Initial import of the CDE 2.1.30 sources from the Open Group.

cde/programs/dtinfo/DtMmdb/storage/page_cache.h

@@ -0,0 +1,77 @@
+/* $XConsortium: page_cache.h /main/3 1996/06/11 17:44:27 cde-hal $ */
+
+#ifndef _page_cache_h
+#define _page_cache_h 1
+
+class page;
+class page_storage;
+
+#define MMDB_CACHED_PAGES 100
+#define MIN_MMDB_CACHED_PAGES 10
+
+#include "dstr/bset.h"
+
+class page_cache_local_part
+{
+
+protected:
+   int f_num_cached_pages ;  // number of cached pages
+
+   heap f_free_space;        // a heap recording free
+                             // space on each page
+
+   bset f_page_pool_index;    // index to pages in the pool
+
+   int f_current_page_num;
+   page* f_current_page_ptr;
+
+public:
+   page_cache_local_part(unsigned int exp_cached_page);
+   virtual ~page_cache_local_part();
+
+// init the heap
+   Boolean init_heap(page_storage*);
+   Boolean quit_heap(page_storage*);
+
+// does the cache hold page 'page_num'?
+   page* in_cache(page_storage* st, int page_num);
+
+// get a non-empty page
+   fbytes_t* find_host_page(page_storage*, Boolean& new_page, int len = 0);
+   void adjust_heap(fbytes_t* v, Boolean new_page);
+
+   friend class page_cache_global_part ;
+};
+
+class lru;
+
+class page_cache_global_part 
+{
+
+public:
+//////////////////////////////////////////////////////////////////////
+// The default value (0) triggers the constructor to 
+// search for the value in the shell variable MMDB_CACHED_PAGES.
+// If the varialble is undefind, the value set by const MMDB_CACHED_PAGES
+// will be used.
+//////////////////////////////////////////////////////////////////////
+   page_cache_global_part(unsigned int total_allowed_pages = 0);
+   virtual ~page_cache_global_part() ;
+
+   void remove_pages(page_storage* st);
+
+// return a free page frame from cache
+   page* load_new_page(page_storage*, int page_num, Boolean byteOrder);
+
+   ostream& print_cached_pages(ostream&); // show cached pages.
+
+   friend class page_cache_local_part;
+   friend class page_storage;
+   friend void remove_from_global_cache(const void*);
+
+protected:
+   unsigned int    f_total_allowed_pages;
+   lru             f_replace_policy;
+};
+
+#endif