cocos2d-x 多线程编程 Posix通用

在手游开发过程中, 经常会用到需要异步的情况, 也就是多线程, cocos2d-x本身并没有关于线程的相关代码.但幸好ios 及 android系统都实现了Posix系统调用. 这里就利用posix手动开启线程方面,做一个总结,以备忘


先介绍一些基本的线程api


就像每个进程有一个进程ID一样，每个线程也有一个线程ID，进程ID在整个系统中是唯一的，但线程不同，线程ID只在它所属的进程环境中有效。线程ID用pthread_t数据类型来表示，实现的时候可以用一个结构来代表pthread_t数据类型，所以可以移植的操作系统不能把它作为整数处理。因此必须使用函数来对来对两个线程ID进行比较。
1．名称：pthread_equal
功能：比较两个线程ID
头文件：#include <pthread.h>
函数原形：int pthread_equal(pthread_t tid1,pthread_t tid2);
参数：tid1 进程1id, tid2 进程2id
返回值：若相等返回非0值，否则返回0
2．名称：pthread_self
功能：获取自身线程的id
头文件：#include <pthread.h>
函数原形：pthread_t pthread_self(void);
参数：无
返回值：调用线程的线程id
六．线程的创建  
3．名称：pthread_create
功能：创建线程
头文件：#include <pthread.h>
函数原形：int pthread_create(pthread_t *restrict tidp,const pthread _attr_t *restrict attr,void *(*start_rtn)(void),void *restrict arg);
参数：
返回值：若成功返回则返回0，否则返回错误编号

举例:一个下载器的实例

DownLoader.h

////  DownLoader.h//  MythLeague////  Created by raochongtao on 13-6-25./////* * 1.开线程 * 2.下载分配给自己的资源 * 3.监听自己是否下载完 * 4.和管理器交互 */#ifndef __MythLeague__DownLoader__#define __MythLeague__DownLoader__#include "Global/Constants.h"typedef enum{    DownloadStatus_Init,    DownloadStatus_Loading,    DownloadStatus_Success,    DownloadStatus_FailedWhen_Init,    DownloadStatus_FailedWhen_GetHandle,    DownloadStatus_FailedWhen_GetInfo,}Enum_DownloadStatus;class DownLoader : public cocos2d::CCObject{    public:    DownLoader();    virtual ~DownLoader();        CREATE_FUNC(DownLoader);    bool init();        //下载资源    void downloadRes(Struct_DownLoadTask p_downloadTask);        //开线程    static void* startNewThread(void* args);    bool startDownload();        //处理下载数据    static size_t process_data(void *buffer, size_t size, size_t nmemb, std::string& user_p);        //监测下载完毕    void checkDownloadStatus(float p_delay);    public:        Struct_DownLoadTask m_downloadTask;    Enum_DownloadStatus m_iDownloadStatus;};#endif /* defined(__MythLeague__DownLoader__) */

