--- /dev/null
+/*
+ *
+ * Copyright 2015 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#ifndef GRPC_SUPPORT_SYNC_H
+#define GRPC_SUPPORT_SYNC_H
+
+#include <grpc/support/port_platform.h>
+
+#include <grpc/impl/codegen/gpr_types.h> /* for gpr_timespec */
+#include <grpc/impl/codegen/sync.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** --- Mutex interface ---
+
+ At most one thread may hold an exclusive lock on a mutex at any given time.
+ Actions taken by a thread that holds a mutex exclusively happen after
+ actions taken by all previous holders of the mutex. Variables of type
+ gpr_mu are uninitialized when first declared. */
+
+/** Initialize *mu. Requires: *mu uninitialized. */
+GPRAPI void gpr_mu_init(gpr_mu* mu);
+
+/** Cause *mu no longer to be initialized, freeing any memory in use. Requires:
+ *mu initialized; no other concurrent operation on *mu. */
+GPRAPI void gpr_mu_destroy(gpr_mu* mu);
+
+/** Wait until no thread has a lock on *mu, cause the calling thread to own an
+ exclusive lock on *mu, then return. May block indefinitely or crash if the
+ calling thread has a lock on *mu. Requires: *mu initialized. */
+GPRAPI void gpr_mu_lock(gpr_mu* mu);
+
+/** Release an exclusive lock on *mu held by the calling thread. Requires: *mu
+ initialized; the calling thread holds an exclusive lock on *mu. */
+GPRAPI void gpr_mu_unlock(gpr_mu* mu);
+
+/** Without blocking, attempt to acquire an exclusive lock on *mu for the
+ calling thread, then return non-zero iff success. Fail, if any thread holds
+ the lock; succeeds with high probability if no thread holds the lock.
+ Requires: *mu initialized. */
+GPRAPI int gpr_mu_trylock(gpr_mu* mu);
+
+/** --- Condition variable interface ---
+
+ A while-loop should be used with gpr_cv_wait() when waiting for conditions
+ to become true. See the example below. Variables of type gpr_cv are
+ uninitialized when first declared. */
+
+/** Initialize *cv. Requires: *cv uninitialized. */
+GPRAPI void gpr_cv_init(gpr_cv* cv);
+
+/** Cause *cv no longer to be initialized, freeing any memory in use. Requires:
+ *cv initialized; no other concurrent operation on *cv.*/
+GPRAPI void gpr_cv_destroy(gpr_cv* cv);
+
+/** Atomically release *mu and wait on *cv. When the calling thread is woken
+ from *cv or the deadline abs_deadline is exceeded, execute gpr_mu_lock(mu)
+ and return whether the deadline was exceeded. Use
+ abs_deadline==gpr_inf_future for no deadline. abs_deadline can be either
+ an absolute deadline, or a GPR_TIMESPAN. May return even when not
+ woken explicitly. Requires: *mu and *cv initialized; the calling thread
+ holds an exclusive lock on *mu. */
+GPRAPI int gpr_cv_wait(gpr_cv* cv, gpr_mu* mu, gpr_timespec abs_deadline);
+
+/** If any threads are waiting on *cv, wake at least one.
+ Clients may treat this as an optimization of gpr_cv_broadcast()
+ for use in the case where waking more than one waiter is not useful.
+ Requires: *cv initialized. */
+GPRAPI void gpr_cv_signal(gpr_cv* cv);
+
+/** Wake all threads waiting on *cv. Requires: *cv initialized. */
+GPRAPI void gpr_cv_broadcast(gpr_cv* cv);
+
+/** --- One-time initialization ---
+
+ gpr_once must be declared with static storage class, and initialized with
+ GPR_ONCE_INIT. e.g.,
+ static gpr_once once_var = GPR_ONCE_INIT; */
+
+/** Ensure that (*init_routine)() has been called exactly once (for the
+ specified gpr_once instance) and then return.
