/*
* MetricsRecord.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;
/**
* A named and optionally tagged set of records to be sent to the metrics
* system. <p/>
*
* A record name identifies the kind of data to be reported. For example, a
* program reporting statistics relating to the disks on a computer might use
* a record name "diskStats".<p/>
*
* A record has zero or more <i>tags</i>. A tag has a name and a value. To
* continue the example, the "diskStats" record might use a tag named
* "diskName" to identify a particular disk. Sometimes it is useful to have
* more than one tag, so there might also be a "diskType" with value "ide" or
* "scsi" or whatever.<p/>
*
* A record also has zero or more <i>metrics</i>. These are the named
* values that are to be reported to the metrics system. In the "diskStats"
* example, possible metric names would be "diskPercentFull", "diskPercentBusy",
* "kbReadPerSecond", etc.<p/>
*
* The general procedure for using a MetricsRecord is to fill in its tag and
* metric values, and then call <code>update()</code> to pass the record to the
* client library.
* Metric data is not immediately sent to the metrics system
* each time that <code>update()</code> is called.
* An internal table is maintained, identified by the record name. This
* table has columns
* corresponding to the tag and the metric names, and rows
* corresponding to each unique set of tag values. An update
* either modifies an existing row in the table, or adds a new row with a set of
* tag values that are different from all the other rows. Note that if there
* are no tags, then there can be at most one row in the table. <p/>
*
* Once a row is added to the table, its data will be sent to the metrics system
* on every timer period, whether or not it has been updated since the previous
* timer period. If this is inappropriate, for example if metrics were being
* reported by some transient object in an application, the <code>remove()</code>
* method can be used to remove the row and thus stop the data from being
* sent.<p/>
*
* Note that the <code>update()</code> method is atomic. This means that it is
* safe for different threads to be updating the same metric. More precisely,
* it is OK for different threads to call <code>update()</code> on MetricsRecord instances
* with the same set of tag names and tag values. Different threads should
* <b>not</b> use the same MetricsRecord instance at the same time.
*/
public interface MetricsRecord {
/**
* Returns the record name.
*
* @return the record name
*/
public abstract String getRecordName();
/**
* Sets the named tag to the specified value. The tagValue may be null,
* which is treated the same as an empty String.
*
* @param tagName name of the tag
* @param tagValue new value of the tag
* @throws MetricsException if the tagName conflicts with the configuration
*/
public abstract void setTag(String tagName, String tagValue);
/**
* Sets the named tag to the specified value.
*
* @param tagName name of the tag
* @param tagValue new value of the tag
* @throws MetricsException if the tagName conflicts with the configuration
*/
public abstract void setTag(String tagName, int tagValue);
/**
* Sets the named tag to the specified value.
*
* @param tagName name of the tag
* @param tagValue new value of the tag
* @throws MetricsException if the tagName conflicts with the configuration
*/
public abstract void setTag(String tagName, long tagValue);
/**
* Sets the named tag to the specified value.
*
* @param tagName name of the tag
* @param tagValue new value of the tag
* @throws MetricsException if the tagName conflicts with the configuration
*/
public abstract void setTag(String tagName, short tagValue);
/**
* Sets the named tag to the specified value.
*
* @param tagName name of the tag
* @param tagValue new value of the tag
* @throws MetricsException if the tagName conflicts with the configuration
*/
public abstract void setTag(String tagName, byte tagValue);
/**
* Removes any tag of the specified name.
*
* @param tagName name of a tag
*/
public abstract void removeTag(String tagName);
/**
* Sets the named metric to the specified value.
*
* @param metricName name of the metric
* @param metricValue new value of the metric
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void setMetric(String metricName, int metricValue);
/**
* Sets the named metric to the specified value.
*
* @param metricName name of the metric
* @param metricValue new value of the metric
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void setMetric(String metricName, long metricValue);
/**
* Sets the named metric to the specified value.
*
* @param metricName name of the metric
* @param metricValue new value of the metric
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void setMetric(String metricName, short metricValue);
/**
* Sets the named metric to the specified value.
*
* @param metricName name of the metric
* @param metricValue new value of the metric
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void setMetric(String metricName, byte metricValue);
/**
* Sets the named metric to the specified value.
*
* @param metricName name of the metric
* @param metricValue new value of the metric
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void setMetric(String metricName, float metricValue);
/**
* Increments the named metric by the specified value.
*
* @param metricName name of the metric
* @param metricValue incremental value
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void incrMetric(String metricName, int metricValue);
/**
* Increments the named metric by the specified value.
*
* @param metricName name of the metric
* @param metricValue incremental value
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void incrMetric(String metricName, long metricValue);
/**
* Increments the named metric by the specified value.
*
* @param metricName name of the metric
* @param metricValue incremental value
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void incrMetric(String metricName, short metricValue);
/**
* Increments the named metric by the specified value.
*
* @param metricName name of the metric
* @param metricValue incremental value
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void incrMetric(String metricName, byte metricValue);
/**
* Increments the named metric by the specified value.
*
* @param metricName name of the metric
* @param metricValue incremental value
* @throws MetricsException if the metricName or the type of the metricValue
* conflicts with the configuration
*/
public abstract void incrMetric(String metricName, float metricValue);
/**
* Updates the table of buffered data which is to be sent periodically.
* If the tag values match an existing row, that row is updated;
* otherwise, a new row is added.
*/
public abstract void update();
/**
* Removes, from the buffered data table, all rows having tags
* that equal the tags that have been set on this record. For example,
* if there are no tags on this record, all rows for this record name
* would be removed. Or, if there is a single tag on this record, then
* just rows containing a tag with the same name and value would be removed.
*/
public abstract void remove();
}