CurlHandlePool.h

// -*- mode: c++; c-basic-offset:4 -*-
 
// This file is part of the BES
 
// Copyright (c) 2018 OPeNDAP, Inc.
// Author: James Gallagher<jgallagher@opendap.org>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// You can contact OPeNDAP, Inc. at PO Box 112, Saunderstown, RI. 02874-0112.
 
#ifndef _HandlePool_h
#define _HandlePool_h 1
 
#include <memory>
#include <string>
#include <vector>
#include <mutex>
 
#include <curl/curl.h>
 
#include "url_impl.h"
 
namespace dmrpp {
 
class Chunk;

class dmrpp_easy_handle {
    bool d_in_use = false;      
    std::shared_ptr<http::url> d_url;  
    Chunk *d_chunk = nullptr;     
    std::vector<char> d_errbuf = std::vector<char>(CURL_ERROR_SIZE, '\0'); 
 
    CURL *d_handle = nullptr;     
    curl_slist *d_request_headers = nullptr; 
 
    friend class CurlHandlePool;
 
public:
    dmrpp_easy_handle();
 
    ~dmrpp_easy_handle();
 
    void read_data();
};

class CurlHandlePool {
private:
    std::string d_cookies_filename;
    std::string d_hyrax_user_agent;
    unsigned long d_max_redirects = 3;
    std::string d_netrc_file;
 
    CURLSH *d_share = nullptr;
 
    static std::recursive_mutex d_share_mutex;
    
    static std::recursive_mutex d_cookie_mutex;
    static std::recursive_mutex d_dns_mutex;
    static std::recursive_mutex d_ssl_session_mutex;
    static std::recursive_mutex d_connect_mutex;
 
    static std::recursive_mutex d_mutex;    // Use this for the default case.
 
    static void lock_cb(CURL */*handle*/, curl_lock_data data, curl_lock_access /*access*/, void */*userptr*/) {
        switch (data) {
            case CURL_LOCK_DATA_SHARE: // CURL_LOCK_DATA_SHARE is used internally
                d_share_mutex.lock();
                break;
 
            case CURL_LOCK_DATA_COOKIE:
                d_cookie_mutex.lock();
                break;
 
            case CURL_LOCK_DATA_DNS:
                d_dns_mutex.lock();
                break;
            case CURL_LOCK_DATA_SSL_SESSION:
                d_ssl_session_mutex.lock();
                break;
            case CURL_LOCK_DATA_CONNECT:
                d_connect_mutex.lock();
                break;
            default:
                d_mutex.lock();
                break;
        }
    }
 
    static void unlock_cb(CURL */*handle*/, curl_lock_data data, void * /*userptr*/) {
        switch (data) {
            case CURL_LOCK_DATA_SHARE: // CURL_LOCK_DATA_SHARE is used internally
                d_share_mutex.unlock();
                break;
 
            case CURL_LOCK_DATA_COOKIE:
                d_cookie_mutex.unlock();
                break;
 
            case CURL_LOCK_DATA_DNS:
                d_dns_mutex.unlock();
                break;
            case CURL_LOCK_DATA_SSL_SESSION:
                d_ssl_session_mutex.unlock();
                break;
            case CURL_LOCK_DATA_CONNECT:
                d_connect_mutex.unlock();
                break;
            default:
                d_mutex.unlock();
                break;
        }
    }
 
public:
    CurlHandlePool() = default;
    ~CurlHandlePool();
 
    void initialize();
    dmrpp_easy_handle *get_easy_handle(Chunk *chunk);
 
    static void release_handle(dmrpp_easy_handle *h);
};
 
} // namespace dmrpp
 
#endif // _HandlePool_h