The
RequestProgressTracker
class provides the functionality to
track the progress of request processing. Instances of this class are
provided through the
org.apache.sling.api.SlingHttpServletRequest#getRequestProgressTracker()method.
The following functionality is provided:
- Track the progress of request processing through the
#log(String) and
#log(String,Object...) methods.
- Ability to measure and track processing times of parts of request
processing through the
#startTimer(String),
#logTimer(String) and
#logTimer(String,String,Object...)methods.
- Dumping the recording messages through the
#dump(PrintWriter)method.
- Return the log messages through the
#getMessages() method.
Tracking Request Processing
As the request being processed, certain steps may be tracked by calling
either of the log
methods. A tracking entry consists of a time
stamp managed by this class and a tracking message noting the actual step
being tracked.
Timing Processing Steps
Certain steps during request processing may need to be timed in that the time
required for processing should be recorded. Instances of this class maintain
a map of named timers. Each timer is started (initialized or reset) by
calling the
#startTimer(String) method. This method just records the
starting time of the named timer and adds a tracking entry with the timer
name as the message.
To record the number of milliseconds elapsed since a timer has been started,
the
#logTimer(String) or
#logTimer(String,String,Object...)method may be called. This method logs a tracking entry with a message
consisting of the name of the timer and the number of milliseconds elapsed
since the timer was last
#startTimer(String). The
logTimer
methods may be called multiple times to record
several timed steps.
Calling the
#startTimer(String) method with the name of timer which
already exists, resets the start time of the named timer to the current
system time.
Retrieving Tracking Entries
The
#dump(PrintWriter) method may be used to write the tracking
entries to the given PrintWriter
to for example log them in a
HTML comment. Alternatively the tracking entries may be retrieved as an
iterator of messages through the
#getMessages() method. The
formatting of the tracking entries is implementation specific.