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Variable size stacks now working
jonroach 27 Dec 2025 23:55
1 contributor
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9 months ago
4
1
 #include "coroutine.h"
2
 #include <assert.h>
3
 #include <setjmp.h>
4
 #include <stdbool.h>
5
 #include <stddef.h>
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6
 #include <stdio.h>
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 #include "cor_platform.h"
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8
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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)
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 # include <malloc.h>
14
 #endif
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15
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 /* 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
8 months ago
25
 static void Coroutine_RunNext(void);
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 static void _Coroutine_Continue(Coroutine *cor, void *value, bool early);
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27
 static unsigned char *StackTopNow(void);
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29
 ///////////////////////////////////////////////////////////////////////////////
30
 // 2-way linked lists...
31
 //
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32
 // Brought inline here to avoid namespace polution
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4
33
 ///////////////////////////////////////////////////////////////////////////////
34
35
 typedef struct List_Link List_Link;
36
 struct List_Link {
37
 List_Link *next;
38
 List_Link *prev;
39
 };
40
41
 typedef struct List_Head List_Head;
42
 struct 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
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55
56
 static inline bool List_IsEmpty(
57
 const List_Head *list
58
 ){
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4
59
 return list->fwd.link.next == &list->back.link;
60
 }
61
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62
63
 static inline List_Link *List_GetHead(
64
 const List_Head *list
65
 ){
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4
66
 return List_IsEmpty(list) ? NULL : list->fwd.link.next;
67
 }
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68
69
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70
 static inline List_Link *List_Begin(
71
 const List_Head *list
72
 ){
73
 return list->fwd.link.next;
74
 }
75
76
77
 static inline bool Link_NextIsLink(
78
 const List_Link *link
79
 ){
80
 return link->next != NULL;
81
 }
82
83
84
 static inline List_Link *Link_Next(
85
 List_Link *link
86
 ){
87
 return link->next;
88
 }
89
90
91
 static inline bool Link_PrevIsLink(
92
 const List_Link *link
93
 ){
94
 return link->prev != NULL;
95
 }
96
97
98
 static inline List_Link *Link_Prev(
99
 List_Link *link
100
 ){
101
 return link->prev;
102
 }
103
6 months ago
104
 static inline List_Link *List_GetTail(
105
 const List_Head *list
106
 ){
107
 return List_IsEmpty(list) ? NULL : list->back.link.prev;
108
 }
9 months ago
109
110
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4
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
9 months ago
114
115
 static inline void List_Init(
116
 List_Head *list
117
 ){
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4
118
 list->fwd.link.next = &list->back.link;
119
 list->fwd.link.prev = NULL;
120
 list->back.link.prev = &list->fwd.link;
121
 }
122
9 months ago
123
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124
 static 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
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135
 static inline void List_AddHead(
136
 List_Head *list,
137
 List_Link *link
138
 ){
6 months ago
139
 Link_AddAfter(link, &list->fwd.link);
9 months ago
4
140
 }
141
9 months ago
142
6 months ago
143
 static 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
9 months ago
154
 static inline void List_AddTail(
155
 List_Head *list,
156
 List_Link *link
157
 ){
6 months ago
158
 Link_AddBefore(link, &list->back.link);
9 months ago
4
159
 }
160
9 months ago
161
6 months ago
162
 static inline void Link_Remove(
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163
 List_Link *link
164
 ){
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165
 link->prev->next = link->next;
166
 link->next->prev = link->prev;
167
 }
168
169
 ///////////////////////////////////////////////////////////////////////////////
170
 // ...2-way linked lists
171
 ///////////////////////////////////////////////////////////////////////////////
172
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173
 typedef struct Coroutines Coroutines;
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4
174
175
 enum {
176
 Coroutines_Starting,
177
 Coroutines_Started,
178
 Coroutines_Active,
179
 Coroutines_Stopping
180
 };
181
182
 enum {
183
 Chunk_Initial,
184
 Chunk_Create,
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185
 Chunk_Split,
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4
186
 Chunk_Enter
187
 };
188
9 months ago
189
 typedef enum Coroutine_State {
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190
 Coroutine_Free,
191
 Coroutine_Idle,
192
 Coroutine_Running,
193
 Coroutine_Waiting,
