SwatDB Class Reference

#include <swatdb.h>

Collaboration diagram for SwatDB:

Public Member Functions
	SwatDB ()
	Constructor. More...
	SwatDB (std::string metadata_filename)
	Constructor to init SwatDB from a metadata file. More...
	~SwatDB ()
	Shutdown SwatDB. More...
void	setDestroyDB ()
	sets the DB to be destroyed on shutdown. More...
void	setSaveDB (std::string filename)
	sets the DB to be saved on shutdown. More...
Catalog *	getCatalog ()
	Gets the SwatDB Catalog.
DiskManager *	getDiskMgr ()
	Gets the SwatDB DiskManager.
BufferManager *	getBufMgr ()
	Gets the SwatDB BufferManager.
FileManager *	getFileMgr ()
	Gets the SwatDB FileManager.

Private Attributes
Catalog *	cat
DiskManager *	disk_mgr
BufferManager *	buf_mgr
FileManager *	file_mgr
bool	saved
std::string	inited_file_name
std::string	saved_file_name

Detailed Description

SwatDB. This is the class definition of the high-level SwatDB object that stores all state about the Swat DBMS system as it runs. This includes:

• The Catalog object of its relations and indices
• The Buffer Manager object
• The Disk Manager object
• The File Manager object
• And possibly others in the future (lock mgr, xact mgr)

It contains methods to boot SwatDB and to save or delete SwatDB, as well as to access layer manager objects for the different parts of the system.

On (or before) shutdown a caller should decide if they want to save or destroy the db and do so before invoking the destructor (the default is to destroy if neither have been invoked):

swatdb->setSaveDB() swatdb->setDestroyDB() delete swatdb delete swatdb

Constructor & Destructor Documentation

SwatDB() [1/2]

SwatDB::SwatDB

(

)

Constructor.

Initialize/boot swatDB. Initializes an empty swatDB and creates default manager objects for all the layers

SwatDB() [2/2]

SwatDB::SwatDB

(

std::string

metadata_filename

)

Constructor to init SwatDB from a metadata file.

This method creates RelationFile and IndexFile objects associated with each stored file listed in the metadata. SwatDB creates the diskmgr before the file manager, and it opens the relation and index files on disk and checks that they exist.

Parameters

metadata_filename

the name of the input file containing information about the DB state to init SwatDB with

Exceptions

exceptions

from system layers with init errors

~SwatDB()

SwatDB::~SwatDB

(

)

Shutdown SwatDB.

If saveDB is not called before the destructor is invoked then the destructor calls destroyDB to remove all relation and index files from the system

Precondition

: SwatDB may have some relation and index files

Postcondition

: Based on if saveDB or destroyDB was invoked prior to the destructory either all index and relation files are saved and metadata about them is written out or all files and indexes removed from the system, and their associated storage on "disk" is also removed from the system. Any state created is removed from the system.

Member Function Documentation

setDestroyDB()

void SwatDB::setDestroyDB

(

)

sets the DB to be destroyed on shutdown.

This method can be called prior to shuting down swatDB if the current state of swatDB does not want to be saved (destroy on exit is the default). This method does not actually remove db files from the system but sets a flag to trigger the right actions by the destructor on shutdown.

setSaveDB()

void SwatDB::setSaveDB

(

std::string

filename

)

sets the DB to be saved on shutdown.

This method should be called prior to shuting down swatDB to save the state of the db on shutdown. This method does not actually save the state at the point it is called but set up the system to save the state on shutdown

Parameters

filename

name of swatDB meta data file to which to save db metadata state on shutdown of swatDB

Precondition

: a file with filename does or does not already exist in the system (or an existing one's contents will be replaced)

Postcondition

: flag is set to trigger saving db metadata to file on shutdown

Member Data Documentation

buf_mgr

BufferManager* SwatDB::buf_mgr

private

SwatDB's Buffer Manager

cat

Catalog* SwatDB::cat

private

SwatDB's Catalog

disk_mgr

DiskManager* SwatDB::disk_mgr

private

SwatDB's Disk Manager

file_mgr

FileManager* SwatDB::file_mgr

private

SwatDB's Buffer Manager

inited_file_name

std::string SwatDB::inited_file_name

private

name of file from which DB was booted, may be nullptr

saved

bool SwatDB::saved

private

Flag to indicate if swatDB metadata should be saved to a file on shutdown (if setSaveDB has been called) true: save it on shutdown, If false, destroies its state on shutdown.

saved_file_name

std::string SwatDB::saved_file_name

private

name of file to save DB to on exit

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

• swatdb.h