com.persistit

Class AlertMonitor

java.lang.Object

javax.management.NotificationBroadcasterSupport

com.persistit.AlertMonitor

All Implemented Interfaces:

AlertMonitorMXBean, NotificationBroadcaster, NotificationEmitter

public final class AlertMonitor
extends NotificationBroadcasterSupport
implements AlertMonitorMXBean

Manage the process of accumulating and logging abnormal events such as IOExceptions and measurements outside of expected thresholds. This class notifies agents by (a) writing log messages and (b) sending JMX Notifications.

This mechanism is designed to organize events generated by background threads, sometimes very frequently. For example, if a disk fails, the JOURNAL_FLUSHER thread may receive many IOExceptions per second. These are treated as Events in this class, and log messages are written periodically but far less frequently. But in addition, this class is also capable of sending a Notification to a management client which may be useful in making the problem known in a timely fashion

Events are collated by category names. For each category value there is a separate AlertMonitor.History of events pertaining to that category. By separately aggregating events of different categories this class avoids discarding important, but older events belonging to one category when receiving new events in a different category. For example, IOExceptions generated frequently by the JOURNAL_FLUSHER do not overwrite previous events indicating that the JOURNAL_COPIER has fallen behind.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AlertMonitor.AlertLevel Severity of an event
static class	AlertMonitor.AlertRecord
static class	AlertMonitor.Event Holder for event data including the event arguments and the time the event was posted.
class	AlertMonitor.History Aggregation of AlertMonitor.Events in a category.

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	AGGREGATION_FORMAT
protected static String	EVENT_FORMAT
protected static String	EXTRA_FORMAT

Fields inherited from interface com.persistit.mxbeans.AlertMonitorMXBean

CLEANUP_CATEGORY, EXTEND_VOLUME_CATEGORY, FLUSH_STATISTICS_CATEGORY, JOURNAL_CATEGORY, MANY_JOURNAL_FILES, MISSING_VOLUME_CATEGORY, MXBEAN_NAME, READ_PAGE_CATEGORY, WRITE_PAGE_CATEGORY

Method Summary

Modifier and Type	Method and Description
String	getAlertLevel() Current maximum AlertLevel in this monitor as a String: one of NORMAL, WARN or ERROR
AlertMonitor.AlertRecord[]	getAlertRecordArray() Generate a list of event data suitable for the Akiban Server in-memory tables implementation.
String	getDetailedHistory(String select) Return a detailed description, including first and recent occurrences of events within the History for the specified category.
long	getErrorLogTimeInterval()
AlertMonitor.History	getHistory(String name)
int	getHistoryLength()
SortedMap<String,AlertMonitor.History>	getHistoryMap()
MBeanNotificationInfo[]	getNotificationInfo()
String	getSummary() Return a summary of this AlertMonitor's current state.
long	getWarnLogTimeInterval()
void	poll(boolean force) Called periodically to issue any pending log messages or notifications.
void	post(AlertMonitor.Event event, String category) Post an event.
void	reset() Restore this alert monitor to level AlertMonitor.AlertLevel.NORMAL with and remove all histories for all categories.
void	setErrorLogTimeInterval(long errorLogTimeInterval) Set the interval between successive log entries for this monitor when its AlertMonitor.AlertLevel.ERROR.
void	setHistoryLength(int historyLength) Set the number of Events per category to keep in the History.
void	setWarnLogTimeInterval(long warnLogTimeInterval) Set the interval between successive log entries for this monitor when its AlertMonitor.AlertLevel.WARN.
String	toString()

Methods inherited from class javax.management.NotificationBroadcasterSupport

addNotificationListener, handleNotification, removeNotificationListener, removeNotificationListener, sendNotification

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

EVENT_FORMAT

protected static final String EVENT_FORMAT

See Also:

Constant Field Values

AGGREGATION_FORMAT

protected static final String AGGREGATION_FORMAT

See Also:

Constant Field Values

EXTRA_FORMAT

protected static final String EXTRA_FORMAT

See Also:

Constant Field Values

Method Detail

post

public final void post(AlertMonitor.Event event,
                       String category)

Post an event. If necessary, create a AlertMonitor.History for the specified category and then add the event to it. Subsequently, poll the History to cause any pending notifications or log messages to be emitted.

