete
195} Coroutine_State;
196
197enum {
198 Coroutines_Init,
199 Coroutines_AllocatedChunk,
200 Coroutines_CoroutineComplete,
201};
202
203struct Coroutine {
204 Coroutines *coroutines; // so can work with it off-thread
205 List_Link link; // for whichever list it's on
206 List_Link all_link; // list of all Coroutines
207 jmp_buf buf; // how to get back to it
208 unsigned char *prev_limit; // the previous Coroutine's stack limit
209 unsigned char *base; // where the base (high address) of this Coroutine's stack is
210 unsigned char *limit; // where the limit (low address) of this Coroutine's stack is
211 unsigned char *guard; // where the stack overrun guard is
212 size_t size;
213 Coroutine_Start start; // entry point
214 void *entry_param; // to pass to start
215 void *value; // yielded/returned
216 unsigned char *stack_top; // recorded at yield
217 Coroutine_State state;
218};
219
220struct Coroutines {
221 _Cor_Mutex mutex;
222 jmp_buf controller; // to return from Coroutine_Run
223 jmp_buf chunk_allocated;// for chunk allocation
224 size_t gap_before; // bytes between previous's stack_top and next's Coroutine
225 size_t gap_after; // bytes between Coroutine and stack_base
226
227 // singletons
228 Coroutine *tip; // top of stack chunk
229 Coroutine *active; // currently running coroutine
230 Coroutine *primary; // Coroutine_Run coroutine
231 unsigned char *stack_limit; // when not NULL, where the stack finishes
232
233 // lists
234 List_Head all; // all Coroutines (in address order)
235 List_Head free; // free Coroutines
236 List_Head inactive; // idle or complete
237 List_Head runable; // running or waiting to run
238 List_Head waiting; // yielded / waiting to run
239 _Cor_Mutex waiting_mutex;
240
241 // Summary of the system
242 Coroutine_Report report;
243
244 // state
245 char state;
246};
247
248_Cor_thread_local Coroutines *g_c;
249
250static void ReserveStackSpace(Coroutines *cors, Coroutine *parent, size_t chunk_size, unsigned char *childs_limit);
251static void stack_chunk_base(Coroutines *cors, Coroutine *parent, unsigned char *prev_limit, unsigned char *limit);
252
253
254#define GUARD_PATTERN_SIZE (4)
255// Check whether the guard is intact
256static inline bool Check_Guard(
257 unsigned char *guard
258){
259 return !guard ||
260 (guard[0] == 0xde &&
261 guard[1] == 0xad &&
262 guard[2] == 0xbe &&
263 guard[3] == 0xef);
264}
265
266
267static inline void Apply_Guard(unsigned char *guard){
268 guard[0] = 0xde;
269 guard[1] = 0xad;
270 guard[2] = 0xbe;
271 guard[3] = 0xef;
272}
273
274
275static bool Coroutine_StackHasOverrun(void){
276 unsigned char *stack_top = StackTopNow();
277 unsigned char *stack_limit = g_c ? g_c->stack_limit : NULL;
278 if (stack_limit && stack_top < stack_limit){
279 // current stack top is beyond limit - we are overrunning NOW
280 return true;
281 }
282 Coroutine *me = g_c ? g_c->active : NULL;
283 if (!me){
284 return false;
285 }
286 if (me->guard){
287 return !Check_Guard(me->guard);
288 }
289 return stack_top < me->limit;
290}
291
292
293static void ReserveStackSpace(
294 Coroutines *cors,
295 Coroutine *parent,
296 size_t chunk_size,
297 unsigned char *childs_limit
298){
299 unsigned char *chunk_of_stack = alloca(chunk_size);
300#if COROUTINE_RECORD_LOWEST_HEADROOM
301 for (size_t i = 0; i <= chunk_size-GUARD_PATTERN_SIZE; i += GUARD_PATTERN_SIZE){
302 Apply_Guard(&chunk_of_stack[i]);
303 }
304#else
305 Apply_Guard(chunk_of_stack);
306#endif
307 if (parent){
308 parent->guard = chunk_of_stack;
309 parent->limit = chunk_of_stack;
310 parent->base = chunk_of_stack + chunk_size;
311 }
312 stack_chunk_base(cors, parent, chunk_of_stack, childs_limit);
313}
314
315
316static void stack_chunk_base(
317 Coroutines *cors,
318 Coroutine *parent,
319 unsigned char *prev_limit,
320 unsigned char *limit
321){
322 Coroutine here;
323 here.coroutines = cors;