194
 Coroutine_Complete
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195
 } Coroutine_State;
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4
196
197
 enum {
198
 Coroutines_Init,
199
 Coroutines_AllocatedChunk,
200
 Coroutines_CoroutineComplete,
201
 };
202
203
 struct Coroutine {
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204
 Coroutines *coroutines; // so can work with it off-thread
205
 List_Link link; // for whichever list it's on
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206
 List_Link all_link; // list of all Coroutines
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207
 jmp_buf buf; // how to get back to it
6 months ago
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
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211
 unsigned char *guard; // where the stack overrun guard is
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212
 size_t size;
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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
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217
 Coroutine_State state;
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4
218
 };
219
220
 struct Coroutines {
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221
 _Cor_Mutex mutex;
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222
 jmp_buf controller; // to return from Coroutine_Run
223
 jmp_buf chunk_allocated;// for chunk allocation
224
 unsigned char *guard; // the stack guard for the startup sequence
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225
 size_t gap_before; // bytes between previous's stack_top and next's Coroutine
226
 size_t gap_after; // bytes between Coroutine and stack_base
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4
227
228
 // singletons
229
 Coroutine *tip; // top of stack chunk
230
 Coroutine *active; // currently running coroutine
231
 Coroutine *primary; // Coroutine_Run coroutine
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232
 unsigned char *stack_limit; // when not NULL, where the stack finishes
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233
234
 // lists
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235
 List_Head all; // all Coroutines (in address order)
236
 List_Head free; // free Coroutines
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237
 List_Head inactive; // idle or complete
238
 List_Head runable; // running or waiting to run
239
 List_Head waiting; // yielded / waiting to run
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240
 _Cor_Mutex waiting_mutex;
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4
241
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242
 // Summary of the system
243
 Coroutine_Report report;
244
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245
 // state
246
 char state;
247
 };
248
6 months ago
249
 _Cor_thread_local Coroutines *g_c;
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250
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251
 static void ReserveStackSpace(Coroutines *cors, Coroutine *parent, size_t chunk_size, unsigned char *childs_limit);
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252
 static void stack_chunk_base(Coroutines *cors, Coroutine *parent, unsigned char *prev_limit, unsigned char *limit);
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253
9 months ago
254
7 months ago
255
 #define GUARD_PATTERN_SIZE (4)
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256
 // Check whether the guard is intact
257
 static inline bool Check_Guard(
258
 unsigned char *guard
259
 ){
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260
 return !guard ||
261
 (guard[0] == 0xde &&
262
 guard[1] == 0xad &&
263
 guard[2] == 0xbe &&
264
 guard[3] == 0xef);
9 months ago
265
 }
266
267
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268
 static inline void Apply_Guard(unsigned char *guard){
269
 guard[0] = 0xde;
270
 guard[1] = 0xad;
271
 guard[2] = 0xbe;
272
 guard[3] = 0xef;
273
 }
274
275
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276
 static bool Coroutine_StackHasOverrun(void){
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277
 unsigned char *stack_top = StackTopNow();
6 months ago
278
 unsigned char *stack_limit = g_c ? g_c->stack_limit : NULL;
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279
 if (stack_limit && stack_top < stack_limit){
280
 // current stack top is beyond limit - we are overrunning NOW
6 months ago
281
 return true;
7 months ago
282
 }
6 months ago
283
 Coroutine *me = g_c ? g_c->active : NULL;
7 months ago
284
 if (!me){
6 months ago
285
 return false;
7 months ago
286
 }
287
 if (me->guard){
6 months ago
288
 return !Check_Guard(me->guard);
7 months ago
289
 }
6 months ago
290
 return stack_top < me->limit;
7 months ago
291
 }
292
293
6 months ago
294
 static void ReserveStackSpace(
295
 Coroutines *cors,
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296
 Coroutine *parent,
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297
 size_t chunk_size,
298
 unsigned char *childs_limit
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299
 ){
7 months ago
300
 unsigned char *chunk_of_stack = alloca(chunk_size);
301
 #if COROUTINE_RECORD_LOWEST_HEADROOM
302
 for (size_t i = 0; i <= chunk_size-GUARD_PATTERN_SIZE; i += GUARD_PATTERN_SIZE){
