org.javasimon.javaee
Class SimonServletFilter

java.lang.Object
  org.javasimon.javaee.SimonServletFilter

All Implemented Interfaces:

javax.servlet.Filter

public class SimonServletFilter
extends Object
implements javax.servlet.Filter

Simon Servlet filter measuring HTTP request execution times. Non-HTTP usages are not supported. Filter provides these functions:

• measures all requests and creates tree of Simons with names derived from URLs
• checks if the request is not longer then a specified threshold and logs warning
• provides basic "console" function if config parameter INIT_PARAM_SIMON_CONSOLE_PATH is used in web.xml

All constants are public and fields protected for easy extension of the class. Following protected methods and classes are provided to override the default function:

• shouldBeReported(javax.servlet.http.HttpServletRequest, long, java.util.List) - compares actual request nano time with getThreshold(javax.servlet.http.HttpServletRequest) (which may become unused if this method is overridden)
• getThreshold(javax.servlet.http.HttpServletRequest) - returns threshold configured in web.xml
• RequestReporter can be implemented and specified using init parameter INIT_PARAM_REQUEST_REPORTER_CLASS
• HttpStopwatchSource can be subclassed and specified using init parameter INIT_PARAM_STOPWATCH_SOURCE_CLASS, specifically following methods are intended for override:
  • HttpStopwatchSource.isMonitored(javax.servlet.http.HttpServletRequest) - true except for request with typical resource suffixes (.gif, .jpg, .css, etc.)
  • HttpStopwatchSource.getMonitorName(javax.servlet.http.HttpServletRequest)

Since:

2.3

Author:

Richard "Virgo" Richter

Nested Class Summary

private class

SimonServletFilter.SplitSaverCallback

Field Summary

protected String	consolePath URL path that displays Simon web console (or null if no console is required).
private static Replacer	FINAL_SLASH_REMOVE
static String	INIT_PARAM_PREFIX Name of filter init parameter for Simon name prefix.
static String	INIT_PARAM_REPORT_THRESHOLD_MS Name of filter init parameter that sets the value of threshold in milliseconds for maximal request duration beyond which all splits will be dumped to log.
static String	INIT_PARAM_REQUEST_REPORTER_CLASS FQN of the RequestReporter implementation that is used to report requests that shouldBeReported(javax.servlet.http.HttpServletRequest, long, java.util.List).
static String	INIT_PARAM_SIMON_CONSOLE_PATH Name of filter init parameter that sets relative ULR path that will provide Simon console page.
static String	INIT_PARAM_STOPWATCH_SOURCE_CACHE Enable/disable caching on Stopwatch resolution.
static String	INIT_PARAM_STOPWATCH_SOURCE_CLASS FQN of the Stopwatch source class implementing MonitorSource.
private Manager	manager Simon Manager used by the filter.
protected String	printTreePath URL path that displays Simon tree - it is console-path without the ending slash.
protected Long	reportThresholdNanos Threshold in ns - any request longer than this will be reported by current requestReporter instance.
private RequestReporter	requestReporter Object responsible for reporting the request over threshold (if shouldBeReported(javax.servlet.http.HttpServletRequest, long, java.util.List) returns true).
private static Replacer	SLASH_TRIM
private SimonServletFilter.SplitSaverCallback	splitSaverCallback Callback that saves all splits in splitsThreadLocal if reportThresholdNanos is configured.
private ThreadLocal<List<Split>>	splitsThreadLocal Thread local list of splits used to cumulate all splits for the request.
private StopwatchSource<javax.servlet.http.HttpServletRequest>	stopwatchSource Stopwatch source is used before/after each request to start/stop a stopwatch.

