547 lines
11 KiB
C++
547 lines
11 KiB
C++
/*++
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CacheMt.h
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This header file defines a template for
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--*/
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#ifndef _CACHEMT_H_
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#define _CACHEMT_H_
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// This callback function is used to issue a stop hint during a
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// long spin while shutting down so that the shutdown won't time
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// out.
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typedef void (*PSTOPHINT_FN)();
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#include "smartptr.h"
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#include <fhashex.h>
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#include <mtlib.h>
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#include "cachemti.h"
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//
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// This is a little helper function for _ASSERT's - returns
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// TRUE if lpv is an address on the calling thread's stack !
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//
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BOOL
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FOnMyStack( LPVOID lpv ) ;
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//
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// CacheCallback class - clients can pass an object derived from
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// this into the Cache for functions which require some kind of user
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// callback processing !
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//
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template< class Data >
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class CacheCallback {
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public :
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virtual BOOL fRemoveCacheItem( Data& d ) {
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return FALSE ;
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}
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} ;
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template< class Data,
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class Key,
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class Constructor
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>
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class CacheImp : public CacheSelector
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{
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//
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// This class exists to implement a generic Caching system.
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// We assume that only a single thread ever enters any of our
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// API's at a time. This class is not to be directly exposed
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// to customers, instead CacheInterface<> exists to provide
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// an API for customers.
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//
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public :
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//
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// Defines an element of the cache !
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//
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typedef TEntry< Data, Key > TENTRY ;
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private :
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//
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// A signature DWORD for identifying these things in memory !
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//
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DWORD m_dwSignature ;
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//
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// Define the hashtable we use to hold Cache Elements !
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//
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typedef TFHashEx< TENTRY, Key > CACHELOOKUP ;
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//
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// The hash table we use to keep track of entries in the cache !
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//
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CACHELOOKUP m_Lookup ;
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//
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// This is the doubly linked list of elements in our cache !
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//
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CacheList m_ExpireList ;
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//
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// The number of subtract from the current time to
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// determine our expire date !
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//
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ULARGE_INTEGER m_qwExpire ;
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public :
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//
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// The following structures and functions define the
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// portion of our interface designed to work with ASYNC
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// mechanisms provide by TMtService<>
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//
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//
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// Defines the structure that holds all of the
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// arguments for FindOrCreate
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// We wrap this stuff all into one struct to make it
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// easy to use the TMtServce<> family of templates !
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//
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struct FORC_ARG {
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DWORD m_dwHash ;
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Key& m_key ;
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Constructor& m_constructor ;
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FORC_ARG( DWORD dw,
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Key& key,
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Constructor& constructor
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) :
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m_dwHash( dw ),
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m_key( key ),
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m_constructor( constructor ) {
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}
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} ;
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//
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// Define the object that selects items for removal from the
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// Cache -
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//
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typedef CacheCallback< Data > CCB_OBJ ;
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//
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// Arguments for Expunge !
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//
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struct EXP_ARG {
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Key* m_pkey ;
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TENTRY* m_pData ;
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EXP_ARG( Key* pkey, TENTRY* pData ) :
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m_pkey( pkey ),
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m_pData( pData ) {
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}
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} ;
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//
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// Define the structure that holds all arguments for
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// Expunge interface.
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//
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struct EXP_SPECIFIC_ARG {
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//
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// The object which selects what is to be removed from the cache
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//
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CCB_OBJ* m_pCacheCallback ;
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//
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// A pointer to an entry which should NOT be removed !
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//
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TENTRY* m_pProtected ;
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//
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// If TRUE kick things out even if they aren't ready to expire !
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//
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BOOL m_fForced ;
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EXP_SPECIFIC_ARG( CCB_OBJ* pCallback,
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TENTRY* pProtected,
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BOOL fForced
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) :
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m_pCacheCallback( pCallback ),
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m_pProtected( pProtected ),
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m_fForced( fForced ) {
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}
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} ;
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protected :
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//
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// When Executing ExpungeSpecific() - this holds onto the user
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// provided Callback for selecting deleted items !
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//
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CCB_OBJ* m_pCurrent ;
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//
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// This member function removes entries from the cache -
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// we remove them from the hash table which leads to destruction !
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//
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void
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RemoveEntry(
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CacheState* pCacheState
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) ;
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//
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// This function checks to see whether we wish to remove an element !
