project_6/upstream_ref/xllm/xllm/api_service/stream_call.h

/* Copyright 2025 The xLLM Authors. All Rights Reserved.

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

    https://github.com/jd-opensource/xllm/blob/main/LICENSE

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.
==============================================================================*/

#pragma once

#include <brpc/controller.h>
#include <butil/iobuf.h>
#include <glog/logging.h>
#include <json2pb/pb_to_json.h>

#include <atomic>
#include <memory>
#include <optional>
#include <string>

#include "api_service/call.h"
#include "core/common/types.h"

namespace xllm {

template <typename Request, typename Response>
class StreamCall : public Call {
 public:
  using ReqType = Request;
  using ResType = Response;

  StreamCall(brpc::Controller* controller,
             ::google::protobuf::Closure* done,
             Request* request,
             Response* response,
             bool use_arena = false)
      : Call(controller),
        done_(done),
        request_(request),
        response_(response),
        use_arena_(use_arena) {
    stream_ = request_->stream();
    if (stream_) {
      pa_ = controller_->CreateProgressiveAttachment();

      // Send the first SSE response
      controller_->http_response().set_content_type(
          "text/event-stream; charset=utf-8");
      controller_->http_response().set_status_code(200);
      controller_->http_response().SetHeader("Connection", "keep-alive");
      controller_->http_response().SetHeader("Cache-Control", "no-cache");
      // Done Run first for steam response
      done_->Run();

    } else {
      controller_->http_response().set_content_type("application/json");
    }

    json_options_.bytes_to_base64 = false;
    json_options_.jsonify_empty_array = true;
  }

  ~StreamCall() override {
    // For non stream response, call brpc done Run
    if (!stream_) {
      done_->Run();
    }
    if (!use_arena_) {
      delete request_;
      delete response_;
    }
  }

  bool write_and_finish(Response& response) {
    butil::IOBufAsZeroCopyOutputStream json_output(
        &controller_->response_attachment());
    std::string err_msg;
    if (!json2pb::ProtoMessageToJson(
            response, &json_output, json_options_, &err_msg)) {
      return finish_with_error(StatusCode::UNKNOWN, err_msg);
    }
    return true;
  }

  bool finish_with_error(const StatusCode& code,
                         const std::string& error_message) {
    if (!stream_) {
      controller_->SetFailed(error_message);

    } else {
      io_buf_.clear();
      io_buf_.append(error_message);
      pa_->Write(io_buf_);
    }

    return true;
  }

  // For stream response
  bool write(Response& response) {
    io_buf_.clear();
    io_buf_.append("data: ");
    butil::IOBufAsZeroCopyOutputStream json_output(&io_buf_);
    std::string err_msg;
    if (!json2pb::ProtoMessageToJson(
            response, &json_output, json_options_, &err_msg)) {
      LOG(ERROR) << "Failed to convert proto to json: " << err_msg;
      return false;
    }
    io_buf_.append("\n\n");

    connection_status_ |= pa_->Write(io_buf_);
    return true;
  }

  // For stream response
  bool finish() {
    io_buf_.clear();
    io_buf_.append("data: [DONE]\n\n");

    pa_->Write(io_buf_);
    return true;
  }

  bool is_disconnected() const override {
    if (stream_) {
      return connection_status_ != 0;
    } else {
      if (controller_) {
        return controller_->IsCanceled();
      }
      return true;
    }
  }

  const Request& request() const { return *request_; }
  Response& response() { return *response_; }
  ::google::protobuf::Closure* done() { return done_; }

 protected:
  ::google::protobuf::Closure* done_;

  Request* request_ = nullptr;
  Response* response_ = nullptr;

  bool stream_ = false;
  bool use_arena_ = false;
  butil::intrusive_ptr<brpc::ProgressiveAttachment> pa_;
  butil::IOBuf io_buf_;

  json2pb::Pb2JsonOptions json_options_;

  int connection_status_ = 0;
};

// Anthropic SSE stream call with custom event formatting
class AnthropicCall : public StreamCall<proto::AnthropicMessagesRequest,
                                        proto::AnthropicMessagesResponse> {
 public:
  AnthropicCall(brpc::Controller* controller,
                ::google::protobuf::Closure* done,
                proto::AnthropicMessagesRequest* request,
                proto::AnthropicMessagesResponse* response,
                bool use_arena = false)
      : StreamCall<proto::AnthropicMessagesRequest,
                   proto::AnthropicMessagesResponse>(controller,
                                                     done,
                                                     request,
                                                     response,
                                                     use_arena) {}

  ~AnthropicCall() {}

  // Write SSE event with Anthropic format: event: <type>\ndata: <json>\n\n
  bool write(const std::string& event_type, const std::string& json_data) {
    this->io_buf_.clear();
    this->io_buf_.append("event: ");
    this->io_buf_.append(event_type);
    this->io_buf_.append("\ndata: ");
    this->io_buf_.append(json_data);
    this->io_buf_.append("\n\n");

    this->connection_status_ |= this->pa_->Write(this->io_buf_);
    return this->connection_status_ == 0;
  }

  // Write SSE event with proto message
  template <typename ProtoMessage>
  bool write(const std::string& event_type, const ProtoMessage& message) {
    this->io_buf_.clear();
    this->io_buf_.append("event: ");
    this->io_buf_.append(event_type);
    this->io_buf_.append("\ndata: ");
    butil::IOBufAsZeroCopyOutputStream json_output(&this->io_buf_);
    std::string err_msg;
    if (!json2pb::ProtoMessageToJson(
            message, &json_output, this->json_options_, &err_msg)) {
      LOG(ERROR) << "Failed to convert proto to json: " << err_msg;
      return false;
    }
    this->io_buf_.append("\n\n");
    this->connection_status_ |= this->pa_->Write(this->io_buf_);
    return this->connection_status_ == 0;
  }
};

template <typename T>
struct is_stream_call : std::false_type {};

template <typename... Args>
struct is_stream_call<StreamCall<Args...>> : std::true_type {};

template <typename T>
inline constexpr bool is_stream_call_v = is_stream_call<T>::value;

}  // namespace xllm