📄 csdn_文档中心_多路复用i-o模型支持多client的实现及效率讨论.htm
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style="MARGIN: 0cm 0cm 0pt 18pt; TEXT-INDENT: -18pt; mso-list: l0 level1 lfo1; tab-stops: list 18.0pt"><FONT
size=2><SPAN lang=EN-US>1.<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">引言</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 18pt"><FONT
size=2><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">多路复用</SPAN><SPAN
lang=EN-US>I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模型</SPAN><SPAN
lang=EN-US>(select)</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是</SPAN><SPAN
lang=EN-US>UNIX/LINUX</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">用得的最多的一种</SPAN><SPAN
lang=EN-US>I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模型，在</SPAN><SPAN
lang=EN-US>Windows</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">下也</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=2><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可做为一种同步</SPAN><SPAN
lang=EN-US>I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">使用。本文给出该</SPAN><SPAN
lang=EN-US>I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模型处理多</SPAN><SPAN
lang=EN-US>Client</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的简单（在主线程中）实现。</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt 18pt; TEXT-INDENT: -18pt; mso-list: l0 level1 lfo1; tab-stops: list 18.0pt"><FONT
size=2><SPAN lang=EN-US>2.<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">关于</SPAN><SPAN
lang=EN-US>select</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt 18pt"><FONT
size=2><SPAN lang=EN-US>select I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模型是一种异步</SPAN><SPAN
lang=EN-US>I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模型，在单线程中</SPAN><SPAN
lang=EN-US>Linux/WinNT</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">默认支持</SPAN><SPAN
lang=EN-US>64</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个客户端套</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=2><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">接字。这种</SPAN><SPAN
lang=EN-US>I/O</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">模型主要涉及以下几个函数及宏：</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21pt; mso-char-indent-count: 2.0; mso-char-indent-size: 10.5pt"><FONT
size=2><SPAN lang=EN-US>int select(…)</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、</SPAN><SPAN
lang=EN-US>FD_ZERO</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、</SPAN><SPAN
lang=EN-US>FD_SET</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">、</SPAN><SPAN
lang=EN-US>FD_ISSET</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">以及</SPAN><SPAN
lang=EN-US>FD_SETSIZE</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt 18pt; TEXT-INDENT: -18pt; mso-list: l0 level1 lfo1; tab-stops: list 18.0pt"><FONT
size=2><SPAN lang=EN-US>3.<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">用</SPAN><SPAN
lang=EN-US>select</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">开发一个</SPAN><SPAN
lang=EN-US>Server</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=2><SPAN
lang=EN-US>3.1 </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">只支持单个</SPAN><SPAN
lang=EN-US>Client</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><FONT size=2><SPAN
lang=EN-US><SPAN style="mso-spacerun: yes">
</SPAN>// </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">相关初始化处理</SPAN><SPAN
lang=EN-US>, </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">创建监听套接字</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>listen(listensock, 5);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes"> </SPAN>clientsock
= accept(listensock, NULL,
NULL);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes"> </SPAN>for (;
;)</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>{</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>FD_ZERO(&readfds);<SPAN
style="mso-spacerun: yes"> </SPAN></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>FD_SET(clientsock, &readfds);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>nResult = select(</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><FONT size=2><SPAN
lang=EN-US><SPAN style="mso-spacerun: yes">
</SPAN><SPAN
style="mso-spacerun: yes">
</SPAN>0,<SPAN
style="mso-spacerun: yes">
</SPAN>// Windows</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中这个参数忽略，</SPAN><SPAN
lang=EN-US>Linux</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中在此处为</SPAN><SPAN
lang=EN-US>1</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><FONT size=2><SPAN
lang=EN-US><SPAN
style="mso-spacerun: yes">
</SPAN>readfds,<SPAN style="mso-spacerun: yes">
</SPAN>// </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">可读套接字集合</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>……</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>)</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>if<SPAN style="mso-spacerun: yes">
</SPAN>(nResult = = SOCKET_ERROR)</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>return –1;</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><FONT size=2><SPAN
lang=EN-US><SPAN
style="mso-spacerun: yes">
</SPAN>// </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">判断</SPAN><SPAN
lang=EN-US>cliensock</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是否处于待读状态</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>if<SPAN style="mso-spacerun: yes">
</SPAN>(FD_ISSET(clientsock, &readfds))</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><FONT size=2><SPAN
lang=EN-US><SPAN
style="mso-spacerun: yes">
</SPAN>{<BR><SPAN
style="mso-spacerun: yes">
</SPAN><SPAN
style="mso-spacerun: yes">
</SPAN>//
</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">相关处理</SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
</SPAN>}</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt"><SPAN
lang=EN-US><FONT size=2><SPAN
style="mso-spacerun: yes">
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