Constructor Summary

SimonServletFilter()

Method Summary

private void	consolePage(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, String localPath)
void	destroy() Removes the splitSaverCallback if initialized.
void	doFilter(javax.servlet.ServletRequest servletRequest, javax.servlet.ServletResponse servletResponse, javax.servlet.FilterChain filterChain) Wraps the HTTP request with Simon measuring.
private void	doFilterWithMonitoring(javax.servlet.FilterChain filterChain, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
Manager	getManager()
protected long	getThreshold(javax.servlet.http.HttpServletRequest request) Returns actual threshold in *nanoseconds* (not ms as configured) which allows to further customize threshold per request - intended for override.
void	init(javax.servlet.FilterConfig filterConfig) Initialization method that processes various init parameters from web.xml and sets manager, if SimonUtils.MANAGER_SERVLET_CTX_ATTRIBUTE servlet context attribute is not null.
private void	pickUpSharedManagerIfExists(javax.servlet.FilterConfig filterConfig)
private void	printSimonTree(javax.servlet.ServletResponse response)
protected boolean	shouldBeReported(javax.servlet.http.HttpServletRequest request, long requestNanoTime, List<Split> splits) Determines whether the request is over the threshold - with all incoming parameters this method can be very flexible.
private void	simonHelp(javax.servlet.ServletResponse response)
private void	stopSplitForRequest(javax.servlet.http.HttpServletRequest request, Split split)

Methods inherited from class java.lang.Object

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

Field Detail

INIT_PARAM_PREFIX

public static final String INIT_PARAM_PREFIX

Name of filter init parameter for Simon name prefix.

See Also:

Constant Field Values

INIT_PARAM_REPORT_THRESHOLD_MS

public static final String INIT_PARAM_REPORT_THRESHOLD_MS

Name of filter init parameter that sets the value of threshold in milliseconds for maximal request duration beyond which all splits will be dumped to log. The actual threshold can be further customized overriding getThreshold(javax.servlet.http.HttpServletRequest) method, but this parameter has to be set to non-null value to enable threshold reporting feature (0 for instance).

See Also:

Constant Field Values

INIT_PARAM_SIMON_CONSOLE_PATH

public static final String INIT_PARAM_SIMON_CONSOLE_PATH

Name of filter init parameter that sets relative ULR path that will provide Simon console page. If the parameter is not used, basic plain text console will be disabled.

See Also:

Constant Field Values

INIT_PARAM_STOPWATCH_SOURCE_CLASS

public static final String INIT_PARAM_STOPWATCH_SOURCE_CLASS

FQN of the Stopwatch source class implementing MonitorSource. One can use DisabledMonitorSource to disabled monitoring. Defaults to HttpStopwatchSource.

See Also:

Constant Field Values

INIT_PARAM_STOPWATCH_SOURCE_CACHE

public static final String INIT_PARAM_STOPWATCH_SOURCE_CACHE

Enable/disable caching on Stopwatch resolution. Warning: as the cache key is the HttpServletRequest.getRequestURI(), this is incompatible with application passing data in their request URI, this is often the case of RESTful services. For instance "/car/1023/driver" and "/car/3624/driver" may point to the same page but with different URLs. Defaults to false.

See Also:

Constant Field Values

INIT_PARAM_REQUEST_REPORTER_CLASS

public static final String INIT_PARAM_REQUEST_REPORTER_CLASS

FQN of the RequestReporter implementation that is used to report requests that shouldBeReported(javax.servlet.http.HttpServletRequest, long, java.util.List). Default is DefaultRequestReporter.

See Also:

Constant Field Values

FINAL_SLASH_REMOVE

private static Replacer FINAL_SLASH_REMOVE

SLASH_TRIM

private static Replacer SLASH_TRIM

reportThresholdNanos

protected Long reportThresholdNanos

Threshold in ns - any request longer than this will be reported by current requestReporter instance. Specified by INIT_PARAM_REPORT_THRESHOLD_MS ("report-threshold-ms") in the web.xml (in ms, converted to ns during servlet init). This is the default value returned by getThreshold(javax.servlet.http.HttpServletRequest) but it may be completely ignored if method is overridden so. However if the field is null threshold reporting feature is disabled.

printTreePath

protected String printTreePath

URL path that displays Simon tree - it is console-path without the ending slash.

consolePath

protected String consolePath

URL path that displays Simon web console (or null if no console is required).

manager

private Manager manager

Simon Manager used by the filter.