Parameters:

event - A Event object describing what happened

category - A String describing the nature of the event. A separate event-history is maintained for each unique category.

reset

public void reset()

Restore this alert monitor to level AlertMonitor.AlertLevel.NORMAL with and remove all histories for all categories. The logging time intervals and history length are not changed.

Specified by:

reset in interface AlertMonitorMXBean

getWarnLogTimeInterval

public long getWarnLogTimeInterval()

Specified by:

getWarnLogTimeInterval in interface AlertMonitorMXBean

Returns:

the interval in milliseconds between successive log entries for this monitor when its AlertMonitor.AlertLevel.WARN.

setWarnLogTimeInterval

public void setWarnLogTimeInterval(long warnLogTimeInterval)

Set the interval between successive log entries for this monitor when its AlertMonitor.AlertLevel.WARN.

Specified by:

setWarnLogTimeInterval in interface AlertMonitorMXBean

Parameters:

warnLogTimeInterval - the interval in milliseconds

getErrorLogTimeInterval

public long getErrorLogTimeInterval()

Specified by:

getErrorLogTimeInterval in interface AlertMonitorMXBean

Returns:

the interval in milliseconds between successive log entries for this monitor when its AlertMonitor.AlertLevel.ERROR.

setErrorLogTimeInterval

public void setErrorLogTimeInterval(long errorLogTimeInterval)

Set the interval between successive log entries for this monitor when its AlertMonitor.AlertLevel.ERROR.

Specified by:

setErrorLogTimeInterval in interface AlertMonitorMXBean

Parameters:

errorLogTimeInterval - the interval in milliseconds

getHistoryLength

public int getHistoryLength()

Specified by:

getHistoryLength in interface AlertMonitorMXBean

Returns:

the number of events to retain in the History per category.

See Also:

setHistoryLength(int)

getHistory

public AlertMonitor.History getHistory(String name)

Parameters:

name - Category name

Returns:

the History for that category or null if the specified category has no History.

getHistoryMap

public SortedMap<String,AlertMonitor.History> getHistoryMap()

Returns:

Map sorted by category name of all History elements.

setHistoryLength

public void setHistoryLength(int historyLength)

Set the number of Events per category to keep in the History. Once the number of events exceeds this count, earlier events are removed when new events are added. (However, the first Event added is retained and get accessed via AlertMonitor.History.getFirstEvent() even when subsequent Events are removed.) The default value is 10.

Specified by:

setHistoryLength in interface AlertMonitorMXBean

Parameters:

historyLength - the historyLength to set

getAlertRecordArray

public AlertMonitor.AlertRecord[] getAlertRecordArray()

Generate a list of event data suitable for the Akiban Server in-memory tables implementation.

Returns:

List of AlertRecord elements.

poll

public void poll(boolean force)

Called periodically to issue any pending log messages or notifications.

Specified by:

poll in interface AlertMonitorMXBean

Parameters:

force - Indicates whether to issue pending log messages and notifications prior to expiration of their respective notification time intervals.

toString

public String toString()

Overrides:

toString in class Object

Returns:

A human-readable summary of all History instances.

getSummary

public String getSummary()

Description copied from interface: AlertMonitorMXBean

Return a summary of this AlertMonitor's current state.

Specified by:

getSummary in interface AlertMonitorMXBean

Returns:

A human-readable summary of all History instances.

See Also:

toString()

getDetailedHistory

public String getDetailedHistory(String select)

Description copied from interface: AlertMonitorMXBean

Return a detailed description, including first and recent occurrences of events within the History for the specified category. If there is no history for the specified category, this method returns null .

Specified by:

getDetailedHistory in interface AlertMonitorMXBean

Parameters:

select - The category name(s) to include, optionally with wildcards '*' and '?'

Returns:

a detailed history report for the specified category

getAlertLevel

public String getAlertLevel()

Description copied from interface: AlertMonitorMXBean

Current maximum AlertLevel in this monitor as a String: one of NORMAL, WARN or ERROR

Specified by:

getAlertLevel in interface AlertMonitorMXBean

Returns:

the String value of the highest current AlertMonitor.AlertLevel among all categories being maintained

getNotificationInfo

public MBeanNotificationInfo[] getNotificationInfo()

Specified by:

getNotificationInfo in interface NotificationBroadcaster

Overrides:

getNotificationInfo in class NotificationBroadcasterSupport

Returns:

the metadata needed by an MBeanServer to know what notifications may be sent by this MBean