303
 Apply_Guard(&chunk_of_stack[i]);
304
 }
305
 #else
7 months ago
306
 Apply_Guard(chunk_of_stack);
7 months ago
307
 #endif
6 months ago
308
 if (parent){
309
 parent->guard = chunk_of_stack;
310
 parent->limit = chunk_of_stack;
311
 parent->base = chunk_of_stack + chunk_size;
312
 }
6 months ago
313
 stack_chunk_base(cors, parent, chunk_of_stack, childs_limit);
9 months ago
4
314
 }
315
9 months ago
316
317
 static void stack_chunk_base(
6 months ago
318
 Coroutines *cors,
6 months ago
319
 Coroutine *parent,
6 months ago
320
 unsigned char *prev_limit,
321
 unsigned char *limit
9 months ago
322
 ){
9 months ago
4
323
 Coroutine here;
6 months ago
324
 here.coroutines = cors;
7 months ago
325
 here.state = Coroutine_Free;
6 months ago
326
 here.prev_limit = prev_limit;
327
 here.size = 0;
328
 here.base = NULL;
329
 here.guard = limit;
330
 here.limit = limit;
331
 if (limit){
332
 here.base = (unsigned char *)&here - cors->gap_after;
333
 here.size = here.base - here.limit;
334
 Apply_Guard(limit);
335
 }
336
6 months ago
337
 // insert into all list
338
 if (parent){
339
 Link_AddAfter(&here.all_link, &parent->all_link);
340
 } else {
341
 List_AddHead(&cors->all, &here.all_link);
6 months ago
342
 }
6 months ago
343
 // add to free list
344
 List_AddTail(&cors->free, &here.link);
6 months ago
345
346
 cors->report.coroutines_pool_size += 1;
347
348
 if (!cors->tip || &here < cors->tip){
349
 cors->tip = &here;
350
 }
351
7 months ago
352
 for(;;){
353
 switch (setjmp(here.buf)) {
354
 case Chunk_Initial:
7 months ago
355
 if (here.state == Coroutine_Free){
7 months ago
356
 // return to the coroutine allocator
6 months ago
357
 longjmp(cors->chunk_allocated, 1);
7 months ago
358
 } else {
359
 assert(here.state == Coroutine_Complete);
360
 // we finish here to ensure the setjmp is redone
6 months ago
361
 if (cors->primary == &here) {
7 months ago
362
 // if primary coroutine - return to Coroutine_Run
6 months ago
363
 longjmp(cors->controller, Coroutines_CoroutineComplete);
7 months ago
364
 }
6 months ago
365
 _Cor_Mutex_Unlock(&cors->mutex);
7 months ago
366
 Coroutine_RunNext();
367
 assert(false);
368
 }
369
 case Chunk_Create:
7 months ago
370
 // Request to create a new chunk on the stack
371
 // We're here if the coroutine is:
372
 // Allocated, but not 'run' (Coroutine_Idle)
373
 // Run, but not not entered yet (Coroutine_Running)
374
 // Completed (Coroutine_Complete)
6 months ago
375
 // Free, and the coroutines system is starting - we're characterising the system
376
 assert(here.state == Coroutine_Idle ||
377
 here.state == Coroutine_Running ||
378
 here.state == Coroutine_Complete ||
379
 (here.state == Coroutine_Free && cors->state == Coroutines_Starting));
380
 ReserveStackSpace(here.coroutines, &here, here.size, NULL);
7 months ago
381
 assert(false);
6 months ago
382
 case Chunk_Split:
383
 // Request to split this free block into two
384
 // here.size will be set to our shorter size
385
 ReserveStackSpace(here.coroutines, &here, here.size, here.limit);
386
 assert(false);
7 months ago
387
 case Chunk_Enter:
388
 // request to start a coroutine (ie use the chunk for a coroutine)
389
 // arrive here with mutex locked
390
 assert(here.state == Coroutine_Running);
6 months ago
391
 here.coroutines->active = &here;
392
 _Cor_Mutex_Unlock(&cors->mutex);
7 months ago
393
 here.value = here.start(here.entry_param);
9 months ago
394
7 months ago
395
 // check the guard
396
 assert(Check_Guard(here.guard));
9 months ago
397
6 months ago
398
 _Cor_Mutex_Lock(&here.coroutines->mutex);
399
 here.coroutines->active = NULL;
7 months ago
400
 assert(here.state == Coroutine_Running);
6 months ago
401
 Link_Remove(&here.link);
7 months ago
402
 here.state = Coroutine_Complete;
6 months ago
403
 List_AddTail(&here.coroutines->inactive, &here.link);
7 months ago
404
 // Coroutine has completed
405
 // Loop round to redo the setjmp() - if this coroutine yielded, then the setjmp will
406
 // need reseting
9 months ago
4
407
 }
408
 }
409
 }
410
9 months ago
411
8 months ago
412
 static void Coroutine_RunNext(void)
9 months ago
413
 {
414
 // arrive here with mutex unlocked
6 months ago
415
 _Cor_Mutex_Lock(&g_c->waiting_mutex);
416
 _Cor_Mutex_Lock(&g_c->mutex);
417
 Coroutine *next = List_Link_Container(Coroutine, link, List_GetHead(&g_c->runable));
9 months ago
418
 assert(next->state == Coroutine_Running);
419
 longjmp(next->buf, Chunk_Enter);
420
 assert(false);
421
 }
422
423
8 months ago
424
 void Coroutine_StartSystem(void)
9 months ago
4
425
 {
6 months ago
426
 assert(!g_c);
9 months ago
427
6 months ago
428
 Coroutines *cors = _Cor_Malloc(sizeof(*g_c));
429
 assert(cors);
9 months ago
430
6 months ago
431
 cors->state = Coroutines_Starting;
432
 _Cor_Mutex_ctor(&cors->mutex);
9 months ago
433
6 months ago
434
 cors->tip = NULL;
435
 cors->active = NULL;
9 months ago
4
436
6 months ago
437
 List_Init(&cors->all);
6 months ago
438
 List_Init(&cors->free);
439
 List_Init(&cors->inactive);
440
 List_Init(&cors->runable);
441
 List_Init(&cors->waiting);
442
 _Cor_Mutex_ctor(&cors->waiting_mutex);
443
 _Cor_Mutex_Lock(&cors->waiting_mutex);
9 months ago
4
444
6 months ago
445
 cors->report.coroutines_created = 0;
446
 cors->report.coroutines_pool_size = 0;
447
 cors->report.largest_stack = 0;
448
449
 // Charactersize the system...
