tkrzw::PageCache Class Reference

Page cache for buffering I/O operations. More...

#include <tkrzw_file_util.h>

Public Types
typedef std::function< Status(int64_t off, void *buf, size_t size)>	ReadType
	Type of callback function to read a clean buffer from the file. More...
typedef std::function< Status(int64_t off, const void *buf, size_t size)>	WriteType
	Type of callback function to write a dirty buffer to the file. More...

Public Member Functions
	PageCache (int64_t page_size, int64_t capacity, ReadType read_func, WriteType write_func)
	Constructor. More...
	~PageCache ()
	Destructor. More...
Status	Read (int64_t off, void *buf, size_t size)
	Reads data. More...
Status	Write (int64_t off, const void *buf, size_t size)
	Writes data. More...
Status	Flush (int64_t off=0, int64_t size=0)
	Flushes all dirty buffers to the file. More...
void	Clear ()
	Clear all data. More...
int64_t	GetRegionSize ()
	Gets the region size used for reading. More...
void	SetRegionSize (int64_t size)
	Sets the region size used for reading. More...

Static Public Attributes
static constexpr int32_t	NUM_SLOTS = 16
	The number of slots for cuncurrency. More...

Detailed Description

Page cache for buffering I/O operations.

Member Typedef Documentation

ReadType

typedef std::function<Status(int64_t off, void* buf, size_t size)> tkrzw::PageCache::ReadType

Type of callback function to read a clean buffer from the file.

WriteType

typedef std::function<Status(int64_t off, const void* buf, size_t size)> tkrzw::PageCache::WriteType

Type of callback function to write a dirty buffer to the file.

Constructor & Destructor Documentation

PageCache()

tkrzw::PageCache::PageCache	(	int64_t	page_size,
		int64_t	capacity,
		ReadType	read_func,
		WriteType	write_func
	)

Constructor.

Parameters

page_size	The page size of the I/O operation.
capacity	The capacity of the cache by the number of pages.
read_func	The callback function to read a clean buffer from the file.
write_func	The callback function to write a dirty buffer to the file.

~PageCache()

tkrzw::PageCache::~PageCache

(

)

Destructor.

Member Function Documentation

Read()

Status tkrzw::PageCache::Read	(	int64_t	off,
		void *	buf,
		size_t	size
	)

Reads data.

Parameters

off	The offset of a source region.
buf	The pointer to the destination buffer.
size	The size of the data to be read.

Returns

The result status.

Write()

Status tkrzw::PageCache::Write	(	int64_t	off,
		const void *	buf,
		size_t	size
	)

Writes data.

Parameters

off	The offset of the destination region.
buf	The pointer to the source buffer.
size	The size of the data to be written.

Returns

The result status.

Flush()

Status tkrzw::PageCache::Flush	(	int64_t	off = 0,
		int64_t	size = 0
	)

Flushes all dirty buffers to the file.

Parameters

off	The offset of the region to be synchronized.
size	The size of the region to be synchronized. If it is zero, the length to the end of file is specified.

Returns

The result status.

Clear()

void tkrzw::PageCache::Clear

(

)

Clear all data.

Dirty buffers are not written back.

GetRegionSize()

int64_t tkrzw::PageCache::GetRegionSize

(

)

Gets the region size used for reading.

Returns

The region size used for reading.

SetRegionSize()

void tkrzw::PageCache::SetRegionSize

(

int64_t

size

)

Sets the region size used for reading.

Parameters

size	The region size used for reading.

Member Data Documentation

NUM_SLOTS

constexpr int32_t tkrzw::PageCache::NUM_SLOTS = 16

staticconstexpr

The number of slots for cuncurrency.