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Merge from eCos master repository on 2000-08-21-22:40:54-BST
author jlarmour
date Fri, 25 Aug 2000 17:32:38 +0000
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children f62680ef1804
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114:5ad2b71d525e 115:6ed91473a1cd
1 #ifndef CYGONCE_KERNEL_MQUEUE_INL
2 #define CYGONCE_KERNEL_MQUEUE_INL
3 /*========================================================================
4 //
5 // mqueue.inl
6 //
7 // Message queues implementation
8 //
9 //========================================================================
10 //####COPYRIGHTBEGIN####
11 //
12 // -------------------------------------------
13 // The contents of this file are subject to the Red Hat eCos Public License
14 // Version 1.1 (the "License"); you may not use this file except in
15 // compliance with the License. You may obtain a copy of the License at
16 // http://www.redhat.com/
17 //
18 // Software distributed under the License is distributed on an "AS IS"
19 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
20 // License for the specific language governing rights and limitations under
21 // the License.
22 //
23 // The Original Code is eCos - Embedded Configurable Operating System,
24 // released September 30, 1998.
25 //
26 // The Initial Developer of the Original Code is Red Hat.
27 // Portions created by Red Hat are
28 // Copyright (C) 1998, 1999, 2000 Red Hat, Inc.
29 // All Rights Reserved.
30 // -------------------------------------------
31 //
32 //####COPYRIGHTEND####
33 //========================================================================
34 //#####DESCRIPTIONBEGIN####
35 //
36 // Author(s): jlarmour
37 // Contributors:
38 // Date: 2000-05-09
39 // Purpose: This file provides the implementation for eCos message
40 // queues
41 // Description: This differs from the message boxes also supported
42 // by eCos primarily because the requirements of message
43 // queues are driven by POSIX semantics. POSIX semantics are
44 // more dynamic and therefore heavyweight than Mboxes,
45 // including prioritization, and variable sized queues and
46 // message lengths
47 // Usage: Do not include this file directly - instead
48 // #include <cyg/kernel/mqueue.hxx>
49 //
50 //####DESCRIPTIONEND####
51 //
52 //======================================================================
53 */
54
55 /* CONFIGURATION */
56
57 #include <pkgconf/system.h>
58 #include <pkgconf/kernel.h> // Configuration header
59
60 /* INCLUDES */
61
62 #include <stddef.h> // size_t, NULL
63 #include <cyg/infra/cyg_type.h> // Types
64 #include <cyg/kernel/mqueue.hxx> // Header for this file, just in case
65 #include <cyg/infra/cyg_ass.h> // Assertion support
66 #include <cyg/infra/cyg_trac.h> // Tracing support
67 #include <cyg/kernel/sched.hxx> // scheduler
68 #include <cyg/kernel/sched.inl> // scheduler inlines
69 #include <cyg/kernel/sema.hxx> // Cyg_Counting_Semaphore
70
71 #ifdef CYGPKG_ISOINFRA
72 # include <string.h> // memcpy
73 #else
74 externC void * memcpy( void *, const void *, size_t );
75 #endif
76
77 // NOTE:
78 // An alternative implementation based on mutexes and condition variables
79 // rather than semaphores/scheduler locking was considered. But it was
80 // not thought quite as good because it isn't driver safe. You would
81 // also have to manage explicitly what counting semaphores do for you
82 // intrinsically. Also with the mutex approach, the message queue would
83 // be locked the whole time a new entry was being filled in, or copied out
84 //
85 // It also makes the non-blocking case properly non-blocking rather than
86 // still being able to block while waiting for a mutex protecting
87 // the message queue internal structures
88
89 /* INLINE FUNCTIONS */
90
91 //------------------------------------------------------------------------
92
93 inline cyg_bool
94 Cyg_Mqueue::check_this( cyg_assert_class_zeal zeal ) const
95 {
96 if (zeal != cyg_none) {
97 CYG_CHECK_DATA_PTRC(this); // extreme paranoia
98
99 #ifdef CYGDBG_USE_ASSERTS