324 here.state = Coroutine_Free;
325 here.prev_limit = prev_limit;
326 here.size = 0;
327 here.base = NULL;
328 here.guard = limit;
329 here.limit = limit;
330 if (limit){
331 here.base = (unsigned char *)&here - cors->gap_after;
332 here.size = here.base - here.limit;
333 Apply_Guard(limit);
334 }
335
336 // insert into all list
337 if (parent){
338 Link_AddAfter(&here.all_link, &parent->all_link);
339 } else {
340 List_AddHead(&cors->all, &here.all_link);
341 }
342 // add to free list
343 List_AddTail(&cors->free, &here.link);
344
345 cors->report.coroutines_pool_size += 1;
346
347 if (!cors->tip || &here < cors->tip){
348 cors->tip = &here;
349 }
350
351 for(;;){
352 switch (setjmp(here.buf)) {
353 case Chunk_Initial:
354 if (here.state == Coroutine_Free){
355 // return to the coroutine allocator
356 longjmp(cors->chunk_allocated, 1);
357 } else {
358 assert(here.state == Coroutine_Complete);
359 // we finish here to ensure the setjmp is redone
360 if (cors->primary == &here) {
361 // if primary coroutine - return to Coroutine_Run
362 longjmp(cors->controller, Coroutines_CoroutineComplete);
363 }
364 _Cor_Mutex_Unlock(&cors->mutex);
365 Coroutine_RunNext();
366 assert(false);
367 }
368 case Chunk_Create:
369 // Request to create a new chunk on the stack
370 // We're here if the coroutine is:
371 // Allocated, but not 'run' (Coroutine_Idle)
372 // Run, but not not entered yet (Coroutine_Running)
373 // Completed (Coroutine_Complete)
374 // Free, and the coroutines system is starting - we're characterising the system
375 assert(here.state == Coroutine_Idle ||
376 here.state == Coroutine_Running ||
377 here.state == Coroutine_Complete ||
378 (here.state == Coroutine_Free && cors->state == Coroutines_Starting));
379 ReserveStackSpace(here.coroutines, &here, here.size, NULL);
380 assert(false);
381 case Chunk_Split:
382 // Request to split this free block into two
383 // here.size will be set to our shorter size
384 ReserveStackSpace(here.coroutines, &here, here.size, here.limit);
385 assert(false);
386 case Chunk_Enter:
387 // request to start a coroutine (ie use the chunk for a coroutine)
388 // arrive here with mutex locked
389 assert(here.state == Coroutine_Running);
390 here.coroutines->active = &here;
391 _Cor_Mutex_Unlock(&cors->mutex);
392 here.value = here.start(here.entry_param);
393
394 // check the guard
395 assert(Check_Guard(here.guard));
396
397 _Cor_Mutex_Lock(&here.coroutines->mutex);
398 here.coroutines->active = NULL;
399 assert(here.state == Coroutine_Running);
400 Link_Remove(&here.link);
401 here.state = Coroutine_Complete;
402 List_AddTail(&here.coroutines->inactive, &here.link);
403 // Coroutine has completed
404 // Loop round to redo the setjmp() - if this coroutine yielded, then the setjmp will
405 // need reseting
406 }
407 }
408}
409
410
411static void Coroutine_RunNext(void)
412{
413 // arrive here with mutex unlocked
414 _Cor_Mutex_Lock(&g_c->waiting_mutex);
415 _Cor_Mutex_Lock(&g_c->mutex);
416 Coroutine *next = List_Link_Container(Coroutine, link, List_GetHead(&g_c->runable));
417 assert(next->state == Coroutine_Running);
418 longjmp(next->buf, Chunk_Enter);
419 assert(false);
420}
421
422
423void Coroutine_StartSystem(void)
424{
425 assert(!g_c);
426
427 Coroutines *cors = _Cor_Malloc(sizeof(*g_c));
428 assert(cors);
429
430 cors->state = Coroutines_Starting;
431 _Cor_Mutex_ctor(&cors->mutex);
432
433 cors->tip = NULL;
434 cors->active = NULL;
435
436 List_Init(&cors->all);
437 List_Init(&cors->free);
438 List_Init(&cors->inactive);
439 List_Init(&cors->runable);
440 List_Init(&cors->waiting);
441 _Cor_Mutex_ctor(&cors->waiting_mutex);
442 _Cor_Mutex_Lock(&cors->waiting_mutex);
443
444 cors->report.coroutines_created = 0;
445 cors->report.coroutines_pool_size = 0;
446 cors->report.largest_stack = 0;
447
448 // Charactersize the system...
