Interface LogEventListener
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- All Known Implementing Classes:
XALogger
public interface LogEventListener
This interface is implemented by users of the Logger.If a LogEventListener is registered, the logger will call the LogEventListener when interesting Log Events occur. For example, the Logger will notify the LogEventListener when the current log file is 50% full to allow the application to copy old log entries forward.
If the application does not register a LogEventListener it will not have visibility to Log events.
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Field Summary
Fields Modifier and Type Field Description static int
DEBUG
used to log low level events.static int
ERROR
used to log non-fatal error messages.static int
FATAL
used to log fatal error messages that should cause shutdown of the application using HOWL.static int
INFO
used to log information messages such as file open/close.static int
TRACE
used to trace method entry/exit and other low level events.static int
WARN
used to log warnings.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description boolean
isLoggable(int level)
determine if log messages for requested level will be written to the log.void
log(int level, java.lang.String message)
write a log message to the event log.void
log(int level, java.lang.String message, java.lang.Throwable thrown)
write a log message to the event log with exception information.void
logOverflowNotification(long logkey)
Called by Logger to notify the LogEventListener that a log file overflow is approaching.
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Field Detail
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TRACE
static final int TRACE
used to trace method entry/exit and other low level events.- See Also:
- Constant Field Values
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DEBUG
static final int DEBUG
used to log low level events.- See Also:
- Constant Field Values
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INFO
static final int INFO
used to log information messages such as file open/close.- See Also:
- Constant Field Values
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WARN
static final int WARN
used to log warnings.- See Also:
- Constant Field Values
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ERROR
static final int ERROR
used to log non-fatal error messages.- See Also:
- Constant Field Values
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FATAL
static final int FATAL
used to log fatal error messages that should cause shutdown of the application using HOWL.- See Also:
- Constant Field Values
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Method Detail
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logOverflowNotification
void logOverflowNotification(long logkey)
Called by Logger to notify the LogEventListener that a log file overflow is approaching.- Parameters:
logkey
- lowest safe log key.LogEventListener should cause log records with keys less than logkey to be copied forward to prevent a LogOverflowException.
Hopefully, the LogEventListener will be able to regenerate the records from memory without having to read the physical log file. For example, a Transaction Manager should maintain a table of transactions that are in the COMMITTING mode, with associated log key for each transaction. The logOverflowNotification method would call Logger.put() for each transaction that has a log key less than logKey .
Before returning from logOverflowNotification the LogEventListener should call Logger.mark(newMark, force) with force set to true to assure that the new records have been committed to physical disk.
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isLoggable
boolean isLoggable(int level)
determine if log messages for requested level will be written to the log.- Returns:
- true if the log level is being logged
- See Also:
java.util.logging.Logger#isLoggable()
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log
void log(int level, java.lang.String message)
write a log message to the event log.- Parameters:
level
- log levelmessage
- text to be logged
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log
void log(int level, java.lang.String message, java.lang.Throwable thrown)
write a log message to the event log with exception information.- Parameters:
level
- log levelmessage
- text to be loggedthrown
- Throwable related to the event being logged.
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