蔡军生先生第二人生的源码分析(四十七)发送下载纹理图片请求

来源：互联网发布：二维数组与一维数组编辑：程序博客网时间：2024/05/10 13:01

这里接着上一次获取纹理图片线程，继续分析发送纹理图片请求到服务器。代码如下：

#001 void LLTextureFetch::sendRequestListToSimulators()

#002 {

#003 const S32 IMAGES_PER_REQUEST = 50;

#004 const F32 LAZY_FLUSH_TIMEOUT = 15.f; // 10.0f // temp

#005 const F32 MIN_REQUEST_TIME = 1.0f;

#006 const F32 MIN_DELTA_PRIORITY = 1000.f;

#007

先同步多线程的访问。

#008 LLMutexLock lock(&mQueueMutex);

#009

#010 // Send requests

#011 typedef std::set<LLTextureFetchWorker*,LLTextureFetchWorker::Compare> request_list_t;

#012 typedef std::map< LLHost, request_list_t > work_request_map_t;

#013 work_request_map_t requests;

下面循环地分析已经放到请求队列里的下载请求。

#014 for (queue_t::iterator iter = mNetworkQueue.begin(); iter != mNetworkQueue.end(); )

#015 {

#016 queue_t::iterator curiter = iter++;

下面获取请求的工作对象。

#017 LLTextureFetchWorker* req = getWorker(*curiter);

#018 if (!req)

#019 {

#020 mNetworkQueue.erase(curiter);

#021 continue; // paranoia

#022 }

#023 if (req->mID == mDebugID)

#024 {

#025 mDebugCount++; // for setting breakpoints

#026 }

检查是否已经下载所有数据。

#027 if (req->mTotalPackets > 0 && req->mLastPacket >= req->mTotalPackets-1)

#028 {

#029 // We have all the packets... make sure this is high priority

#030 // req->setPriority(LLWorkerThread::PRIORITY_HIGH | req->mWorkPriority);

#031 continue;

#032 }

#033 F32 elapsed = req->mRequestedTimer.getElapsedTimeF32();

#034 F32 delta_priority = llabs(req->mRequestedPriority - req->mImagePriority);

按优先级和请求到达的时间来分类放到请求下载队列。

#035 if ((req->mSimRequestedDiscard != req->mDesiredDiscard) ||

#036 (delta_priority > MIN_DELTA_PRIORITY && elapsed >= MIN_REQUEST_TIME) ||

#037 (elapsed >= LAZY_FLUSH_TIMEOUT))

#038 {

#039 requests[req->mHost].insert(req);

#040 }

#041 }

#042

#043 std::string http_url;

#044 #if 0

#045 if (gSavedSettings.getBOOL("ImagePipelineUseHTTP"))

#046 {

#047 LLViewerRegion* region = gAgent.getRegion();

#048 if (region)

#049 {

#050 http_url = region->getCapability("RequestTextureDownload");

#051 }

#052 }

#053 #endif

#054

下面开始循环地发送纹理图片请求到服务器。

#055 for (work_request_map_t::iterator iter1 = requests.begin();

#056 iter1 != requests.end(); ++iter1)

#057 {

#058 bool use_http = http_url.empty() ? false : true;

#059 LLHost host = iter1->first;

#060 // invalid host = use agent host

#061 if (host == LLHost::invalid)

#062 {

#063 host = gAgent.getRegionHost();

#064 }

#065 else

#066 {

#067 use_http = false;

#068 }

#069

#070 if (use_http)

#071 {

#072 }

#073 else

#074 {

通过消息系统向服务器发送请求。

#075 S32 request_count = 0;

#076 for (request_list_t::iterator iter2 = iter1->second.begin();

#077 iter2 != iter1->second.end(); ++iter2)

#078 {

取得请求对象。

#079 LLTextureFetchWorker* req = *iter2;

#080 req->mSentRequest = LLTextureFetchWorker::SENT_SIM;

创建一个新的消息来发送请求。

#081 if (0 == request_count)

#082 {

#083 gMessageSystem->newMessageFast(_PREHASH_RequestImage);

#084 gMessageSystem->nextBlockFast(_PREHASH_AgentData);

#085 gMessageSystem->addUUIDFast(_PREHASH_AgentID, gAgent.getID());

#086 gMessageSystem->addUUIDFast(_PREHASH_SessionID, gAgent.getSessionID());

#087 }

#088 S32 packet = req->mLastPacket + 1;

下面开始创始消息新块数据。

#089 gMessageSystem->nextBlockFast(_PREHASH_RequestImage);