100 if ( qlen <= 0 || msgsize <= 0 )
101 return false;
102 #endif
103
104 if ( queuespacesize < sizeof(struct qentry)+1 )
105 return false;
106
107 CYG_CHECK_DATA_PTRC(queuespace);
108 CYG_CHECK_FUNC_PTRC(free_fn);
109
110 // prevent pre-emption through this. Not so bad since
111 // this is only a diagnostic function
112 Cyg_Scheduler::lock();
113
114 if (NULL != q)
115 CYG_CHECK_DATA_PTRC(q);
116 if (NULL != freelist)
117 CYG_CHECK_DATA_PTRC(freelist);
118 if (NULL != callback)
119 CYG_CHECK_FUNC_PTRC(callback);
120
121 // check each queue entry
122 long msgs=0, busymsgs=0;
123 unsigned int oldprio=0;
124 struct qentry *qtmp;
125
126 if ( NULL != q )
127 oldprio = q->priority;
128 for ( qtmp=q; NULL != qtmp; qtmp=qtmp->next ) {
129 if ( NULL != qtmp->next )
130 CYG_CHECK_DATA_PTRC( qtmp->next );
131
132 // queue should be priority ordered
133 if ( qtmp->priority > oldprio )
134 goto fail;
135 oldprio = qtmp->priority;
136
137 #ifdef CYGDBG_USE_ASSERTS
138 // valid length
139 if ( !qtmp->busy )
140 if ( qtmp->buflen > msgsize )
141 goto fail;
142 #endif
143 if ( qtmp->busy )
144 busymsgs++;
145 else
146 msgs++;
147 } // for
148
149 long freemsgs=0;
150
151 // check that number of used and unused messages == q length
152 for ( qtmp=freelist; NULL != qtmp; qtmp=qtmp->next ) {
153 if ( NULL != qtmp->next )
154 CYG_CHECK_DATA_PTRC( qtmp->next );
155 if ( qtmp->busy )
156 busymsgs++;
157 else
158 freemsgs++;
159 }
160
161 #ifdef CYGDBG_USE_ASSERTS
162 // and sum of all messages should be the total q length
163 if ( qlen != (msgs+freemsgs+busymsgs) )
164 goto fail;
165 #endif
166
167 Cyg_Scheduler::unlock();
168
169 }
170 return true; // object OK
171 fail:
172 Cyg_Scheduler::unlock();
173 return false; // object fubar'd
174 }
175
176 //------------------------------------------------------------------------
177
178 inline
179 Cyg_Mqueue::Cyg_Mqueue( long maxmsgs, long maxmsgsize,
180 qalloc_fn_t qalloc, qfree_fn_t qfree, qerr_t *err )
181 : putsem(maxmsgs), getsem(0)
182 {
183 CYG_REPORT_FUNCTION();
184 CYG_REPORT_FUNCARG5( "maxmsgs=%ld, maxmsgsize=%ld, qalloc=%08x, "
185 "qfree=%08x, &err=%08x", maxmsgs, maxmsgsize,
186 qalloc, qfree, err);
187 CYG_PRECONDITIONC( (maxmsgs > 0) && (maxmsgsize > 0) );
188 CYG_CHECK_DATA_PTRC( err );
189 CYG_CHECK_FUNC_PTRC( qalloc );
190 CYG_CHECK_FUNC_PTRC( qfree );
191
192 // mem to allocate for entire queue size. Also wants to be rounded
193 // up so that the structs are aligned.
194 const long addralign = sizeof(void *) - 1;
195 long entrysize = (sizeof(struct qentry) + maxmsgsize + addralign)
196 & ~addralign;
197
198 queuespacesize = entrysize * maxmsgs;
199 queuespace = qalloc( queuespacesize );
200
201 if (NULL == queuespace) {
202 *err=NOMEM;
203 CYG_REPORT_RETURN();
204 return;
205 }
206
207 // link up freelist
208 long i;
209 struct qentry *qtmp;
210 for ( i=0, qtmp=(struct qentry *)queuespace;
211 i<maxmsgs-1;
212 i++, qtmp=qtmp->next ) {
213 qtmp->busy = false;
214 qtmp->next = (struct qentry *)((char *)qtmp + entrysize);
215 } // for
216
217 freelist = (struct qentry *)queuespace;
218
219 // set the last entry in the chain to the start to make the list circular
220 qtmp->next = NULL;
221 callback = NULL;
222 q = NULL;
223 free_fn = qfree;
224 #ifdef CYGDBG_USE_ASSERTS
225 qlen = maxmsgs;
226 msgsize = maxmsgsize;
227 #endif
228
229 *err = OK;
230
231 // object should be valid now
232 CYG_ASSERT_THISC();
233
234 CYG_REPORT_RETURN();
235 }
236
237 //------------------------------------------------------------------------
238
239 inline
240 Cyg_Mqueue::~Cyg_Mqueue()
241 {
242 CYG_REPORT_FUNCTION();
243
244 if ( NULL != queuespace ) {
245 // object should be valid if queuespace was successfully allocated
246 CYG_ASSERT_THISC();
247 free_fn( queuespace, queuespacesize );
248 }
249
250 #ifdef CYGDBG_USE_ASSERTS
251 qlen = msgsize = 0; // deliberately make it fail check_this() if used
252 #endif
253
254 CYG_REPORT_RETURN();
255 }
256
257 //------------------------------------------------------------------------
258
259 // put() copies len bytes of *buf into the queue at priority prio
