it.unimi.dsi.logging

Class ProgressLogger

java.lang.Object

it.unimi.dsi.logging.ProgressLogger

public final class ProgressLogger
extends Object

Tunable progress logger.

This class provides a simple way to log progress information about long-lasting activities. While originally based on Log4J 1.2, it is currently based on SLF4J.

To use this class, you first create a new instance by passing an SLF4J logger, a time interval and a name for the items that are being logged. Information will be logged about the current state of affairs no more often than the given time interval. Note that the name of the logged items can be changed at any time.

To log the progress of an activity, you call start(CharSequence) at the beginning, which will display the given string. Then, each time you want to mark progress, you call usually update() or lightUpdate(). The latter methods increase the item counter, and will log progress information if enough time has passed since the last log (and if the counter is a multiple of LIGHT_UPDATE_MASK + 1, in the case of lightUpdate()). Other update methods (e.g., update(long), updateAndDisplay(), …) make the update and display process very flexible. When the activity is over, you call stop(). At that point, the method toString() returns information about the internal state of the logger (elapsed time, number of items per second) that can be printed or otherwise processed. If update() has never been called, you will just get the elapsed time. By calling done() instead of stop, this information will be logged for you.

Additionally:

• by setting the expected amount of updates before calling start() you can get some estimations on the completion time;
• by setting displayFreeMemory you can display information about the memory usage;
• by setting displayLocalSpeed you can display, beside the average speed since the start of the activity, the speed since the last log;
• by setting info you can display arbitrary additional information.
• by setting speedTimeUnit and itemTimeUnit you can fix the time unit used to measure the speed and the time per item.

After you finished a run of the progress logger, you can change its attributes and call start() again to measure another activity.

A typical call sequence to a progress logger is as follows:

 ProgressLogger pl = new ProgressLogger( logger, 1, TimeUnit.MINUTES );
 pl.start( "Smashing pumpkins..." );
 ... activity on pumpkins that calls update() on each pumpkin ...
 pl.done();
 

A more flexible behaviour can be obtained at the end of the process by calling stop():

 ProgressLogger pl = new ProgressLogger( logger, 1, TimeUnit.MINUTES, "pumpkins" );
 pl.start( "Smashing pumpkins..." );
 ... activity on pumpkins that calls update() on each pumpkin ...
 pl.stop( "Really done!" );
 pl.logger.info( pl.toString() );
 

An instance of this class can also be used as a handy timer:

 ProgressLogger pl = new ProgressLogger();
 pl.start( "Smashing pumpkins..." );
 ... activity on pumpkins (no update() calls) ...
 pl.done( howManyPumpkins );
 

Should you need to display additional information, you can set the field info to any object: it will be printed just after the timing (and possibly memory) information.

Since:

0.9.3

Author:

Sebastiano Vigna

Field Summary

Fields

Modifier and Type	Field and Description
long	count The number of calls to update() since the last start() (but it be changed also with update(long) and set(long)).
static long	DEFAULT_LOG_INTERVAL
boolean	displayFreeMemory Whether to display the free memory at each progress log (default: false).
boolean	displayLocalSpeed Whether to display additionally the local speed, that is, the detected speed between two consecutive logs, as opposed to the average speed since start() (default: false).
long	expectedUpdates The number of expected calls to update() (used to compute the percentages, ignored if negative).
Object	info If non-null, this object will be printed after the timing information.
String	itemsName The name of several counted items.
TimeUnit	itemTimeUnit A fixed time unit for printing the timing of an item.
int	LIGHT_UPDATE_MASK Calls to lightUpdate() will cause a call to System.currentTimeMillis() only if the current value of count is a multiple of this mask plus one.
Logger	logger The SLF4J logger used by this progress logger.
long	logInterval The time interval for a new log in milliseconds.
static long	ONE_HOUR
static long	ONE_MINUTE
static long	ONE_SECOND
TimeUnit	speedTimeUnit A fixed time unit for printing the speed.
static long	TEN_MINUTES
static long	TEN_SECONDS

Constructor Summary

Constructors

Constructor and Description
ProgressLogger() Creates a new progress logger using items as items name and logging every 10000L milliseconds to the root logger.
ProgressLogger(Logger logger) Creates a new progress logger using items as items name and logging every 10000L milliseconds.
ProgressLogger(Logger logger, long logInterval, TimeUnit timeUnit) Creates a new progress logger using items as items name.
ProgressLogger(Logger logger, long logInterval, TimeUnit timeUnit, String itemsName) Creates a new progress logger.
ProgressLogger(Logger logger, String itemsName) Creates a new progress logger logging every 10000L milliseconds.
ProgressLogger(String itemsName) Creates a new progress logger logging every 10000L milliseconds to the root logger.

