Re: [patch][rfa] Inheriting from cache_component and friends

Received some feedback offline. I've now committed this.

Dave

Dave Brolley wrote:

> Following up on my recent posting regarding specializing on the 
> existing cache_component. Here is the patch which allows use of 
> cache_component and cache_line as base classes. The purpose of this is 
> to allow me to implement a target-specific cache with a unique cache 
> line implementation. The main changes are:
>
> 1) Make cache_line into a virtual base class. The original cache_line 
> class is now called internal_cache_line (it keeps its data internally) 
> and its functionality is unchanged.
>
> 2) Introduce a new cache_line_factory class which is used to allocate 
> cache lines. Each cache_component is now passed a reference to a 
> cache_line_factory which it uses to allocate its cache lines.  An 
> instance called internal_line_factory is used to create lines of type 
> internal_cache_line.
>
> 3) The find mechanism of cache and cache_set previously passed cache 
> lines by assignment via reference arguments. This is no longer 
> possible with a virtual class implementation. The mechanism now 
> returns a pointer to the found line (if found) and NULL otherwise.
>
> 4) Similarly, the 'replace' method of cache_replacement_algorithm 
> previously passed in a new line and returned the old one by assignment 
> using reference arguments. Now, a pointer to the expelled line is 
> returned (if any --- all lines might be locked) and NULL otherwise. 
> The expelled line is updated using access methods. The 'replace' 
> method has been renamed to 'expell' since the line is no longer 
> replaced. This also eliminates construction and destruction overhead 
> for each cache miss. Also, the copy constructor and assignment 
> operator for cache_line are no longer necessary.
>
> 5) The 'insert' and 'extract' methods of cache_line are now declared 
> using a macro for the cartesian product of possible datatypes as is 
> common elsewhere. It was not possible to instantiate the necessary 
> termplate methods automatically in the virtual base class.
>
> 6) The changes the sid/component/cfgroot were found necessary while 
> debugging problems in my implementation.
>
> 7) The changes to main/dynamic/commonCfg.h were necessary in order to 
> allow me to inherit from CacheCfg for my specialized cache 
> configurator and to get a handle to the loader configuration from the 
> SessionCfg so that I could connect the loader's "set-endian" pin to my 
> cache line implementation.
>
> I have tested this against my own port (with specialized cache and 
> cache lines) as well as against xstormy16. All of the sid testsuite 
> checks without regression (including the cache-specific tests). I'm 
> seeking comments and approval to commit.
>
> Regards,
> Dave
>
>
>------------------------------------------------------------------------
>
>2004-04-27  Dave Brolley  <[email protected]>
>
>	* cache.cxx: Update calls to cache::find.
>	* cacheutil.cxx (cache_set::allocate_lines): Now takes cache index as
>	an argument. Update all callers.
>	(cache_set::find): Now returns a pointer to the line, if found. Update
>	all callers.
>	(cache::find): Ditto.
>	(cache_set::expell_line): Update the status of the expelled line.
>	* cacheutil.h (cache_line_factory::make_line): Now takes cache index as
>	an argument. Update all callers.
>	(cache_set::allocate_lines): Now takes cache index as
>	an argument. Update all callers.
>	(cache_set::find): Now returns a pointer to the line, if found. Update
>	all callers.
>	(cache::find): Ditto.
>
>2004-04-27  Dave Brolley  <[email protected]>
>
>	* cacheutil.h (cache_line): Removed copy constructor. Now virtual base
>	class.
>	(cache_line::operator=): Removed.
>	(internal_cache_line): New class implements former cache_line class.
>	(cache_set): Now takes cache_line_factory.
>	(allocate_lines): New method moves line allocation from the constructor.
>	(cache_set::set_line): Now takes reference to cache_line.
>	(cache_set::replace_line): Renamed to expell_line. Now returns a pointer
>	to the expelled line.
>	(cache): Now takes cache_line_factory argument.
>	(cache::init): New method moves set allocation from the constructor.
>	(cache_set::expell_line): Renamed to expell_line. Now returns a pointer
>	to the expelled line.
>	(cache_line_factory): New class.
>	* cacheutil.cxx (cache_line): Removed copy constructor. Now virtual base
>	class.
>	(cache_line::operator=): Removed.
>	(internal_cache_line): New class implements former cache_line class.
>	(cache_set): Now takes cache_line_factory.
>	(allocate_lines): New method moves line allocation from the constructor.
>	(cache_set::set_line): Now takes reference to cache_line.
>	(dummy): Now internal to cache_set::find.
>	(cache_set::replace_line): Renamed to expell_line. Now returns a pointer
>	to the expelled line.
>	(cache): Now takes cache_line_factory argument.
>	(cache::init): New method moves set allocation from the constructor.
>	(cache_set::expell_line): Renamed to expell_line. Now returns a pointer
>	to the expelled line.
>	* cache.h (cache_replacement_algorithm::expell): Renamed from 'replace'.
>	Returns a pointer to the expelled line. Update specializations.
>	(cache_component): Now takes a cache_line_factory as an argument.
>	Private data now protected.
>	(line_factory): New member of cache_component.
>	(~cache_component): Now virtual.
>	(CacheCreate): Pass internal_line_factory to cache_component.
>	* cache.cxx (line_sizes): Make it static.
>	(line_sizes): Ditto.
>	(replacement_algorithms): Ditto.
>	(internal_line_factory): New static cache_line_factory.
>	(cache_component): Now takes a cache_line_factory as an argument. Pass
>	the cache line factory to the constructor for acache. Save a reference
>	to the line factory. Call acache.init
>	(write_any): Rewrite to use cache::expell_line instead of the former
>	cache::replace.
>	(read_any): Ditto.
>	(cache_replacement_algorithm::expell): Renamed from 'replace'. Returns
>	a pointer to the expelled line. Update all callers and specializations.
>	(CacheCreate): Pass internal_line_factory to cache_component.
>
>2004-04-27  Dave Brolley  <[email protected]>
>
>	* compConfig.cxx (register_dso): Check dl_handle before attempting to
>	open ".a".
>	* Makefile.am (libconfig_la_DEPENDENCIES): Add @LIBLTDL@.
>	* Makefile.in: Regenerated.
>
>2004-04-27  Dave Brolley  <[email protected]>
>
>	* commonCfg.h (CacheCfg::compute_comptype): Now virtual.
>	(SessionCfg::get_loader): New method.
>
>  
>
>  
>