450
 if (!setjmp(cors->chunk_allocated)){
451
 ReserveStackSpace(cors, NULL, COROUTINE_STARTUP_STACK_SIZE, NULL);
9 months ago
4
452
 }
6 months ago
453
 Coroutine *cor = List_Link_Container(Coroutine, link, List_GetHead(&cors->free));
454
 cor->size = COROUTINE_STARTUP_STACK_SIZE;
455
 if (!setjmp(cors->chunk_allocated)){
456
 longjmp(cor->buf, Chunk_Create);
457
 }
458
 cors->gap_before = cor->prev_limit - (unsigned char *)cor;
459
 cors->gap_after = (unsigned char *)cor - cor->base;
460
 // ...charactersize the system
9 months ago
461
6 months ago
462
 // discard what we've just created
463
 List_Init(&cors->free);
464
 cors->tip = NULL;
465
466
 cors->state = Coroutines_Started;
467
468
 g_c = cors;
9 months ago
4
469
 }
470
9 months ago
471
7 months ago
472
 void Coroutine_SetStackLimit(void *limit){
6 months ago
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);
475
 g_c->stack_limit = limit;
7 months ago
476
 }
477
478
8 months ago
479
 Coroutine_Report Coroutine_StopSystem(void)
9 months ago
4
480
 {
6 months ago
481
 assert(g_c);
482
 assert(g_c->state == Coroutines_Started);
483
 _Cor_Mutex_Lock(&g_c->mutex);
484
 g_c->state = Coroutines_Stopping;
9 months ago
4
485
6 months ago
486
 uintptr_t stackminheadroom;
7 months ago
487
 #if COROUTINE_RECORD_LOWEST_HEADROOM
6 months ago
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)){
9 months ago
490
 Coroutine *cor = List_Link_Container(Coroutine, link, link);
7 months ago
491
 if (cor->guard){
6 months ago
492
 for (uintptr_t i = 4; i < cor->size-3; i += 4){
7 months ago
493
 if (!Check_Guard(&cor->guard[i])){
494
 stackminheadroom = i < stackminheadroom ? i : stackminheadroom;
495
 break;
496
 }
9 months ago
497
 }
498
 }
499
 }
7 months ago
500
 #else
501
 stackminheadroom = 0;
502
 #endif
6 months ago
503
 g_c->report.lowest_headroom = stackminheadroom;
9 months ago
504
6 months ago
505
 assert(List_IsEmpty(&g_c->inactive));
506
 _Cor_Mutex_Unlock(&g_c->waiting_mutex);
507
 _Cor_Mutex_dtor(&g_c->waiting_mutex);
9 months ago
4
508
6 months ago
509
 assert(g_c->state == Coroutines_Stopping);
510
 _Cor_Mutex_Unlock(&g_c->mutex);
511
 _Cor_Mutex_dtor(&g_c->mutex);
9 months ago
512
6 months ago
513
 Coroutine_Report ret = g_c->report;
514
515
 _Cor_Free(g_c);
516
 g_c = NULL;
517
518
 return ret;
9 months ago
4
519
 }
520
9 months ago
521
9 months ago
522
 void Coroutine_Run_Coroutine(
523
 Coroutine *cor,
9 months ago
524
 void *value
525
 ){
526
 Coroutines *cors = cor->coroutines;
6 months ago
527
528
 // Can't Coroutine_Run_Coroutine() off-thread
529
 assert(g_c == cors);
530
8 months ago
531
 _Cor_Mutex_Lock(&cors->mutex);
9 months ago
532
 assert(cors->state == Coroutines_Started);
533
 cors->state = Coroutines_Active;
534
 cors->primary = cor;
9 months ago
535
8 months ago
536
 _Coroutine_Continue(cor, value, true);
9 months ago
4
537
9 months ago
538
 if (!setjmp(cors->controller)){
8 months ago
539
 _Cor_Mutex_Unlock(&cors->mutex);
9 months ago
540
541
 // check the guard
8 months ago
542
 assert(Check_Guard(cors->guard));
9 months ago
543
9 months ago
4
544
 // start the first coroutine
545
 Coroutine_RunNext();
546
 }
9 months ago
547
 // arrive here with mutex locked
9 months ago
548
 assert(List_IsEmpty(&cors->runable));
549
 assert(List_IsEmpty(&cors->waiting));
550
 assert(cors->state == Coroutines_Active);
551
 cors->state = Coroutines_Started;
8 months ago
552
 _Cor_Mutex_Unlock(&cors->mutex);
9 months ago
553
 }
554
555
6 months ago
556
 bool Coroutine_Run(
6 months ago
557
 size_t stack,
9 months ago
558
 Coroutine_Start start,
6 months ago
559
 void *value,
560
 void **result
9 months ago
561
 ){
6 months ago
562
 if (g_c && g_c->active){
6 months ago
563
 void *res = start(value);
564
 if (result){
565
 *result = res;
566
 }
567
 // no failures, so...
568
 return false;
7 months ago
569
 }
6 months ago
570
 assert(!g_c || g_c->state == Coroutines_Started);
571
 bool need_start = !g_c;
7 months ago
572
 if (need_start){
573
 Coroutine_StartSystem();
574
 }
6 months ago
575
 Coroutine *cor = Coroutine_New(stack, start);
6 months ago
576
 if (!cor){
577
 // that didn't work
578
 return true;
579
 }
9 months ago
580
 Coroutine_Run_Coroutine(cor, value);
6 months ago
581
 if (result){
582
 *result = Coroutine_GetValue(cor);
583
 }
9 months ago
584
 Coroutine_Delete(cor);
7 months ago
585
 if (need_start){
586
 Coroutine_StopSystem();
587
 }
6 months ago
588
 // no failures, so...