添加图片ID到消息里。

#090 gMessageSystem->addUUIDFast(_PREHASH_Image, req->mID);

#091 gMessageSystem->addS8Fast(_PREHASH_DiscardLevel, (S8)req->mSimRequestedDiscard);

#092 gMessageSystem->addF32Fast(_PREHASH_DownloadPriority, req->mImagePriority);

#093 gMessageSystem->addU32Fast(_PREHASH_Packet, packet);

#094 gMessageSystem->addU8Fast(_PREHASH_Type, req->mType);

#095 // llinfos << "IMAGE REQUEST: " << req->mID << " Discard: " << req->mDesiredDiscard

#096 // << " Packet: " << packet << " Priority: " << req->mImagePriority << llendl;

#097

#098 req->lockWorkData();

#099 req->mSimRequestedDiscard = req->mDesiredDiscard;

#100 req->mRequestedPriority = req->mImagePriority;

#101 req->mRequestedTimer.reset();

#102 req->unlockWorkData();

#103 request_count++;

#104 if (request_count >= IMAGES_PER_REQUEST)

#105 {

#106 // llinfos << "REQUESTING " << request_count << " IMAGES FROM HOST: " << host.getIPString() << llendl;

#107 gMessageSystem->sendSemiReliable(host, NULL, NULL);

#108 request_count = 0;

#109 }

#110 }

#111 if (request_count > 0 && request_count < IMAGES_PER_REQUEST)

#112 {

#113 // llinfos << "REQUESTING " << request_count << " IMAGES FROM HOST: " << host.getIPString() << llendl;

通过消息系统发送纹理请求下载到服务器。

#114 gMessageSystem->sendSemiReliable(host, NULL, NULL);

#115 request_count = 0;

#116 }

#117 }

#118 }

#119

发送一些取消下载的纹理图片。

#120 // Send cancelations

#121 if (!mCancelQueue.empty())

#122 {

#123 for (cancel_queue_t::iterator iter1 = mCancelQueue.begin();

#124 iter1 != mCancelQueue.end(); ++iter1)

#125 {

#126 LLHost host = iter1->first;

#127 if (host == LLHost::invalid)

#128 {

#129 host = gAgent.getRegionHost();

#130 }

#131 S32 request_count = 0;

#132 for (queue_t::iterator iter2 = iter1->second.begin();

#133 iter2 != iter1->second.end(); ++iter2)

#134 {

#135 if (0 == request_count)

#136 {

#137 gMessageSystem->newMessageFast(_PREHASH_RequestImage);

#138 gMessageSystem->nextBlockFast(_PREHASH_AgentData);

#139 gMessageSystem->addUUIDFast(_PREHASH_AgentID, gAgent.getID());

#140 gMessageSystem->addUUIDFast(_PREHASH_SessionID, gAgent.getSessionID());

#141 }

#142 gMessageSystem->nextBlockFast(_PREHASH_RequestImage);

#143 gMessageSystem->addUUIDFast(_PREHASH_Image, *iter2);

#144 gMessageSystem->addS8Fast(_PREHASH_DiscardLevel, -1);

#145 gMessageSystem->addF32Fast(_PREHASH_DownloadPriority, 0);

#146 gMessageSystem->addU32Fast(_PREHASH_Packet, 0);

#147 gMessageSystem->addU8Fast(_PREHASH_Type, 0);

#148 // llinfos << "CANCELING IMAGE REQUEST: " << (*iter2) << llendl;

#149

#150 request_count++;

#151 if (request_count >= IMAGES_PER_REQUEST)

#152 {

#153 gMessageSystem->sendSemiReliable(host, NULL, NULL);

#154 request_count = 0;

#155 }

#156 }

#157 if (request_count > 0 && request_count < IMAGES_PER_REQUEST)

#158 {

#159 gMessageSystem->sendSemiReliable(host, NULL, NULL);

#160 }

#161 }

#162 mCancelQueue.clear();

#163 }

#164 }

通过上面的代码，就可以清晰地看到怎么样把纹理的图片请求发送到服务器的，它是先把请求分类，主要按请求的时间和优先级来决定的。接着把这些需要下载的请求组成一个消息包，通过网络消息系统向服务器发送出去。在这里还处理了那些需要取消下载的纹理请求，由于下载比较大的纹理图片是非常耗费时间和带宽的，应该添加取消下载的功能，这是一个比较好的设计。

//蔡军生 2008/4/27 QQ:9073204 深圳