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//
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BOOL
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QueryRemoveEntry(
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CacheState* pState
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) ;
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//
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// FindOrCreate results
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//
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typedef CRefPtr< Data > FORC_RES ;
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public :
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CacheImp() ;
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//
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// If this function returns TRUE then callers can be
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// notified at arbitrary times of the results.
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// The BOOL return value is required by the TMtService templates.
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//
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//
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BOOL
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FindOrCreate(
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FORC_ARG& args,
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FORC_RES& result
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) ;
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//
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// This function removes specified items from the cache !
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//
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BOOL
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Expunge(
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EXP_ARG& args,
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DWORD& countExpunged
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) ;
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BOOL
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ExpungeSpecific(
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EXP_SPECIFIC_ARG& args,
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DWORD& countExpunged
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) ;
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BOOL
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Expire(
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DWORD& countExpunged
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) ;
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//
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// The following set of functions are for synchronous use
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// such as Initialization and Termination of the Cache.
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//
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//
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// Initialization function - take pointer to function
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// which should be used to compute hash values on Key's
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// Also takes the number of seconds objects should live in
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// the cache !
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//
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BOOL
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Init(
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DWORD (*pfnHash)( const Key& ),
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DWORD dwLifetimeSeconds,
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DWORD cMaxInstances,
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PSTOPHINT_FN pfnStopHint = NULL
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) ;
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//
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// Compute the hash of a key - provided for debug purposes and _ASSERT's
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// not for regular use !
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//
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DWORD
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ComputeHash( Key& k ) ;
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} ;
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template< class Data,
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class Key,
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class Constructor >
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class TAsyncCache {
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public :
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//
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// The template class that implements the Cache.
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//
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typedef CacheImp< Data, Key, Constructor > IMP ;
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private:
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//
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// Singature for identifying these Async Cache things
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//
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DWORD m_dwSignature ;
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//
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// This is the object which actually implements the Cache functionality
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// NOTE: appears before CACHE_SERVICE so its constructor is called first !
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//
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IMP m_Implementation ;
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public :
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//
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// A typedef for the objects we will take in our
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// interface which get completion notifications.
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//
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typedef TCompletion< IMP::FORC_RES > COMP_OBJ ;
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//
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// A typedef for the objects which handle Expunge Completions !
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// The completion function gets the number of objects expunged
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// from the cache !
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//
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typedef TCompletion< DWORD > EXP_COMP_OBJ ;
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//
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// Some typedefs so that users can extract our template parameters
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// back out !
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//
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typedef Data CACHEDATA ;
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typedef Key CACHEKEY ;
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private :
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//
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// The kind of object we use to encapsulate a call
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// to the cache.
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//
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typedef TMFnDelay<
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IMP,
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IMP::FORC_RES,
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IMP::FORC_ARG
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> CACHE_CREATE_CALL ;
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//
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// The kind of object we use to encapsulate an Expunge Call
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//
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typedef TMFnDelay<
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IMP,
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DWORD,
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IMP::EXP_ARG
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> EXPUNGE_CALL ;
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typedef TMFnDelay<
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IMP,
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DWORD,
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IMP::EXP_SPECIFIC_ARG
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> EXPUNGE_SPECIFIC ;
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typedef TMFnNoArgDelay<
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IMP,
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DWORD
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> EXPIRE_CALL ;
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//
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// Define the type of our CACHE_SERVICE
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//
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typedef TMtService< IMP > CACHE_SERVICE ;
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//
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// This is the object which manages the Queue of Async Cache requests !
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//
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CACHE_SERVICE m_Service ;
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//
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// Set to TRUE if we have been successfully initialized.
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//
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BOOL m_fGood ;
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public :
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//
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// Default constructor
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//
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TAsyncCache() ;
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//
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// Find an Item in the Cache or Create an Item to be held in the Cache !
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//
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BOOL
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FindOrCreate( CStateStackInterface& allocator,
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DWORD dwHash,
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Key& key,
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Constructor& constructor,
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COMP_OBJ* pComplete ) ;
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//
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// Remove an Item from the cache !
