scrubbed codegen/sync.h

7 files changed, 307 insertions, 265 deletions

diff --git a/include/grpc++/impl/codegen/core_codegen.h b/include/grpc++/impl/codegen/core_codegen.h
index 9ad5902763..cfec4a246f 100644
--- a/include/grpc++/impl/codegen/core_codegen.h
+++ b/include/grpc++/impl/codegen/core_codegen.h
@@ -52,6 +52,17 @@ class CoreCodegen : public CoreCodegenInterface {
   void* gpr_malloc(size_t size) GRPC_OVERRIDE;
   void gpr_free(void* p) GRPC_OVERRIDE;
 
+  void gpr_mu_init(gpr_mu* mu) GRPC_OVERRIDE;
+  void gpr_mu_destroy(gpr_mu* mu) GRPC_OVERRIDE;
+  void gpr_mu_lock(gpr_mu* mu) GRPC_OVERRIDE;
+  void gpr_mu_unlock(gpr_mu* mu) GRPC_OVERRIDE;
+  void gpr_cv_init(gpr_cv* cv) GRPC_OVERRIDE;
+  void gpr_cv_destroy(gpr_cv* cv) GRPC_OVERRIDE;
+  int gpr_cv_wait(gpr_cv* cv, gpr_mu* mu,
+                  gpr_timespec abs_deadline) GRPC_OVERRIDE;
+  void gpr_cv_signal(gpr_cv* cv) GRPC_OVERRIDE;
+  void gpr_cv_broadcast(gpr_cv* cv) GRPC_OVERRIDE;
+
   void grpc_byte_buffer_destroy(grpc_byte_buffer* bb) GRPC_OVERRIDE;
 
   int grpc_byte_buffer_reader_init(grpc_byte_buffer_reader* reader,
diff --git a/include/grpc++/impl/codegen/core_codegen_interface.h b/include/grpc++/impl/codegen/core_codegen_interface.h
index 132f7a0a5e..68851f15c6 100644
--- a/include/grpc++/impl/codegen/core_codegen_interface.h
+++ b/include/grpc++/impl/codegen/core_codegen_interface.h
@@ -38,6 +38,7 @@
 #include <grpc++/impl/codegen/status.h>
 #include <grpc/impl/codegen/byte_buffer_reader.h>
 #include <grpc/impl/codegen/grpc_types.h>
+#include <grpc/impl/codegen/sync.h>
 
 extern "C" {
 struct grpc_byte_buffer;
@@ -68,6 +69,17 @@ class CoreCodegenInterface {
   virtual void* gpr_malloc(size_t size) = 0;
   virtual void gpr_free(void* p) = 0;
 
+  virtual void gpr_mu_init(gpr_mu* mu) = 0;
+  virtual void gpr_mu_destroy(gpr_mu* mu) = 0;
+  virtual void gpr_mu_lock(gpr_mu* mu) = 0;
+  virtual void gpr_mu_unlock(gpr_mu* mu) = 0;
+  virtual void gpr_cv_init(gpr_cv* cv) = 0;
+  virtual void gpr_cv_destroy(gpr_cv* cv) = 0;
+  virtual int gpr_cv_wait(gpr_cv* cv, gpr_mu* mu,
+                          gpr_timespec abs_deadline) = 0;
+  virtual void gpr_cv_signal(gpr_cv* cv) = 0;
+  virtual void gpr_cv_broadcast(gpr_cv* cv) = 0;
+
   virtual void grpc_byte_buffer_destroy(grpc_byte_buffer* bb) = 0;
 
   virtual int grpc_byte_buffer_reader_init(grpc_byte_buffer_reader* reader,
diff --git a/include/grpc++/impl/codegen/sync_no_cxx11.h b/include/grpc++/impl/codegen/sync_no_cxx11.h
index 55c059ede7..87a6594f7d 100644
--- a/include/grpc++/impl/codegen/sync_no_cxx11.h
+++ b/include/grpc++/impl/codegen/sync_no_cxx11.h
@@ -34,18 +34,20 @@
 #ifndef GRPCXX_IMPL_CODEGEN_SYNC_NO_CXX11_H
 #define GRPCXX_IMPL_CODEGEN_SYNC_NO_CXX11_H
 
-#include <grpc/impl/codegen/sync.h>
+#include <grpc++/impl/codegen/core_codegen_interface.h>
 
 namespace grpc {
 
+extern CoreCodegenInterface *g_core_codegen_interface;
+
 template <class mutex>
 class lock_guard;
 class condition_variable;
 
 class mutex {
  public:
-  mutex() { gpr_mu_init(&mu_); }
-  ~mutex() { gpr_mu_destroy(&mu_); }
+  mutex() { g_core_codegen_interface->gpr_mu_init(&mu_); }
+  ~mutex() { g_core_codegen_interface->gpr_mu_destroy(&mu_); }
 
  private:
   ::gpr_mu mu_;
@@ -57,16 +59,18 @@ class mutex {
 template <class mutex>
 class lock_guard {
  public:
-  lock_guard(mutex &mu) : mu_(mu), locked(true) { gpr_mu_lock(&mu.mu_); }
+  lock_guard(mutex &mu) : mu_(mu), locked(true) {
+    g_core_codegen_interface->gpr_mu_lock(&mu.mu_);
+  }
   ~lock_guard() { unlock_internal(); }
 
  protected:
   void lock_internal() {
-    if (!locked) gpr_mu_lock(&mu_.mu_);
+    if (!locked) g_core_codegen_interface->gpr_mu_lock(&mu_.mu_);
     locked = true;
   }
   void unlock_internal() {
-    if (locked) gpr_mu_unlock(&mu_.mu_);
+    if (locked) g_core_codegen_interface->gpr_mu_unlock(&mu_.mu_);
     locked = false;
   }
 
