Index: fusl/src/thread/pthread_cond_timedwait.c |
diff --git a/fusl/src/thread/pthread_cond_timedwait.c b/fusl/src/thread/pthread_cond_timedwait.c |
new file mode 100644 |
index 0000000000000000000000000000000000000000..3526ecfb6d2eee92817dd00da769fe9dc3bdb4f4 |
--- /dev/null |
+++ b/fusl/src/thread/pthread_cond_timedwait.c |
@@ -0,0 +1,214 @@ |
+#include "pthread_impl.h" |
+ |
+void __pthread_testcancel(void); |
+int __pthread_mutex_lock(pthread_mutex_t *); |
+int __pthread_mutex_unlock(pthread_mutex_t *); |
+int __pthread_setcancelstate(int, int *); |
+ |
+/* |
+ * struct waiter |
+ * |
+ * Waiter objects have automatic storage on the waiting thread, and |
+ * are used in building a linked list representing waiters currently |
+ * waiting on the condition variable or a group of waiters woken |
+ * together by a broadcast or signal; in the case of signal, this is a |
+ * degenerate list of one member. |
+ * |
+ * Waiter lists attached to the condition variable itself are |
+ * protected by the lock on the cv. Detached waiter lists are never |
+ * modified again, but can only be traversed in reverse order, and are |
+ * protected by the "barrier" locks in each node, which are unlocked |
+ * in turn to control wake order. |
+ * |
+ * Since process-shared cond var semantics do not necessarily allow |
+ * one thread to see another's automatic storage (they may be in |
+ * different processes), the waiter list is not used for the |
+ * process-shared case, but the structure is still used to store data |
+ * needed by the cancellation cleanup handler. |
+ */ |
+ |
+struct waiter { |
+ struct waiter *prev, *next; |
+ volatile int state, barrier; |
+ volatile int *notify; |
+}; |
+ |
+/* Self-synchronized-destruction-safe lock functions */ |
+ |
+static inline void lock(volatile int *l) |
+{ |
+ if (a_cas(l, 0, 1)) { |
+ a_cas(l, 1, 2); |
+ do __wait(l, 0, 2, 1); |
+ while (a_cas(l, 0, 2)); |
+ } |
+} |
+ |
+static inline void unlock(volatile int *l) |
+{ |
+ if (a_swap(l, 0)==2) |
+ __wake(l, 1, 1); |
+} |
+ |
+static inline void unlock_requeue(volatile int *l, volatile int *r, int w) |
+{ |
+ a_store(l, 0); |
+ if (w) __wake(l, 1, 1); |
+ else __syscall(SYS_futex, l, FUTEX_REQUEUE|128, 0, 1, r) != -ENOSYS |
+ || __syscall(SYS_futex, l, FUTEX_REQUEUE, 0, 1, r); |
+} |
+ |
+enum { |
+ WAITING, |
+ SIGNALED, |
+ LEAVING, |
+}; |
+ |
+int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m, const struct timespec *restrict ts) |
+{ |
+ struct waiter node = { 0 }; |
+ int e, seq, clock = c->_c_clock, cs, shared=0, oldstate, tmp; |
+ volatile int *fut; |
+ |
+ if ((m->_m_type&15) && (m->_m_lock&INT_MAX) != __pthread_self()->tid) |
+ return EPERM; |
+ |
+ if (ts && ts->tv_nsec >= 1000000000UL) |
+ return EINVAL; |
+ |
+ __pthread_testcancel(); |
+ |
+ if (c->_c_shared) { |
+ shared = 1; |
+ fut = &c->_c_seq; |
+ seq = c->_c_seq; |
+ a_inc(&c->_c_waiters); |
+ } else { |
+ lock(&c->_c_lock); |
+ |
+ seq = node.barrier = 2; |
+ fut = &node.barrier; |
+ node.state = WAITING; |
+ node.next = c->_c_head; |
+ c->_c_head = &node; |
+ if (!c->_c_tail) c->_c_tail = &node; |
+ else node.next->prev = &node; |
+ |
+ unlock(&c->_c_lock); |
+ } |
+ |
+ __pthread_mutex_unlock(m); |
+ |
