text: /*
   * Copyright 2018 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.
   *
   */
  
  #include <grpc/support/port_platform.h>
  
  #include <memory>
  
  #include <grpc/support/log.h>
  #include <grpcpp/alarm.h>
  #include <grpcpp/completion_queue.h>
  #include <grpcpp/impl/grpc_library.h>
  #include <grpcpp/support/time.h>
  
  #include "src/core/lib/debug/trace.h"
  #include "src/core/lib/iomgr/exec_ctx.h"
  #include "src/core/lib/iomgr/executor.h"
  #include "src/core/lib/iomgr/timer.h"
  #include "src/core/lib/surface/completion_queue.h"
  
  namespace grpc {
  
  namespace internal {
  class AlarmImpl : public grpc::internal::CompletionQueueTag {
   public:
    AlarmImpl() : cq_(nullptr), tag_(nullptr) {
      gpr_ref_init(&refs_, 1);
      grpc_timer_init_unset(&timer_);
    }
    ~AlarmImpl() override {}
    bool FinalizeResult(void** tag, bool* /*status*/) override {
      *tag = tag_;
      Unref();
      return true;
    }
    void Set(grpc::CompletionQueue* cq, gpr_timespec deadline, void* tag) {
      grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
      grpc_core::ExecCtx exec_ctx;
      GRPC_CQ_INTERNAL_REF(cq->cq(), "alarm");
      cq_ = cq->cq();
      tag_ = tag;
      GPR_ASSERT(grpc_cq_begin_op(cq_, this));
      GRPC_CLOSURE_INIT(
          &on_alarm_,
          [](void* arg, grpc_error_handle error) {
            // queue the op on the completion queue
            AlarmImpl* alarm = static_cast<AlarmImpl*>(arg);
            alarm->Ref();
            // Preserve the cq and reset the cq_ so that the alarm
            // can be reset when the alarm tag is delivered.
            grpc_completion_queue* cq = alarm->cq_;
            alarm->cq_ = nullptr;
            grpc_cq_end_op(
                cq, alarm, error,
                [](void* /*arg*/, grpc_cq_completion* /*completion*/) {}, arg,
                &alarm->completion_);
            GRPC_CQ_INTERNAL_UNREF(cq, "alarm");
          },
          this, grpc_schedule_on_exec_ctx);
      grpc_timer_init(&timer_, grpc_timespec_to_millis_round_up(deadline),
                      &on_alarm_);
    }
    void Set(gpr_timespec deadline, std::function<void(bool)> f) {
      grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
      grpc_core::ExecCtx exec_ctx;
      // Don't use any CQ at all. Instead just use the timer to fire the function
      callback_ = std::move(f);
      Ref();
      GRPC_CLOSURE_INIT(
          &on_alarm_,
          [](void* arg, grpc_error_handle error) {
            grpc_core::Executor::Run(
                GRPC_CLOSURE_CREATE(
                    [](void* arg, grpc_error_handle error) {
                      AlarmImpl* alarm = static_cast<AlarmImpl*>(arg);
                      alarm->callback_(error == GRPC_ERROR_NONE);
                      alarm->Unref();
                    },
                    arg, nullptr),
                error);
          },
          this, grpc_schedule_on_exec_ctx);
      grpc_timer_init(&timer_, grpc_timespec_to_millis_round_up(deadline),
                      &on_alarm_);
    }
    void Cancel() {
      grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;
      grpc_core::ExecCtx exec_ctx;
      grpc_timer_cancel(&timer_);
    }
    void Destroy() {
      Cancel();
      Unref();
    }
  
   private:
    void Ref() { gpr_ref(&refs_); }
    void Unref() {
      if (gpr_unref(&refs_)) {
        delete this;
      }
    }
  
    grpc_timer timer_;
    gpr_refcount refs_;
    grpc_closure on_alarm_;
    grpc_cq_completion completion_;
    // completion queue where events about this alarm will be posted
    grpc_completion_queue* cq_;
    void* tag_;
    std::function<void(bool)> callback_;
  };
  }  // namespace internal
  
  static grpc::internal::GrpcLibraryInitializer g_gli_initializer;
  
  Alarm::Alarm() : alarm_(new internal::AlarmImpl()) {
    g_gli_initializer.summon();
  }
  
  void Alarm::SetInternal(grpc::CompletionQueue* cq, gpr_timespec deadline,
                          void* tag) {
    // Note that we know that alarm_ is actually an internal::AlarmImpl
    // but we declared it as the base pointer to avoid a forward declaration
    // or exposing core data structures in the C++ public headers.
    // Thus it is safe to use a static_cast to the subclass here, and the
    // C++ style guide allows us to do so in this case
    static_cast<internal::AlarmImpl*>(alarm_)->Set(cq, deadline, tag);
  }
  
  void Alarm::SetInternal(gpr_timespec deadline, std::function<void(bool)> f) {
    // Note that we know that alarm_ is actually an internal::AlarmImpl
    // but we declared it as the base pointer to avoid a forward declaration
    // or exposing core data structures in the C++ public headers.
    // Thus it is safe to use a static_cast to the subclass here, and the
    // C++ style guide allows us to do so in this case
    static_cast<internal::AlarmImpl*>(alarm_)->Set(deadline, std::move(f));
  }
  
  Alarm::~Alarm() {
    if (alarm_ != nullptr) {
      static_cast<internal::AlarmImpl*>(alarm_)->Destroy();
    }
  }
  
  void Alarm::Cancel() { static_cast<internal::AlarmImpl*>(alarm_)->Cancel(); }
  }  // namespace grpc
  