260 inline Cyg_Mqueue::qerr_t
261 Cyg_Mqueue::put( const char *buf, size_t len, unsigned int prio, bool block )
262 {
263 CYG_REPORT_FUNCTYPE( "err=%d");
264 CYG_REPORT_FUNCARG4( "buf=%08x, len=%ld, prio=%ud, block=%d",
265 buf, len, prio, block==true );
266 CYG_CHECK_DATA_PTRC( buf );
267 CYG_ASSERT_THISC();
268 CYG_PRECONDITIONC( len <= (size_t)msgsize );
269
270 qerr_t err;
271 struct qentry *qtmp, *qent;
272
273 // wait till a freelist entry is available
274 if ( true == block ) {
275 if ( false == putsem.wait() ) {
276 err = INTR;
277 goto exit;
278 }
279 } else {
280 if ( false == putsem.trywait() ) {
281 err = WOULDBLOCK;
282 goto exit;
283 }
284 }
285
286 // prevent preemption when fiddling with important members
287 Cyg_Scheduler::lock();
288
289 CYG_ASSERT_THISC();
290
291 // get a queue entry from the freelist
292 // don't need to check the freelist - the semaphore tells us there's
293 // definitely a usable non-busy one there. It's just a question of
294 // locating it.
295
296 if (!freelist->busy) { // fast-track common case
297 qent = freelist;
298 freelist = freelist->next;
299 } else {
300 for ( qtmp=freelist; !qtmp->next->busy; qtmp=qtmp->next )
301 CYG_EMPTY_STATEMENT; // skip through
302 qent = qtmp->next;
303 qtmp->next = qent->next;
304 }
305
306 // now put it in place in q
307
308 if ( NULL == q ) {
309 q = qent;
310 q->next = NULL;
311 } else {
312 struct qentry **qentp;
313
314 // insert into queue according to prio
315 for ( qentp=&q; NULL != *qentp; qentp = &((*qentp)->next) ) {
316 if ((*qentp)->priority < prio)
317 break;
318 } // for
319
320 qent->next = *qentp;
321 *qentp = qent;
322 } // else
323
324 qent->priority = prio; // have to set this now so when the sched is
325 // unlocked, other qent's can be added in the
326 // right place
327 qent->busy = true; // let things know this entry should be ignored until
328 // it's finished having its data copied
329
330 // unlock the scheduler, and potentially switch threads, but
331 // that's okay now. We don't want it locked for the expensive memcpy
332 Cyg_Scheduler::unlock();
333
334 qent->buflen = len;
335 memcpy( qent->buf(), buf, len );
336
337 // make available now - setting non-atomically is alright if you think
338 // about it - the only thing that matters is that it's completed before
339 // the post()
340 qent->busy = false;
341
342 // if we have to notify someone, we only do it if no-one's already
343 // sitting waiting for a message to appear, AND if it's a transition
344 // from empty to non-empty
345
346 if ( callback != NULL && !getsem.waiting() && (0 == getsem.peek()) ) {
347 getsem.post();
348 callback( *this, callback_data );
349 } else
350 getsem.post();
351
352 err = OK;
353
354 exit:
355 CYG_ASSERT_THISC();
356 CYG_REPORT_RETVAL(err);
357 return err;
358 } // Cyg_Mqueue::put()
359
360 //------------------------------------------------------------------------
361
362
363 // get() returns the oldest highest priority message in the queue in *buf
364 // and sets *prio to the priority (if prio is non-NULL) and *len to the
365 // actual message size
366
367 inline Cyg_Mqueue::qerr_t
368 Cyg_Mqueue::get( char *buf, size_t *len, unsigned int *prio, bool block )
369 {
370 CYG_REPORT_FUNCTYPE( "err=%d");
371 CYG_REPORT_FUNCARG4( "buf=%08x, len=%08x, prio=%08x, block=%d",
372 buf, len, prio, block==true );
373 CYG_CHECK_DATA_PTRC( buf );
374 CYG_CHECK_DATA_PTRC( len );
375 if ( NULL != prio )
376 CYG_CHECK_DATA_PTRC( prio );
377 CYG_ASSERT_THISC();
378
379 qerr_t err;
380 struct qentry *qent;
381
382 // wait till a q entry is available
383 if ( true == block ) {
384 if ( false == getsem.wait() ) {
385 err = INTR;
386 goto exit;
387 }
388 } else {
389 if ( false == getsem.trywait() ) {
390 err = WOULDBLOCK;
391 goto exit;
392 }
393 }
394
395 // prevent preemption when fiddling with important members
396
397 Cyg_Scheduler::lock();
398
399 // don't need to check the q - the semaphore tells us there's
400 // definitely a usable non-busy one there. It's just a question of
401 // locating it.
