mongo::dur::JournalWriter Class Reference

Manages the thread and queues used for writing the journal to disk and notify parties with are waiting on the write concern. More...

#include <dur_journal_writer.h>

Detailed Description

Manages the thread and queues used for writing the journal to disk and notify parties with are waiting on the write concern.

NOTE: Not thread-safe and must not be used from more than one thread.

Classes
class	Buffer
	Stores the memory and the header for a complete journal buffer which is pending to be written by the journal writer thread. More...

Public Member Functions
	JournalWriter (CommitNotifier *commitNotify, CommitNotifier *applyToDataFilesNotify, size_t numBuffers)
	Initializes the journal writer. More...
	~JournalWriter ()
void	start ()
	Allocates buffer memory and starts the journal writer thread. More...
void	shutdown ()
	Terminates the journal writer thread and frees memory for the buffers. More...
void	assertIdle ()
	Asserts that there are no pending journal writes. More...
Buffer *	newBuffer ()
	Obtains a new empty buffer into which a journal entry should be written. More...
void	writeBuffer (Buffer *buffer, CommitNotifier::When commitNumber)
	Requests that the specified buffer be written asynchronously. More...
void	flush ()
	Ensures that all previously submitted write requests complete. More...

Private Types
enum	{ InitialBufferSizeBytes = 4 * 1024 * 1024 }
typedef BlockingQueue< Buffer * >	BufferQueue

Private Member Functions
	MONGO_DISALLOW_COPYING (JournalWriter)
void	_journalWriterThread ()

Private Attributes
CommitNotifier *const	_commitNotify
CommitNotifier *const	_applyToDataFilesNotify
stdx::thread	_journalWriterThreadHandle
bool	_shutdownRequested
BufferQueue	_journalQueue
CommitNotifier::When	_lastCommitNumber
BufferQueue	_readyQueue

Friends
class	BufferGuard

Member Typedef Documentation

BufferQueue

typedef BlockingQueue<Buffer*> mongo::dur::JournalWriter::BufferQueue

private

Member Enumeration Documentation

anonymous enum

anonymous enum

private

Enumerator
InitialBufferSizeBytes

Constructor & Destructor Documentation

JournalWriter()

mongo::dur::JournalWriter::JournalWriter	(	CommitNotifier *	commitNotify,
		CommitNotifier *	applyToDataFilesNotify,
		size_t	numBuffers
	)

Initializes the journal writer.

Parameters

commitNotify	Notification object to be called after journal entries have been written to disk. The caller retains ownership and the notify object must outlive the journal writer object.
applyToDataFilesNotify	Notification object to be called after journal entries have been applied to the shared view. This means that if the shared view were to be flushed at this point, the journal files before this point are not necessary. The caller retains ownership and the notify object must outlive the journal writer object.
numBuffers	How many buffers to create to hold outstanding writes. If there are more than this number of journal writes that have not completed, the write calls will block.

~JournalWriter()

mongo::dur::JournalWriter::~JournalWriter

(

)

Member Function Documentation

_journalWriterThread()

void mongo::dur::JournalWriter::_journalWriterThread ( )

private

assertIdle()

void mongo::dur::JournalWriter::assertIdle

(

)

Asserts that there are no pending journal writes.

flush()

void mongo::dur::JournalWriter::flush

(

)

Ensures that all previously submitted write requests complete.

This call is blocking.

MONGO_DISALLOW_COPYING()

mongo::dur::JournalWriter::MONGO_DISALLOW_COPYING ( JournalWriter  )

private

newBuffer()

JournalWriter::Buffer * mongo::dur::JournalWriter::newBuffer

(

)

Obtains a new empty buffer into which a journal entry should be written.

This method may block if there are no free buffers.

The caller does not own the buffer and needs to "return" it to the writer by calling writeBuffer. Buffers with data on them should never be discarded until they are written.

shutdown()

void mongo::dur::JournalWriter::shutdown

(

)

Terminates the journal writer thread and frees memory for the buffers.

Must not be called if there are any pending journal writes.

start()

void mongo::dur::JournalWriter::start

(

)

Allocates buffer memory and starts the journal writer thread.

writeBuffer()

void mongo::dur::JournalWriter::writeBuffer	(	Buffer *	buffer,
		CommitNotifier::When	commitNumber
	)

Requests that the specified buffer be written asynchronously.

This method may block if there are too many outstanding unwritten buffers.

Parameters

buffer	Buffer entry to be written. The buffer object must not be used anymore after it has been given to this function.
commitNumber	What commit number to be notified once the buffer has been written to disk.

Friends And Related Function Documentation

BufferGuard

friend class BufferGuard

friend

Member Data Documentation

_applyToDataFilesNotify

CommitNotifier* const mongo::dur::JournalWriter::_applyToDataFilesNotify

private

_commitNotify

CommitNotifier* const mongo::dur::JournalWriter::_commitNotify

private

_journalQueue

BufferQueue mongo::dur::JournalWriter::_journalQueue

private

_journalWriterThreadHandle

stdx::thread mongo::dur::JournalWriter::_journalWriterThreadHandle

private

_lastCommitNumber

CommitNotifier::When mongo::dur::JournalWriter::_lastCommitNumber

private

_readyQueue

BufferQueue mongo::dur::JournalWriter::_readyQueue

private

_shutdownRequested

bool mongo::dur::JournalWriter::_shutdownRequested

private

---

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

• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/mmap_v1/dur_journal_writer.h
• /home/louis/git/mongodbsource.github.io/src/src/mongo/db/storage/mmap_v1/dur_journal_writer.cpp