449 if (!setjmp(cors->chunk_allocated)){
450 ReserveStackSpace(cors, NULL, COROUTINE_STARTUP_STACK_SIZE, NULL);
451 }
452 Coroutine *cor = List_Link_Container(Coroutine, link, List_GetHead(&cors->free));
453 cor->size = COROUTINE_STARTUP_STACK_SIZE;
454 if (!setjmp(cors->chunk_allocated)){
455 longjmp(cor->buf, Chunk_Create);
456 }
457 cors->gap_before = cor->prev_limit - (unsigned char *)cor;
458 cors->gap_after = (unsigned char *)cor - cor->base;
459 // ...charactersize the system
460
461 // discard what we've just created
462 List_Init(&cors->all);
463 List_Init(&cors->free);
464 cors->tip = NULL;
465
466 cors->state = Coroutines_Started;
467
468 g_c = cors;
469}
470
471
472void Coroutine_SetStackLimit(void *limit){
473 assert(g_c);
474 assert(!limit || !(g_c->state == Coroutines_Started || g_c->state == Coroutines_Active) || (unsigned char *)limit < (unsigned char *)g_c->tip || !g_c->tip);
475 g_c->stack_limit = limit;
476}
477
478
479Coroutine_Report Coroutine_StopSystem(void)
480{
481 assert(g_c);
482 assert(g_c->state == Coroutines_Started);
483 _Cor_Mutex_Lock(&g_c->mutex);
484 g_c->state = Coroutines_Stopping;
485
486 uintptr_t stackminheadroom;
487#if COROUTINE_RECORD_LOWEST_HEADROOM
488 stackminheadroom = g_c->report.largest_stack;
489 for (List_Link *link = g_c->free.fwd.link.next; Link_NextIsLink(link); link = Link_Next(link)){
490 Coroutine *cor = List_Link_Container(Coroutine, link, link);
491 if (cor->guard){
492 for (uintptr_t i = 4; i < cor->size-3; i += 4){
493 if (!Check_Guard(&cor->guard[i])){
494 stackminheadroom = i < stackminheadroom ? i : stackminheadroom;
495 break;
496 }
497 }
498 }
499 }
500#else
501 stackminheadroom = 0;
502#endif
503 g_c->report.lowest_headroom = stackminheadroom;
504
505 assert(List_IsEmpty(&g_c->inactive));
506 _Cor_Mutex_Unlock(&g_c->waiting_mutex);
507 _Cor_Mutex_dtor(&g_c->waiting_mutex);
508
509 assert(g_c->state == Coroutines_Stopping);
510 _Cor_Mutex_Unlock(&g_c->mutex);
511 _Cor_Mutex_dtor(&g_c->mutex);
512
513 Coroutine_Report ret = g_c->report;
514
515 _Cor_Free(g_c);
516 g_c = NULL;
517
518 return ret;
519}
520
521
522void Coroutine_Run_Coroutine(
523 Coroutine *cor,
524 void *value
525){
526 Coroutines *cors = cor->coroutines;
527
528 // Can't Coroutine_Run_Coroutine() off-thread
529 assert(g_c == cors);
530
531 _Cor_Mutex_Lock(&cors->mutex);
532 assert(cors->state == Coroutines_Started);
533 cors->state = Coroutines_Active;
534 cors->primary = cor;
535
536 _Coroutine_Continue(cor, value, true);
537
538 if (!setjmp(cors->controller)){
539 _Cor_Mutex_Unlock(&cors->mutex);
540
541 // start the first coroutine
542 Coroutine_RunNext();
543 }
544 // arrive here with mutex locked
545 assert(List_IsEmpty(&cors->runable));
546 assert(List_IsEmpty(&cors->waiting));
547 assert(cors->state == Coroutines_Active);
548 cors->state = Coroutines_Started;
549 _Cor_Mutex_Unlock(&cors->mutex);
550}
551
552
553bool Coroutine_Run(
554 size_t stack,
555 Coroutine_Start start,
556 void *value,
557 void **result
558){
559 if (g_c && g_c->active){
560 void *res = start(value);
561 if (result){
562 *result = res;
563 }
564 // no failures, so...