+ If multiple threads call gpr_once() on the same gpr_once instance, one of
+ them will call (*init_routine)(), and the others will block until that call
+ finishes.*/
+GPRAPI void gpr_once_init(gpr_once* once, void (*init_routine)(void));
+
+/** --- One-time event notification ---
+
+ These operations act on a gpr_event, which should be initialized with
+ gpr_ev_init(), or with GPR_EVENT_INIT if static, e.g.,
+ static gpr_event event_var = GPR_EVENT_INIT;
+ It requires no destruction. */
+
+/** Initialize *ev. */
+GPRAPI void gpr_event_init(gpr_event* ev);
+
+/** Set *ev so that gpr_event_get() and gpr_event_wait() will return value.
+ Requires: *ev initialized; value != NULL; no prior or concurrent calls to
+ gpr_event_set(ev, ...) since initialization. */
+GPRAPI void gpr_event_set(gpr_event* ev, void* value);
+
+/** Return the value set by gpr_event_set(ev, ...), or NULL if no such call has
+ completed. If the result is non-NULL, all operations that occurred prior to
+ the gpr_event_set(ev, ...) set will be visible after this call returns.
+ Requires: *ev initialized. This operation is faster than acquiring a mutex
+ on most platforms. */
+GPRAPI void* gpr_event_get(gpr_event* ev);
+
+/** Wait until *ev is set by gpr_event_set(ev, ...), or abs_deadline is
+ exceeded, then return gpr_event_get(ev). Requires: *ev initialized. Use
+ abs_deadline==gpr_inf_future for no deadline. When the event has been
+ signalled before the call, this operation is faster than acquiring a mutex
+ on most platforms. */
+GPRAPI void* gpr_event_wait(gpr_event* ev, gpr_timespec abs_deadline);
+
+/** --- Reference counting ---
+
+ These calls act on the type gpr_refcount. It requires no destruction. */
+
+/** Initialize *r to value n. */
+GPRAPI void gpr_ref_init(gpr_refcount* r, int n);
+
+/** Increment the reference count *r. Requires *r initialized. */
+GPRAPI void gpr_ref(gpr_refcount* r);
+
+/** Increment the reference count *r. Requires *r initialized.
+ Crashes if refcount is zero */
+GPRAPI void gpr_ref_non_zero(gpr_refcount* r);
+
+/** Increment the reference count *r by n. Requires *r initialized, n > 0. */
+GPRAPI void gpr_refn(gpr_refcount* r, int n);
+
+/** Decrement the reference count *r and return non-zero iff it has reached
+ zero. . Requires *r initialized. */
+GPRAPI int gpr_unref(gpr_refcount* r);
+
+/** Return non-zero iff the reference count of *r is one, and thus is owned
+ by exactly one object. */
+GPRAPI int gpr_ref_is_unique(gpr_refcount* r);
+
+/** --- Stats counters ---
+
+ These calls act on the integral type gpr_stats_counter. It requires no
+ destruction. Static instances may be initialized with
+ gpr_stats_counter c = GPR_STATS_INIT;
+ Beware: These operations do not imply memory barriers. Do not use them to
+ synchronize other events. */
+
+/** Initialize *c to the value n. */
+GPRAPI void gpr_stats_init(gpr_stats_counter* c, intptr_t n);
+
+/** *c += inc. Requires: *c initialized. */
+GPRAPI void gpr_stats_inc(gpr_stats_counter* c, intptr_t inc);
+
+/** Return *c. Requires: *c initialized. */
+GPRAPI intptr_t gpr_stats_read(const gpr_stats_counter* c);
+
+/** ==================Example use of interface===================
+ A producer-consumer queue of up to N integers,
+ illustrating the use of the calls in this interface. */
+#if 0
+
+#define N 4
+
+ typedef struct queue {
+ gpr_cv non_empty; /* Signalled when length becomes non-zero. */
+ gpr_cv non_full; /* Signalled when length becomes non-N. */
+ gpr_mu mu; /* Protects all fields below.
