| javax.media.jai.TileScheduler
| TileScheduler | | public interface TileScheduler (Code) | | A class implementing a mechanism for scheduling tile calculation.
In various implementations tile computation may make use of multithreading
and multiple simultaneous network connections for improved performance.
If multithreading is used then the implementation of the interface
must be thread-safe. In particular it must be possible to invoke any of
the tile scheduling methods on the same image simultaneously from different
threads and obtain the same results as if all invocations had been from
the same thread.
Errors and exceptions which occur within the scheduler and which prevent
tile computation will be thrown via the usual mechanism for all blocking
methods, i.e., those which perform the computations while the invoking
thread blocks. Failure conditions encountered in computations effected
via non-blocking methods will be indicated by notifying any listeners.
In neither case is it expected that the tiles will be re-scheduled for
computation this instead being left to the application.
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| Method Summary | |
| void | cancelTiles(TileRequest request, Point[] tileIndices)
Issues an advisory cancellation request to the
TileScheduler stating that the indicated tiles of the
specified request should not be processed. | | int | getParallelism()
Returns the degree of parallelism of the scheduler. | | int | getPrefetchParallelism()
Identical to getParallelism() but applies only to
prefetchTiles(). | | int | getPrefetchPriority()
Identical to getPriority() but applies only to
prefetchTiles(). | | int | getPriority()
Returns the priority of scheduleTiles() processing. | | void | prefetchTiles(PlanarImage target, Point[] tileIndices)
Hints to the TileScheduler that the specified tiles from
the given PlanarImage might be needed in the near future.
Some TileScheduler implementations may spawn a low
priority thread to compute the tiles while others may ignore the hint.
Parameters:
target - The OpImage from which to prefetch tiles. | | Raster | scheduleTile(OpImage target, int tileX, int tileY)
Schedules a tile for computation. | | Raster[] | scheduleTiles(OpImage target, Point tileIndices)
Schedules a list of tiles for computation. | | TileRequest | scheduleTiles(PlanarImage target, Point[] tileIndices, TileComputationListener[] tileListeners)
Schedule a list of tiles for computation. | | void | setParallelism(int parallelism)
Suggests to the scheduler the degree of parallelism to use in
processing invocations of scheduleTiles(). | | void | setPrefetchParallelism(int parallelism)
Identical to setParallelism() but applies only to
prefetchTiles(). | | void | setPrefetchPriority(int priority)
Identical to setPriority() but applies only to
prefetchTiles().
In the Sun Microsystems reference implementation of
TileScheduler, this method sets the priority of any threads
spawned to prefetch tiles. | | void | setPriority(int priority)
Suggests to the scheduler the priority to assign to processing
effected by scheduleTiles(). |
| cancelTiles | | void cancelTiles(TileRequest request, Point[] tileIndices)(Code) | | Issues an advisory cancellation request to the
TileScheduler stating that the indicated tiles of the
specified request should not be processed. The handling of cancellation
is at the discretion of the scheduler which may cancel tile processing
in progress and remove tiles from its internal queue, remove tiles from
the queue but not terminate current processing, or simply do nothing.
In the Sun Microsystems reference implementation of
TileScheduler the second tile cancellation option is
implemented, i.e., tiles are removed from the internal queue but
computation already in progress is not terminated. If there is at
least one worker thread this method should be non-blocking. Any tiles
allowed to complete computation subsequent to this call are complete
and will be treated as if they had not been cancelled, e.g., with
respect to caching, notification of registered listeners, etc.
Furthermore, cancelling a tile request in no way invalidates the tile
as a candidate for future recomputation.
Parameters:
request - The request for which tiles are to be cancelled.
Parameters:
tileIndices - The tiles to be cancelled; may be null.Any tiles not actually in the TileRequest will beignored.
throws:
IllegalArgumentException - if request isnull.
since:
JAI 1.1 |
| getParallelism | | int getParallelism()(Code) | | Returns the degree of parallelism of the scheduler.
since:
JAI 1.1 |
| getPrefetchParallelism | | int getPrefetchParallelism()(Code) | | Identical to getParallelism() but applies only to
prefetchTiles().
since:
JAI 1.1 |
| getPrefetchPriority | | int getPrefetchPriority()(Code) | | Identical to getPriority() but applies only to
prefetchTiles().
since:
JAI 1.1 |
| getPriority | | int getPriority()(Code) | | Returns the priority of scheduleTiles() processing.
since:
JAI 1.1 |
| prefetchTiles | | void prefetchTiles(PlanarImage target, Point[] tileIndices)(Code) | | Hints to the TileScheduler that the specified tiles from
the given PlanarImage might be needed in the near future.