565 return false;
566 }
567 assert(!g_c || g_c->state == Coroutines_Started);
568 bool need_start = !g_c;
569 if (need_start){
570 Coroutine_StartSystem();
571 }
572 Coroutine *cor = Coroutine_New(stack, start);
573 if (!cor){
574 // that didn't work
575 return true;
576 }
577 Coroutine_Run_Coroutine(cor, value);
578 if (result){
579 *result = Coroutine_GetValue(cor);
580 }
581 Coroutine_Delete(cor);
582 if (need_start){
583 Coroutine_StopSystem();
584 }
585 // no failures, so...
586 return false;
587}
588
589
590static void Coroutine_FreeToIdle(
591 Coroutine *cor,
592 Coroutine_Start start
593){
594 assert(cor->state == Coroutine_Free);
595 cor->state = Coroutine_Idle;
596 cor->start = start;
597 cor->value = NULL;
598 Link_Remove(&cor->link);
599 List_AddHead(&g_c->inactive, &cor->link);
600
601 g_c->report.coroutines_created += 1;
602}
603
604
605static void Coroutine_FreeToIdleSize(
606 Coroutine *cor,
607 Coroutine_Start start,
608 size_t size
609){
610 assert(!cor->guard);
611 cor->size = size;
612 cor->base = (unsigned char *)cor - g_c->gap_after;
613 cor->limit = cor->base - cor->size;
614 Coroutine_FreeToIdle(cor, start);
615}
616
617
618static Coroutine *Coroutine_New_Lock_Assumed(
619 size_t size,
620 Coroutine_Start start
621){
622 List_Link *link;
623
624 if (!g_c->tip){
625 // no tip - time to create one
626
627 // we're the non-Coroutine which starts the Coroutine system.
628 // Add a single free block
629 if (!setjmp(g_c->chunk_allocated)){
630 ReserveStackSpace(g_c, NULL, COROUTINE_STARTUP_STACK_SIZE, NULL);
631 }
632 }
633
634 Coroutine *cor = NULL;
635 for (link = List_Begin(&g_c->free); Link_NextIsLink(link); link = Link_Next(link)){
636 Coroutine *candidate = List_Link_Container(Coroutine, link, link);
637 if (!candidate->guard) {
638 // this must be the tip
639 assert(candidate == g_c->tip);
640
641 // If this is the only Coroutine in the system, go ahead and use it regardless of size.
642 // Note: there can only be one free block if there's no other sort of blocks as we merge on free
643 if (List_IsEmpty(&g_c->inactive) &&
644 List_IsEmpty(&g_c->runable) &&
645 List_IsEmpty(&g_c->waiting) ){
646 if (g_c->stack_limit){
647 size_t available = (unsigned char *)candidate - g_c->stack_limit - g_c->gap_after;
648 size = available < size ? available : size;
649 }
650 Coroutine_FreeToIdleSize(candidate, start, size);
651 return candidate;
652 }
653
654 // Not the only coroutine in the system - check size
655 if (g_c->stack_limit){
656 // there's a limit - see what that space allows....