@@ -86,15 +90,17 @@ class unique_lock : public lock_guard<mutex> {
 
 class condition_variable {
  public:
-  condition_variable() { gpr_cv_init(&cv_); }
-  ~condition_variable() { gpr_cv_destroy(&cv_); }
+  condition_variable() { g_core_codegen_interface->gpr_cv_init(&cv_); }
+  ~condition_variable() { g_core_codegen_interface->gpr_cv_destroy(&cv_); }
   void wait(lock_guard<mutex> &mu) {
     mu.locked = false;
-    gpr_cv_wait(&cv_, &mu.mu_.mu_, gpr_inf_future(GPR_CLOCK_REALTIME));
+    g_core_codegen_interface->gpr_cv_wait(
+        &cv_, &mu.mu_.mu_,
+        g_core_codegen_interface->gpr_inf_future(GPR_CLOCK_REALTIME));
     mu.locked = true;
   }
-  void notify_one() { gpr_cv_signal(&cv_); }
-  void notify_all() { gpr_cv_broadcast(&cv_); }
+  void notify_one() { g_core_codegen_interface->gpr_cv_signal(&cv_); }
+  void notify_all() { g_core_codegen_interface->gpr_cv_broadcast(&cv_); }
 
  private:
   gpr_cv cv_;
diff --git a/include/grpc/impl/codegen/sync.h b/include/grpc/impl/codegen/sync.h
index 3eabc5c17b..96aec0c2c0 100644
--- a/include/grpc/impl/codegen/sync.h
+++ b/include/grpc/impl/codegen/sync.h
@@ -64,257 +64,4 @@
 #error Unable to determine platform for sync
 #endif
 
-#include <grpc/impl/codegen/grpc_types.h> /* for gpr_timespec */
-
-#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);
-
-/* --- 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
-}
-#endif
-
 #endif /* GRPC_IMPL_CODEGEN_SYNC_H */
diff --git a/include/grpc/support/slice.h b/include/grpc/support/slice.h
index 291e884427..b31fe6c0c5 100644
--- a/include/grpc/support/slice.h
+++ b/include/grpc/support/slice.h
@@ -35,7 +35,7 @@
 #define GRPC_SUPPORT_SLICE_H
 
 #include <grpc/impl/codegen/slice.h>
-#include <grpc/impl/codegen/sync.h>
+#include <grpc/support/sync.h>
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/grpc/support/sync.h b/include/grpc/support/sync.h
index a0145803c2..fbcc470ae2 100644
--- a/include/grpc/support/sync.h
+++ b/include/grpc/support/sync.h
@@ -34,6 +34,258 @@
 #ifndef GRPC_SUPPORT_SYNC_H
 #define GRPC_SUPPORT_SYNC_H
 
+#include <grpc/impl/codegen/grpc_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);
+
+/* --- 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
+}
+#endif
+
 #endif /* GRPC_SUPPORT_SYNC_H */
diff --git a/src/cpp/common/core_codegen.cc b/src/cpp/common/core_codegen.cc
index c64f6514ab..ce02202976 100644
--- a/src/cpp/common/core_codegen.cc
+++ b/src/cpp/common/core_codegen.cc
@@ -44,6 +44,7 @@
 #include <grpc/support/port_platform.h>
 #include <grpc/support/slice.h>
 #include <grpc/support/slice_buffer.h>
+#include <grpc/support/sync.h>
 
 #include "src/core/lib/profiling/timers.h"
 
@@ -73,6 +74,19 @@ void* CoreCodegen::gpr_malloc(size_t size) { return ::gpr_malloc(size); }
 
 void CoreCodegen::gpr_free(void* p) { return ::gpr_free(p); }
 
+void CoreCodegen::gpr_mu_init(gpr_mu* mu) { ::gpr_mu_init(mu); };
+void CoreCodegen::gpr_mu_destroy(gpr_mu* mu) { ::gpr_mu_destroy(mu); }
+void CoreCodegen::gpr_mu_lock(gpr_mu* mu) { ::gpr_mu_lock(mu); }
+void CoreCodegen::gpr_mu_unlock(gpr_mu* mu) { ::gpr_mu_unlock(mu); }
+void CoreCodegen::gpr_cv_init(gpr_cv* cv) { ::gpr_cv_init(cv); }
+void CoreCodegen::gpr_cv_destroy(gpr_cv* cv) { ::gpr_cv_destroy(cv); }
+int CoreCodegen::gpr_cv_wait(gpr_cv* cv, gpr_mu* mu,
+                             gpr_timespec abs_deadline) {
+  return ::gpr_cv_wait(cv, mu, abs_deadline);
+}
+void CoreCodegen::gpr_cv_signal(gpr_cv* cv) { ::gpr_cv_signal(cv); }
+void CoreCodegen::gpr_cv_broadcast(gpr_cv* cv) { ::gpr_cv_broadcast(cv); }
+
 void CoreCodegen::grpc_byte_buffer_destroy(grpc_byte_buffer* bb) {
   ::grpc_byte_buffer_destroy(bb);
 }