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/*
* AbstractMetricsContext.java
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.metrics.spi;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
import java.util.TreeMap;
import java.util.Map.Entry;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.metrics.ContextFactory;
import org.apache.hadoop.metrics.MetricsContext;
import org.apache.hadoop.metrics.MetricsException;
import org.apache.hadoop.metrics.MetricsRecord;
import org.apache.hadoop.metrics.Updater;
/**
* The main class of the Service Provider Interface. This class should be
* extended in order to integrate the Metrics API with a specific metrics
* client library.
*
* This class implements the internal table of metric data, and the timer
* on which data is to be sent to the metrics system. Subclasses must
* override the abstract emitRecord method in order to transmit
* the data.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class AbstractMetricsContext implements MetricsContext {
private int period = MetricsContext.DEFAULT_PERIOD;
private Timer timer = null;
private Set updaters = new HashSet(1);
private volatile boolean isMonitoring = false;
private ContextFactory factory = null;
private String contextName = null;
@InterfaceAudience.Private
public static class TagMap extends TreeMap {
private static final long serialVersionUID = 3546309335061952993L;
TagMap() {
super();
}
TagMap(TagMap orig) {
super(orig);
}
/**
* Returns true if this tagmap contains every tag in other.
*/
public boolean containsAll(TagMap other) {
for (Map.Entry entry : other.entrySet()) {
Object value = get(entry.getKey());
if (value == null || !value.equals(entry.getValue())) {
// either key does not exist here, or the value is different
return false;
}
}
return true;
}
}
@InterfaceAudience.Private
public static class MetricMap extends TreeMap {
private static final long serialVersionUID = -7495051861141631609L;
MetricMap() {
super();
}
MetricMap(MetricMap orig) {
super(orig);
}
}
static class RecordMap extends HashMap {
private static final long serialVersionUID = 259835619700264611L;
}
private Map bufferedData = new HashMap();
/**
* Creates a new instance of AbstractMetricsContext
*/
protected AbstractMetricsContext() {
}
/**
* Initializes the context.
*/
public void init(String contextName, ContextFactory factory)
{
this.contextName = contextName;
this.factory = factory;
}
/**
* Convenience method for subclasses to access factory attributes.
*/
protected String getAttribute(String attributeName) {
String factoryAttribute = contextName + "." + attributeName;
return (String) factory.getAttribute(factoryAttribute);
}
/**
* Returns an attribute-value map derived from the factory attributes
* by finding all factory attributes that begin with
* contextName.tableName. The returned map consists of
* those attributes with the contextName and tableName stripped off.
*/
protected Map getAttributeTable(String tableName) {
String prefix = contextName + "." + tableName + ".";
Map result = new HashMap();
for (String attributeName : factory.getAttributeNames()) {
if (attributeName.startsWith(prefix)) {
String name = attributeName.substring(prefix.length());
String value = (String) factory.getAttribute(attributeName);
result.put(name, value);
}
}
return result;
}
/**
* Returns the context name.
*/
public String getContextName() {
return contextName;
}
/**
* Returns the factory by which this context was created.
*/
public ContextFactory getContextFactory() {
return factory;
}
/**
* Starts or restarts monitoring, the emitting of metrics records.
*/
public synchronized void startMonitoring()
throws IOException {
if (!isMonitoring) {
startTimer();
isMonitoring = true;
}
}
/**
* Stops monitoring. This does not free buffered data.
* @see #close()
*/
public synchronized void stopMonitoring() {
if (isMonitoring) {
stopTimer();
isMonitoring = false;
}
}
/**
* Returns true if monitoring is currently in progress.
*/
public boolean isMonitoring() {
return isMonitoring;
}
/**
* Stops monitoring and frees buffered data, returning this
* object to its initial state.
*/
public synchronized void close() {
stopMonitoring();
clearUpdaters();
}
/**
* Creates a new AbstractMetricsRecord instance with the given recordName.
* Throws an exception if the metrics implementation is configured with a fixed
* set of record names and recordName is not in that set.
*
* @param recordName the name of the record
* @throws MetricsException if recordName conflicts with configuration data
*/
public final synchronized MetricsRecord createRecord(String recordName) {
if (bufferedData.get(recordName) == null) {
bufferedData.put(recordName, new RecordMap());
}
return newRecord(recordName);
}
/**
* Subclasses should override this if they subclass MetricsRecordImpl.
* @param recordName the name of the record
* @return newly created instance of MetricsRecordImpl or subclass
*/
protected MetricsRecord newRecord(String recordName) {
return new MetricsRecordImpl(recordName, this);
}
/**
* Registers a callback to be called at time intervals determined by
* the configuration.
*
* @param updater object to be run periodically; it should update
* some metrics records
*/
public synchronized void registerUpdater(final Updater updater) {
if (!updaters.contains(updater)) {
updaters.add(updater);
}
}
/**
* Removes a callback, if it exists.
*
* @param updater object to be removed from the callback list
*/
public synchronized void unregisterUpdater(Updater updater) {
updaters.remove(updater);
}
private synchronized void clearUpdaters() {
updaters.clear();
}
/**
* Starts timer if it is not already started
*/
private synchronized void startTimer() {
if (timer == null) {
timer = new Timer("Timer thread for monitoring " + getContextName(),
true);
TimerTask task = new TimerTask() {
public void run() {
try {
timerEvent();
}
catch (IOException ioe) {
ioe.printStackTrace();
}
}
};
long millis = period * 1000;
timer.scheduleAtFixedRate(task, millis, millis);
}
}
/**
* Stops timer if it is running
*/
private synchronized void stopTimer() {
if (timer != null) {
timer.cancel();
timer = null;
}
}
/**
* Timer callback.
