第二人生的源码分析(六十一)LLCurl类实现libcurl库封装

通过上面介绍了libcurl库的功能，那么在第二人生里到底是怎么样使用它的呢？又是怎么样封装它，才会更好用呢？下面就来分析一下它的类声明：
#001 // For whatever reason, this is not typedef'd in curl.h
#002 typedef size_t (*curl_header_callback)(void *ptr, size_t size, size_t nmemb, void *stream);
#003
#004 class LLCurl
#005 {

定义LOG类型信息。
#006 LOG_CLASS(LLCurl);
#007
#008 public:

声明两个嵌套类。
#009 class Easy;
#010 class Multi;
#011

声明传送数据信息的结构。
#012 struct TransferInfo
#013 {
#014 TransferInfo() : mSizeDownload(0.0), mTotalTime(0.0), mSpeedDownload(0.0) {}
#015 F64 mSizeDownload;
#016 F64 mTotalTime;
#017 F64 mSpeedDownload;
#018 };
#019

下面是定义数据响应类。
#020 class Responder
#021 {
#022 //LOG_CLASS(Responder);
#023 public:
#024
#025 Responder();
#026 virtual ~Responder();
#027
#028 /**
#029 * @brief return true if the status code indicates success.
#030 */
#031 static bool isGoodStatus(U32 status)
#032 {
#033 return((200 <= status) && (status < 300));
#034 }
#035
#036 virtual void error(U32 status, const std::string& reason);
#037 // called with non-200 status codes
#038
#039 virtual void result(const LLSD& content);
#040
#041 // Override point for clients that may want to use this class when the response is some other format besides LLSD
#042 virtual void completedRaw(U32 status, const std::string& reason,
#043 const LLChannelDescriptors& channels,
#044 const LLIOPipe::buffer_ptr_t& buffer);
#045
#046 virtual void completed(U32 status, const std::string& reason, const LLSD& content);
#047 /**< The default implemetnation calls
#048 either:
#049 * result(), or
#050 * error()
#051 */
#052
#053 // Override to handle parsing of the header only. Note: this is the only place where the contents
#054 // of the header can be parsed. In the ::completed call above only the body is contained in the LLSD.
#055 virtual void completedHeader(U32 status, const std::string& reason, const LLSD& content);
#056
#057 public: /* but not really -- don't touch this */
#058 U32 mReferenceCount;
#059 };
#060 typedef boost::intrusive_ptr<Responder> ResponderPtr;
#061
#062

下面函数设置HTTPS授权认证文件。
#063 /**
#064 * @ brief Set certificate authority file used to verify HTTPS certs.
#065 */
#066 static void setCAFile(const std::string& file);
#067

下面函数设置HTTPS授权认证的路径。
#068 /**
#069 * @ brief Set certificate authority path used to verify HTTPS certs.
#070 */
#071 static void setCAPath(const std::string& path);
#072

下面函数获取HTTPS授权认证文件。
#073 /**
#074 * @ brief Get certificate authority file used to verify HTTPS certs.
#075 */
#076 static const std::string& getCAFile() { return sCAFile; }
#077

下面函数获取HTTPS授权文件路径。
#078 /**
#079 * @ brief Get certificate authority path used to verify HTTPS certs.
#080 */
#081 static const std::string& getCAPath() { return sCAPath; }
#082

下面函数初始化LLCurl类。
#083 /**
#084 * @ brief Initialize LLCurl class
#085 */
#086 static void initClass();
#087

下面函数清除LLCurl类。
#088 /**
#089 * @ brief Cleanup LLCurl class
#090 */
#091 static void cleanupClass();
#092

获取类LLCurl的出错码字符串。
#093 /**
#094 * @ brief curl error code -> string
#095 */
#096 static std::string strerror(CURLcode errorcode);
#097

设置SSL回调函数。
#098 // For OpenSSL callbacks
#099 static std::vector<LLMutex*> sSSLMutex;
#100
#101 // OpenSSL callbacks
#102 static void LLCurl::ssl_locking_callback(int mode, int type, const char *file, int line);
#103 static unsigned long LLCurl::ssl_thread_id(void);
#104
#105
#106
#107 private:
#108
#109 static std::string sCAPath;
#110 static std::string sCAFile;
#111 };

上面就定义LLCurl类，声明了两个重要的嵌套类Easy和Multi，在类Easy里会封装libcurl基本的功能，下一次再仔细地分析它。