Method Summary

Methods

Modifier and Type	Method and Description
void	done() Completes a run of this progress logger, logging “Completed.” and the logger itself.
void	done(long count) Completes a run of this progress logger and sets the internal counter, logging “Completed.” and the logger itself.
void	lightUpdate() Updates the internal count of this progress logger by adding one in a lightweight fashion.
Logger	logger() The SLF4J logger used by this progress logger; it just returns the content of the field logger.
long	millis() Returns the number of milliseconds between present time and the last call to start(), if this progress logger is running, or between the last call to stop() and the last call to start(), if this progress logger is stopped.
void	set(long count) Sets the internal count of this progress logger to a specified value; if enough time has passed since the last log, information will be logged.
void	setAndDisplay(long count) Sets the internal count of this progress logger to a specified value, forcing a display.
void	start() Starts the progress logger, resetting the count.
void	start(CharSequence message) Starts the progress logger, displaying a message and resetting the count.
void	start(CharSequence message, long alreadyElapsed) Starts the progress logger, displaying a message, resetting the count and assuming that a given amount of time has already passed.
void	start(long alreadyElapsed) Starts the progress logger, resetting the count and assuming that a given amount of time has already passed.
void	stop() Stops the progress logger.
void	stop(CharSequence message) Stops the progress logger, displaying a message.
String	toString() Converts the data currently stored in this progress logger to a string.
void	update() Updates the internal count of this progress logger by adding one; if enough time has passed since the last log, information will be logged.
void	update(long count) Updates the internal count of this progress logger by adding a specified value; if enough time has passed since the last log, information will be logged.
void	updateAndDisplay() Updates the internal count of this progress logger by adding one, forcing a display.
void	updateAndDisplay(long count) Updates the internal count of this progress logger by adding a specified value, forcing a display.

Methods inherited from class java.lang.Object

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

Field Detail

ONE_SECOND

public static final long ONE_SECOND

See Also:

Constant Field Values

TEN_SECONDS

public static final long TEN_SECONDS

See Also:

Constant Field Values

ONE_MINUTE

public static final long ONE_MINUTE

See Also:

Constant Field Values

TEN_MINUTES

public static final long TEN_MINUTES

See Also:

Constant Field Values

ONE_HOUR

public static final long ONE_HOUR

See Also:

Constant Field Values

DEFAULT_LOG_INTERVAL

public static final long DEFAULT_LOG_INTERVAL

See Also:

Constant Field Values

LIGHT_UPDATE_MASK

public final int LIGHT_UPDATE_MASK

Calls to lightUpdate() will cause a call to System.currentTimeMillis() only if the current value of count is a multiple of this mask plus one.

See Also:

Constant Field Values

logger

public final Logger logger

The SLF4J logger used by this progress logger.

logInterval

public long logInterval

The time interval for a new log in milliseconds. Can be set at any time (e.g., using TimeUnit.toMillis(long)).

info

public Object info

If non-null, this object will be printed after the timing information.

count

public long count

The number of calls to update() since the last start() (but it be changed also with update(long) and set(long)).

expectedUpdates

public long expectedUpdates

The number of expected calls to update() (used to compute the percentages, ignored if negative).

itemsName

public String itemsName

The name of several counted items.

displayFreeMemory

public boolean displayFreeMemory

Whether to display the free memory at each progress log (default: false).

displayLocalSpeed

public boolean displayLocalSpeed

Whether to display additionally the local speed, that is, the detected speed between two consecutive logs, as opposed to the average speed since start() (default: false).

speedTimeUnit

public TimeUnit speedTimeUnit

A fixed time unit for printing the speed. If null, ProgressLogger will choose a time unit that is easy to understand. In some cases (e.g., machine-parsed logs) you might want to have always the speed in items per seconds, minues, hours or days.

itemTimeUnit

public TimeUnit itemTimeUnit

A fixed time unit for printing the timing of an item. If null, ProgressLogger chooses a unit that is easy to understand. In some cases (e.g., machine-parsed logs) you might want to have always have the time for an item in nanoseconds, milliseconds, milliseconds, seconds, minutes or hours.

Constructor Detail

ProgressLogger

public ProgressLogger()

Creates a new progress logger using items as items name and logging every 10000L milliseconds to the root logger.

ProgressLogger

public ProgressLogger(String itemsName)

Creates a new progress logger logging every 10000L milliseconds to the root logger.

Parameters:

itemsName - a plural name denoting the counted items.

ProgressLogger

public ProgressLogger(Logger logger)

Creates a new progress logger using items as items name and logging every 10000L milliseconds.

Parameters:

logger - the logger to which messages will be sent.

