#include <diskmgr.h>

Collaboration diagram for DiskManager:

Classes
struct	DiskFileInfo

struct	SerializedFileHeader

Public Member Functions
	DiskManager (Catalog *catalog)
	DiskManager constructor. Uses Catalog object pointer and a vector of FileIds to initialize file_map. More...

	~DiskManager ()
	DiskManager destructor. All pages have been written to disk prior to this call. More...

void	createFile (FileId file_id)
	Creates a new Unix file, opens the fstream, initializes DiskFileInfo object, and adds <FileId, DiskFileInfo*> pair to fileMap. Adds header data to Unix file via SerializedFileInfo. More...

void	removeFile (FileId file_id)
	Deletes the Unix file corresponding to file_id, and removes the <FileId, DiskFileInfo*> key-value pair from fileMap. More...

PageId	allocatePage (FileId file_id)
	Allocates a Page to the file which corresponds to file_id. More...

void	deallocatePage (PageId page_id)
	Deallocates page by adding its offest to unused_pages in the appropriate DiskFileInfo struct. More...

void	readPage (PageId page_id, Page *page)
	Reads the page data from the Unix file into the Page object pointer. More...

void	writePage (PageId page_id, Page *page)
	Writes the page data of the given Page object at the right offset in the appropriate Unix file. More...

bool	isValidPage (PageId page_id)
	Checks if the page of a given pageId is valid. More...

void	printFile (FileId file_id)
	THIS METHOD IS FOR DEBUGGING ONLY. Prints contents of a file inlcuding FileId, size, capacity, and contents of each page. More...

std::uint32_t	getCapacity (FileId file_id)
	Get method for the capacity of a file. More...

std::uint32_t	getSize (FileId file_id)
	Get method for size of a file. More...

Private Member Functions
void	_getDiskFileInfo (FileId file_id, DiskFileInfo **disk_file_info)
	Initializes DiskFileInfo** of the given FileId. More...

void	_flushDiskFileInfo (FileId file_id)
	Writes data from DiskFileInfo struct to Unix file for the given FileId. More...

void	_serializeFileHeader (SerializedFileHeader file_header, DiskFileInfo disk_file_info)
	Serializes Unix file metadata by initializing SerializedFileHeader object given DiskFileInfo object. More...

void	_deserializeFileHeader (SerializedFileHeader file_header, DiskFileInfo disk_file_info)
	Intializes DiskFileInfo object given SerializedFileHeader object. More...

Private Attributes
std::unordered_map< FileId, DiskFileInfo * >	file_map

Catalog *	catalog

std::mutex	file_map_mtx

char	temp_page [PAGE_SIZE]

Static Private Attributes
static const std::uint32_t	DISK_HEADER_SIZE

static const std::uint32_t	DISK_HEADER_BITMAP_SIZE

Detailed Description

SwatDB DiskManager Class. DiskManager manages page level disk operations of SwatDB, including writing, reading, allocating, and deallocating pages. As SwatDB is built for pedagogical reason, this layer is built on top of regular Unix file system, rather than raw device/DIRECT_IO.

Constructor & Destructor Documentation

◆ DiskManager()

DiskManager::DiskManager ( Catalog * catalog )

DiskManager constructor. Uses Catalog object pointer and a vector of FileIds to initialize file_map.

Precondition: Valid Catalog* is passed as an input.

Postcondition: A vector of FileIds are retrieved from the Catalog and appropriate fstream is opened for each FileId. Then a DiskManager object is initialized and each <FileId, DiskFileInfo*> pair is added to file_map.

Parameters

catalog A pointer to the DBMS's catalog object (Catalog*).

Exceptions

DiskErrorDiskMgr if file operation fails

◆ ~DiskManager()

DiskManager::~DiskManager ( )

DiskManager destructor. All pages have been written to disk prior to this call.

Precondition: None

Postcondition: The metadata for each relation/index file is written to the appropriate Unix file via _flushDiskFileInfo().

See also: DiskManager::_flushDiskFileInfo()

Member Function Documentation

◆ _deserializeFileHeader()

void DiskManager::_deserializeFileHeader	(	SerializedFileHeader *	file_header,
		DiskFileInfo *	disk_file_info
	)

private

Intializes DiskFileInfo object given SerializedFileHeader object.

Precondition: A valid SerializedFileHeader* and a valid DiskFileInfo* are provided as input.

Postcondition: Data members of disk_file_info, including capacity and unused_pages are initialized to a state consistent with file_header.

Parameters

file_header	SerializedFileHeader object to be used for initializing SerializedFileHeader.
disk_file_info	DiskFileInfo to be initialized.

◆ _flushDiskFileInfo()

void DiskManager::_flushDiskFileInfo ( FileId file_id )

private

Writes data from DiskFileInfo struct to Unix file for the given FileId.

Precondition: FileId in file_map is provided as input.

Postcondition: The metadata from the corresponding DiskFileInfo struct is written to the Unix file.