*/
private void timerEvent() throws IOException {
if (isMonitoring) {
Collection myUpdaters;
synchronized (this) {
myUpdaters = new ArrayList(updaters);
}
// Run all the registered updates without holding a lock
// on this context
for (Updater updater : myUpdaters) {
try {
updater.doUpdates(this);
}
catch (Throwable throwable) {
throwable.printStackTrace();
}
}
emitRecords();
}
}
/**
* Emits the records.
*/
private synchronized void emitRecords() throws IOException {
for (String recordName : bufferedData.keySet()) {
RecordMap recordMap = bufferedData.get(recordName);
synchronized (recordMap) {
Set> entrySet = recordMap.entrySet ();
for (Entry entry : entrySet) {
OutputRecord outRec = new OutputRecord(entry.getKey(), entry.getValue());
emitRecord(contextName, recordName, outRec);
}
}
}
flush();
}
/**
* Retrieves all the records managed by this MetricsContext.
* Useful for monitoring systems that are polling-based.
* @return A non-null collection of all monitoring records.
*/
public synchronized Map> getAllRecords() {
Map> out = new TreeMap>();
for (String recordName : bufferedData.keySet()) {
RecordMap recordMap = bufferedData.get(recordName);
synchronized (recordMap) {
List records = new ArrayList();
Set> entrySet = recordMap.entrySet();
for (Entry entry : entrySet) {
OutputRecord outRec = new OutputRecord(entry.getKey(), entry.getValue());
records.add(outRec);
}
out.put(recordName, records);
}
}
return out;
}
/**
* Sends a record to the metrics system.
*/
protected abstract void emitRecord(String contextName, String recordName,
OutputRecord outRec) throws IOException;
/**
* Called each period after all records have been emitted, this method does nothing.
* Subclasses may override it in order to perform some kind of flush.
*/
protected void flush() throws IOException {
}
/**
* Called by MetricsRecordImpl.update(). Creates or updates a row in
* the internal table of metric data.
*/
protected void update(MetricsRecordImpl record) {
String recordName = record.getRecordName();
TagMap tagTable = record.getTagTable();
Map metricUpdates = record.getMetricTable();
RecordMap recordMap = getRecordMap(recordName);
synchronized (recordMap) {
MetricMap metricMap = recordMap.get(tagTable);
if (metricMap == null) {
metricMap = new MetricMap();
TagMap tagMap = new TagMap(tagTable); // clone tags
recordMap.put(tagMap, metricMap);
}
Set> entrySet = metricUpdates.entrySet();
for (Entry entry : entrySet) {
String metricName = entry.getKey ();
MetricValue updateValue = entry.getValue ();
Number updateNumber = updateValue.getNumber();
Number currentNumber = metricMap.get(metricName);
if (currentNumber == null || updateValue.isAbsolute()) {
metricMap.put(metricName, updateNumber);
}
else {
Number newNumber = sum(updateNumber, currentNumber);
metricMap.put(metricName, newNumber);
}
}
}
}
private synchronized RecordMap getRecordMap(String recordName) {
return bufferedData.get(recordName);
}
/**
* Adds two numbers, coercing the second to the type of the first.
*
*/
private Number sum(Number a, Number b) {
if (a instanceof Integer) {
return Integer.valueOf(a.intValue() + b.intValue());
}
else if (a instanceof Float) {
return new Float(a.floatValue() + b.floatValue());
}
else if (a instanceof Short) {
return Short.valueOf((short)(a.shortValue() + b.shortValue()));
}
else if (a instanceof Byte) {
return Byte.valueOf((byte)(a.byteValue() + b.byteValue()));
}
else if (a instanceof Long) {
return Long.valueOf((a.longValue() + b.longValue()));
}
else {
// should never happen
throw new MetricsException("Invalid number type");
}
}
/**
* Called by MetricsRecordImpl.remove(). Removes all matching rows in
* the internal table of metric data. A row matches if it has the same
* tag names and values as record, but it may also have additional
* tags.
*/
protected void remove(MetricsRecordImpl record) {
String recordName = record.getRecordName();
TagMap tagTable = record.getTagTable();
RecordMap recordMap = getRecordMap(recordName);
synchronized (recordMap) {
Iterator it = recordMap.keySet().iterator();
while (it.hasNext()) {
TagMap rowTags = it.next();
if (rowTags.containsAll(tagTable)) {
it.remove();
}
}
}
}
/**
* Returns the timer period.
*/
public int getPeriod() {
return period;
}
/**
* Sets the timer period
*/
protected void setPeriod(int period) {
this.period = period;
}
/**
* If a period is set in the attribute passed in, override
* the default with it.
*/
protected void parseAndSetPeriod(String attributeName) {
String periodStr = getAttribute(attributeName);
if (periodStr != null) {
int period = 0;
try {
period = Integer.parseInt(periodStr);
} catch (NumberFormatException nfe) {
}
if (period <= 0) {
throw new MetricsException("Invalid period: " + periodStr);
}
setPeriod(period);
}
}
}
