Cache management system for continuous media system

Abstract

A cache management scheme is disclosed for buffering one or more continuous media files being simultaneously accessed from a continuous media server by a plurality of media clients. The continuous media server stores pages of data that will likely be accessed in a cache or buffer. The continuous media server implements a cache management strategy that exploits the sequential page access patterns for continuous media data, in order to determine the buffer pages to be replaced from the cache. The cache management strategy initially identifies unpinned pages as potential victims for replacement. Each unpinned page is evaluated by the continuous media server and assigned a weight. Generally, the assigned weight ensures that a buffer with a larger weight will be accessed by a client later in time than a buffer with a smaller weight. A page associated with a larger weight will be accessed later and hence, is replaced earlier. A current buffer list is preferably allocated to monitor the buffer pages associated with a given continuous media file. The current buffer list is a data structure pointing to a set of buffer pages in the cache buffer containing the currently buffered pages of the associated continuous media file. Each buffer page in the buffer cache is preferably represented by a buffer header. The current buffer list (CBL) data structure preferably stores, among other things, a pointer to the buffer pages associated with the CBL, identifier information for the CBL and related continuous media file, and information regarding the number of buffered pages associated with the CBL and number of clients currently accessing the associated continuous media file. The buffer header is a data structure containing information describing the state of the corresponding page. The buffer header preferably includes, among other things, a pointer to an actual area of the buffer cache storing a page of data, a number of pointers to create various relationships among the various pages in a CBL, and a fixed count indicating the number many of clients currently accessing the corresponding page of the continuous media file.