source: src/libcfa/concurrency/monitor.c @ be3d020

ADTaaron-thesisarm-ehast-experimentalcleanup-dtorsdeferred_resndemanglerenumforall-pointer-decayjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerpthread-emulationqualifiedEnumresolv-newwith_gc
Last change on this file since be3d020 was be3d020, checked in by Thierry Delisle <tdelisle@…>, 7 years ago
  • signal/signal_block now returns true if the queue was not empty
  • wait now supports passing in a user define value
  • Property mode set to 100644
File size: 13.8 KB
Line 
1//                              -*- Mode: CFA -*-
2//
3// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
4//
5// The contents of this file are covered under the licence agreement in the
6// file "LICENCE" distributed with Cforall.
7//
8// monitor_desc.c --
9//
10// Author           : Thierry Delisle
11// Created On       : Thd Feb 23 12:27:26 2017
12// Last Modified By : Thierry Delisle
13// Last Modified On : --
14// Update Count     : 0
15//
16
17#include "monitor"
18
19#include <stdlib>
20
21#include "kernel_private.h"
22#include "libhdr.h"
23
24//-----------------------------------------------------------------------------
25// Forward declarations
26static inline void set_owner( monitor_desc * this, thread_desc * owner );
27static inline thread_desc * next_thread( monitor_desc * this );
28
29static inline void lock_all( spinlock ** locks, unsigned short count );
30static inline void lock_all( monitor_desc ** source, spinlock ** /*out*/ locks, unsigned short count );
31static inline void unlock_all( spinlock ** locks, unsigned short count );
32static inline void unlock_all( monitor_desc ** locks, unsigned short count );
33
34static inline void save_recursion   ( monitor_desc ** ctx, unsigned int * /*out*/ recursions, unsigned short count );
35static inline void restore_recursion( monitor_desc ** ctx, unsigned int * /*in */ recursions, unsigned short count );
36
37static inline thread_desc * check_condition( __condition_criterion_t * );
38static inline void brand_condition( condition * );
39static inline unsigned short insert_unique( thread_desc ** thrds, unsigned short end, thread_desc * val );
40
41//-----------------------------------------------------------------------------
42// Enter/Leave routines
43
44
45extern "C" {
46        void __enter_monitor_desc(monitor_desc * this) {
47                lock( &this->lock );
48                thread_desc * thrd = this_thread();
49
50                LIB_DEBUG_PRINT_SAFE("%p Entering %p (o: %p, r: %i)\n", thrd, this, this->owner, this->recursion);
51
52                if( !this->owner ) {
53                        //No one has the monitor, just take it
54                        set_owner( this, thrd );
55                }
56                else if( this->owner == thrd) {
57                        //We already have the monitor, just not how many times we took it
58                        assert( this->recursion > 0 );
59                        this->recursion += 1;
60                }
61                else {
62                        //Some one else has the monitor, wait in line for it
63                        append( &this->entry_queue, thrd );
64                        LIB_DEBUG_PRINT_SAFE("%p Blocking on entry\n", thrd);
65                        ScheduleInternal( &this->lock );
66
67                        //ScheduleInternal will unlock spinlock, no need to unlock ourselves
68                        return; 
69                }
70
71                unlock( &this->lock );
72                return;
73        }
74
75        // leave pseudo code :
76        //      TODO
77        void __leave_monitor_desc(monitor_desc * this) {
78                lock( &this->lock );
79
80                thread_desc * thrd = this_thread();
81
82                LIB_DEBUG_PRINT_SAFE("%p Leaving %p (o: %p, r: %i)\n", thrd, this, this->owner, this->recursion);
83                assertf( thrd == this->owner, "Expected owner to be %p, got %p (r: %i)", thrd, this->owner, this->recursion );
84
85                //Leaving a recursion level, decrement the counter
86                this->recursion -= 1;
87
88                //If we haven't left the last level of recursion
89                //it means we don't need to do anything
90                if( this->recursion != 0) {
91                        unlock( &this->lock );
92                        return;
93                }
94
95                thread_desc * new_owner = next_thread( this );
96
97                //We can now let other threads in safely
98                unlock( &this->lock );
99
100                LIB_DEBUG_PRINT_SAFE("Next owner is %p\n", new_owner);
101
102                //We need to wake-up the thread