589
 return false;
9 months ago
4
590
 }
591
592
6 months ago
593
 static void Coroutine_FreeToIdle(
594
 Coroutine *cor,
9 months ago
595
 Coroutine_Start start
596
 ){
6 months ago
597
 assert(cor->state == Coroutine_Free);
598
 cor->state = Coroutine_Idle;
599
 cor->start = start;
600
 cor->value = NULL;
601
 Link_Remove(&cor->link);
602
 List_AddHead(&g_c->inactive, &cor->link);
9 months ago
603
6 months ago
604
 g_c->report.coroutines_created += 1;
605
 }
606
607
608
 static void Coroutine_FreeToIdleSize(
609
 Coroutine *cor,
610
 Coroutine_Start start,
611
 size_t size
612
 ){
613
 assert(!cor->guard);
614
 cor->size = size;
615
 cor->base = (unsigned char *)cor - g_c->gap_after;
616
 cor->limit = cor->base - cor->size;
617
 Coroutine_FreeToIdle(cor, start);
618
 }
619
620
621
 static Coroutine *Coroutine_New_Lock_Assumed(
622
 size_t size,
623
 Coroutine_Start start
624
 ){
625
 List_Link *link;
626
627
 if (!g_c->tip){
628
 // no tip - time to create one
629
630
 // we're the non-Coroutine which starts the Coroutine system.
631
 // Add a single free block
632
 if (!setjmp(g_c->chunk_allocated)){
633
 ReserveStackSpace(g_c, NULL, COROUTINE_STARTUP_STACK_SIZE, NULL);
6 months ago
634
 }
6 months ago
635
 }
636
6 months ago
637
 Coroutine *cor = NULL;
6 months ago
638
 for (link = List_Begin(&g_c->free); Link_NextIsLink(link); link = Link_Next(link)){
6 months ago
639
 Coroutine *candidate = List_Link_Container(Coroutine, link, link);
640
 if (!candidate->guard) {
6 months ago
641
 // this must be the tip
6 months ago
642
 assert(candidate == g_c->tip);
6 months ago
643
644
 // If this is the only Coroutine in the system, go ahead and use it regardless of size.
645
 // Note: there can only be one free block if there's no other sort of blocks as we merge on free
646
 if (List_IsEmpty(&g_c->inactive) &&
647
 List_IsEmpty(&g_c->runable) &&
648
 List_IsEmpty(&g_c->waiting) ){
649
 if (g_c->stack_limit){
6 months ago
650
 size_t available = (unsigned char *)candidate - g_c->stack_limit - g_c->gap_after;
6 months ago
651
 size = available < size ? available : size;
652
 }
6 months ago
653
 Coroutine_FreeToIdleSize(candidate, start, size);
654
 return candidate;
7 months ago
655
 }
6 months ago
656
657
 // Not the only coroutine in the system - check size
658
 if (g_c->stack_limit){
659
 // there's a limit - see what that space allows....
6 months ago
660
 size_t available = (unsigned char *)candidate - g_c->stack_limit - g_c->gap_after;
6 months ago
661
662
 if (available < size){
663
 // not enough space for this coroutine
664
 return NULL;
665
 }
666
667
 if (available >= size + g_c->gap_before + g_c->gap_after + COROUTINE_MINIMUM_STACK_SIZE) {
668
 // not enough space for another coroutine - use all the space for this one
669
 size = available;
670
 }
7 months ago
671
 }
6 months ago
672
 Coroutine_FreeToIdleSize(candidate, start, size);
673
 return candidate;
9 months ago
4
674
 }
6 months ago
675
 if (candidate->size >= size && candidate > cor){
676
 // chunk big enough, and a better choice than cor
677
 cor = candidate;
678
 }
679
 }
680
681
 if (cor){
682
 // - work out whether we're splitting or using the whole chunk
683
 if (cor->size >= size + g_c->gap_before + g_c->gap_after + COROUTINE_MINIMUM_STACK_SIZE){
684
 // enough space for a second coroutine so split this free block
685
 cor->size = size;
686
 if (!setjmp(g_c->chunk_allocated)){
687
 longjmp(cor->buf, Chunk_Split);
6 months ago
688
 }
689
 }
6 months ago
690
 // cor now ready to use
691
 Coroutine_FreeToIdle(cor, start);
692
 return cor;
9 months ago
4
693
 }
694
6 months ago
695
 // No big-enough free blocks - check if there's space beyond the tip block
696
697
 if (g_c->stack_limit && g_c->stack_limit > (unsigned char *)g_c->tip->limit - sizeof(Coroutine) - size){
698
 // no space for a new stack block
699
 return NULL;
700
 }
701
 Coroutine *tip = g_c->tip;
702
 Coroutine *me = g_c->active;
703
 if (tip == me) {
704
 if (!setjmp(g_c->chunk_allocated)){
705
 ReserveStackSpace(g_c, me, StackTopNow() - me->limit, NULL);
706
 }
707
 } else {
708
 if (!setjmp(g_c->chunk_allocated)){
709
 longjmp(tip->buf, Chunk_Create);
