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      1 /*
      2  * Copyright 2018 gRPC authors.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  *
     16  */
     17 
     18 #include <grpcpp/alarm.h>
     19 
     20 #include <memory>
     21 
     22 #include <grpc/support/log.h>
     23 #include <grpc/support/port_platform.h>
     24 #include <grpcpp/completion_queue.h>
     25 #include <grpcpp/impl/grpc_library.h>
     26 #include <grpcpp/support/time.h>
     27 #include "src/core/lib/iomgr/exec_ctx.h"
     28 #include "src/core/lib/iomgr/timer.h"
     29 #include "src/core/lib/surface/completion_queue.h"
     30 
     31 #include <grpc/support/log.h>
     32 #include "src/core/lib/debug/trace.h"
     33 
     34 namespace grpc {
     35 
     36 namespace internal {
     37 class AlarmImpl : public CompletionQueueTag {
     38  public:
     39   AlarmImpl() : cq_(nullptr), tag_(nullptr) {
     40     gpr_ref_init(&refs_, 1);
     41     grpc_timer_init_unset(&timer_);
     42   }
     43   ~AlarmImpl() {
     44     grpc_core::ExecCtx exec_ctx;
     45     if (cq_ != nullptr) {
     46       GRPC_CQ_INTERNAL_UNREF(cq_, "alarm");
     47     }
     48   }
     49   bool FinalizeResult(void** tag, bool* status) override {
     50     *tag = tag_;
     51     Unref();
     52     return true;
     53   }
     54   void Set(CompletionQueue* cq, gpr_timespec deadline, void* tag) {
     55     grpc_core::ExecCtx exec_ctx;
     56     GRPC_CQ_INTERNAL_REF(cq->cq(), "alarm");
     57     cq_ = cq->cq();
     58     tag_ = tag;
     59     GPR_ASSERT(grpc_cq_begin_op(cq_, this));
     60     GRPC_CLOSURE_INIT(&on_alarm_,
     61                       [](void* arg, grpc_error* error) {
     62                         // queue the op on the completion queue
     63                         AlarmImpl* alarm = static_cast<AlarmImpl*>(arg);
     64                         alarm->Ref();
     65                         grpc_cq_end_op(
     66                             alarm->cq_, alarm, error,
     67                             [](void* arg, grpc_cq_completion* completion) {},
     68                             arg, &alarm->completion_);
     69                       },
     70                       this, grpc_schedule_on_exec_ctx);
     71     grpc_timer_init(&timer_, grpc_timespec_to_millis_round_up(deadline),
     72                     &on_alarm_);
     73   }
     74   void Set(gpr_timespec deadline, std::function<void(bool)> f) {
     75     grpc_core::ExecCtx exec_ctx;
     76     // Don't use any CQ at all. Instead just use the timer to fire the function
     77     callback_ = std::move(f);
     78     Ref();
     79     GRPC_CLOSURE_INIT(&on_alarm_,
     80                       [](void* arg, grpc_error* error) {
     81                         AlarmImpl* alarm = static_cast<AlarmImpl*>(arg);
     82                         alarm->callback_(error == GRPC_ERROR_NONE);
     83                         alarm->Unref();
     84                       },
     85                       this, grpc_schedule_on_exec_ctx);
     86     grpc_timer_init(&timer_, grpc_timespec_to_millis_round_up(deadline),
     87                     &on_alarm_);
     88   }
     89   void Cancel() {
     90     grpc_core::ExecCtx exec_ctx;
     91     grpc_timer_cancel(&timer_);
     92   }
     93   void Destroy() {
     94     Cancel();
     95     Unref();
     96   }
     97 
     98  private:
     99   void Ref() { gpr_ref(&refs_); }
    100   void Unref() {
    101     if (gpr_unref(&refs_)) {
    102       delete this;
    103     }
    104   }
    105 
    106   grpc_timer timer_;
    107   gpr_refcount refs_;
    108   grpc_closure on_alarm_;
    109   grpc_cq_completion completion_;
    110   // completion queue where events about this alarm will be posted
    111   grpc_completion_queue* cq_;
    112   void* tag_;
    113   std::function<void(bool)> callback_;
    114 };
    115 }  // namespace internal
    116 
    117 static internal::GrpcLibraryInitializer g_gli_initializer;
    118 
    119 Alarm::Alarm() : alarm_(new internal::AlarmImpl()) {
    120   g_gli_initializer.summon();
    121 }
    122 
    123 void Alarm::SetInternal(CompletionQueue* cq, gpr_timespec deadline, void* tag) {
    124   // Note that we know that alarm_ is actually an internal::AlarmImpl
    125   // but we declared it as the base pointer to avoid a forward declaration
    126   // or exposing core data structures in the C++ public headers.
    127   // Thus it is safe to use a static_cast to the subclass here, and the
    128   // C++ style guide allows us to do so in this case
    129   static_cast<internal::AlarmImpl*>(alarm_)->Set(cq, deadline, tag);
    130 }
    131 
    132 void Alarm::SetInternal(gpr_timespec deadline, std::function<void(bool)> f) {
    133   // Note that we know that alarm_ is actually an internal::AlarmImpl
    134   // but we declared it as the base pointer to avoid a forward declaration
    135   // or exposing core data structures in the C++ public headers.
    136   // Thus it is safe to use a static_cast to the subclass here, and the
    137   // C++ style guide allows us to do so in this case
    138   static_cast<internal::AlarmImpl*>(alarm_)->Set(deadline, std::move(f));
    139 }
    140 
    141 Alarm::~Alarm() {
    142   if (alarm_ != nullptr) {
    143     static_cast<internal::AlarmImpl*>(alarm_)->Destroy();
    144   }
    145 }
    146 
    147 void Alarm::Cancel() { static_cast<internal::AlarmImpl*>(alarm_)->Cancel(); }
    148 }  // namespace grpc
    149