splitsThreadLocal

private final ThreadLocal<List<Split>> splitsThreadLocal

Thread local list of splits used to cumulate all splits for the request. Every instance of the Servlet has its own thread-local to bind its lifecycle to the callback that servlet is registering. Then even more callbacks registered from various servlets in the same manager do not interfere.

splitSaverCallback

private SimonServletFilter.SplitSaverCallback splitSaverCallback

Callback that saves all splits in splitsThreadLocal if reportThresholdNanos is configured.

stopwatchSource

private StopwatchSource<javax.servlet.http.HttpServletRequest> stopwatchSource

Stopwatch source is used before/after each request to start/stop a stopwatch.

requestReporter

private RequestReporter requestReporter

Object responsible for reporting the request over threshold (if shouldBeReported(javax.servlet.http.HttpServletRequest, long, java.util.List) returns true).

Constructor Detail

SimonServletFilter

public SimonServletFilter()

Method Detail

init

public final void init(javax.servlet.FilterConfig filterConfig)

Initialization method that processes various init parameters from web.xml and sets manager, if SimonUtils.MANAGER_SERVLET_CTX_ATTRIBUTE servlet context attribute is not null.

Specified by:

init in interface javax.servlet.Filter

Parameters:

filterConfig - filter config object

pickUpSharedManagerIfExists

private void pickUpSharedManagerIfExists(javax.servlet.FilterConfig filterConfig)

doFilter

public final void doFilter(javax.servlet.ServletRequest servletRequest,
                           javax.servlet.ServletResponse servletResponse,
                           javax.servlet.FilterChain filterChain)
                    throws IOException,
                           javax.servlet.ServletException

Wraps the HTTP request with Simon measuring. Separate Simons are created for different URIs (parameters ignored).

Specified by:

doFilter in interface javax.servlet.Filter

Parameters:

servletRequest - HTTP servlet request

servletResponse - HTTP servlet response

filterChain - filter chain

Throws:

IOException - possibly thrown by other filter/servlet in the chain

javax.servlet.ServletException - possibly thrown by other filter/servlet in the chain

doFilterWithMonitoring

private void doFilterWithMonitoring(javax.servlet.FilterChain filterChain,
                                    javax.servlet.http.HttpServletRequest request,
                                    javax.servlet.http.HttpServletResponse response)
                             throws IOException,
                                    javax.servlet.ServletException

Throws:

IOException

javax.servlet.ServletException

stopSplitForRequest

private void stopSplitForRequest(javax.servlet.http.HttpServletRequest request,
                                 Split split)

shouldBeReported

protected boolean shouldBeReported(javax.servlet.http.HttpServletRequest request,
                                   long requestNanoTime,
                                   List<Split> splits)

Determines whether the request is over the threshold - with all incoming parameters this method can be very flexible. Default implementation just compares the actual requestNanoTime with getThreshold(javax.servlet.http.HttpServletRequest) (which by default returns value configured in web.xml)

Parameters:

request - HTTP servlet request

requestNanoTime - actual HTTP request nano time

splits - all splits started for the request

Returns:

true, if request should be reported as over threshold

getThreshold

protected long getThreshold(javax.servlet.http.HttpServletRequest request)

Returns actual threshold in *nanoseconds* (not ms as configured) which allows to further customize threshold per request - intended for override. Default behavior returns configured reportThresholdNanos (already converted to ns).

Parameters:

request - HTTP Request

Returns:

threshold in ns for current request

Since:

3.2

consolePage

private void consolePage(javax.servlet.http.HttpServletRequest request,
                         javax.servlet.http.HttpServletResponse response,
                         String localPath)
                  throws IOException

Throws:

IOException

simonHelp

private void simonHelp(javax.servlet.ServletResponse response)
                throws IOException

Throws:

IOException

printSimonTree

private void printSimonTree(javax.servlet.ServletResponse response)
                     throws IOException

Throws:

IOException

getManager

public Manager getManager()

destroy

public void destroy()

Removes the splitSaverCallback if initialized.

Specified by:

destroy in interface javax.servlet.Filter