710
 }
711
 }
712
6 months ago
713
 cor = List_Link_Container(Coroutine, link, List_GetTail(&g_c->free));
9 months ago
4
714
 assert(cor->state == Coroutine_Free);
6 months ago
715
 cor->size = size;
716
 cor->limit = (unsigned char *)cor - g_c->gap_after - size;
9 months ago
4
717
 cor->state = Coroutine_Idle;
718
 cor->start = start;
719
 cor->value = NULL;
6 months ago
720
 Link_Remove(&cor->link);
721
 List_AddHead(&g_c->inactive, &cor->link);
9 months ago
4
722
6 months ago
723
 g_c->report.coroutines_created += 1;
724
 return cor;
725
 }
9 months ago
726
6 months ago
727
728
 Coroutine *Coroutine_New(
729
 size_t stack,
730
 Coroutine_Start start
731
 ){
732
 assert(g_c);
733
 assert((g_c->state == Coroutines_Started && List_IsEmpty(&g_c->inactive)) || g_c->state == Coroutines_Active);
734
 assert(!Coroutine_StackHasOverrun());
735
736
 _Cor_Mutex_Lock(&g_c->mutex);
737
738
 Coroutine *cor = Coroutine_New_Lock_Assumed(stack, start);
739
740
 if (cor && cor->size > g_c->report.largest_stack){
741
 g_c->report.largest_stack = cor->size;
742
 }
743
744
 _Cor_Mutex_Unlock(&g_c->mutex);
745
9 months ago
4
746
 return cor;
747
 }
748
9 months ago
749
750
 void Coroutine_Delete(
751
 Coroutine *cor
752
 ){
6 months ago
753
 assert(!Coroutine_StackHasOverrun());
6 months ago
754
 if (cor){
755
 Coroutines *cors = cor->coroutines;
756
 _Cor_Mutex_Lock(&cors->mutex);
757
 assert(cor->state == Coroutine_Idle || cor->state == Coroutine_Complete);
758
 cor->state = Coroutine_Free;
6 months ago
759
 Link_Remove(&cor->link);
760
6 months ago
761
 // insert into free list
762
 List_AddHead(&cors->free, &cor->link);
6 months ago
763
764
 // Check for merge with following Coroutine
6 months ago
765
 List_Link *link = Link_Next(&cor->all_link);
6 months ago
766
 if (Link_NextIsLink(link)){
6 months ago
767
 Coroutine *listcor = List_Link_Container(Coroutine, all_link, link);
768
 if (listcor->state == Coroutine_Free){
6 months ago
769
 // merge
6 months ago
770
 cor->size += cor->limit - listcor->limit;
6 months ago
771
 cor->limit = listcor->limit;
772
 cor->guard = listcor->guard;
6 months ago
773
 Link_Remove(&listcor->all_link);
6 months ago
774
 Link_Remove(&listcor->link);
6 months ago
775
 if (g_c->tip == listcor){
776
 g_c->tip = cor;
777
 }
6 months ago
778
 }
779
 }
780
781
 // check for merge with prev coroutine
6 months ago
782
 link = Link_Prev(&cor->all_link);
6 months ago
783
 if (Link_PrevIsLink(link)){
6 months ago
784
 Coroutine *listcor = List_Link_Container(Coroutine, all_link, link);
785
 if (listcor->state == Coroutine_Free){
6 months ago
786
 // merge
6 months ago
787
 listcor->size += listcor->limit - cor->limit;
6 months ago
788
 listcor->limit = cor->limit;
789
 listcor->guard = cor->guard;
6 months ago
790
 Link_Remove(&cor->all_link);
6 months ago
791
 Link_Remove(&cor->link);
6 months ago
792
 if (g_c->tip == cor){
793
 g_c->tip = listcor;
794
 }
6 months ago
795
 }
796
 }
797
6 months ago
798
 _Cor_Mutex_Unlock(&cors->mutex);
799
 }
9 months ago
4
800
 }
801
9 months ago
802
8 months ago
803
 // Coroutine_Continue, assuming the mutex is claimed
804
 static void _Coroutine_Continue(
9 months ago
805
 Coroutine *cor,
806
 void *value,
807
 bool early
808
 ){
809
 Coroutines *cors = cor->coroutines;
9 months ago
4
810
 assert(cor->state == Coroutine_Idle || cor->state == Coroutine_Waiting);
811
 cor->entry_param = value;
812
 cor->state = Coroutine_Running;
6 months ago
813
 Link_Remove(&cor->link);
9 months ago
4
814
 if ( early ) {
9 months ago
815
 List_AddHead(&cors->runable, &cor->link);
9 months ago
4
816
 } else {
9 months ago
817
 List_AddTail(&cors->runable, &cor->link);
9 months ago
4
818
 }
8 months ago
819
 _Cor_Mutex_Unlock(&cors->waiting_mutex);
8 months ago
820
 }
821
822
823
 void Coroutine_Continue(
824
 Coroutine *cor,
825
 void *value,
826
 bool early
827
 ){
6 months ago
828
 assert(!Coroutine_StackHasOverrun());
8 months ago
829
 Coroutines *cors = cor->coroutines;
8 months ago
830
 _Cor_Mutex_Lock(&cors->mutex);
8 months ago
831
 _Coroutine_Continue(cor, value, early);
8 months ago
832
 _Cor_Mutex_Unlock(&cors->mutex);
9 months ago