ProgressLogger

public ProgressLogger(Logger logger,
              String itemsName)

Creates a new progress logger logging every 10000L milliseconds.

Parameters:

logger - the logger to which messages will be sent.

itemsName - a plural name denoting the counted items.

ProgressLogger

public ProgressLogger(Logger logger,
              long logInterval,
              TimeUnit timeUnit)

Creates a new progress logger using items as items name.

Parameters:

logger - the logger to which messages will be sent.

logInterval - the logging interval.

timeUnit - the unit of time of logInterval.

ProgressLogger

public ProgressLogger(Logger logger,
              long logInterval,
              TimeUnit timeUnit,
              String itemsName)

Creates a new progress logger.

Parameters:

logger - the logger to which messages will be sent.

logInterval - the logging interval.

timeUnit - the unit of time of logInterval.

itemsName - a plural name denoting the counted items.

Method Detail

logger

public Logger logger()

The SLF4J logger used by this progress logger; it just returns the content of the field logger.

update

public void update()

Updates the internal count of this progress logger by adding one; if enough time has passed since the last log, information will be logged.

This method is kept intentionally short (it delegates most of the work to an internal private method) so to suggest inlining. However, it performs a call to System.currentTimeMillis() that takes microseconds (not nanoseconds). If you plan on calling this method more than a few thousands times per second, you should use lightUpdate().

update

public void update(long count)

Updates the internal count of this progress logger by adding a specified value; if enough time has passed since the last log, information will be logged.

See Also:

update()

updateAndDisplay

public void updateAndDisplay()

Updates the internal count of this progress logger by adding one, forcing a display.

See Also:

update()

set

public void set(long count)

Sets the internal count of this progress logger to a specified value; if enough time has passed since the last log, information will be logged.

See Also:

update()

setAndDisplay

public void setAndDisplay(long count)

Sets the internal count of this progress logger to a specified value, forcing a display.

See Also:

update()

updateAndDisplay

public void updateAndDisplay(long count)

Updates the internal count of this progress logger by adding a specified value, forcing a display.

See Also:

update()

lightUpdate

public final void lightUpdate()

Updates the internal count of this progress logger by adding one in a lightweight fashion.

This call updates the progress logger internal counter as update(). However, it will actually call System.currentTimeMillis() only if the new count is a multiple of LIGHT_UPDATE_MASK + 1. This mechanism makes it possible to reduce the number of calls to System.currentTimeMillis() significantly.

This method is useful when the operations being counted take less than a few microseconds.

See Also:

update()

start

public void start()

Starts the progress logger, resetting the count.

start

public void start(CharSequence message)

Starts the progress logger, displaying a message and resetting the count.

Parameters:

message - the message to display.

start

public void start(long alreadyElapsed)

Starts the progress logger, resetting the count and assuming that a given amount of time has already passed.

Parameters:

alreadyElapsed - the number of milliseconds already elapsed.

See Also:

start(CharSequence, long)

start

public void start(CharSequence message,
         long alreadyElapsed)

Starts the progress logger, displaying a message, resetting the count and assuming that a given amount of time has already passed.

The effect of the alreadyElapsed parameter is that the start time of this ProgressLogger will be set to System.currentTimeMillis() minus alreadyElapsed.

Parameters:

message - the message to display.

alreadyElapsed - the number of milliseconds already elapsed.

stop

public void stop(CharSequence message)

Stops the progress logger, displaying a message.

This method will also mark expectedUpdates as invalid, to avoid erroneous reuses of previous values.

Parameters:

message - the message to display.

stop

public void stop()

Stops the progress logger.

done

public void done()

Completes a run of this progress logger, logging “Completed.” and the logger itself.

done

public void done(long count)

Completes a run of this progress logger and sets the internal counter, logging “Completed.” and the logger itself.

This method is particularly useful in two circumstances:

• you have updated the logger with some approximate values (e.g., in a multicore computation) but before printing the final statistics you want the internal counter to contain an exact value;
• you have used the logger as a handy timer, calling just start() and this method.

Parameters:

count - will replace the internal counter value.

millis

public long millis()

Returns the number of milliseconds between present time and the last call to start(), if this progress logger is running, or between the last call to stop() and the last call to start(), if this progress logger is stopped.

Returns:

the number of milliseconds between present time and the last call to start(), if this progress logger is running, or between the last call to stop() and the last call to start(), if this progress logger is stopped.

toString

public String toString()

Converts the data currently stored in this progress logger to a string.

If this progress logger has been stopped, statistics are computed using the stop time. Otherwise, they are computed using the current time (i.e., the method call time).

Overrides:

toString in class Object

Returns:

the current data in this progress logger in a printable form.