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 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
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package org.glassfish.jersey.server.monitoring;

Monitoring statistics of execution of any target (resource, resource method, application). The main parameter of TimeWindowStatistics is the size of the time window. This is the time for which the statistics are measured (for example for time window 1 hour, the statistics are evaluated for last one hour and older statistics are dropped). The size of the time window can be retrieved by getTimeWindow(). 
 Statistics retrieved from Jersey runtime might be mutable and thanks to it might provide inconsistent data as not all statistics are updated in the same time. To retrieve the immutable and consistent statistics data the method snapshot() should be used. 

Author:
Miroslav Fuksa
See Also:
See monitoring statistics for general details about statistics./**
 * Monitoring statistics of execution of any target (resource, resource method, application).
 * The main parameter of {@code TimeWindowStatistics} is the size of the time window. This is the time
 * for which the statistics are measured (for example for time window 1 hour, the statistics are evaluated
 * for last one hour and older statistics are dropped). The size of the time window can be retrieved by
 * {@link #getTimeWindow()}.
 * <p/>
 * Statistics retrieved from Jersey runtime might be mutable and thanks to it might provide inconsistent data
 * as not all statistics are updated in the same time. To retrieve the immutable and consistent
 * statistics data the method {@link #snapshot()} should be used.
 * <p/>
 *
 * @author Miroslav Fuksa
 * @see MonitoringStatistics See monitoring statistics for general details about statistics.
 */
public interface TimeWindowStatistics {

    
Returns the size of time window in milliseconds. Returned value denotes in how many last milliseconds
the statistics are evaluated.
Returns:
Time window in milliseconds./**
     * Returns the size of time window in milliseconds. Returned value denotes in how many last milliseconds
     * the statistics are evaluated.
     *
     * @return Time window in milliseconds.
     */
    public long getTimeWindow();

    
Returns average value of how many requests per second were received by application in the time window.
Returns:
Average of requests per second./**
     * Returns average value of how many requests per second were received by application in the time window.
     *
     * @return Average of requests per second.
     */
    public double getRequestsPerSecond();

    
Returns the minimum duration (processing time) in milliseconds of the request processing measured
in the time window.
The time measures the
processing of the request since the start of request processing by Jersey until the response is
written or request processing fails and all resources for request processing are released.
Returns:
Minimum processing time of the request or -1 if no request has been processed./**
     * Returns the minimum duration (processing time) in milliseconds of the request processing measured
     * in the time window.
     * The time measures the
     * processing of the request since the start of request processing by Jersey until the response is
     * written or request processing fails and all resources for request processing are released.
     *
     * @return Minimum processing time of the request or -1 if no request has been processed.
     */
    public long getMinimumDuration();

    
Returns the maximum duration (processing time) in milliseconds of the request processing measured
in the time window.
processing of the request since the start of request processing by Jersey until the response is
written or request processing fails and all resources for request processing are released.
Returns:
Maximum processing time of the request or -1 if no request has been processed./**
     * Returns the maximum duration (processing time) in milliseconds of the request processing measured
     * in the time window.
     * processing of the request since the start of request processing by Jersey until the response is
     * written or request processing fails and all resources for request processing are released.
     *
     * @return Maximum processing time of the request or -1 if no request has been processed.
     */
    public long getMaximumDuration();

    
Returns the average duration (processing time) in milliseconds of the request processing measured
in the time window.
The time measures the
processing of the request since the start of request processing by Jersey until the response is
written or request processing fails and all resources for request processing are released.
Returns:
Average processing time of the request or -1 if no request has been processed./**
     * Returns the average duration (processing time) in milliseconds of the request processing measured
     * in the time window.
     * The time measures the
     * processing of the request since the start of request processing by Jersey until the response is
     * written or request processing fails and all resources for request processing are released.
     *
     * @return Average processing time of the request or -1 if no request has been processed.
     */
    public long getAverageDuration();

    
Returns the count of requests received measured in the time window.
Returns:
Count of requests that were handled by the application./**
     * Returns the count of requests received measured in the time window.
     *
     * @return Count of requests that were handled by the application.
     */
    public long getRequestCount();

    
Get the immutable and consistent snapshot of the monitoring statistics. Working with snapshots might
have negative performance impact as snapshot must be created but ensures consistency of data over time.
However, the usage of snapshot is encouraged to avoid working with inconsistent data. Not all statistics
must be updated in the same time on mutable version of statistics.
Returns:
Snapshot of time window statistics.
Deprecated:
implementing class is immutable hence snapshot creation is not needed anymore/**
     * Get the immutable and consistent snapshot of the monitoring statistics. Working with snapshots might
     * have negative performance impact as snapshot must be created but ensures consistency of data over time.
     * However, the usage of snapshot is encouraged to avoid working with inconsistent data. Not all statistics
     * must be updated in the same time on mutable version of statistics.
     *
     * @return Snapshot of time window statistics.
     * @deprecated implementing class is immutable hence snapshot creation is not needed anymore
     */
    @Deprecated
    public TimeWindowStatistics snapshot();
}