ref: d376fac66cbd5efbe2f9f61a1e8b31af03a84a92
dir: /sys/src/9/port/qlock.c/
#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "../port/error.h" struct { ulong rlock; ulong rlockq; ulong wlock; ulong wlockq; ulong qlock; ulong qlockq; } rwstats; void eqlock(QLock *q) { Proc *p; if(m->ilockdepth != 0) print("eqlock: %#p: ilockdepth %d\n", getcallerpc(&q), m->ilockdepth); if(up != nil && up->nlocks) print("eqlock: %#p: nlocks %d\n", getcallerpc(&q), up->nlocks); if(up != nil && up->eql != nil) print("eqlock: %#p: eql %p\n", getcallerpc(&q), up->eql); if(q->use.key == 0x55555555) panic("eqlock: q %#p, key 5*", q); lock(&q->use); rwstats.qlock++; if(!q->locked) { q->locked = 1; unlock(&q->use); return; } if(up == nil) panic("eqlock"); if(up->notepending){ up->notepending = 0; unlock(&q->use); interrupted(); } rwstats.qlockq++; p = q->tail; if(p == nil) q->head = up; else p->qnext = up; q->tail = up; up->eql = q; up->qnext = nil; up->qpc = getcallerpc(&q); up->state = Queueing; unlock(&q->use); sched(); if(up->eql == nil){ up->notepending = 0; interrupted(); } up->eql = nil; } void qlock(QLock *q) { Proc *p; if(m->ilockdepth != 0) print("qlock: %#p: ilockdepth %d\n", getcallerpc(&q), m->ilockdepth); if(up != nil && up->nlocks) print("qlock: %#p: nlocks %d\n", getcallerpc(&q), up->nlocks); if(up != nil && up->eql != nil) print("qlock: %#p: eql %p\n", getcallerpc(&q), up->eql); if(q->use.key == 0x55555555) panic("qlock: q %#p, key 5*", q); lock(&q->use); rwstats.qlock++; if(!q->locked) { q->locked = 1; unlock(&q->use); return; } if(up == nil) panic("qlock"); rwstats.qlockq++; p = q->tail; if(p == nil) q->head = up; else p->qnext = up; q->tail = up; up->eql = nil; up->qnext = nil; 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); if (q->locked == 0) print("qunlock called with qlock not held, from %#p\n", getcallerpc(&q)); p = q->head; if(p != nil){ q->head = p->qnext; if(q->head == nil) q->tail = nil; 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 == nil) q->head = up; else p->qnext = up; q->tail = up; up->qnext = nil; 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 == nil) q->tail = nil; 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 = nil; 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; }