BlockAssembly Class Reference

Component that consumes a partially-sorted log record stream and generates indexed runs from it. More...

#include <logarchive_writer.h>

Classes
struct	BlockHeader

Public Member Functions
	BlockAssembly (ArchiveIndex *index, unsigned level=1, bool compression=true)
virtual	~BlockAssembly ()
bool	start (run_number_t run)
bool	add (logrec_t *lr)
void	finish ()
void	shutdown ()
bool	hasPendingBlocks ()
void	resetWriter ()
PageID	getCurrentMaxPID ()

Static Public Member Functions
static run_number_t	getRunFromBlock (const char *b)
static lsn_t	getLSNFromBlock (const char *b)
static size_t	getEndOfBlock (const char *b)
static PageID	getMaxPIDFromBlock (const char *b)

Private Attributes
char *	dest
AsyncRingBuffer *	writebuf
WriterThread *	writer
ArchiveIndex *	archIndex
size_t	blockSize
size_t	pos
size_t	fpos
lsn_t	maxLSNInBlock
int	maxLSNLength
run_number_t	lastRun
PageID	currentPID
size_t	currentPIDpos
size_t	currentPIDfpos
lsn_t	currentPIDprevLSN
bool	enableCompression
size_t	bucketSize
std::vector< pair< PageID, size_t > >	buckets
size_t	nextBucket
unsigned	level
PageID	maxPID
size_t	spaceToReserve

Detailed Description

Component that consumes a partially-sorted log record stream and generates indexed runs from it.

This class serves two purposes:

• It assembles individual log records into blocks which are written to persistent storage using an asynchronous writer thread (see WriterThread).
• For each block generated, it generates an entry on the archive index, allowing direct access to each block based on log record attributes (page id & lsn).

The writer thread is controlled solely using an asynchronous ring buffer. This works because the writer should keep writing as long as there are blocks available – unlike the reader thread, which must stop once a certain LSN is reached.

Each generated block contains a header, which specifies the run number, the offset up to which valid log records are found within that block, and the LSN of the last log record in the block. The run number is used by the writer thread to write blocks to the correct run file – once it changes from one block to another, it must close the currently generated run file an open a new one. The LSN in the last block header is then used to rename the file with the correct LSN range. (We used to control these LSN boundaries with an additional queue structure, but it required too many dependencies between modules that are otherwise independent)

Author

Caetano Sauer

Constructor & Destructor Documentation

BlockAssembly()

BlockAssembly::BlockAssembly	(	ArchiveIndex *	index,
		unsigned	level = 1,
		bool	compression = true
	)

~BlockAssembly()

BlockAssembly::~BlockAssembly ( )

virtual

Member Function Documentation

add()

bool BlockAssembly::add

(

logrec_t *

lr

)

finish()

void BlockAssembly::finish

(

)

getCurrentMaxPID()

PageID BlockAssembly::getCurrentMaxPID ( )

inline

getEndOfBlock()

size_t BlockAssembly::getEndOfBlock ( const char *  b )

static

getLSNFromBlock()

lsn_t BlockAssembly::getLSNFromBlock ( const char *  b )

static

getMaxPIDFromBlock()

PageID BlockAssembly::getMaxPIDFromBlock ( const char *  b )

static

getRunFromBlock()

run_number_t BlockAssembly::getRunFromBlock ( const char *  b )

static

hasPendingBlocks()

bool BlockAssembly::hasPendingBlocks

(

)

resetWriter()

void BlockAssembly::resetWriter ( )

inline

shutdown()

void BlockAssembly::shutdown

(

)

start()

bool BlockAssembly::start

(

run_number_t

run

)

Member Data Documentation

archIndex

ArchiveIndex* BlockAssembly::archIndex

private

blockSize

size_t BlockAssembly::blockSize

private

buckets

std::vector<pair<PageID, size_t> > BlockAssembly::buckets

private

bucketSize

size_t BlockAssembly::bucketSize

private

currentPID

PageID BlockAssembly::currentPID

private

currentPIDfpos

size_t BlockAssembly::currentPIDfpos

private

currentPIDpos

size_t BlockAssembly::currentPIDpos

private

currentPIDprevLSN

lsn_t BlockAssembly::currentPIDprevLSN

private

dest

char* BlockAssembly::dest

private

enableCompression

bool BlockAssembly::enableCompression

private

fpos

size_t BlockAssembly::fpos

private

lastRun

run_number_t BlockAssembly::lastRun

private

level

unsigned BlockAssembly::level

private

maxLSNInBlock

lsn_t BlockAssembly::maxLSNInBlock

private

maxLSNLength

int BlockAssembly::maxLSNLength

private

maxPID

PageID BlockAssembly::maxPID

private

nextBucket

size_t BlockAssembly::nextBucket

private

pos

size_t BlockAssembly::pos

private

spaceToReserve

size_t BlockAssembly::spaceToReserve

private

writebuf

AsyncRingBuffer* BlockAssembly::writebuf

private

writer

WriterThread* BlockAssembly::writer

private

---

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

• src/sm/logarchive_writer.h
• src/sm/logarchive_writer.cpp