Some TileScheduler implementations may spawn a low
priority thread to compute the tiles while others may ignore the hint.
Parameters:
target - The OpImage from which to prefetch tiles.
Parameters:
tileIndices - A list of tile indices indicating which tilesto prefetch.
throws:
IllegalArgumentException - if target ortileIndices is null. |
| scheduleTile | | Raster scheduleTile(OpImage target, int tileX, int tileY)(Code) | | Schedules a tile for computation. Called by
OpImage.getTile(), this method makes
OpImage.computeTile() calls to calculate
the destination tile. This will provoke the computation
of any required source tiles as well.
Parameters:
target - An OpImage whose tile is to be computed.
Parameters:
tileX - The X index of the tile to be computed.
Parameters:
tileY - The Y index of the tile to be computed. A Raster containing the contents of the tile.
throws:
IllegalArgumentException - if target isnull. |
| scheduleTiles | | Raster[] scheduleTiles(OpImage target, Point tileIndices)(Code) | | Schedules a list of tiles for computation. Called by
OpImage.getTiles, this method makes
OpImage.computeTile() calls to calculate
the destination tiles. This will provoke the computation
of any required source tiles as well.
Parameters:
target - An OpImage whose tiles are to be computed.
Parameters:
tileIndices - A list of tile indices indicating which tilesto schedule for computation. An array of Rasters containing a computedraster for every tile index passed in.
throws:
IllegalArgumentException - if target ortileIndices is null. |
| scheduleTiles | | TileRequest scheduleTiles(PlanarImage target, Point[] tileIndices, TileComputationListener[] tileListeners)(Code) | | Schedule a list of tiles for computation. The supplied listeners
will be notified of the status of each tile, i.e., when each tile
is computed, cancelled, or encounters an error. This
method ideally should be non-blocking. If the TileScheduler
implementation uses multithreading, it is at the discretion of the
implementation which thread invokes the
TileComputationListener methods. The event source
parameter passed to each listener will be the TileScheduler
itself and the image parameter will be the specified target image.
In the Sun Microsystems reference implementation of
TileScheduler the TileComputationListener
methods are invoked by the thread which performs the actual
tile computation. This will be the primary thread if the
parallelism is zero, or a worker thread if it is positive.
Parameters:
target - A PlanarImage whose tiles are to be computed.
Parameters:
tileIndices - A list of tile indices indicating which tilesto schedule for computation.
Parameters:
tileListeners - TileComputationListeners to beinformed of tile computation status; may be null. The TileRequest for this set of tiles.
throws:
IllegalArgumentException - if target ortileIndices is null.
since:
JAI 1.1 |
| setParallelism | | void setParallelism(int parallelism)(Code) | | Suggests to the scheduler the degree of parallelism to use in
processing invocations of scheduleTiles(). For
example, this might set the number of threads to spawn. It is
legal to implement this method as a no-op.
In the Sun Microsystems reference implementation of TileScheduler
this method sets the number of worker threads actually used for tile
computation. Ideally this number should equal the number of processors
actually available on the system. It is the responsibility of the
application to set this value as the number of processors is not
available via the virtual machine. A parallelism value of zero
indicates that all tile computation will be effected in the primary
thread. A parallelism value of N indicates that there will be
N worker threads in addition to the primary scheduler thread.
In JAI the parallelism defaults to a value of 2 unless explicity set
by the application.
Parameters:
parallelism - The suggested degree of parallelism.
throws:
IllegalArgumentException - if parallelismis negative.
since:
JAI 1.1 |
| setPrefetchParallelism | | void setPrefetchParallelism(int parallelism)(Code) | | Identical to setParallelism() but applies only to
prefetchTiles().
since:
JAI 1.1 |
| setPrefetchPriority | | void setPrefetchPriority(int priority)(Code) | | Identical to setPriority() but applies only to
prefetchTiles().
In the Sun Microsystems reference implementation of
TileScheduler, this method sets the priority of any threads
spawned to prefetch tiles. Its initial value is
Thread.MIN_PRIORITY.
since:
JAI 1.1 |
| setPriority | | void setPriority(int priority)(Code) | | Suggests to the scheduler the priority to assign to processing
effected by scheduleTiles(). For example, this might
set thread priority. Values outside of the accepted priority range
will be clamped to the nearest extremum. An implementation may clamp
the prefetch priority to less than the scheduling priority. It is
legal to implement this method as a no-op.
In the Sun Microsystems reference implementation of TileScheduler
this method sets the priority of the worker threads used for tile
computation. Its initial value is Thread.NORM_PRIORITY.
Parameters:
priority - The suggested priority.
since:
JAI 1.1 |
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