657 size_t available = (unsigned char *)candidate - g_c->stack_limit - g_c->gap_after;
658
659 if (available < size){
660 // not enough space for this coroutine
661 return NULL;
662 }
663
664 if (available >= size + g_c->gap_before + g_c->gap_after + COROUTINE_MINIMUM_STACK_SIZE) {
665 // not enough space for another coroutine - use all the space for this one
666 size = available;
667 }
668 }
669 Coroutine_FreeToIdleSize(candidate, start, size);
670 return candidate;
671 }
672 if (candidate->size >= size && candidate > cor){
673 // chunk big enough, and a better choice than cor
674 cor = candidate;
675 }
676 }
677
678 if (cor){
679 // - work out whether we're splitting or using the whole chunk
680 if (cor->size >= size + g_c->gap_before + g_c->gap_after + COROUTINE_MINIMUM_STACK_SIZE){
681 // enough space for a second coroutine so split this free block
682 cor->size = size;
683 if (!setjmp(g_c->chunk_allocated)){
684 longjmp(cor->buf, Chunk_Split);
685 }
686 }
687 // cor now ready to use
688 Coroutine_FreeToIdle(cor, start);
689 return cor;
690 }
691
692 // No big-enough free blocks - check if there's space beyond the tip block
693
694 if (g_c->stack_limit && g_c->stack_limit > (unsigned char *)g_c->tip->limit - sizeof(Coroutine) - size){
695 // no space for a new stack block
696 return NULL;
697 }
698 Coroutine *tip = g_c->tip;
699 Coroutine *me = g_c->active;
700 if (tip == me) {
701 if (!setjmp(g_c->chunk_allocated)){
702 ReserveStackSpace(g_c, me, StackTopNow() - me->limit, NULL);
703 }
704 } else {
705 if (!setjmp(g_c->chunk_allocated)){
706 longjmp(tip->buf, Chunk_Create);
707 }
708 }
709
710 cor = List_Link_Container(Coroutine, link, List_GetTail(&g_c->free));
711 assert(cor->state == Coroutine_Free);
712 cor->size = size;
713 cor->limit = (unsigned char *)cor - g_c->gap_after - size;
714 cor->state = Coroutine_Idle;
715 cor->start = start;
716 cor->value = NULL;
717 Link_Remove(&cor->link);
718 List_AddHead(&g_c->inactive, &cor->link);
719
720 g_c->report.coroutines_created += 1;
721 return cor;
722}
723
724
725Coroutine *Coroutine_New(
726 size_t stack,
727 Coroutine_Start start
728){
729 assert(g_c);
730 assert((g_c->state == Coroutines_Started && List_IsEmpty(&g_c->inactive)) || g_c->state == Coroutines_Active);
731 assert(!Coroutine_StackHasOverrun());
732
733 _Cor_Mutex_Lock(&g_c->mutex);
734
735 Coroutine *cor = Coroutine_New_Lock_Assumed(stack, start);
736
737 if (cor && cor->size > g_c->report.largest_stack){
738 g_c->report.largest_stack = cor->size;
739 }
740
741 _Cor_Mutex_Unlock(&g_c->mutex);
742
743 return cor;
744}
745
746
747void Coroutine_Delete(
748 Coroutine *cor
749){
750 assert(!Coroutine_StackHasOverrun());
751 if (cor){
752 Coroutines *cors = cor->coroutines;
753 _Cor_Mutex_Lock(&cors->mutex);
754 assert(cor->state == Coroutine_Idle || cor->state == Coroutine_Complete);
755 cor->state = Coroutine_Free;
756 Link_Remove(&cor->link);
757
758 // insert into free list
759 List_AddHead(&cors->free, &cor->link);
760
761 // Check for merge with following Coroutine
762 List_Link *link = Link_Next(&cor->all_link);
763 if (Link_NextIsLink(link)){
764 Coroutine *listcor = List_Link_Container(Coroutine, all_link, link);
765 if (listcor->state == Coroutine_Free){
766 // merge
767 cor->size += cor->limit - listcor->limit;
768 cor->limit = listcor->limit;
769 cor->guard = listcor->guard;
770 Link_Remove(&listcor->all_link);
771 Link_Remove(&listcor->link);
772 if (g_c->tip == listcor){
773 g_c->tip = cor;
774 }
775 }
776 }
777
778 // check for merge with prev coroutine
779 link = Link_Prev(&cor->all_link);
780 if (Link_PrevIsLink(link)){
781 Coroutine *listcor = List_Link_Container(Coroutine, all_link, link);
782 if (listcor->state == Coroutine_Free){
783 // merge
784 listcor->size += listcor->limit - cor->limit;
785 listcor->limit = cor->limit;
786 listcor->guard = cor->guard;