4
833
 }
834
9 months ago
835
836
 void *Coroutine_Yield(
837
 void *value,
838
 Coroutine_YieldCallback on_yield,
9 months ago
839
 void *yield_me
9 months ago
840
 ){
6 months ago
841
 assert(g_c);
842
 Coroutine *me = g_c->active;
7 months ago
843
 assert(me);
6 months ago
844
 assert(!Coroutine_StackHasOverrun());
9 months ago
845
6 months ago
846
 _Cor_Mutex_Lock(&g_c->mutex);
9 months ago
847
 Coroutines *cors = me->coroutines;
6 months ago
848
 assert(me && me->state == Coroutine_Running && cors == g_c);
7 months ago
849
 me->stack_top = StackTopNow();
9 months ago
4
850
 me->value = value;
851
 me->state = Coroutine_Waiting;
9 months ago
852
6 months ago
853
 Link_Remove(&me->link);
8 months ago
854
 if (!List_IsEmpty(&cors->runable)){
8 months ago
855
 _Cor_Mutex_Unlock(&cors->waiting_mutex);
8 months ago
856
 }
9 months ago
857
 List_AddTail(&cors->waiting, &me->link);
9 months ago
858
9 months ago
859
 switch (setjmp(me->buf)){
860
 case Chunk_Initial:
8 months ago
861
 _Cor_Mutex_Unlock(&cors->mutex);
9 months ago
862
 on_yield(yield_me);
9 months ago
4
863
 Coroutine_RunNext();
7 months ago
864
 assert(false);
9 months ago
865
 case Chunk_Create:
6 months ago
866
 assert(me == g_c->tip);
867
 ReserveStackSpace(me->coroutines, me, me->stack_top - me->limit, NULL);
9 months ago
868
 assert(false);
869
 case Chunk_Enter:
870
 // arrive here with mutex locked
9 months ago
871
 cors->active = me;
6 months ago
872
 assert(!Coroutine_StackHasOverrun());
9 months ago
873
 // when we return here - we are running again
874
 assert(me->state == Coroutine_Running);
875
 void *res = me->entry_param;
8 months ago
876
 _Cor_Mutex_Unlock(&cors->mutex);
9 months ago
877
 return res;
9 months ago
4
878
 }
9 months ago
879
 return NULL;
9 months ago
4
880
 }
881
9 months ago
882
883
 void *Coroutine_GetValue(
884
 Coroutine *cor
885
 ){
9 months ago
4
886
 return cor->value;
887
 }
888
9 months ago
889
8 months ago
890
 Coroutine *Coroutine_GetActive(void)
9 months ago
4
891
 {
6 months ago
892
 return g_c ? g_c->active : NULL;
9 months ago
4
893
 }
894
9 months ago
895
8 months ago
896
 intptr_t Coroutine_GetStackHeadroom(void){
6 months ago
897
 assert(g_c);
898
 assert(!Coroutine_StackHasOverrun());
899
 Coroutine *me = g_c->active;
7 months ago
900
 if (!me){
901
 // no active coroutine
6 months ago
902
 unsigned char *stack_limit = g_c->stack_limit;
7 months ago
903
 if (stack_limit){
904
 // no stack limit - assume we'll use COROUTINE_STACK_SIZE
905
 return StackTopNow() - stack_limit;
906
 } else {
907
 // no information where the stack ends - return something
6 months ago
908
 return COROUTINE_MINIMUM_STACK_SIZE;
7 months ago
909
 }
910
 }
6 months ago
911
 return StackTopNow() - me->limit;
9 months ago
912
 }
913
914
7 months ago
915
 // This is used to avoid compiler warnings about returning the address of a local
916
 static inline void *StopAddressWarnings(void *p)
917
 {
918
 return p;
9 months ago
919
 }
920
921
7 months ago
922
 void *Coroutine_GetStackHWM(void){
6 months ago
923
 assert(g_c);
924
 assert(g_c->state == Coroutines_Active);
925
 assert(!Coroutine_StackHasOverrun());
7 months ago
926
 // Find where the guards end
927
 unsigned char *guard;
6 months ago
928
 for (guard = g_c->active->guard; Check_Guard(guard); guard += 4){
7 months ago
929
 // do nothing
930
 }
931
 return guard;
932
 }
8 months ago
933
934
7 months ago
935
 void Coroutine_ClearStackForHWM(void){
6 months ago
936
 assert(g_c);
937
 assert(g_c->state == Coroutines_Active);
938
 assert(!Coroutine_StackHasOverrun());
7 months ago
939
 unsigned char *end = StackTopNow() - GUARD_PATTERN_SIZE;
6 months ago
940
 for (unsigned char *guard = g_c->active->guard+GUARD_PATTERN_SIZE; guard <= end; guard += GUARD_PATTERN_SIZE){
7 months ago
941
 Apply_Guard(guard);
7 months ago
942
 }
943
 }
944
945
6 months ago
946
 static bool Coroutine_CanStartCoroutine_Lock_Assumed(
947
 size_t size
948
 ){
949
 assert(g_c);
950
 assert(g_c->state == Coroutines_Started || g_c->state == Coroutines_Active);
951
 assert(!Coroutine_StackHasOverrun());
952
953
 if (!g_c->stack_limit){
7 months ago
954
 return true;
955