+ __pthread_setcancelstate(PTHREAD_CANCEL_MASKED, &cs); |
+ if (cs == PTHREAD_CANCEL_DISABLE) __pthread_setcancelstate(cs, 0); |
+ |
+ do e = __timedwait_cp(fut, seq, clock, ts, !shared); |
+ while (*fut==seq && (!e || e==EINTR)); |
+ if (e == EINTR) e = 0; |
+ |
+ if (shared) { |
+ /* Suppress cancellation if a signal was potentially |
+ * consumed; this is a legitimate form of spurious |
+ * wake even if not. */ |
+ if (e == ECANCELED && c->_c_seq != seq) e = 0; |
+ if (a_fetch_add(&c->_c_waiters, -1) == -0x7fffffff) |
+ __wake(&c->_c_waiters, 1, 0); |
+ oldstate = WAITING; |
+ goto relock; |
+ } |
+ |
+ oldstate = a_cas(&node.state, WAITING, LEAVING); |
+ |
+ if (oldstate == WAITING) { |
+ /* Access to cv object is valid because this waiter was not |
+ * yet signaled and a new signal/broadcast cannot return |
+ * after seeing a LEAVING waiter without getting notified |
+ * via the futex notify below. */ |
+ |
+ lock(&c->_c_lock); |
+ |
+ if (c->_c_head == &node) c->_c_head = node.next; |
+ else if (node.prev) node.prev->next = node.next; |
+ if (c->_c_tail == &node) c->_c_tail = node.prev; |
+ else if (node.next) node.next->prev = node.prev; |
+ |
+ unlock(&c->_c_lock); |
+ |
+ if (node.notify) { |
+ if (a_fetch_add(node.notify, -1)==1) |
+ __wake(node.notify, 1, 1); |
+ } |
+ } else { |
+ /* Lock barrier first to control wake order. */ |
+ lock(&node.barrier); |
+ } |
+ |
+relock: |
+ /* Errors locking the mutex override any existing error or |
+ * cancellation, since the caller must see them to know the |
+ * state of the mutex. */ |
+ if ((tmp = pthread_mutex_lock(m))) e = tmp; |
+ |
+ if (oldstate == WAITING) goto done; |
+ |
+ if (!node.next) a_inc(&m->_m_waiters); |
+ |
+ /* Unlock the barrier that's holding back the next waiter, and |
+ * either wake it or requeue it to the mutex. */ |
+ if (node.prev) |
+ unlock_requeue(&node.prev->barrier, &m->_m_lock, m->_m_type & 128); |
+ else |
+ a_dec(&m->_m_waiters); |
+ |
+ /* Since a signal was consumed, cancellation is not permitted. */ |
+ if (e == ECANCELED) e = 0; |
+ |
+done: |
+ __pthread_setcancelstate(cs, 0); |
+ |
+ if (e == ECANCELED) { |
+ __pthread_testcancel(); |
+ __pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, 0); |
+ } |
+ |
+ return e; |
+} |
+ |
+int __private_cond_signal(pthread_cond_t *c, int n) |
+{ |
+ struct waiter *p, *first=0; |
+ volatile int ref = 0; |
+ int cur; |
+ |
+ lock(&c->_c_lock); |
+ for (p=c->_c_tail; n && p; p=p->prev) { |
+ if (a_cas(&p->state, WAITING, SIGNALED) != WAITING) { |
+ ref++; |
+ p->notify = &ref; |
+ } else { |
+ n--; |
+ if (!first) first=p; |
+ } |
+ } |
+ /* Split the list, leaving any remainder on the cv. */ |
+ if (p) { |
+ if (p->next) p->next->prev = 0; |
+ p->next = 0; |
+ } else { |
+ c->_c_head = 0; |
+ } |
+ c->_c_tail = p; |
+ unlock(&c->_c_lock); |
+ |
+ /* Wait for any waiters in the LEAVING state to remove |
+ * themselves from the list before returning or allowing |
+ * signaled threads to proceed. */ |
+ while ((cur = ref)) __wait(&ref, 0, cur, 1); |
+ |
+ /* Allow first signaled waiter, if any, to proceed. */ |
+ if (first) unlock(&first->barrier); |
+ |
+ return 0; |
+} |
+ |
+weak_alias(__pthread_cond_timedwait, pthread_cond_timedwait); |