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TclObjectPagePoolPagePool/CompMathPagePool/MathPagePool/ClientPagePool/ProxyTraceFigure 39.3: Class hierarchy of page pools• name(char *buf) - Print the page’s name into the given buffer. A page’s name is in the format of: 〈ServerName〉:〈PageID〉.• split_name(const char *name, PageID& id) - Split a given page name into its two components. This isa static method.• mtime() - Returns the last modification time of the page.• age() - Returns the lifetime of the page.39.4 Page poolsPagePool and its derived classes are used by servers to generate page information (name, size, modification time, lifetime,etc.), by caches to describe which pages are in storage, and by clients to generate a request stream. Figure 39.3 provides anoverview of the class hierarchy here.Among these, class PagePool/Client is mostly used by caches to store pages and other cache-related information; other threeclasses are used by servers and clients. In the following we describe these classes one by one.39.4.1 PagePool/MathThis is the simplest type of page pool. It has only one page, whose size can be generated by a given random variable. Pagemodification sequence and request sequence are generated using two given random variables. It has the following OTclmethods:gen-pageidgen-sizegen-modtime 〈pageID〉 〈mt〉ranvar-age 〈rv〉ranvar-size 〈rv〉Returns the page ID which will be requested next. Because it has only one page, it alwaysreturns 0.Returns the size of the page. It can be generated by a given random variable.Returns the next modification time of the page. 〈mt〉 gives the last modification time. Ituses the lifetime random variable.Set the file lifetime random variable as 〈rv〉.Set the file size random variable to be 〈rv〉.NOTE: There are two ways to generate a request sequence. With all page pools except PagePool/ProxyTrace, request sequenceis generated with a random variable which describes the request interval, and the gen-pageid method of other page pools348