StandardStManAccessor.h
Classes
- ROStandardStManAccessor -- Give access to some StandardStMan functions (full description)
Interface
- Public Members
- ROStandardStManAccessor (const Table& aTable, const String& aDataManagerName)
- ~ROStandardStManAccessor()
- ROStandardStManAccessor (const ROStandardStManAccessor& that)
- ROStandardStManAccessor& operator= (const ROStandardStManAccessor& that)
- void setCacheSize (uInt aSize)
- uInt getCacheSize() const
- void clearCache()
- void showCacheStatistics (ostream& anOs) const
- void showBaseStatistics (ostream& anOs) const
- void showIndexStatistics (ostream& anOs) const
Review Status
- Reviewed By:
- UNKNOWN
- Date Reviewed:
- before2004/08/25
- Programs:
- Tests:
Prerequisite
Synopsis
The Table system has one or more storage managers underneath.
One of these possible storage managers is the
StandardStMan.
This storage manager uses a cache of buckets. The default
cache size is defined when the StandardStMan object was
constructed at the time the table was created.
Sometimes it can be useful to change the cache size. E.g. when
the table is accessed in a random way, the hit rate may drop
when the cache is too small. The class ROStandardStManAccessor makes
it possible to change the cache size in a temporary way.
It is also possible to get the cache size.
Furthermore it is possible to show some statistics (about the cache
and the internals of SSM classes).
Motivation
In principle a pointer to StandardStMan could be used.
However, that would give access to all public functions.
Furthermore it could not distinguish between read/write and readonly
tables.
Example
This example shows how to set the cache size for
the standard storage manager with the name "SSMExample". The cache
size is not persistent, i.e. when the same table is reopened
at a later time, this cache size is not remembered.
// Open a table.
Table table("someName.data");
// Set the cache size of its standard storage manager SSMExample
// to 5 buckets.
ROStandardStManAccessor accessor(table, "SSMExample");
accessor.setCacheSize (5);
Member Description
Construct the object for the data manager in the table.
An exception is thrown if the data manager type does not
match the type of this ROStandardStManAccessor object.
Copy constructor (reference semantics).
ROStandardStManAccessor& operator= (const ROStandardStManAccessor& that)
Assignment (reference semantics).
Set the cache size (in buckets) to be used by the
storage manager.
The cache size given in this way is not persistent.
Only the cache size given to the constructors of the Standard
storage managers, is persistent.
Get the cache size (in buckets).
Clear the cache used by this storage manager.
It will flush the cache as needed and remove all buckets from it
resulting in a drop in memory used.
Show the statistics for the cache used by this storage manager.
Show the statistics for the base class.
Show the statistics for each index used by this storage manager.