diff options
author | David Garcia Quintas <dgq@google.com> | 2015-08-13 14:44:12 -0700 |
---|---|---|
committer | David Garcia Quintas <dgq@google.com> | 2015-08-13 14:44:12 -0700 |
commit | 1665059f632c0b753e5551eac374d790546e4dbc (patch) | |
tree | 7f691c68201b4b236a261c0f5dd20a1731c64a57 /src/core | |
parent | b802fc7732996719c85f8196d5fa6702cc4fcb77 (diff) | |
parent | c16d9e4af81856e7e95e0f77775ab5e47dc68c2c (diff) |
Merge branch 'master' of github.com:grpc/grpc into compression-interop
Diffstat (limited to 'src/core')
-rw-r--r-- | src/core/support/cancellable.c | 157 | ||||
-rw-r--r-- | src/core/support/sync.c | 15 |
2 files changed, 0 insertions, 172 deletions
diff --git a/src/core/support/cancellable.c b/src/core/support/cancellable.c deleted file mode 100644 index 4756f1e125..0000000000 --- a/src/core/support/cancellable.c +++ /dev/null @@ -1,157 +0,0 @@ -/* - * - * Copyright 2015, Google Inc. - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are - * met: - * - * * Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * * Redistributions in binary form must reproduce the above - * copyright notice, this list of conditions and the following disclaimer - * in the documentation and/or other materials provided with the - * distribution. - * * Neither the name of Google Inc. nor the names of its - * contributors may be used to endorse or promote products derived from - * this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR - * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT - * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - * - */ - -/* Implementation for gpr_cancellable */ - -#include <grpc/support/atm.h> -#include <grpc/support/sync.h> -#include <grpc/support/time.h> - -void gpr_cancellable_init(gpr_cancellable *c) { - gpr_mu_init(&c->mu); - c->cancelled = 0; - c->waiters.next = &c->waiters; - c->waiters.prev = &c->waiters; - c->waiters.mu = NULL; - c->waiters.cv = NULL; -} - -void gpr_cancellable_destroy(gpr_cancellable *c) { gpr_mu_destroy(&c->mu); } - -int gpr_cancellable_is_cancelled(gpr_cancellable *c) { - return gpr_atm_acq_load(&c->cancelled) != 0; -} - -/* Threads in gpr_cv_cancellable_wait(cv, mu, ..., c) place themselves on a - linked list c->waiters of gpr_cancellable_list_ before waiting on their - condition variables. They check for cancellation while holding *mu. Thus, - to wake a thread from gpr_cv_cancellable_wait(), it suffices to: - - set c->cancelled - - acquire and release *mu - - gpr_cv_broadcast(cv) - - However, gpr_cancellable_cancel() may not use gpr_mu_lock(mu), since the - caller may already hold *mu---a possible deadlock. (If we knew the caller - did not hold *mu, care would still be needed, because c->mu follows *mu in - the locking order, so *mu could not be acquired while holding c->mu---which - is needed to iterate over c->waiters.) - - Therefore, gpr_cancellable_cancel() uses gpr_mu_trylock() rather than - gpr_mu_lock(), and retries until either gpr_mu_trylock() succeeds or the - thread leaves gpr_cv_cancellable_wait() for other reasons. In the first - case, gpr_cancellable_cancel() removes the entry from the waiters list; in - the second, the waiting thread removes itself from the list. - - A one-entry cache of mutexes and condition variables processed is kept to - avoid doing the same work again and again if many threads are blocked in the - same place. However, it's important to broadcast on a condition variable if - the corresponding mutex has been locked successfully, even if the condition - variable has been signalled before. */ - -void gpr_cancellable_cancel(gpr_cancellable *c) { - if (!gpr_cancellable_is_cancelled(c)) { - int failures; - int backoff = 1; - do { - struct gpr_cancellable_list_ *l; - struct gpr_cancellable_list_ *nl; - gpr_mu *omu = 0; /* one-element cache of a processed gpr_mu */ - gpr_cv *ocv = 0; /* one-element cache of a processd gpr_cv */ - gpr_mu_lock(&c->mu); - gpr_atm_rel_store(&c->cancelled, 1); - failures = 0; - for (l = c->waiters.next; l != &c->waiters; l = nl) { - nl = l->next; - if (omu != l->mu) { - omu = l->mu; - if (gpr_mu_trylock(l->mu)) { - gpr_mu_unlock(l->mu); - l->next->prev = l->prev; /* remove *l from list */ - l->prev->next = l->next; - /* allow unconditional dequeue in gpr_cv_cancellable_wait() */ - l->next = l; - l->prev = l; - ocv = 0; /* force broadcast */ - } else { - failures++; - } - } - if (ocv != l->cv) { - ocv = l->cv; - gpr_cv_broadcast(l->cv); - } - } - gpr_mu_unlock(&c->mu); - if (failures != 0) { - if (backoff < 10) { - volatile int i; - for (i = 0; i != (1 << backoff); i++) { - } - backoff++; - } else { - gpr_event ev; - gpr_event_init(&ev); - gpr_event_wait( - &ev, gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), - gpr_time_from_micros(1000, GPR_TIMESPAN))); - } - } - } while (failures != 0); - } -} - -int gpr_cv_cancellable_wait(gpr_cv *cv, gpr_mu *mu, gpr_timespec abs_deadline, - gpr_cancellable *c) { - gpr_int32 timeout; - gpr_mu_lock(&c->mu); - timeout = gpr_cancellable_is_cancelled(c); - if (!timeout) { - struct gpr_cancellable_list_ le; - le.mu = mu; - le.cv = cv; - le.next = c->waiters.next; - le.prev = &c->waiters; - le.next->prev = ≤ - le.prev->next = ≤ - gpr_mu_unlock(&c->mu); - timeout = gpr_cv_wait(cv, mu, abs_deadline); - gpr_mu_lock(&c->mu); - le.next->prev = le.prev; - le.prev->next = le.next; - if (!timeout) { - timeout = gpr_cancellable_is_cancelled(c); - } - } - gpr_mu_unlock(&c->mu); - return timeout; -} diff --git a/src/core/support/sync.c b/src/core/support/sync.c index 856b5adb86..d3cf77faea 100644 --- a/src/core/support/sync.c +++ b/src/core/support/sync.c @@ -94,21 +94,6 @@ void *gpr_event_wait(gpr_event *ev, gpr_timespec abs_deadline) { return result; } -void *gpr_event_cancellable_wait(gpr_event *ev, gpr_timespec abs_deadline, - gpr_cancellable *c) { - void *result = (void *)gpr_atm_acq_load(&ev->state); - if (result == NULL) { - struct sync_array_s *s = hash(ev); - gpr_mu_lock(&s->mu); - do { - result = (void *)gpr_atm_acq_load(&ev->state); - } while (result == NULL && - !gpr_cv_cancellable_wait(&s->cv, &s->mu, abs_deadline, c)); - gpr_mu_unlock(&s->mu); - } - return result; -} - void gpr_ref_init(gpr_refcount *r, int n) { gpr_atm_rel_store(&r->count, n); } void gpr_ref(gpr_refcount *r) { gpr_atm_no_barrier_fetch_add(&r->count, 1); } |