grpc/include/grpc++/impl/call.h

/*
 *
 * Copyright 2015, Google Inc.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
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 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#ifndef GRPCXX_IMPL_CALL_H
#define GRPCXX_IMPL_CALL_H

#include <grpc/support/alloc.h>
#include <grpc++/client_context.h>
#include <grpc++/completion_queue.h>
#include <grpc++/config.h>
#include <grpc++/status.h>
#include <grpc++/impl/serialization_traits.h>

#include <functional>
#include <memory>
#include <map>

#include <string.h>

struct grpc_call;
struct grpc_op;

namespace grpc {

class ByteBuffer;
class Call;

void FillMetadataMap(grpc_metadata_array* arr,
                     std::multimap<grpc::string, grpc::string>* metadata);
grpc_metadata* FillMetadataArray(
    const std::multimap<grpc::string, grpc::string>& metadata);

/// Default argument for CallOpSet. I is unused by the class, but can be
/// used for generating multiple names for the same thing.
template <int I>
class CallNoOp {
 protected:
  void AddOp(grpc_op* ops, size_t* nops) {}
  void FinishOp(bool* status, int max_message_size) {}
};

class CallOpSendInitialMetadata {
 public:
  CallOpSendInitialMetadata() : send_(false) {}

  void SendInitialMetadata(
      const std::multimap<grpc::string, grpc::string>& metadata) {
    send_ = true;
    initial_metadata_count_ = metadata.size();
    initial_metadata_ = FillMetadataArray(metadata);
  }

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (!send_) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_SEND_INITIAL_METADATA;
    op->flags = 0;
    op->data.send_initial_metadata.count = initial_metadata_count_;
    op->data.send_initial_metadata.metadata = initial_metadata_;
  }
  void FinishOp(bool* status, int max_message_size) {
    if (!send_) return;
    gpr_free(initial_metadata_);
    send_ = false;
  }

  bool send_;
  size_t initial_metadata_count_;
  grpc_metadata* initial_metadata_;
};

class CallOpSendMessage {
 public:
  CallOpSendMessage() : send_buf_(nullptr), own_buf_(false) {}

  template <class M>
  Status SendMessage(const M& message) GRPC_MUST_USE_RESULT;

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (send_buf_ == nullptr) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_SEND_MESSAGE;
    op->flags = 0;
    op->data.send_message = send_buf_;
  }
  void FinishOp(bool* status, int max_message_size) {
    if (own_buf_) grpc_byte_buffer_destroy(send_buf_);
    send_buf_ = nullptr;
  }

 private:
  grpc_byte_buffer* send_buf_;
  bool own_buf_;
};

template <class M>
Status CallOpSendMessage::SendMessage(const M& message) {
  return SerializationTraits<M>::Serialize(message, &send_buf_, &own_buf_);
}

template <class R>
class CallOpRecvMessage {
 public:
  CallOpRecvMessage() : got_message(false), message_(nullptr) {}

  void RecvMessage(R* message) { message_ = message; }

  bool got_message;

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (message_ == nullptr) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_RECV_MESSAGE;
    op->flags = 0;
    op->data.recv_message = &recv_buf_;
  }

  void FinishOp(bool* status, int max_message_size) {
    if (message_ == nullptr) return;
    if (recv_buf_) {
      if (*status) {
        got_message = true;
        *status = SerializationTraits<R>::Deserialize(recv_buf_, message_,
                                                      max_message_size)
                      .ok();
      } else {
        got_message = false;
        grpc_byte_buffer_destroy(recv_buf_);
      }
    } else {
      got_message = false;
      *status = false;
    }
    message_ = nullptr;
  }

 private:
  R* message_;
  grpc_byte_buffer* recv_buf_;
};

namespace CallOpGenericRecvMessageHelper {
class DeserializeFunc {
 public:
  virtual Status Deserialize(grpc_byte_buffer* buf, int max_message_size) = 0;
};

template <class R>
class DeserializeFuncType : public DeserializeFunc {
 public:
  DeserializeFuncType(R* message) : message_(message) {}
  Status Deserialize(grpc_byte_buffer* buf, int max_message_size) {
    return SerializationTraits<R>::Deserialize(buf, message_, max_message_size);
  }

 private:
  R* message_;  // Not a managed pointer because management is external to this
};
}  // namespace CallOpGenericRecvMessageHelper

class CallOpGenericRecvMessage {
 public:
  CallOpGenericRecvMessage() : got_message(false) {}

  template <class R>
  void RecvMessage(R* message) {
    deserialize_.reset(
        new CallOpGenericRecvMessageHelper::DeserializeFuncType<R>(message));
  }

  bool got_message;