 }
7 months ago
956
6 months ago
957
 if (!g_c->tip){
958
 return true;
959
 }
960
961
 if (g_c->tip->state == Coroutine_Free){
962
 // last block is free
963
 if ((unsigned char *)g_c->tip - g_c->stack_limit >= (ptrdiff_t)(g_c->gap_after + size)){
964
 // enough room in free block, which is the last block
965
 return true;
966
 }
967
 } else {
968
 // last block is allocated
969
 if (g_c->tip->limit - g_c->stack_limit >= (ptrdiff_t)(g_c->gap_before + g_c->gap_after + size)){
970
 // enough room after the last block, which is allocated
971
 return true;
972
 }
973
 }
974
975
 // not enough room between allocated blocks and stack limit, so check free list
976
 List_Link *link;
977
 for (link = List_Begin(&g_c->free); Link_NextIsLink(link); link = Link_Next(link)){
978
 Coroutine *cor = List_Link_Container(Coroutine, link, link);
979
 if (cor->size >= size){
980
 return true;
981
 }
982
 }
983
984
 return false;
7 months ago
985
 }
986
987
6 months ago
988
 bool Coroutine_CanStartCoroutine(
989
 size_t size
990
 ){
991
 _Cor_Mutex_Lock(&g_c->mutex);
992
993
 bool result = Coroutine_CanStartCoroutine_Lock_Assumed(size);
994
995
 _Cor_Mutex_Unlock(&g_c->mutex);
996
997
 return result;
998
 }
999
8 months ago
1000
 void *Coroutine_GetCStackTop(void){
6 months ago
1001
 assert(!Coroutine_StackHasOverrun());
1002
 if ((g_c->state == Coroutines_Started || g_c->state == Coroutines_Active) && g_c->tip != g_c->active) {
1003
 return g_c->tip->stack_top;
7 months ago
1004
 } else {
1005
 return StackTopNow();
1006
 }
9 months ago
1007
 }
1008
1009
7 months ago
1010
 static unsigned char *StackTopNow(void){
7 months ago
1011
 unsigned char here[4];
1012
 return StopAddressWarnings(here);
1013
 }
1014
1015
9 months ago
1016
 struct Coroutine_ChainParam {
1017
 Coroutine_Start start;
1018
 void *value;
1019
 Coroutine *ret;
1020
 };
1021
1022
1023
 static void *Coroutine_ChainFn(
1024
 void *param
1025
 ){
1026
 struct Coroutine_ChainParam *params = (struct Coroutine_ChainParam *)param;
1027
 Coroutine_Continue(params->ret, params->start(params->value), true);
1028
 return NULL;
1029
 }
1030
1031
1032
 static void Coroutine_ChainYield(
1033
 void *unused
1034
 ){
1035
 (void)unused;
1036
 }
1037
1038
6 months ago
1039
 bool Coroutine_Chain(
6 months ago
1040
 size_t size,
9 months ago
1041
 Coroutine_Start start,
6 months ago
1042
 void *value,
1043
 void **result
9 months ago
1044
 ){
8 months ago
1045
 assert(Check_Guard(Coroutine_GetActive()->guard));
6 months ago
1046
 Coroutine *cor = Coroutine_New(size, Coroutine_ChainFn);
6 months ago
1047
 if (!cor){
1048
 // failed
1049
 return true;
1050
 }
9 months ago
1051
 struct Coroutine_ChainParam params = {
1052
 start,
1053
 value,
1054
 Coroutine_GetActive()
1055
 };
1056
 Coroutine_Continue(cor, &params, true);
1057
 void *res = Coroutine_Yield(NULL, Coroutine_ChainYield, NULL);
1058
 Coroutine_Delete(cor);
6 months ago
1059
 if (result){
1060
 *result = res;
1061
 }
1062
 // success!
1063
 return false;
9 months ago
1064
 }
1065
1066
9 months ago
1067
 bool Coroutine_IsRunning(
1068
 Coroutine *cor
1069
 )
9 months ago
4
1070
 {
9 months ago
1071
 int state = cor->state;
1072
 return state == Coroutine_Running || state == Coroutine_Waiting;
9 months ago
4
1073
 }
9 months ago
1074
1075
7 months ago
1076
 bool Coroutine_IsComplete(
1077
 Coroutine *cor
1078
 )
1079
 {
1080
 int state = cor->state;
1081
 return state == Coroutine_Complete;
1082
 }
1083
1084
8 months ago
1085
 bool Coroutine_IsStarted(void){
6 months ago
1086
 return g_c && (g_c->state == Coroutines_Active || g_c->state == Coroutines_Started);
9 months ago
1087
 }
6 months ago
1088
1089
 void _Coroutine_Dump(void){
1090
 char *state_to_text[] = {
1091
 "Free",
1092
 "Idle",
1093
 "Running",
1094
 "Waiting",
1095
 "Complete"
1096
 };
1097
 unsigned idx = 0;
1098
 List_Link *link;
1099
 for (link = List_Begin(&g_c->all); Link_NextIsLink(link); link = Link_Next(link)){
1100
 Coroutine *cor = List_Link_Container(Coroutine, all_link, link);
1101
 printf("%d) %p (%s) %ld%s\n", idx++, cor, state_to_text[cor->state], cor->size, cor == g_c->tip ? " (TIP)" : "");
1102
 }
1103
 }
1104