libcurl.hpp

/*
 * SPDX-FileCopyrightText: Copyright (c) 2024-2025, NVIDIA CORPORATION.
 * SPDX-License-Identifier: Apache-2.0
 */
#pragma once
 
#ifndef KVIKIO_LIBCURL_FOUND
#error \
  "cannot include the remote IO API, please build KvikIO with libcurl (-DKvikIO_REMOTE_SUPPORT=ON)"
#endif
 
#include <functional>
#include <memory>
#include <mutex>
#include <sstream>
#include <string>
#include <vector>
 
#include <curl/curl.h>
 
#include <kvikio/error.hpp>
 
namespace kvikio {
 
class LibCurl {
 public:
  // We hold a unique pointer to the raw curl handle and set `curl_easy_cleanup` as its Deleter.
  using UniqueHandlePtr = std::unique_ptr<CURL, std::function<decltype(curl_easy_cleanup)>>;
 
 private:
  std::mutex _mutex{};
  // Curl handles free to be used.
  std::vector<UniqueHandlePtr> _free_curl_handles{};
 
  LibCurl();
  ~LibCurl() noexcept;
 
 public:
  static LibCurl& instance();
 
  UniqueHandlePtr get_free_handle();
 
  UniqueHandlePtr get_handle();
 
  void retain_handle(UniqueHandlePtr handle);
};
 
class CurlHandle {
 private:
  char _errbuf[CURL_ERROR_SIZE];
  LibCurl::UniqueHandlePtr _handle;
 
 public:
  CurlHandle(LibCurl::UniqueHandlePtr handle, std::string source_file, std::string source_line);
  ~CurlHandle() noexcept;
 
  CurlHandle(CurlHandle const&)            = delete;
  CurlHandle& operator=(CurlHandle const&) = delete;
  CurlHandle(CurlHandle&& o)               = delete;
  CurlHandle& operator=(CurlHandle&& o)    = delete;
 
  CURL* handle() noexcept;
 
  template <typename VAL>
  void setopt(CURLoption option, VAL value)
  {
    CURLcode err = curl_easy_setopt(handle(), option, value);
    if (err != CURLE_OK) {
      std::stringstream ss;
      ss << "curl_easy_setopt() error "
         << "(" << curl_easy_strerror(err) << ")";
      KVIKIO_FAIL(ss.str(), std::runtime_error);
    }
  }
 
  void perform();
 
  template <typename OUTPUT>
  void getinfo(CURLINFO info, OUTPUT* output)
  {
    CURLcode err = curl_easy_getinfo(handle(), info, output);
    if (err != CURLE_OK) {
      std::stringstream ss;
      ss << "curl_easy_getinfo() error "
         << "(" << curl_easy_strerror(err) << ")";
      KVIKIO_FAIL(ss.str(), std::runtime_error);
    }
  }
};
 
namespace detail {
__attribute__((noinline)) inline std::string fix_conda_file_path_hack(std::string filename)
{
  if (filename.data() != nullptr) { return std::string{filename.data()}; }
  return std::string{};
}
}  // namespace detail
 
#define create_curl_handle()                                             \
  kvikio::CurlHandle(kvikio::LibCurl::instance().get_handle(),           \
                     kvikio::detail::fix_conda_file_path_hack(__FILE__), \
                     KVIKIO_STRINGIFY(__LINE__))
 
}  // namespace kvikio