Parameters

file_id FileId of the file to have its data written.

Exceptions

InvalidFileIdDiskMgr	If file_id is not in file_map.
DiskErrorDiskMgr	If file operation fails.

◆ _getDiskFileInfo()

void DiskManager::_getDiskFileInfo	(	FileId	file_id,
		DiskFileInfo **	disk_file_info
	)

private

Initializes DiskFileInfo** of the given FileId.

Precondition: FileId in file_map and a valid DiskFileInfo** are provided as input. file_map_mtx is locked.

Postcondition: Corresponding DiskFileInfo* is initialized.

Parameters

file_id FileId of the DiskFileInfo* to be retrieved.

Exceptions

InvalidFileIdDiskMgr If file_id is not in file_map.

◆ _serializeFileHeader()

void DiskManager::_serializeFileHeader	(	SerializedFileHeader *	file_header,
		DiskFileInfo *	disk_file_info
	)

private

Serializes Unix file metadata by initializing SerializedFileHeader object given DiskFileInfo object.

Precondition: _serializeFileHeader must recieve a valid SerializedFileHeader* and a valid DiskFileInfo*.

Postcondition: Data members of file_header, including size, capacity and bitmap are initialized to a state consistent with disk_file_info.

Parameters

file_header	SerializedFileHeader object to be initialized.
disk_file_info	DiskFileInfo to be used for initializing SerializedFileHeader.

◆ allocatePage()

PageId DiskManager::allocatePage ( FileId file_id )

Allocates a Page to the file which corresponds to file_id.

Precondition: A FileId in file_map is provided as input and there is enough space in the corresponding Unix file.

Postcondition: If unused_pages set of the corresponding DiskFileInfo struct is not empty, then a PageNum in the set is popped, and is used with the file_id to construct an appropriate PageId, which is returned. If the unused_pages set of the corresponding DiskFileInfo struct is empty, and capacity is less than MAX_PAGE_NUM, then it is used with the file_id to construct an appropriate PageId, which is returned. Capacity is incremented and the size of underlying Unix file is increased by PAGE_SIZE. The updated metadata about the file is not immediately written to the file to minimize disk I/O.

Parameters

file_id A FileId corresponding to the file in which a page will be allocated.

Returns: PageId of the allocated page.

Exceptions

InsufficientSpaceDiskMgr	If file_id is in file_map and of the file is equal to MAX_CAPCITY.
InvalidFileIdDiskMgr	If file_id is not in file_map.
DiskErrorDiskMgr	If file operation fails.

◆ createFile()

void DiskManager::createFile ( FileId file_id )

Creates a new Unix file, opens the fstream, initializes DiskFileInfo object, and adds <FileId, DiskFileInfo*> pair to fileMap. Adds header data to Unix file via SerializedFileInfo.

Precondition: A FileId that is added to catalog and is not in file_map.

Postcondition: A new Unix file is created, the fstream is opened, DiskFileInfo is initialized for that file and <FileId, DiskFileInfo*> pair is added to file_map.

Parameters

file_id A FileId of the file to be created.

Exceptions

FileIdAlreadyExistDiskMgr	If file_id is already in file_map.
FileAlreadyExistDiskMgr	If Unix file already exists.
DiskErrorDiskMgr	If file operation fails.

◆ deallocatePage()

void DiskManager::deallocatePage ( PageId page_id )

Deallocates page by adding its offest to unused_pages in the appropriate DiskFileInfo struct.

Precondition: PageId of an allocated Page is provided as input.

Postcondition: page_id.page_num is added to the unused_pages set in the appropriate DiskFileInfo struct. The updated metadata about the file is not immediately written to the file due to performance reasons.

Parameters

page_id A PageId corresponding to the page to be deallocated.

Exceptions

InvalidPageNumDiskMgr	If page_id.page_num is out of range or if the page_id.page_num is in unused_pages.
InvalidFileIdDiskMgr	If page_id.file_id is not in file_map.

◆ getCapacity()

std::uint32_t DiskManager::getCapacity ( FileId file_id )

Get method for the capacity of a file.

Precondition: A FileId in file_map is provided as input.

Postcondition: capacity of the corresponding file is returned.

Parameters

file_id A FileId corresponding to the Unix file to get capacity.

Returns: capacity of the corresponding file.

Exceptions

InvalidFileIdDiskMgr If file_id is not in file_map.

◆ getSize()

std::uint32_t DiskManager::getSize ( FileId file_id )

Get method for size of a file.

Precondition: A FileId in file_map is provided as input.

Postcondition: size of the corresponding file is returned.

Parameters

file_id A FileId corresponding to the Unix file to get size.

Returns: size of the corresponding file.

Exceptions

InvalidFileIdDiskMgr If file_id is not in file_map.

◆ isValidPage()

bool DiskManager::isValidPage ( PageId page_id )

Checks if the page of a given pageId is valid.

Precondition: PageId of a Page is provided as input.

Postcondition: If page_id.file_id is not in file_map or page_id.page_num is out of range or is in unused_pages, false is returned. Otherwise true is returned.

