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

/*
 *
 * Copyright 2015 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 GRPCXX_IMPL_CODEGEN_CALL_H
#define GRPCXX_IMPL_CODEGEN_CALL_H

#include <assert.h>
#include <cstring>
#include <functional>
#include <map>
#include <memory>

#include <grpc++/impl/codegen/call_hook.h>
#include <grpc++/impl/codegen/client_context.h>
#include <grpc++/impl/codegen/completion_queue_tag.h>
#include <grpc++/impl/codegen/config.h>
#include <grpc++/impl/codegen/core_codegen_interface.h>
#include <grpc++/impl/codegen/serialization_traits.h>
#include <grpc++/impl/codegen/slice.h>
#include <grpc++/impl/codegen/status.h>
#include <grpc++/impl/codegen/string_ref.h>

#include <grpc/impl/codegen/atm.h>
#include <grpc/impl/codegen/compression_types.h>
#include <grpc/impl/codegen/grpc_types.h>

struct grpc_byte_buffer;

namespace grpc {

class ByteBuffer;
class Call;
class CallHook;
class CompletionQueue;
extern CoreCodegenInterface* g_core_codegen_interface;

const char kBinaryErrorDetailsKey[] = "grpc-status-details-bin";

// TODO(yangg) if the map is changed before we send, the pointers will be a
// mess. Make sure it does not happen.
inline grpc_metadata* FillMetadataArray(
    const std::multimap<grpc::string, grpc::string>& metadata,
    size_t* metadata_count, const grpc::string& optional_error_details) {
  *metadata_count = metadata.size() + (optional_error_details.empty() ? 0 : 1);
  if (*metadata_count == 0) {
    return nullptr;
  }
  grpc_metadata* metadata_array =
      (grpc_metadata*)(g_core_codegen_interface->gpr_malloc(
          (*metadata_count) * sizeof(grpc_metadata)));
  size_t i = 0;
  for (auto iter = metadata.cbegin(); iter != metadata.cend(); ++iter, ++i) {
    metadata_array[i].key = SliceReferencingString(iter->first);
    metadata_array[i].value = SliceReferencingString(iter->second);
  }
  if (!optional_error_details.empty()) {
    metadata_array[i].key =
        g_core_codegen_interface->grpc_slice_from_static_buffer(
            kBinaryErrorDetailsKey, sizeof(kBinaryErrorDetailsKey) - 1);
    metadata_array[i].value = SliceReferencingString(optional_error_details);
  }
  return metadata_array;
}

/// Per-message write options.
class WriteOptions {
 public:
  WriteOptions() : flags_(0), last_message_(false) {}
  WriteOptions(const WriteOptions& other)
      : flags_(other.flags_), last_message_(other.last_message_) {}

  /// Clear all flags.
  inline void Clear() { flags_ = 0; }

  /// Returns raw flags bitset.
  inline uint32_t flags() const { return flags_; }

  /// Sets flag for the disabling of compression for the next message write.
  ///
  /// \sa GRPC_WRITE_NO_COMPRESS
  inline WriteOptions& set_no_compression() {
    SetBit(GRPC_WRITE_NO_COMPRESS);
    return *this;
  }

  /// Clears flag for the disabling of compression for the next message write.
  ///
  /// \sa GRPC_WRITE_NO_COMPRESS
  inline WriteOptions& clear_no_compression() {
    ClearBit(GRPC_WRITE_NO_COMPRESS);
    return *this;
  }

  /// Get value for the flag indicating whether compression for the next
  /// message write is forcefully disabled.
  ///
  /// \sa GRPC_WRITE_NO_COMPRESS
  inline bool get_no_compression() const {
    return GetBit(GRPC_WRITE_NO_COMPRESS);
  }

  /// Sets flag indicating that the write may be buffered and need not go out on
  /// the wire immediately.
  ///
  /// \sa GRPC_WRITE_BUFFER_HINT
  inline WriteOptions& set_buffer_hint() {
    SetBit(GRPC_WRITE_BUFFER_HINT);
    return *this;
  }