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (!deserialize_) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_RECV_MESSAGE;
    op->flags = 0;
    op->data.recv_message = &recv_buf_;
  }

  void FinishOp(bool* status, int max_message_size) {
    if (!deserialize_) return;
    if (recv_buf_) {
      if (*status) {
        got_message = true;
        *status = deserialize_->Deserialize(recv_buf_, max_message_size).ok();
      } else {
        got_message = false;
        grpc_byte_buffer_destroy(recv_buf_);
      }
    } else {
      got_message = false;
      *status = false;
    }
    deserialize_.reset();
  }

 private:
  std::unique_ptr<CallOpGenericRecvMessageHelper::DeserializeFunc> deserialize_;
  grpc_byte_buffer* recv_buf_;
};

class CallOpClientSendClose {
 public:
  CallOpClientSendClose() : send_(false) {}

  void ClientSendClose() { send_ = true; }

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (!send_) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_SEND_CLOSE_FROM_CLIENT;
    op->flags = 0;
  }
  void FinishOp(bool* status, int max_message_size) { send_ = false; }

 private:
  bool send_;
};

class CallOpServerSendStatus {
 public:
  CallOpServerSendStatus() : send_status_available_(false) {}

  void ServerSendStatus(
      const std::multimap<grpc::string, grpc::string>& trailing_metadata,
      const Status& status) {
    trailing_metadata_count_ = trailing_metadata.size();
    trailing_metadata_ = FillMetadataArray(trailing_metadata);
    send_status_available_ = true;
    send_status_code_ = static_cast<grpc_status_code>(status.error_code());
    send_status_details_ = status.error_message();
  }

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (!send_status_available_) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_SEND_STATUS_FROM_SERVER;
    op->data.send_status_from_server.trailing_metadata_count =
        trailing_metadata_count_;
    op->data.send_status_from_server.trailing_metadata = trailing_metadata_;
    op->data.send_status_from_server.status = send_status_code_;
    op->data.send_status_from_server.status_details =
        send_status_details_.empty() ? nullptr : send_status_details_.c_str();
    op->flags = 0;
  }

  void FinishOp(bool* status, int max_message_size) {
    if (!send_status_available_) return;
    gpr_free(trailing_metadata_);
    send_status_available_ = false;
  }

 private:
  bool send_status_available_;
  grpc_status_code send_status_code_;
  grpc::string send_status_details_;
  size_t trailing_metadata_count_;
  grpc_metadata* trailing_metadata_;
};

class CallOpRecvInitialMetadata {
 public:
  CallOpRecvInitialMetadata() : recv_initial_metadata_(nullptr) {}

  void RecvInitialMetadata(ClientContext* context) {
    context->initial_metadata_received_ = true;
    recv_initial_metadata_ = &context->recv_initial_metadata_;
  }

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (!recv_initial_metadata_) return;
    memset(&recv_initial_metadata_arr_, 0, sizeof(recv_initial_metadata_arr_));
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_RECV_INITIAL_METADATA;
    op->data.recv_initial_metadata = &recv_initial_metadata_arr_;
    op->flags = 0;
  }
  void FinishOp(bool* status, int max_message_size) {
    if (recv_initial_metadata_ == nullptr) return;
    FillMetadataMap(&recv_initial_metadata_arr_, recv_initial_metadata_);
    recv_initial_metadata_ = nullptr;
  }

 private:
  std::multimap<grpc::string, grpc::string>* recv_initial_metadata_;
  grpc_metadata_array recv_initial_metadata_arr_;
};

class CallOpClientRecvStatus {
 public:
  CallOpClientRecvStatus() : recv_status_(nullptr) {}

  void ClientRecvStatus(ClientContext* context, Status* status) {
    recv_trailing_metadata_ = &context->trailing_metadata_;
    recv_status_ = status;
  }

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (recv_status_ == nullptr) return;
    memset(&recv_trailing_metadata_arr_, 0,
           sizeof(recv_trailing_metadata_arr_));
    status_details_ = nullptr;
    status_details_capacity_ = 0;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
    op->data.recv_status_on_client.trailing_metadata =
        &recv_trailing_metadata_arr_;
    op->data.recv_status_on_client.status = &status_code_;
    op->data.recv_status_on_client.status_details = &status_details_;
    op->data.recv_status_on_client.status_details_capacity =
        &status_details_capacity_;
    op->flags = 0;
  }

  void FinishOp(bool* status, int max_message_size) {
    if (recv_status_ == nullptr) return;
    FillMetadataMap(&recv_trailing_metadata_arr_, recv_trailing_metadata_);
    *recv_status_ = Status(
        static_cast<StatusCode>(status_code_),
        status_details_ ? grpc::string(status_details_) : grpc::string());
    gpr_free(status_details_);
    recv_status_ = nullptr;
  }

 private:
  std::multimap<grpc::string, grpc::string>* recv_trailing_metadata_;
  Status* recv_status_;
  grpc_metadata_array recv_trailing_metadata_arr_;
  grpc_status_code status_code_;
  char* status_details_;
  size_t status_details_capacity_;
};