103                ScheduleThread( new_owner );
104        }
105}
106
107static inline void enter(monitor_desc ** monitors, int count) {
108        for(int i = 0; i < count; i++) {
109                __enter_monitor_desc( monitors[i] );
110        }
111}
112
113static inline void leave(monitor_desc ** monitors, int count) {
114        for(int i = count - 1; i >= 0; i--) {
115                __leave_monitor_desc( monitors[i] );
116        }
117}
118
119void ?{}( monitor_guard_t * this, monitor_desc ** m, int count ) {
120        this->m = m;
121        this->count = count;
122        qsort(this->m, count);
123        enter( this->m, this->count );
124
125        this->prev_mntrs = this_thread()->current_monitors;
126        this->prev_count = this_thread()->current_monitor_count;
127
128        this_thread()->current_monitors      = m;
129        this_thread()->current_monitor_count = count;
130}
131
132void ^?{}( monitor_guard_t * this ) {
133        leave( this->m, this->count );
134
135        this_thread()->current_monitors      = this->prev_mntrs;
136        this_thread()->current_monitor_count = this->prev_count;
137}
138
139void ?{}(__condition_node_t * this, thread_desc * waiting_thread, unsigned short count, uintptr_t user_info ) {
140        this->waiting_thread = waiting_thread;
141        this->count = count;
142        this->next = NULL;
143        this->user_info = user_info;
144}
145
146void ?{}(__condition_criterion_t * this ) {
147        this->ready  = false;
148        this->target = NULL;
149        this->owner  = NULL;
150        this->next   = NULL;
151}
152
153void ?{}(__condition_criterion_t * this, monitor_desc * target, __condition_node_t * owner ) {
154        this->ready  = false;
155        this->target = target;
156        this->owner  = owner;
157        this->next   = NULL;
158}
159
160//-----------------------------------------------------------------------------
161// Internal scheduling
162void wait( condition * this, uintptr_t user_info = 0 ) {
163        LIB_DEBUG_PRINT_SAFE("Waiting\n");
164
165        brand_condition( this );
166
167        //Check that everything is as expected
168        assertf( this->monitors != NULL, "Waiting with no monitors (%p)", this->monitors );
169        assertf( this->monitor_count != 0, "Waiting with 0 monitors (%i)", this->monitor_count );
170        assertf( this->monitor_count < 32u, "Excessive monitor count (%i)", this->monitor_count );
171
172        unsigned short count = this->monitor_count;
173        unsigned int recursions[ count ];               //Save the current recursion levels to restore them later
174        spinlock *   locks     [ count ];               //We need to pass-in an array of locks to ScheduleInternal
175
176        LIB_DEBUG_PRINT_SAFE("count %i\n", count);
177
178        __condition_node_t waiter = { this_thread(), count, user_info };
179
180        __condition_criterion_t criteria[count];
181        for(int i = 0; i < count; i++) {
182                (&criteria[i]){ this->monitors[i], &waiter };
183                LIB_DEBUG_PRINT_SAFE( "Criterion %p\n", &criteria[i] );
184        }
185
186        waiter.criteria = criteria;
187        append( &this->blocked, &waiter );
188
189        lock_all( this->monitors, locks, count );
190        save_recursion( this->monitors, recursions, count );
191        //DON'T unlock, ask the kernel to do it
192
193        //Find the next thread(s) to run
194        unsigned short thread_count = 0;
195        thread_desc * threads[ count ];
196        for(int i = 0; i < count; i++) {
197                threads[i] = 0;
198        }
199
200        for( int i = 0; i < count; i++) {
201                thread_desc * new_owner = next_thread( this->monitors[i] );
202                thread_count = insert_unique( threads, thread_count, new_owner );
203        }
204
205        LIB_DEBUG_PRINT_SAFE("Will unblock: ");
206        for(int i = 0; i < thread_count; i++) {
207                LIB_DEBUG_PRINT_SAFE("%p ", threads[i]);
208        }
209        LIB_DEBUG_PRINT_SAFE("\n");
210
211        // Everything is ready to go to sleep
212        ScheduleInternal( locks, count, threads, thread_count );
213
214        //WE WOKE UP
215
216
217        //We are back, restore the owners and recursions
218        lock_all( locks, count );
219        restore_recursion( this->monitors, recursions, count );
220        unlock_all( locks, count );
221}
222
223bool signal( condition * this ) {
224        if( is_empty( this ) ) {
225                LIB_DEBUG_PRINT_SAFE("Nothing to signal\n");
226                return false;
227        }
228
229        //Check that everything is as expected
230        assert( this->monitors );
231        assert( this->monitor_count != 0 );