  /// Clears flag indicating that the write may be buffered and need not go out
  /// on the wire immediately.
  ///
  /// \sa GRPC_WRITE_BUFFER_HINT
  inline WriteOptions& clear_buffer_hint() {
    ClearBit(GRPC_WRITE_BUFFER_HINT);
    return *this;
  }

  /// Get value for the flag indicating that the write may be buffered and need
  /// not go out on the wire immediately.
  ///
  /// \sa GRPC_WRITE_BUFFER_HINT
  inline bool get_buffer_hint() const { return GetBit(GRPC_WRITE_BUFFER_HINT); }

  /// corked bit: aliases set_buffer_hint currently, with the intent that
  /// set_buffer_hint will be removed in the future
  inline WriteOptions& set_corked() {
    SetBit(GRPC_WRITE_BUFFER_HINT);
    return *this;
  }

  inline WriteOptions& clear_corked() {
    ClearBit(GRPC_WRITE_BUFFER_HINT);
    return *this;
  }

  inline bool is_corked() const { return GetBit(GRPC_WRITE_BUFFER_HINT); }

  /// last-message bit: indicates this is the last message in a stream
  /// client-side:  makes Write the equivalent of performing Write, WritesDone
  /// in a single step
  /// server-side:  hold the Write until the service handler returns (sync api)
  /// or until Finish is called (async api)
  inline WriteOptions& set_last_message() {
    last_message_ = true;
    return *this;
  }

  /// Clears flag indicating that this is the last message in a stream,
  /// disabling coalescing.
  inline WriteOptions& clear_last_messsage() {
    last_message_ = false;
    return *this;
  }

  /// Get value for the flag indicating that this is the last message, and
  /// should be coalesced with trailing metadata.
  ///
  /// \sa GRPC_WRITE_LAST_MESSAGE
  bool is_last_message() const { return last_message_; }

  WriteOptions& operator=(const WriteOptions& rhs) {
    flags_ = rhs.flags_;
    return *this;
  }

 private:
  void SetBit(const uint32_t mask) { flags_ |= mask; }

  void ClearBit(const uint32_t mask) { flags_ &= ~mask; }

  bool GetBit(const uint32_t mask) const { return (flags_ & mask) != 0; }

  uint32_t flags_;
  bool last_message_;
};

/// 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) {}
};

class CallOpSendInitialMetadata {
 public:
  CallOpSendInitialMetadata() : send_(false) {
    maybe_compression_level_.is_set = false;
  }

  void SendInitialMetadata(
      const std::multimap<grpc::string, grpc::string>& metadata,
      uint32_t flags) {
    maybe_compression_level_.is_set = false;
    send_ = true;
    flags_ = flags;
    initial_metadata_ =
        FillMetadataArray(metadata, &initial_metadata_count_, "");
  }

  void set_compression_level(grpc_compression_level level) {
    maybe_compression_level_.is_set = true;
    maybe_compression_level_.level = level;
  }

 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 = flags_;
    op->reserved = NULL;
    op->data.send_initial_metadata.count = initial_metadata_count_;
    op->data.send_initial_metadata.metadata = initial_metadata_;
    op->data.send_initial_metadata.maybe_compression_level.is_set =
        maybe_compression_level_.is_set;
    if (maybe_compression_level_.is_set) {
      op->data.send_initial_metadata.maybe_compression_level.level =
          maybe_compression_level_.level;
    }
  }
  void FinishOp(bool* status) {
    if (!send_) return;
    g_core_codegen_interface->gpr_free(initial_metadata_);
    send_ = false;
  }

  bool send_;
  uint32_t flags_;
  size_t initial_metadata_count_;
  grpc_metadata* initial_metadata_;
  struct {
    bool is_set;
    grpc_compression_level level;
  } maybe_compression_level_;
};

