/*
 *
 * Copyright 2015-2016 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_CORE_LIB_SURFACE_COMPLETION_QUEUE_H
#define GRPC_CORE_LIB_SURFACE_COMPLETION_QUEUE_H

/* Internal API for completion queues */

#include <grpc/support/port_platform.h>

#include <grpc/grpc.h>
#include "src/core/lib/debug/trace.h"
#include "src/core/lib/gprpp/abstract.h"
#include "src/core/lib/iomgr/pollset.h"

/* These trace flags default to 1. The corresponding lines are only traced
   if grpc_api_trace is also truthy */
extern grpc_core::TraceFlag grpc_cq_pluck_trace;
extern grpc_core::TraceFlag grpc_trace_operation_failures;
extern grpc_core::DebugOnlyTraceFlag grpc_trace_pending_tags;
extern grpc_core::DebugOnlyTraceFlag grpc_trace_cq_refcount;

typedef struct grpc_cq_completion {
  gpr_mpscq_node node;

  /** user supplied tag */
  void* tag;
  /** done callback - called when this queue element is no longer
      needed by the completion queue */
  void (*done)(void* done_arg, struct grpc_cq_completion* c);
  void* done_arg;
  /** next pointer; low bit is used to indicate success or not */
  uintptr_t next;
} grpc_cq_completion;

/// For callback CQs, the tag that is passed in for an operation must
/// actually be a pointer to an implementation of the following class.
/// When the operation completes, the tag will be typecasted from void*
/// to grpc_core::CQCallbackInterface* and then the Run method will be
/// invoked on it. In practice, the language binding (e.g., C++ API
/// implementation) is responsible for providing and using an implementation
/// of this abstract base class.
namespace grpc_core {
class CQCallbackInterface {
 public:
  virtual ~CQCallbackInterface() {}
  virtual void Run(bool) GRPC_ABSTRACT;

  GRPC_ABSTRACT_BASE_CLASS
};
}  // namespace grpc_core

#ifndef NDEBUG
void grpc_cq_internal_ref(grpc_completion_queue* cc, const char* reason,
                          const char* file, int line);
void grpc_cq_internal_unref(grpc_completion_queue* cc, const char* reason,
                            const char* file, int line);
#define GRPC_CQ_INTERNAL_REF(cc, reason) \
  grpc_cq_internal_ref(cc, reason, __FILE__, __LINE__)
#define GRPC_CQ_INTERNAL_UNREF(cc, reason) \
  grpc_cq_internal_unref(cc, reason, __FILE__, __LINE__)
#else
void grpc_cq_internal_ref(grpc_completion_queue* cc);
void grpc_cq_internal_unref(grpc_completion_queue* cc);
#define GRPC_CQ_INTERNAL_REF(cc, reason) grpc_cq_internal_ref(cc)
#define GRPC_CQ_INTERNAL_UNREF(cc, reason) grpc_cq_internal_unref(cc)
#endif

/* Initializes global variables used by completion queues */
void grpc_cq_global_init();

/* Flag that an operation is beginning: the completion channel will not finish
   shutdown until a corrensponding grpc_cq_end_* call is made.
   \a tag is currently used only in debug builds. Return true on success, and
   false if completion_queue has been shutdown. */
bool grpc_cq_begin_op(grpc_completion_queue* cc, void* tag);

/* Queue a GRPC_OP_COMPLETED operation; tag must correspond to the tag passed to
   grpc_cq_begin_op */
void grpc_cq_end_op(grpc_completion_queue* cc, void* tag, grpc_error* error,
                    void (*done)(void* done_arg, grpc_cq_completion* storage),
                    void* done_arg, grpc_cq_completion* storage);

grpc_pollset* grpc_cq_pollset(grpc_completion_queue* cc);

bool grpc_cq_can_listen(grpc_completion_queue* cc);

grpc_cq_completion_type grpc_get_cq_completion_type(grpc_completion_queue* cc);

int grpc_get_cq_poll_num(grpc_completion_queue* cc);

grpc_completion_queue* grpc_completion_queue_create_internal(
    grpc_cq_completion_type completion_type, grpc_cq_polling_type polling_type,
    grpc_core::CQCallbackInterface* shutdown_callback);

#endif /* GRPC_CORE_LIB_SURFACE_COMPLETION_QUEUE_H */