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- #include "u.h"
- #include "../port/lib.h"
- #include "mem.h"
- #include "dat.h"
- #include "fns.h"
- struct {
- ulong rlock;
- ulong rlockq;
- ulong wlock;
- ulong wlockq;
- ulong qlock;
- ulong qlockq;
- } rwstats;
- void
- qlock(QLock *q)
- {
- Proc *p;
- if(m->ilockdepth != 0)
- print("qlock: %lux: ilockdepth %d\n", getcallerpc(&q), m->ilockdepth);
- if(up != nil && up->nlocks.ref)
- print("qlock: %lux: nlocks %lud\n", getcallerpc(&q), up->nlocks.ref);
- if(q->use.key == 0x55555555)
- panic("qlock: q %p, key 5*\n", q);
- lock(&q->use);
- rwstats.qlock++;
- if(!q->locked) {
- q->locked = 1;
- unlock(&q->use);
- return;
- }
- if(up == 0)
- panic("qlock");
- rwstats.qlockq++;
- p = q->tail;
- if(p == 0)
- q->head = up;
- else
- p->qnext = up;
- q->tail = up;
- up->qnext = 0;
- up->state = Queueing;
- up->qpc = getcallerpc(&q);
- unlock(&q->use);
- sched();
- }
- int
- canqlock(QLock *q)
- {
- if(!canlock(&q->use))
- return 0;
- if(q->locked){
- unlock(&q->use);
- return 0;
- }
- q->locked = 1;
- unlock(&q->use);
- return 1;
- }
- void
- qunlock(QLock *q)
- {
- Proc *p;
- lock(&q->use);
- p = q->head;
- if(p){
- q->head = p->qnext;
- if(q->head == 0)
- q->tail = 0;
- unlock(&q->use);
- ready(p);
- return;
- }
- q->locked = 0;
- unlock(&q->use);
- }
- void
- rlock(RWlock *q)
- {
- Proc *p;
- lock(&q->use);
- rwstats.rlock++;
- if(q->writer == 0 && q->head == nil){
- /* no writer, go for it */
- q->readers++;
- unlock(&q->use);
- return;
- }
- rwstats.rlockq++;
- p = q->tail;
- if(up == nil)
- panic("rlock");
- if(p == 0)
- q->head = up;
- else
- p->qnext = up;
- q->tail = up;
- up->qnext = 0;
- up->state = QueueingR;
- unlock(&q->use);
- sched();
- }
- void
- runlock(RWlock *q)
- {
- Proc *p;
- lock(&q->use);
- p = q->head;
- if(--(q->readers) > 0 || p == nil){
- unlock(&q->use);
- return;
- }
- /* start waiting writer */
- if(p->state != QueueingW)
- panic("runlock");
- q->head = p->qnext;
- if(q->head == 0)
- q->tail = 0;
- q->writer = 1;
- unlock(&q->use);
- ready(p);
- }
- void
- wlock(RWlock *q)
- {
- Proc *p;
- lock(&q->use);
- rwstats.wlock++;
- if(q->readers == 0 && q->writer == 0){
- /* noone waiting, go for it */
- q->wpc = getcallerpc(&q);
- q->wproc = up;
- q->writer = 1;
- unlock(&q->use);
- return;
- }
- /* wait */
- rwstats.wlockq++;
- p = q->tail;
- if(up == nil)
- panic("wlock");
- if(p == nil)
- q->head = up;
- else
- p->qnext = up;
- q->tail = up;
- up->qnext = 0;
- up->state = QueueingW;
- unlock(&q->use);
- sched();
- }
- void
- wunlock(RWlock *q)
- {
- Proc *p;
- lock(&q->use);
- p = q->head;
- if(p == nil){
- q->writer = 0;
- unlock(&q->use);
- return;
- }
- if(p->state == QueueingW){
- /* start waiting writer */
- q->head = p->qnext;
- if(q->head == nil)
- q->tail = nil;
- unlock(&q->use);
- ready(p);
- return;
- }
- if(p->state != QueueingR)
- panic("wunlock");
- /* waken waiting readers */
- while(q->head != nil && q->head->state == QueueingR){
- p = q->head;
- q->head = p->qnext;
- q->readers++;
- ready(p);
- }
- if(q->head == nil)
- q->tail = nil;
- q->writer = 0;
- unlock(&q->use);
- }
- /* same as rlock but punts if there are any writers waiting */
- int
- canrlock(RWlock *q)
- {
- lock(&q->use);
- rwstats.rlock++;
- if(q->writer == 0 && q->head == nil){
- /* no writer, go for it */
- q->readers++;
- unlock(&q->use);
- return 1;
- }
- unlock(&q->use);
- return 0;
- }
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