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

  /// Send \a message using \a options for the write. The \a options are cleared
  /// after use.
  template <class M>
  Status SendMessage(const M& message,
                     WriteOptions options) GRPC_MUST_USE_RESULT;

  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 = write_options_.flags();
    op->reserved = NULL;
    op->data.send_message.send_message = send_buf_;
    // Flags are per-message: clear them after use.
    write_options_.Clear();
  }
  void FinishOp(bool* status) {
    if (own_buf_) g_core_codegen_interface->grpc_byte_buffer_destroy(send_buf_);
    send_buf_ = nullptr;
  }

 private:
  grpc_byte_buffer* send_buf_;
  WriteOptions write_options_;
  bool own_buf_;
};

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

template <class M>
Status CallOpSendMessage::SendMessage(const M& message) {
  return SendMessage(message, WriteOptions());
}

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

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

  // Do not change status if no message is received.
  void AllowNoMessage() { allow_not_getting_message_ = true; }

  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->reserved = NULL;
    op->data.recv_message.recv_message = &recv_buf_;
  }

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

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

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

  template <class R>
  void RecvMessage(R* message) {
    deserialize_ = [message](grpc_byte_buffer* buf) -> Status {
      return SerializationTraits<R>::Deserialize(buf, message);
    };
  }

  // Do not change status if no message is received.
  void AllowNoMessage() { allow_not_getting_message_ = true; }

  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->reserved = NULL;
    op->data.recv_message.recv_message = &recv_buf_;
  }

  void FinishOp(bool* status) {
    if (!deserialize_) return;
    if (recv_buf_) {
      if (*status) {
        got_message = true;
        *status = deserialize_(recv_buf_).ok();
      } else {
        got_message = false;
        g_core_codegen_interface->grpc_byte_buffer_destroy(recv_buf_);
      }
    } else {
      got_message = false;
      if (!allow_not_getting_message_) {
        *status = false;
      }
    }
    deserialize_ = DeserializeFunc();
  }

 private:
  typedef std::function<Status(grpc_byte_buffer*)> DeserializeFunc;
  DeserializeFunc deserialize_;
  grpc_byte_buffer* recv_buf_;
  bool allow_not_getting_message_;
};

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;
    op->reserved = NULL;
  }
  void FinishOp(bool* status) { 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) {
    send_error_details_ = status.error_details();
    trailing_metadata_ = FillMetadataArray(
        trailing_metadata, &trailing_metadata_count_, send_error_details_);
    send_status_available_ = true;
    send_status_code_ = static_cast<grpc_status_code>(status.error_code());
    send_error_message_ = 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_;
    error_message_slice_ = SliceReferencingString(send_error_message_);
    op->data.send_status_from_server.status_details =
        send_error_message_.empty() ? nullptr : &error_message_slice_;
    op->flags = 0;
    op->reserved = NULL;
  }

  void FinishOp(bool* status) {
    if (!send_status_available_) return;
    g_core_codegen_interface->gpr_free(trailing_metadata_);
    send_status_available_ = false;
  }

 private:
  bool send_status_available_;
  grpc_status_code send_status_code_;
  grpc::string send_error_details_;
  grpc::string send_error_message_;
  size_t trailing_metadata_count_;
  grpc_metadata* trailing_metadata_;
  grpc_slice error_message_slice_;
};

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

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

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (metadata_map_ == nullptr) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_RECV_INITIAL_METADATA;
    op->data.recv_initial_metadata.recv_initial_metadata = metadata_map_->arr();
    op->flags = 0;
    op->reserved = NULL;
  }

  void FinishOp(bool* status) {
    if (metadata_map_ == nullptr) return;
    metadata_map_->FillMap();
    metadata_map_ = nullptr;
  }

 private:
  MetadataMap* metadata_map_;
};

