casa::TableCache Class Reference [Tables_module_internal_classes]

Cache of open tables. More...

#include <TableCache.h>

List of all members.

Public Member Functions
	TableCache ()
	Construct an empty cache of open tables.
	~TableCache ()
PlainTable *	operator() (const String &tableName) const
	Try to find a table with the given name in the cache.
PlainTable *	operator() (uInt index) const
	Try to find a table at the given index in the cache.
uInt	ntable () const
	Return the number of open tables in the cache.
void	define (const String &tableName, PlainTable *)
	Add an open table to the cache.
void	remove (const String &tableName)
	Remove an open table.
void	rename (const String &newName, const String &oldName)
	Rename an open table.
Private Attributes
SimpleOrderedMap< String, void * >	tableMap_p

---

Detailed Description

Cache of open tables.

Intended use:

Internal

Review Status

Reviewed By:

UNKNOWN

Date Reviewed:

before2004/08/25

Etymology

TableCache represents a cache of open tables.

Synopsis

A TableCache object keeps track of the tables which have already been opened in a program. It maps the name of a table to its PlainTable object. In principle only one TableCache object (statically defined in class PlainTable) exists in a process. The cache is used to prevent a table from being opened more than once, which is not only a waste of space, but more importantly, may give rise to synchronization problems. Synchronization between the same table in multiple processes must be done by a locking mechanism.

TableCache is used by class Table and PlainTable. Before opening a table, Table will first look in the cache. Newly opened or created tables will be added to the cache. When a table is actually closed, it will be removed from the cache.

Motivation

When a RefTable is read back, it will also read back the table it references. However, that table may have been opened before and it is bad to have a table open more than once in the same program. The TableCache class catches this and will not reopen the table.

To Do

• Currently only PlainTables are taken into account. Maybe RefTables should be too.

Definition at line 90 of file TableCache.h.

---

Constructor & Destructor Documentation

casa::TableCache::TableCache

(

)

Construct an empty cache of open tables.

casa::TableCache::~TableCache

(

)

---

Member Function Documentation

void casa::TableCache::define	(	const String &	tableName,
		PlainTable *
	)

Add an open table to the cache.

uInt casa::TableCache::ntable

(

)

const

Return the number of open tables in the cache.

PlainTable* casa::TableCache::operator()

(

uInt

index

)

const

Try to find a table at the given index in the cache.

Return a pointer to a table if found (thus if already open). Return a zero pointer if not found.

PlainTable* casa::TableCache::operator()

(

const String &

tableName

)

const

Try to find a table with the given name in the cache.

Return a pointer to a table if found (thus if already open). Return a zero pointer if not found.

void casa::TableCache::remove

(

const String &

tableName

)

Remove an open table.

void casa::TableCache::rename	(	const String &	newName,
		const String &	oldName
	)

Rename an open table.

If oldName is not in the cache, nothing will be done.

---

Member Data Documentation

SimpleOrderedMap<String,void*> casa::TableCache::tableMap_p [private]

Definition at line 126 of file TableCache.h.

---

The documentation for this class was generated from the following file:

• tables/Tables/TableCache.h