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@ -9,39 +9,62 @@
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#endif
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#include <errno.h>
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// return the next event, waiting of none are queued
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// wait at most timeout milliseconds
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// on success, return 1 and return the fd in *s and the events on it in *revents
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// if we waited but ran into a timeout, return 0
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// if we run into a system error, return -1
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// if another thread aborted this iomux, return -2
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int iom_wait(iomux_t* c,int64* s,unsigned int* revents,unsigned long timeout) {
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for (;;) {
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/* If we have an event in the queue, use that one */
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int r;
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if (c->working==-2) return -2; /* iomux was aborted */
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for (;;) {
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for (;;) { // CAS-loop get the first element from the queue
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unsigned int f=c->l;
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if (f == c->h)
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break; /* no elements in queue */
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int n=(f+1)%SLOTS;
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if (__sync_bool_compare_and_swap(&c->l,f,n)) {
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/* we got one, and its index is in f */
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*s=c->q[f].fd;
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*revents=c->q[f].events;
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if (__sync_bool_compare_and_swap(&c->l,f,n)) {
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/* we got one */
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return 1;
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}
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/* collided with another thread, try again */
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}
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/* The queue was empty. If someone else is already calling
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* epoll_wait/kevent, then use the semaphore */
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if (__sync_bool_compare_and_swap(&c->working,0,1)) {
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/* race avoidance: another thread could have come in between and
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* refilled the job queue */
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if (c->h != c->l) {
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/* set working back to 0 unless someone set it to -2 in the mean time (iom_abort) */
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if (__sync_val_compare_and_swap(&c->working,1,0)==-2) return -2;
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continue;
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}
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/* we have the job to fill the struct. */
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int freeslots = (c->h - c->l);
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if (!freeslots) freeslots=SLOTS;
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#ifdef HAVE_EPOLL
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struct epoll_event ee[SLOTS];
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int i;
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r=epoll_wait(c->ctx, ee, freeslots, timeout);
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if (r<=0) {
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/* we ran into a timeout, so let someone else take over */
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r=epoll_wait(c->ctx, ee, SLOTS, timeout);
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if (r <= 0) {
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/* epoll_wait returned a timeout or an error! */
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/* relinquish the lock and return 0 / -1 */
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if (__sync_val_compare_and_swap(&c->working,1,0)==-2) return -2;
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#ifdef __dietlibc__
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cnd_broadcast(&c->sem);
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// for timeout we want to hand off to one other thread, no need
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// to wake them all up. Error might be transient (EINTR) and the
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// next guy might succeed, so only wake one up. If the error was
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// not transient, then they will also get an error and wake the
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// next up
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cnd_signal(&c->sem);
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#else
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sem_post(&c->sem);
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#endif
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@ -56,7 +79,10 @@ int iom_wait(iomux_t* c,int64* s,unsigned int* revents,unsigned long timeout) {
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/* return last event instead of enqueueing it */
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*s=ee[i].data.fd;
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*revents=e;
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/* loop terminates here, but no return statement because we
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* still need to signal the semaphore below */
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} else {
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/* The CAS loop on c->working above ensures we are the only one writing to c->h */
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c->q[c->h].fd=ee[i].data.fd;
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c->q[c->h].events=e;
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c->h = (c->h + 1) % SLOTS;
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@ -65,12 +91,14 @@ int iom_wait(iomux_t* c,int64* s,unsigned int* revents,unsigned long timeout) {
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#elif defined(HAVE_KQUEUE)
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struct kevent kev[SLOTS];
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struct timespec ts = { .tv_sec=timeout/1000, .tv_nsec=(timeout%1000)*1000000 };
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int r=kevent(c->ctx, 0, 0, kev, freeslots, &ts);
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int r=kevent(c->ctx, 0, 0, kev, SLOTS, &ts);
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int i;
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if (r<=0) {
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/* we ran into a timeout, so let someone else take over */
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/* kevent returned a timeout or an error! */
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/* relinquish the lock and return 0 / -1 */
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if (__sync_val_compare_and_swap(&c->working,1,0)==-2) return -2;
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#ifdef __dietlibc__
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// no dietlibc for kqueue based systems yet
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cnd_broadcast(&c->sem);
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#else
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sem_post(&c->sem);
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@ -85,7 +113,10 @@ int iom_wait(iomux_t* c,int64* s,unsigned int* revents,unsigned long timeout) {
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/* return last event instead of enqueueing it */
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*s=kev[i].ident;
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*revents=e;
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/* loop terminates here, but no return statement because we
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* still need to signal the semaphore below */
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} else {
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/* The CAS loop on c->working above ensures we are the only one writing to c->h */
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c->q[c->h].fd=kev[i].ident;
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c->q[c->h].events=e;
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c->h = (c->h + 1) % SLOTS;
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@ -100,7 +131,10 @@ int iom_wait(iomux_t* c,int64* s,unsigned int* revents,unsigned long timeout) {
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doing it anymore */
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if (__sync_val_compare_and_swap(&c->working,1,0)==-2) return -2;
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#ifdef __dietlibc__
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if (c->h == (c->l + 1) % SLOTS)
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cnd_signal(&c->sem);
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else
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cnd_broadcast(&c->sem);
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#else
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sem_post(&c->sem);
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#endif
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