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

  void ClientRecvStatus(ClientContext* context, Status* status) {
    metadata_map_ = &context->trailing_metadata_;
    recv_status_ = status;
    error_message_ = g_core_codegen_interface->grpc_empty_slice();
  }

 protected:
  void AddOp(grpc_op* ops, size_t* nops) {
    if (recv_status_ == nullptr) return;
    grpc_op* op = &ops[(*nops)++];
    op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
    op->data.recv_status_on_client.trailing_metadata = metadata_map_->arr();
    op->data.recv_status_on_client.status = &status_code_;
    op->data.recv_status_on_client.status_details = &error_message_;
    op->flags = 0;
    op->reserved = NULL;
  }

  void FinishOp(bool* status) {
    if (recv_status_ == nullptr) return;
    metadata_map_->FillMap();
    grpc::string binary_error_details;
    auto iter = metadata_map_->map()->find(kBinaryErrorDetailsKey);
    if (iter != metadata_map_->map()->end()) {
      binary_error_details =
          grpc::string(iter->second.begin(), iter->second.length());
    }
    *recv_status_ = Status(static_cast<StatusCode>(status_code_),
                           grpc::string(GRPC_SLICE_START_PTR(error_message_),
                                        GRPC_SLICE_END_PTR(error_message_)),
                           binary_error_details);
    g_core_codegen_interface->grpc_slice_unref(error_message_);
    recv_status_ = nullptr;
  }

 private:
  MetadataMap* metadata_map_;
  Status* recv_status_;
  grpc_status_code status_code_;
  grpc_slice error_message_;
};

/// TODO(vjpai): Remove the existence of CallOpSetCollectionInterface
/// and references to it. This code is deprecated-on-arrival and is
/// only added for users that bypassed the code-generator.
class CallOpSetCollectionInterface {
 public:
  virtual ~CallOpSetCollectionInterface() {}
};

/// 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:
  /// Fills in grpc_op, starting from ops[*nops] and moving
  /// upwards.
  virtual void FillOps(grpc_call* call, grpc_op* ops, size_t* nops) = 0;

  /// TODO(vjpai): Remove the SetCollection method and comment. This is only
  /// a short-term workaround for users that bypassed the code generator
  /// Mark this as belonging to a collection if needed
  void SetCollection(std::shared_ptr<CallOpSetCollectionInterface> collection) {
    collection_ = collection;
  }

 protected:
  /// TODO(vjpai): Remove the collection_ field once the idea of bypassing the
  /// code generator is forbidden. This is already deprecated
  std::shared_ptr<CallOpSetCollectionInterface> collection_;
};

/// 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_call* call, grpc_op* ops, size_t* nops) 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);
    g_core_codegen_interface->grpc_call_ref(call);
    call_ = call;
  }

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

    // TODO(vjpai): Remove the reference to collection_ once the idea of
    // bypassing the code generator is forbidden. It is already deprecated
    grpc_call* call = call_;
    collection_.reset();

    g_core_codegen_interface->grpc_call_unref(call);

    return true;
  }

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

 private:
  void* return_tag_;
  grpc_call* call_;
};

/// 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 : public CallOpSet<Op1, Op2, Op3, Op4, Op5, Op6> {
 public:
  bool FinalizeResult(void** tag, bool* status) override {
    typedef CallOpSet<Op1, Op2, Op3, Op4, Op5, Op6> Base;
    return Base::FinalizeResult(tag, status) && false;
  }
};

/// Straightforward wrapping of the C call object
class Call final {
 public:
  /** call is owned by the caller */
  Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq)
      : call_hook_(call_hook),
        cq_(cq),
        call_(call),
        max_receive_message_size_(-1) {}

  Call(grpc_call* call, CallHook* call_hook, CompletionQueue* cq,
       int max_receive_message_size)
      : call_hook_(call_hook),
        cq_(cq),
        call_(call),
        max_receive_message_size_(max_receive_message_size) {}

  void PerformOps(CallOpSetInterface* ops) {
    call_hook_->PerformOpsOnCall(ops, this);
  }

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

  int max_receive_message_size() const { return max_receive_message_size_; }

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

}  // namespace grpc

#endif  // GRPCXX_IMPL_CODEGEN_CALL_H