402
403 if ( !q->busy ) { // fast-track the common case
404 qent = q;
405 q = qent->next;
406 } else {
407 struct qentry *qtmp;
408
409 for ( qtmp=q; !qtmp->next->busy; qtmp=qtmp->next )
410 CYG_EMPTY_STATEMENT; // skip through
411
412 qent = qtmp->next;
413 qtmp->next = qent->next;
414 } // else
415
416 // now stick at front of freelist, but marked busy
417 qent->next = freelist;
418 freelist = qent;
419
420 qent->busy = true; // don't let it truly be part of the freelist just yet
421 // till the data is copied out
422
423 // unlock the scheduler, and potentially switch threads, but
424 // that's okay now. We don't want it locked for the expensive memcpy
425 Cyg_Scheduler::unlock();
426
427 *len = qent->buflen;
428 if ( NULL != prio )
429 *prio = qent->priority;
430 memcpy( buf, qent->buf(), *len );
431
432 // make available now - setting non-atomically is alright if you think
433 // about it - the only thing that matters is that it's completed before
434 // the post()
435 qent->busy = false;
436
437 putsem.post();
438
439 err = OK;
440
441 exit:
442 CYG_ASSERT_THISC();
443 CYG_REPORT_RETVAL(err);
444 return err;
445
446 } // Cyg_Mqueue::get()
447
448 //------------------------------------------------------------------------
449
450 // count() returns the number of messages in the queue
451 inline long
452 Cyg_Mqueue::count()
453 {
454 CYG_REPORT_FUNCTYPE("curmsgs=%d");
455
456 long curmsgs = (long)getsem.peek();
457
458 CYG_REPORT_RETVAL(curmsgs);
459 return curmsgs;
460 } // Cyg_Mqueue::count()
461
462 //------------------------------------------------------------------------
463
464
465 // Supply a callback function to call (with the supplied data argument)
466 // when the queue goes from empty to non-empty (unless someone's already
467 // doing a get()). This returns the old callback_fn, and if olddata is
468 // non-NULL sets it to the old data (yes, really!)
469 inline Cyg_Mqueue::callback_fn_t
470 Cyg_Mqueue::setnotify( callback_fn_t callback_fn, CYG_ADDRWORD data,
471 CYG_ADDRWORD *olddata)
472 {
473 CYG_REPORT_FUNCTYPE("old callback=%08x");
474 CYG_REPORT_FUNCARG3XV( callback_fn, data, olddata );
475 if ( NULL != callback_fn )
476 CYG_CHECK_FUNC_PTRC( callback_fn );
477 if (NULL != olddata)
478 CYG_CHECK_DATA_PTRC( olddata );
479
480 callback_fn_t oldfn;
481
482 // Need to prevent preemption for accessing common structures
483 // Just locking the scheduler has the least overhead
484 Cyg_Scheduler::lock();
485
486 oldfn = callback;
487 if (NULL != olddata)
488 *olddata = callback_data;
489
490 callback_data = data;
491 callback = callback_fn;
492
493 Cyg_Scheduler::unlock();
494
495 CYG_REPORT_RETVAL(oldfn);
496 return oldfn;
497 }
498
499 //------------------------------------------------------------------------
500
501 #endif /* CYGONCE_KERNEL_MQUEUE_INL multiple inclusion protection */
502
503 /* EOF mqueue.inl */