787 Link_Remove(&cor->all_link);
788 Link_Remove(&cor->link);
789 if (g_c->tip == cor){
790 g_c->tip = listcor;
791 }
792 }
793 }
794
795 _Cor_Mutex_Unlock(&cors->mutex);
796 }
797}
798
799
800// Coroutine_Continue, assuming the mutex is claimed
801static void _Coroutine_Continue(
802 Coroutine *cor,
803 void *value,
804 bool early
805){
806 Coroutines *cors = cor->coroutines;
807 assert(cor->state == Coroutine_Idle || cor->state == Coroutine_Waiting);
808 cor->entry_param = value;
809 cor->state = Coroutine_Running;
810 Link_Remove(&cor->link);
811 if ( early ) {
812 List_AddHead(&cors->runable, &cor->link);
813 } else {
814 List_AddTail(&cors->runable, &cor->link);
815 }
816 _Cor_Mutex_Unlock(&cors->waiting_mutex);
817}
818
819
820void Coroutine_Continue(
821 Coroutine *cor,
822 void *value,
823 bool early
824){
825 assert(!Coroutine_StackHasOverrun());
826 Coroutines *cors = cor->coroutines;
827 _Cor_Mutex_Lock(&cors->mutex);
828 _Coroutine_Continue(cor, value, early);
829 _Cor_Mutex_Unlock(&cors->mutex);
830}
831
832
833void *Coroutine_Yield(
834 void *value,
835 Coroutine_YieldCallback on_yield,
836 void *yield_me
837){
838 assert(g_c);
839 Coroutine *me = g_c->active;
840 assert(me);
841 assert(!Coroutine_StackHasOverrun());
842
843 _Cor_Mutex_Lock(&g_c->mutex);
844 Coroutines *cors = me->coroutines;
845 assert(me && me->state == Coroutine_Running && cors == g_c);
846 me->stack_top = StackTopNow();
847 me->value = value;
848 me->state = Coroutine_Waiting;
849
850 Link_Remove(&me->link);
851 if (!List_IsEmpty(&cors->runable)){
852 _Cor_Mutex_Unlock(&cors->waiting_mutex);
853 }
854 List_AddTail(&cors->waiting, &me->link);
855
856 switch (setjmp(me->buf)){
857 case Chunk_Initial:
858 _Cor_Mutex_Unlock(&cors->mutex);
859 on_yield(yield_me);
860 Coroutine_RunNext();
861 assert(false);
862 case Chunk_Create:
863 assert(me == g_c->tip);
864 ReserveStackSpace(me->coroutines, me, me->stack_top - me->limit, NULL);
865 assert(false);
866 case Chunk_Enter:
867 // arrive here with mutex locked
868 cors->active = me;
869 assert(!Coroutine_StackHasOverrun());
870 // when we return here - we are running again
871 assert(me->state == Coroutine_Running);
872 void *res = me->entry_param;
873 _Cor_Mutex_Unlock(&cors->mutex);
874 return res;
875 }
876 return NULL;
877}
878
879
880void *Coroutine_GetValue(
881 Coroutine *cor
882){
883 return cor->value;
884}
885
886
887Coroutine *Coroutine_GetActive(void)
888{
889 return g_c ? g_c->active : NULL;
890}
891
892
893intptr_t Coroutine_GetStackHeadroom(void){
894 assert(g_c);
895 assert(!Coroutine_StackHasOverrun());
896 Coroutine *me = g_c->active;
897 if (!me){
898 // no active coroutine
899 unsigned char *stack_limit = g_c->stack_limit;
900 if (stack_limit){
901 // no stack limit - assume we'll use COROUTINE_STACK_SIZE
902 return StackTopNow() - stack_limit;
903 } else {
904 // no information where the stack ends - return something
905 return COROUTINE_MINIMUM_STACK_SIZE;
906 }
907 }
908 return StackTopNow() - me->limit;
909}
910
911
912// This is used to avoid compiler warnings about returning the address of a local
913static inline void *StopAddressWarnings(void *p)
914{
915 return p;
916}
917
918
919void *Coroutine_GetStackHWM(void){
920 assert(g_c);
921 assert(g_c->state == Coroutines_Active);
922 assert(!Coroutine_StackHasOverrun());
923 // Find where the guards end
924 unsigned char *guard;
925 for (guard = g_c->active->guard; Check_Guard(guard); guard += 4){
926 // do nothing
927 }
928 return guard;
929}
930
931
932void Coroutine_ClearStackForHWM(void){
933 assert(g_c);
934 assert(g_c->state == Coroutines_Active);
935 assert(!Coroutine_StackHasOverrun());
936 unsigned char *end = StackTopNow() - GUARD_PATTERN_SIZE;
937 for (unsigned char *guard = g_c->active->guard+GUARD_PATTERN_SIZE; guard <= end; guard += GUARD_PATTERN_SIZE){
938 Apply_Guard(guard);
939 }
