com.neeve.rog

Interface IRogMessageLogger

All Known Implementing Classes:

RogMessageLog

public interface IRogMessageLogger

Represents a message logger.

This interface defines a message logger. Message loggers are used to persist messages to a log.

Threading:

A logger is not safe for concurrent access by multiple threads.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	IRogMessageLogger.ErrorHandler Callback interface to report logging errors
static interface	IRogMessageLogger.IMessageReceiver Receiver of messages read by read(com.neeve.rog.IRogMessageLogger.IMessageReceiver)
static interface	IRogMessageLogger.Stats Logger statistics

Method Summary

Modifier and Type	Method and Description
void	close() Close a message logger.
void	delete() Delete the underlying log file
void	flush(boolean sync) Flush cached message to the log.
IRogMessageLogger.ErrorHandler	getErrorHandler() Get a logger's error handler.
String	getName() Get the name of a logger.
long	getPositionInLog(IRogMessage message) Get the position of a read message in the log
int	getSizeInLog(IRogMessage message) Get the size of a read message in the log
IRogMessageLogger.Stats	getStats() Gets a logger's stats.
boolean	isOpen() Get if the log is open
boolean	isReadInProgress() Get if a log read is in progress
void	log(IRogMessage message) Log a message.
void	log(IRogMessage message, boolean commitStart, boolean commitEnd) Log a message.
void	log(IRogMessage message, boolean commitStart, boolean commitEnd, boolean sync) Log a message.
void	open() Open a message logger.
void	read(IRogMessageLogger.IMessageReceiver receiver) Read the contents of the log from the beginning of the log.
IRogMessage	readAt(long pos) Read the one message from a specific position in the log
void	readFrom(long pos, IRogMessageLogger.IMessageReceiver receiver) Read the contents of the log from a specific position in the log.
IRogMessage	readOne() Read the one message from the current position in the log
void	setErrorHandler(IRogMessageLogger.ErrorHandler errorHandler) Set a logger's error handler.
void	stopRead() Stop a read started via readFrom(long, com.neeve.rog.IRogMessageLogger.IMessageReceiver) or read(com.neeve.rog.IRogMessageLogger.IMessageReceiver)
boolean	wasRepaired() Indicates whether the message log was repaired during open.

Method Detail

getName

String getName()

Get the name of a logger.

setErrorHandler

void setErrorHandler(IRogMessageLogger.ErrorHandler errorHandler)

Set a logger's error handler.

getErrorHandler

IRogMessageLogger.ErrorHandler getErrorHandler()

Get a logger's error handler.

open

void open()
   throws Exception

Open a message logger.

Throws:

Exception

isOpen

boolean isOpen()

Get if the log is open

wasRepaired

boolean wasRepaired()

Indicates whether the message log was repaired during open.

getStats

IRogMessageLogger.Stats getStats()

Gets a logger's stats.

isReadInProgress

boolean isReadInProgress()

Get if a log read is in progress

readAt

IRogMessage readAt(long pos)

Read the one message from a specific position in the log

Parameters:

pos - The position in the log the message from

Returns:

The read message

readOne

IRogMessage readOne()

Read the one message from the current position in the log

Returns:

The read message

readFrom

void readFrom(long pos,
              IRogMessageLogger.IMessageReceiver receiver)

Read the contents of the log from a specific position in the log.

Parameters:

pos - The position in the log to read from. A value of 0 will read the message from the beginning of the file.

cb - The callback to invoke to dispatch messages read from the log.

read

void read(IRogMessageLogger.IMessageReceiver receiver)

Read the contents of the log from the beginning of the log.

Parameters:

cb - The callback to invoke to dispatch messages read from the log.

stopRead

void stopRead()

Stop a read started via readFrom(long, com.neeve.rog.IRogMessageLogger.IMessageReceiver) or read(com.neeve.rog.IRogMessageLogger.IMessageReceiver)

getPositionInLog

long getPositionInLog(IRogMessage message)

Get the position of a read message in the log

Throws:

IllegalArgumentException - thrown if the supplied message was not one received via the a message logger read method

getSizeInLog

int getSizeInLog(IRogMessage message)

Get the size of a read message in the log

Throws:

IllegalArgumentException - thrown if the supplied message was not one received via the a message logger read method

log

void log(IRogMessage message,
         boolean commitStart,
         boolean commitEnd,
         boolean sync)

Log a message.

Parameters:

message - The message to log.

commitStart - Indicates whether to mark this log entry as the start of an application commit leg.

commitEnd - Indicates whether to mark this log entry as the end of an application commit leg.

sync - Indicates whether this write should trigger a flush with a sync i.e. any data buffered in local memory by prior calls to this method should be synchornously flushed through to its destination i.e. cut through all intermediate caches and buffers such as OS caches, CPU caches and network buffers to it final destination.

Threading:

This method is not safe for concurrent access with itself or any other methods in this class

Note: The logger can be configured to log a message is a detached manner i.e. upon return from this call, the message may still be in flight for logging. Therefore, a message being logged CANNOT be modified after return from this call.

log

void log(IRogMessage message,
         boolean commitStart,
         boolean commitEnd)

Log a message.

Invoking this method is equivalent to invoking log(message, commitStart, commitEnd, false)

log

void log(IRogMessage message)

Log a message.

Invoking this method is equivalent to invoking log(message, true, true)

flush

void flush(boolean sync)

Flush cached message to the log.

Parameters:

sync - Indicates if the flush should sync to the durable media

Threading:

This method is not safe for concurrent access with itself or any other methods in this class

delete

void delete()
     throws IOException

Delete the underlying log file

Throws:

IOException

close

void close()

Close a message logger.