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//
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//
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// Function which can be used to remove items from the Cache
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//
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BOOL
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Expunge(
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CStateStackInterface& allocator,
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EXP_COMP_OBJ* pComplete,
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Key* key = 0,
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IMP::TENTRY* pData = 0
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) ;
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//
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// Function which can be passed a function pointer to determine
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// exactly what items are to be removed from the Cache.
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// if fForced == TRUE then items are removed from the Cache
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// no matter what.
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//
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BOOL
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ExpungeSpecific(
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CStateStackInterface& allocator,
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EXP_COMP_OBJ* pComplete,
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class CacheCallback< Data >* pSelector,
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BOOL fForced,
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TEntry<Data,Key>* pProtected = 0
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) ;
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//
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// Expire old stuff in the cache - everything older than
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// dwLifetimeSeconds (specified at Init() time
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// which is NOT in use should be kicked out.
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//
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BOOL
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Expire(
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CStateStackInterface& allocator,
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EXP_COMP_OBJ* pComplete
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) ;
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//
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// Initialization function - take pointer to function
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// which should be used to compute hash values on Key's
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// Also takes the number of seconds objects should live in
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// the cache !
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//
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BOOL
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Init(
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DWORD (*pfnHash)( const Key& ),
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DWORD dwLifetimeSeconds,
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DWORD cMaxInstances,
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PSTOPHINT_FN pfnStopHint = NULL
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) ;
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} ;
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template< class Data,
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class Key,
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class Constructor
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>
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class TMultiAsyncCache {
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private :
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typedef TAsyncCache< Data, Key, Constructor > ASYNCCACHEINSTANCE ;
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//
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// Signature for these objects in memory !
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//
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DWORD m_dwSignature ;
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//
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// Array of Caches to use for client requests
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//
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ASYNCCACHEINSTANCE* m_pCaches ;
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//
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// Number of ASYNCCACHEINSTANCE objects pointed to be m_pCaches !
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//
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DWORD m_cSubCaches ;
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//
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// The Hash Function to be used !
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//
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DWORD (*m_pfnHash)( const Key& ) ;
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//
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// Function which computes which of our child caches to use !
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//
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DWORD
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ChooseInstance( DWORD dwHash ) ;
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public :
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typedef ASYNCCACHEINSTANCE::COMP_OBJ COMP_OBJ ;
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typedef ASYNCCACHEINSTANCE::EXP_COMP_OBJ EXP_COMP_OBJ ;
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TMultiAsyncCache() ;
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~TMultiAsyncCache() ;
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//
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// Initialization function - take pointer to function
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// which should be used to compute hash values on Key's
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// Also takes the number of seconds objects should live in
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// the cache !
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//
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BOOL
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Init(
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DWORD cCaches,
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DWORD (*pfnHash)( const Key& ),
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DWORD dwLifetimeSeconds,
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DWORD cMaxInstances,
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PSTOPHINT_FN pfnStopHint = NULL
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) ;
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//
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// Find an Item in the Cache or Create an Item to be held in the Cache !
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//
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BOOL
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FindOrCreate( CStateStackInterface& allocator,
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DWORD dwHash,
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Key& key,
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Constructor& constructor,
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COMP_OBJ* pComplete ) ;
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//
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//
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//
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BOOL
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FindOrCreate( CStateStackInterface& allocator,
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Key& key,
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Constructor& constructor,
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COMP_OBJ* pComplete
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) ;
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//
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// Remove an Item from the cache !
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//
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//
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// Function which can be used to remove items from the Cache
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//
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BOOL
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Expunge(
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CStateStackInterface& allocator,
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EXP_COMP_OBJ* pComplete,
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Key* key = 0
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) ;
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//
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// Function which can be passed a function pointer to determine
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// exactly what items are to be removed from the Cache.
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// if fForced == TRUE then items are removed from the Cache
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// no matter what.
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//
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BOOL
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ExpungeSpecific(
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CStateStackInterface& allocator,
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EXP_COMP_OBJ* pComplete,
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class CacheCallback< Data >* pSelector,
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BOOL fForced
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) ;
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//
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// Expire old stuff in the cache - everything older than
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// dwLifetimeSeconds (specified at Init() time
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// which is NOT in use should be kicked out.
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//
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BOOL
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Expire(
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CStateStackInterface& allocator,
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EXP_COMP_OBJ* pComplete
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) ;
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} ;
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#include "cachemtx.h"
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#endif // _CACHEMT_H_
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