+ (That is, except during initialization or
+ destruction, the fields below should be accessed
+ only by a thread that holds mu.) */
+ int head; /* Index of head of queue 0..N-1. */
+ int length; /* Number of valid elements in queue 0..N. */
+ int elem[N]; /* elem[head .. head+length-1] are queue elements. */
+ } queue;
+
+ /* Initialize *q. */
+ void queue_init(queue *q) {
+ gpr_mu_init(&q->mu);
+ gpr_cv_init(&q->non_empty);
+ gpr_cv_init(&q->non_full);
+ q->head = 0;
+ q->length = 0;
+ }
+
+ /* Free storage associated with *q. */
+ void queue_destroy(queue *q) {
+ gpr_mu_destroy(&q->mu);
+ gpr_cv_destroy(&q->non_empty);
+ gpr_cv_destroy(&q->non_full);
+ }
+
+ /* Wait until there is room in *q, then append x to *q. */
+ void queue_append(queue *q, int x) {
+ gpr_mu_lock(&q->mu);
+ /* To wait for a predicate without a deadline, loop on the negation of the
+ predicate, and use gpr_cv_wait(..., gpr_inf_future) inside the loop
+ to release the lock, wait, and reacquire on each iteration. Code that
+ makes the condition true should use gpr_cv_broadcast() on the
+ corresponding condition variable. The predicate must be on state
+ protected by the lock. */
+ while (q->length == N) {
+ gpr_cv_wait(&q->non_full, &q->mu, gpr_inf_future);
+ }
+ if (q->length == 0) { /* Wake threads blocked in queue_remove(). */
+ /* It's normal to use gpr_cv_broadcast() or gpr_signal() while
+ holding the lock. */
+ gpr_cv_broadcast(&q->non_empty);
+ }
+ q->elem[(q->head + q->length) % N] = x;
+ q->length++;
+ gpr_mu_unlock(&q->mu);
+ }
+
+ /* If it can be done without blocking, append x to *q and return non-zero.
+ Otherwise return 0. */
+ int queue_try_append(queue *q, int x) {
+ int result = 0;
+ if (gpr_mu_trylock(&q->mu)) {
+ if (q->length != N) {
+ if (q->length == 0) { /* Wake threads blocked in queue_remove(). */
+ gpr_cv_broadcast(&q->non_empty);
+ }
+ q->elem[(q->head + q->length) % N] = x;
+ q->length++;
+ result = 1;
+ }
+ gpr_mu_unlock(&q->mu);
+ }
+ return result;
+ }
+
+ /* Wait until the *q is non-empty or deadline abs_deadline passes. If the
+ queue is non-empty, remove its head entry, place it in *head, and return
+ non-zero. Otherwise return 0. */
+ int queue_remove(queue *q, int *head, gpr_timespec abs_deadline) {
+ int result = 0;
+ gpr_mu_lock(&q->mu);
+ /* To wait for a predicate with a deadline, loop on the negation of the
+ predicate or until gpr_cv_wait() returns true. Code that makes
+ the condition true should use gpr_cv_broadcast() on the corresponding
+ condition variable. The predicate must be on state protected by the
+ lock. */
+ while (q->length == 0 &&
+ !gpr_cv_wait(&q->non_empty, &q->mu, abs_deadline)) {
+ }
+ if (q->length != 0) { /* Queue is non-empty. */
+ result = 1;
+ if (q->length == N) { /* Wake threads blocked in queue_append(). */
+ gpr_cv_broadcast(&q->non_full);
+ }
+ *head = q->elem[q->head];
+ q->head = (q->head + 1) % N;
+ q->length--;
+ } /* else deadline exceeded */
+ gpr_mu_unlock(&q->mu);
+ return result;
+ }
+#endif /* 0 */
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* GRPC_SUPPORT_SYNC_H */
git://repos.xcallymotion.com / motion2.git / blobdiff