232
233        unsigned short count = this->monitor_count;
234       
235        //Some more checking in debug
236        LIB_DEBUG_DO(
237                thread_desc * this_thrd = this_thread();
238                if ( this->monitor_count != this_thrd->current_monitor_count ) {
239                        abortf( "Signal on condition %p made with different number of monitor(s), expected %i got %i", this, this->monitor_count, this_thrd->current_monitor_count );
240                } // if
241
242                for(int i = 0; i < this->monitor_count; i++) {
243                        if ( this->monitors[i] != this_thrd->current_monitors[i] ) {
244                                abortf( "Signal on condition %p made with different monitor, expected %p got %i", this, this->monitors[i], this_thrd->current_monitors[i] );
245                        } // if
246                }
247        );
248
249        //Lock all the monitors
250        lock_all( this->monitors, NULL, count );
251        LIB_DEBUG_PRINT_SAFE("Signalling");
252
253        //Pop the head of the waiting queue
254        __condition_node_t * node = pop_head( &this->blocked );
255
256        //Add the thread to the proper AS stack
257        for(int i = 0; i < count; i++) {
258                __condition_criterion_t * crit = &node->criteria[i];
259                LIB_DEBUG_PRINT_SAFE(" %p", crit->target);
260                assert( !crit->ready );
261                push( &crit->target->signal_stack, crit );
262        }
263
264        LIB_DEBUG_PRINT_SAFE("\n");
265
266        //Release
267        unlock_all( this->monitors, count );
268
269        return true;
270}
271
272bool signal_block( condition * this ) {
273        if( !this->blocked.head ) {
274                LIB_DEBUG_PRINT_SAFE("Nothing to signal\n");
275                return false;
276        }
277
278        //Check that everything is as expected
279        assertf( this->monitors != NULL, "Waiting with no monitors (%p)", this->monitors );
280        assertf( this->monitor_count != 0, "Waiting with 0 monitors (%i)", this->monitor_count );
281
282        unsigned short count = this->monitor_count;
283        unsigned int recursions[ count ];               //Save the current recursion levels to restore them later
284        spinlock *   locks     [ count ];               //We need to pass-in an array of locks to ScheduleInternal
285
286        lock_all( this->monitors, locks, count );
287
288        //create creteria
289        __condition_node_t waiter = { this_thread(), count, 0 };
290
291        __condition_criterion_t criteria[count];
292        for(int i = 0; i < count; i++) {
293                (&criteria[i]){ this->monitors[i], &waiter };
294                LIB_DEBUG_PRINT_SAFE( "Criterion %p\n", &criteria[i] );
295                push( &criteria[i].target->signal_stack, &criteria[i] );
296        }
297
298        waiter.criteria = criteria;
299
300        //save contexts
301        save_recursion( this->monitors, recursions, count );
302
303        //Find the thread to run
304        thread_desc * signallee = pop_head( &this->blocked )->waiting_thread;
305        for(int i = 0; i < count; i++) {
306                set_owner( this->monitors[i], signallee );
307        }
308
309        LIB_DEBUG_PRINT_SAFE( "Waiting on signal block\n" );
310
311        //Everything is ready to go to sleep
312        ScheduleInternal( locks, count, &signallee, 1 );
313
314        LIB_DEBUG_PRINT_SAFE( "Back from signal block\n" );
315
316        //We are back, restore the owners and recursions
317        lock_all( locks, count );
318        restore_recursion( this->monitors, recursions, count );
319        unlock_all( locks, count );
320
321        return true;
322}
323
324uintptr_t front( condition * this ) {
325        LIB_DEBUG_DO(
326                if( is_empty(this) ) {
327                        abortf( "Attempt to access user data on an empty condition.\n"
328                    "Possible cause is not checking if the condition is empty before reading stored data." );
329                }
330        );
331        return this->blocked.head->user_info;
332}
333
334//-----------------------------------------------------------------------------
335// Utilities
336
337static inline void set_owner( monitor_desc * this, thread_desc * owner ) {
338        //Pass the monitor appropriately
339        this->owner = owner;
340
341        //We are passing the monitor to someone else, which means recursion level is not 0
342        this->recursion = owner ? 1 : 0;
343}
344
345static inline thread_desc * next_thread( monitor_desc * this ) {
346        //Check the signaller stack
347        __condition_criterion_t * urgent = pop( &this->signal_stack );