DownLoader.cpp

////  DownLoader.cpp//  MythLeague////  Created by raochongtao on 13-6-25.////#include "DownLoader.h"#include "DownloadMgr.h"#include "Global/Tools.h"#define FILE_EXIST (200)#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)#include "CURL/curl.h"#elif (CC_TARGET_PLATFORM == CC_PLATFORM_WIN32)#include "platform/third_party/win32/curl/curl.h"#elif (CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)#include "platform/third_party/android/modules/libcurl/include/curl/curl.h"#endifusing namespace std;using namespace cocos2d;#define DownLoader_Check_Interval (0.5f)DownLoader::DownLoader(){    m_iDownloadStatus = DownloadStatus_Init;}DownLoader::~DownLoader(){    }bool DownLoader::init(){    return true;}//下载资源void DownLoader::downloadRes(Struct_DownLoadTask p_downloadTask){    m_downloadTask = p_downloadTask;            pthread_t l_pid;    pthread_attr_t l_attr;    pthread_attr_init(&l_attr);    int l_iPriority = sched_get_priority_max(SCHED_OTHER);    pthread_attr_setschedpolicy(&l_attr, l_iPriority);        pthread_create(&l_pid, &l_attr, DownLoader::startNewThread, this);        CCDirector::sharedDirector()->getScheduler()->scheduleSelector(schedule_selector(DownLoader::checkDownloadStatus), this, DownLoader_Check_Interval, false);}//开线程(静态方法)void* DownLoader::startNewThread(void* p_args){    //线程独立    pthread_detach(pthread_self());        //自己新线程里下载    DownLoader* l_thisDownloader = (DownLoader*)p_args;    l_thisDownloader->startDownload();    return NULL;}bool DownLoader::startDownload(){    m_iDownloadStatus = DownloadStatus_Loading;#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS || CC_TARGET_PLATFORM == CC_PLATFORM_ANDROID)        // 初始化libcurlCURLcode return_code;return_code = curl_global_init(CURL_GLOBAL_ALL);if (CURLE_OK != return_code){CCLog("init libcurl failed.");curl_global_cleanup();                m_iDownloadStatus = DownloadStatus_FailedWhen_Init;return false;}    // 获取easy handleCURL *easy_handle = curl_easy_init();if (NULL == easy_handle){CCLog("get a easy handle failed.");curl_easy_cleanup(easy_handle);curl_global_cleanup();                m_iDownloadStatus = DownloadStatus_FailedWhen_GetHandle;return false;}    // 设置easy handle属性return_code = curl_easy_setopt(easy_handle, CURLOPT_URL, m_downloadTask.resUrl.c_str());    //设置回调函数//return_code = curl_easy_setopt(easy_handle, CURLOPT_WRITEFUNCTION, &process_data);    curl_easy_setopt(easy_handle, CURLOPT_WRITEFUNCTION, process_data);    //回调函数的额外参数std::string connectx;return_code = curl_easy_setopt(easy_handle, CURLOPT_WRITEDATA, &connectx);// 执行数据请求return_code = curl_easy_perform(easy_handle);    //判断获取响应的http地址是否存在,若存在则返回200,400以上则为不存在,一般不存在为404错误int retcode = 0;return_code = curl_easy_getinfo(easy_handle, CURLINFO_RESPONSE_CODE , &retcode);if (CURLE_OK == return_code && FILE_EXIST == retcode){double length = 0;return_code = curl_easy_getinfo(easy_handle, CURLINFO_CONTENT_LENGTH_DOWNLOAD , &length);                string l_fullPath = Tools::getWritableFilePath(m_downloadTask.fileName.c_str());        FILE *fp = fopen(l_fullPath.c_str(), "wb+");        if(fp != NULL){            fwrite(connectx.c_str(), 1, length, fp);//返回实际写入文本的长度,若不等于length则写文件发生错误.            fclose(fp);        }else{            CCLog("error here file: %s line: %d", __FILE__, __LINE__);        }}else{CCLog("......url文件不存在!");curl_easy_cleanup(easy_handle);curl_global_cleanup();                m_iDownloadStatus = DownloadStatus_FailedWhen_GetInfo;return false;}    // 释放资源curl_easy_cleanup(easy_handle);curl_global_cleanup();#endif    m_iDownloadStatus = DownloadStatus_Success;return 0;}//处理下载数据size_t DownLoader::process_data(void *buffer, size_t size, size_t nmemb, std::string& user_p){    user_p.append((char*)buffer, size*nmemb);    return size*nmemb;}//监测下载完毕void DownLoader::checkDownloadStatus(float p_delay){    if (m_iDownloadStatus >= DownloadStatus_Success) {        CCDirector::sharedDirector()->getScheduler()->unscheduleSelector(schedule_selector(DownLoader::checkDownloadStatus), this);        //成功回调        if (m_iDownloadStatus == DownloadStatus_Success) {            DownloadMgr::sharedMgr()->callWhenDownloaderFinish_success(this);        }        //失败回调        else{            DownloadMgr::sharedMgr()->callWhenDownloaderFinish_failed(this);        }    }}

这样实现了，一个下载器的基本功能，但在处理异常方面还有待完善。

其它需要做的还有，需要写一个下载管理器，管理器的基本功能要包括:

/*

 * 1.管理下载器,一个或多个

 * 2.显示DownLoading及进度

 *   并屏蔽事件

 * 3.与外部交互的接口

 */

另外，还需要一个用于显示下载内容及下载进度的显示层。

这两个层，会陆续传上来。