/// An abstract collection of call ops, used to generate the
/// grpc_call_op structure to pass down to the lower layers,
/// and as it is-a CompletionQueueTag, also massages the final
/// completion into the correct form for consumption in the C++
/// API.
class CallOpSetInterface : public CompletionQueueTag {
 public:
  CallOpSetInterface() : max_message_size_(0) {}
  /// Fills in grpc_op, starting from ops[*nops] and moving
  /// upwards.
  virtual void FillOps(grpc_op* ops, size_t* nops) = 0;

  void set_max_message_size(int max_message_size) {
    max_message_size_ = max_message_size;
  }

 protected:
  int max_message_size_;
};

/// Primary implementaiton of CallOpSetInterface.
/// Since we cannot use variadic templates, we declare slots up to
/// the maximum count of ops we'll need in a set. We leverage the
/// empty base class optimization to slim this class (especially
/// when there are many unused slots used). To avoid duplicate base classes,
/// the template parmeter for CallNoOp is varied by argument position.
template <class Op1 = CallNoOp<1>, class Op2 = CallNoOp<2>,
          class Op3 = CallNoOp<3>, class Op4 = CallNoOp<4>,
          class Op5 = CallNoOp<5>, class Op6 = CallNoOp<6>>
class CallOpSet : public CallOpSetInterface,
                  public Op1,
                  public Op2,
                  public Op3,
                  public Op4,
                  public Op5,
                  public Op6 {
 public:
  CallOpSet() : return_tag_(this) {}
  void FillOps(grpc_op* ops, size_t* nops) GRPC_OVERRIDE {
    this->Op1::AddOp(ops, nops);
    this->Op2::AddOp(ops, nops);
    this->Op3::AddOp(ops, nops);
    this->Op4::AddOp(ops, nops);
    this->Op5::AddOp(ops, nops);
    this->Op6::AddOp(ops, nops);
  }

  bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
    this->Op1::FinishOp(status, max_message_size_);
    this->Op2::FinishOp(status, max_message_size_);
    this->Op3::FinishOp(status, max_message_size_);
    this->Op4::FinishOp(status, max_message_size_);
    this->Op5::FinishOp(status, max_message_size_);
    this->Op6::FinishOp(status, max_message_size_);
    *tag = return_tag_;
    return true;
  }

  void set_output_tag(void* return_tag) { return_tag_ = return_tag; }

 private:
  void* return_tag_;
};

/// A CallOpSet that does not post completions to the completion queue.
///
/// Allows hiding some completions that the C core must generate from
/// C++ users.
template <class Op1 = CallNoOp<1>, class Op2 = CallNoOp<2>,
          class Op3 = CallNoOp<3>, class Op4 = CallNoOp<4>,
          class Op5 = CallNoOp<5>, class Op6 = CallNoOp<6>>
class SneakyCallOpSet GRPC_FINAL
    : public CallOpSet<Op1, Op2, Op3, Op4, Op5, Op6> {
 public:
  bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
    typedef CallOpSet<Op1, Op2, Op3, Op4, Op5, Op6> Base;
    return Base::FinalizeResult(tag, status) && false;
  }
};

// Channel and Server implement this to allow them to hook performing ops
class CallHook {
 public:
  virtual ~CallHook() {}
  virtual void PerformOpsOnCall(CallOpSetInterface* ops, Call* call) = 0;
};

// Straightforward wrapping of the C call object
class Call GRPC_FINAL {
 public:
  /* call is owned by the caller */
  Call(grpc_call* call, CallHook* call_hook_, CompletionQueue* cq);
  Call(grpc_call* call, CallHook* call_hook_, CompletionQueue* cq,
       int max_message_size);

  void PerformOps(CallOpSetInterface* ops);

  grpc_call* call() { return call_; }
  CompletionQueue* cq() { return cq_; }

  int max_message_size() { return max_message_size_; }

 private:
  CallHook* call_hook_;
  CompletionQueue* cq_;
  grpc_call* call_;
  int max_message_size_;
};

}  // namespace grpc

#endif  // GRPCXX_IMPL_CALL_H