348        if( urgent ) {
349                //The signaller stack is not empty,
350                //regardless of if we are ready to baton pass,
351                //we need to set the monitor as in use
352                set_owner( this,  urgent->owner->waiting_thread );
353
354                return check_condition( urgent );
355        }
356
357        // No signaller thread
358        // Get the next thread in the entry_queue
359        thread_desc * new_owner = pop_head( &this->entry_queue );
360        set_owner( this, new_owner );
361
362        return new_owner;
363}
364
365static inline void lock_all( spinlock ** locks, unsigned short count ) {
366        for( int i = 0; i < count; i++ ) {
367                lock( locks[i] );
368        }
369}
370
371static inline void lock_all( monitor_desc ** source, spinlock ** /*out*/ locks, unsigned short count ) {
372        for( int i = 0; i < count; i++ ) {
373                spinlock * l = &source[i]->lock;
374                lock( l );
375                if(locks) locks[i] = l;
376        }
377}
378
379static inline void unlock_all( spinlock ** locks, unsigned short count ) {
380        for( int i = 0; i < count; i++ ) {
381                unlock( locks[i] );
382        }
383}
384
385static inline void unlock_all( monitor_desc ** locks, unsigned short count ) {
386        for( int i = 0; i < count; i++ ) {
387                unlock( &locks[i]->lock );
388        }
389}
390
391
392static inline void save_recursion   ( monitor_desc ** ctx, unsigned int * /*out*/ recursions, unsigned short count ) {
393        for( int i = 0; i < count; i++ ) {
394                recursions[i] = ctx[i]->recursion;
395        }
396}
397
398static inline void restore_recursion( monitor_desc ** ctx, unsigned int * /*in */ recursions, unsigned short count ) {
399        for( int i = 0; i < count; i++ ) {
400                ctx[i]->recursion = recursions[i];
401        }
402}
403
404// Function has 2 different behavior
405// 1 - Marks a monitors as being ready to run
406// 2 - Checks if all the monitors are ready to run
407//     if so return the thread to run
408static inline thread_desc * check_condition( __condition_criterion_t * target ) {
409        __condition_node_t * node = target->owner;
410        unsigned short count = node->count;
411        __condition_criterion_t * criteria = node->criteria;
412
413        bool ready2run = true;
414
415        for(    int i = 0; i < count; i++ ) {
416
417                LIB_DEBUG_PRINT_SAFE( "Checking %p for %p\n", &criteria[i], target );
418                if( &criteria[i] == target ) {
419                        criteria[i].ready = true;
420                        LIB_DEBUG_PRINT_SAFE( "True\n" );
421                }
422
423                ready2run = criteria[i].ready && ready2run;
424        }
425
426        LIB_DEBUG_PRINT_SAFE( "Runing %i\n", ready2run );
427        return ready2run ? node->waiting_thread : NULL;
428}
429
430static inline void brand_condition( condition * this ) {
431        thread_desc * thrd = this_thread();
432        if( !this->monitors ) {
433                LIB_DEBUG_PRINT_SAFE("Branding\n");
434                assertf( thrd->current_monitors != NULL, "No current monitor to brand condition", thrd->current_monitors );
435                this->monitor_count = thrd->current_monitor_count;
436
437                this->monitors = malloc( this->monitor_count * sizeof( *this->monitors ) );
438                for( int i = 0; i < this->monitor_count; i++ ) {
439                        this->monitors[i] = thrd->current_monitors[i];
440                }
441        }
442}
443
444static inline unsigned short insert_unique( thread_desc ** thrds, unsigned short end, thread_desc * val ) {
445        if( !val ) return end;
446
447        for(int i = 0; i <= end; i++) {
448                if( thrds[i] == val ) return end;
449        }
450
451        thrds[end] = val;
452        return end + 1;
453}
454
455void ?{}( __condition_blocked_queue_t * this ) {
456        this->head = NULL;
457        this->tail = &this->head;
458}
459
460void append( __condition_blocked_queue_t * this, __condition_node_t * c ) {
461        assert(this->tail != NULL);
462        *this->tail = c;
463        this->tail = &c->next;
464}
465
466__condition_node_t * pop_head( __condition_blocked_queue_t * this ) {
467        __condition_node_t * head = this->head;
468        if( head ) {
469                this->head = head->next;
470                if( !head->next ) {
471                        this->tail = &this->head;
472                }
473                head->next = NULL;
474        }
475        return head;
476}
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