940}
941
942
943static bool Coroutine_CanStartCoroutine_Lock_Assumed(
944 size_t size
945){
946 assert(g_c);
947 assert(g_c->state == Coroutines_Started || g_c->state == Coroutines_Active);
948 assert(!Coroutine_StackHasOverrun());
949
950 if (!g_c->stack_limit){
951 return true;
952 }
953
954 if (!g_c->tip){
955 return true;
956 }
957
958 if (g_c->tip->state == Coroutine_Free){
959 // last block is free
960 if ((unsigned char *)g_c->tip - g_c->stack_limit >= (ptrdiff_t)(g_c->gap_after + size)){
961 // enough room in free block, which is the last block
962 return true;
963 }
964 } else {
965 // last block is allocated
966 if (g_c->tip->limit - g_c->stack_limit >= (ptrdiff_t)(g_c->gap_before + g_c->gap_after + size)){
967 // enough room after the last block, which is allocated
968 return true;
969 }
970 }
971
972 // not enough room between allocated blocks and stack limit, so check free list
973 List_Link *link;
974 for (link = List_Begin(&g_c->free); Link_NextIsLink(link); link = Link_Next(link)){
975 Coroutine *cor = List_Link_Container(Coroutine, link, link);
976 if (cor->size >= size){
977 return true;
978 }
979 }
980
981 return false;
982}
983
984
985bool Coroutine_CanStartCoroutine(
986 size_t size
987){
988 _Cor_Mutex_Lock(&g_c->mutex);
989
990 bool result = Coroutine_CanStartCoroutine_Lock_Assumed(size);
991
992 _Cor_Mutex_Unlock(&g_c->mutex);
993
994 return result;
995}
996
997void *Coroutine_GetCStackTop(void){
998 assert(!Coroutine_StackHasOverrun());
999 if ((g_c->state == Coroutines_Started || g_c->state == Coroutines_Active) && g_c->tip != g_c->active) {
1000 return g_c->tip->stack_top;
1001 } else {
1002 return StackTopNow();
1003 }
1004}
1005
1006
1007static unsigned char *StackTopNow(void){
1008 unsigned char here[4];
1009 return StopAddressWarnings(here);
1010}
1011
1012
1013struct Coroutine_ChainParam {
1014 Coroutine_Start start;
1015 void *value;
1016 Coroutine *ret;
1017};
1018
1019
1020static void *Coroutine_ChainFn(
1021 void *param
1022){
1023 struct Coroutine_ChainParam *params = (struct Coroutine_ChainParam *)param;
1024 Coroutine_Continue(params->ret, params->start(params->value), true);
1025 return NULL;
1026}
1027
1028
1029static void Coroutine_ChainYield(
1030 void *unused
1031){
1032 (void)unused;
1033}
1034
1035
1036bool Coroutine_Chain(
1037 size_t size,
1038 Coroutine_Start start,
1039 void *value,
1040 void **result
1041){
1042 assert(Check_Guard(Coroutine_GetActive()->guard));
1043 Coroutine *cor = Coroutine_New(size, Coroutine_ChainFn);
1044 if (!cor){
1045 // failed
1046 return true;
1047 }
1048 struct Coroutine_ChainParam params = {
1049 start,
1050 value,
1051 Coroutine_GetActive()
1052 };
1053 Coroutine_Continue(cor, &params, true);
1054 void *res = Coroutine_Yield(NULL, Coroutine_ChainYield, NULL);
1055 Coroutine_Delete(cor);
1056 if (result){
1057 *result = res;
1058 }
1059 // success!
1060 return false;
1061}
1062
1063
1064bool Coroutine_IsRunning(
1065 Coroutine *cor
1066)
1067{
1068 int state = cor->state;
1069 return state == Coroutine_Running || state == Coroutine_Waiting;
1070}
1071
1072
1073bool Coroutine_IsComplete(
1074 Coroutine *cor
1075)
1076{
1077 int state = cor->state;
1078 return state == Coroutine_Complete;
1079}
1080
1081
1082bool Coroutine_IsStarted(void){
1083 return g_c && (g_c->state == Coroutines_Active || g_c->state == Coroutines_Started);
1084}
1085
1086void _Coroutine_Dump(void){
1087 char *state_to_text[] = {
1088 "Free",
1089 "Idle",
1090 "Running",
1091 "Waiting",
1092 "Complete"
1093 };
1094 unsigned idx = 0;
1095 List_Link *link;
1096 for (link = List_Begin(&g_c->all); Link_NextIsLink(link); link = Link_Next(link)){
1097 Coroutine *cor = List_Link_Container(Coroutine, all_link, link);
1098 printf("%d) %p (%s) %ld%s\n", idx++, cor, state_to_text[cor->state], cor->size, cor == g_c->tip ? " (TIP)" : "");
1099 }
1100}
1101