Parameters

page_id A PageId for validity to be checked.

Returns: bool indicating whether the page is valid.

◆ printFile()

void DiskManager::printFile ( FileId file_id )

THIS METHOD IS FOR DEBUGGING ONLY. Prints contents of a file inlcuding FileId, size, capacity, and contents of each page.

Precondition: A FileId in file_map is provided as input.

Postcondition: The content of the corresponding file,including size, capacity and content of each page is printed.

Parameters

file_id A FileId corresponding to the Unix file to be printed

Exceptions

InvalidFileIdDiskMgr	If file_id is not in file_map.
DiskErrorDiskMgr	If file operation fails.

◆ readPage()

void DiskManager::readPage	(	PageId	page_id,
		Page *	page
	)

Reads the page data from the Unix file into the Page object pointer.

Precondition: PageId of an allocated Page, and a valid Page object pointer are provided as input.

Postcondition: The data of the page is read from the Unix file into the Page object.

Parameters

page_id	A PageId of the page to be read from Unix file.
page	A Page pointer to be initialized.

Exceptions

InvalidFileIdDiskMgr	If page_id.file_id is not in file_map.
InvalidPageNumDiskMgr	If page_id.page_num is out of range or if the page_id.page_num is in unused_pages.
DiskErrorDiskMgr	If file operation fails.

◆ removeFile()

void DiskManager::removeFile ( FileId file_id )

Deletes the Unix file corresponding to file_id, and removes the <FileId, DiskFileInfo*> key-value pair from fileMap.

Precondition: A FileId in file_map is provided as input.

Postcondition: The corresponding file's fstream is closed, the Unix file is removed, and the <FileId, DiskFileInfo*> pair is removed from file_map.

Parameters

file_id A file_id of the file to be removed.

Exceptions

InvalidFileIdDiskMgr If file_id is not in file_map.

◆ writePage()

void DiskManager::writePage	(	PageId	page_id,
		Page *	page
	)

Writes the page data of the given Page object at the right offset in the appropriate Unix file.

Precondition: PageId of an allocated Page, and a valid Page reference are provided as input.

Postcondition: The Page object data is written to the Unix file at the right offset.

Parameters

page_id	A PageId to write Page object data in the appropriate Unix file.
page	A Page* object containing data to be written to the appropriate Unix file.

Exceptions

InvalidFileIdDiskMgr	If page_id.file_id is not in file_map.
InvalidPageNumDiskMgr	If page_id.page_num is out of range or if the page_id.page_num is in unused_pages.
DiskErrorDiskMgr	If file operation fails.

Member Data Documentation

◆ catalog

Catalog* DiskManager::catalog

private

Pointer to catalog object that stores the entire metadata and catalog information about SwatDB. Used by the DiskManager to retrieve file names of given FileIds and initialize file_map.

◆ DISK_HEADER_BITMAP_SIZE

const std::uint32_t DiskManager::DISK_HEADER_BITMAP_SIZE

staticprivate

Initial value:

=

DISK_HEADER_SIZE - (sizeof(std::uint32_t)*2)

number of bytes in the bitmap part of the SerializedFileHeader struct (it is the DISK_HEADER_SIZE minus the space for size and capacity fields)

◆ DISK_HEADER_SIZE

const std::uint32_t DiskManager::DISK_HEADER_SIZE

staticprivate

Initial value:

=

((((MAX_PAGE_NUM/8)+1+(sizeof(std::uint32_t)*2))/PAGE_SIZE)+1)*PAGE_SIZE

The size of the disk header. Computed based on the MAX_PAGE_NUM as the bitmap should be big enough to represent valid state of MAX_PAGE_NUM number of pages. The size is evenly divisible by PAGE_SIZE.

◆ file_map

std::unordered_map<FileId, DiskFileInfo*> DiskManager::file_map

private

A map that stores <FileId (uint32_t), DiskFileInfo pointer> key-value pairs. Allows access to file (read, write, rm) given FileId.

◆ file_map_mtx

std::mutex DiskManager::file_map_mtx

private

std:mutex for synchronized access to file_map.

◆ temp_page

char DiskManager::temp_page[PAGE_SIZE]

private

Temporary Page for writing into Unix file when allocating page.

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

diskmgr.h

Classes

Public Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ DiskManager()

◆ ~DiskManager()

Member Function Documentation

◆ _deserializeFileHeader()

◆ _flushDiskFileInfo()

◆ _getDiskFileInfo()

◆ _serializeFileHeader()

◆ allocatePage()

◆ createFile()

◆ deallocatePage()

◆ getCapacity()

◆ getSize()

◆ isValidPage()

◆ printFile()

◆ readPage()

◆ removeFile()

◆ writePage()

Member Data Documentation

◆ catalog

◆ DISK_HEADER_BITMAP_SIZE

◆ DISK_HEADER_SIZE

◆ file_map

◆ file_map_mtx

◆ temp_page