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casacore::TableCache Class Reference

Cache of open tables. More...

#include <TableCache.h>

Public Member Functions

 TableCache ()
 Construct an empty cache of open tables. More...
 
 ~TableCache ()
 
PlainTableoperator() (const String &tableName) const
 Try to find a table with the given name in the cache. More...
 
void define (const String &tableName, PlainTable *)
 Add an open table to the cache. More...
 
void remove (const String &tableName)
 Remove an open table. More...
 
void rename (const String &newName, const String &oldName)
 Rename an open table. More...
 
uInt nAutoLocks ()
 Determine the number of locked tables opened with the AutoLock option (Locked table means locked for read and/or write). More...
 
void relinquishAutoLocks (Bool all)
 Unlock locked tables opened with the AutoLock option. More...
 
Vector< StringgetTableNames () const
 Get the names of the tables in the cache. More...
 
Vector< StringgetLockedTables (FileLocker::LockType, int lockOption)
 Get the names of tables locked in this process. More...
 
void flushTable (const String &tableName, Bool fsync, Bool recursive)
 Flush a possibly cached Table. More...
 
PlainTablelookCache (const String &name, int tableOption, const TableLock &tableInfo)
 Look in the cache if the table is already open. More...
 

Private Member Functions

 TableCache (const TableCache &)
 The copy constructor is forbidden. More...
 
TableCacheoperator= (const TableCache &)
 The assignment operator is forbidden. More...
 
PlainTablegetTable (const String &tableName) const
 Get the table without doing a mutex lock (for operator()). More...
 

Private Attributes

std::map< String, void * > tableMap_p
 
Mutex itsMutex
 

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

Definition at line 94 of file TableCache.h.

Constructor & Destructor Documentation

casacore::TableCache::TableCache ( )

Construct an empty cache of open tables.

casacore::TableCache::~TableCache ( )
casacore::TableCache::TableCache ( const TableCache )
private

The copy constructor is forbidden.

Member Function Documentation

void casacore::TableCache::define ( const String tableName,
PlainTable  
)

Add an open table to the cache.

void casacore::TableCache::flushTable ( const String tableName,
Bool  fsync,
Bool  recursive 
)

Flush a possibly cached Table.

Vector<String> casacore::TableCache::getLockedTables ( FileLocker::LockType  ,
int  lockOption 
)

Get the names of tables locked in this process.

By default all locked tables are given (note that a write lock implies a read lock), but it is possible to select on lock type FileLocker::Write and on option (TableLock::AutoLocking, TableLock::ReadLocking, or TableLock::PermanentLocking).

PlainTable* casacore::TableCache::getTable ( const String tableName) const
private

Get the table without doing a mutex lock (for operator()).

Vector<String> casacore::TableCache::getTableNames ( ) const

Get the names of the tables in the cache.

PlainTable* casacore::TableCache::lookCache ( const String name,
int  tableOption,
const TableLock tableInfo 
)

Look in the cache if the table is already open.

If so, check if table option matches. If needed reopen the table for read/write and merge the lock options.

uInt casacore::TableCache::nAutoLocks ( )

Determine the number of locked tables opened with the AutoLock option (Locked table means locked for read and/or write).

PlainTable* casacore::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.

TableCache& casacore::TableCache::operator= ( const TableCache )
private

The assignment operator is forbidden.

void casacore::TableCache::relinquishAutoLocks ( Bool  all)

Unlock locked tables opened with the AutoLock option.

If all=True all such tables will be unlocked. If all=False only tables requested by another process will be unlocked.

void casacore::TableCache::remove ( const String tableName)

Remove an open table.

void casacore::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

Mutex casacore::TableCache::itsMutex
mutableprivate

Definition at line 163 of file TableCache.h.

std::map<String,void*> casacore::TableCache::tableMap_p
private

Definition at line 161 of file TableCache.h.


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