/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.nc2.iosp;
import ucar.ma2.InvalidRangeException;
import ucar.ma2.Section;
import java.io.IOException;
/**
* For datasets where the data are stored in chunks.
* "Tiled" means that all chunks are assumed to be equal size.
* Chunks have an offset into the complete array.
* Chunks do not necessarily cover the array, missing data is possible.
*
* @author caron
* @since Jan 9, 2008
*/
public class LayoutTiled implements Layout {
private Section want;
private int[] chunkSize; // all chunks assumed to be the same size
private int elemSize;
private long startSrcPos;
private DataChunkIterator chunkIterator; // iterate across chunks
private IndexChunkerTiled index = null; // iterate within a chunk
// track the overall iteration
private long totalNelems, totalNelemsDone; // total number of elemens
private boolean debug = false, debugNext= false;
/**
* Constructor.
*
* @param chunkIterator iterator over all available data chunks
* @param chunkSize all chunks assumed to be the same size
* @param elemSize size of an element in bytes.
* @param wantSection the wanted section of data, contains a List of Range objects. Must be complete
* @throws ucar.ma2.InvalidRangeException if section invalid for this variable
* @throws java.io.IOException on io error
*/
public LayoutTiled(DataChunkIterator chunkIterator, int[] chunkSize, int elemSize, Section wantSection) throws InvalidRangeException, IOException {
this.chunkIterator = chunkIterator;
this.chunkSize = chunkSize;
this.elemSize = elemSize;
this.want = wantSection;
this.totalNelems = this.want.computeSize();
this.totalNelemsDone = 0;
}
public long getTotalNelems() {
return totalNelems;
}
public int getElemSize() {
return elemSize;
}
private Layout.Chunk next = null;
public boolean hasNext() { // have to actually fetch the thing here
if (totalNelemsDone >= totalNelems) return false;
if ((index == null) || !index.hasNext()) { // get new data node
try {
Section dataSection;
DataChunk dataChunk;
while (true) { // look for intersecting sections
if (!chunkIterator.hasNext()) {
next = null;
return false;
}
// get next dataChunk
try {
dataChunk = chunkIterator.next();
} catch (IOException e) {
e.printStackTrace();
next = null;
return false;
}
// make the dataSection for this chunk
dataSection = new Section(dataChunk.offset, chunkSize);
if (dataSection.intersects(want)) // does it intersect ?
break;
}
if (debug)
System.out.println(" found intersecting section: " + dataSection + " for filePos " + dataChunk.filePos);
index = new IndexChunkerTiled(dataSection, want);
startSrcPos = dataChunk.filePos;
} catch (InvalidRangeException e) {
throw new IllegalStateException(e);
}
}
IndexChunker.Chunk chunk = index.next();
totalNelemsDone += chunk.getNelems();
chunk.setSrcPos(startSrcPos + chunk.getSrcElem() * elemSize);
next = chunk;
return true;
}
public Layout.Chunk next() throws IOException {
if (debugNext) System.out.println(" next="+next);
return next;
}
public String toString() {
StringBuilder sbuff = new StringBuilder();
sbuff.append("want=").append(want).append("; ");
sbuff.append("chunkSize=[");
for (int i = 0; i < chunkSize.length; i++) {
if (i > 0) sbuff.append(",");
sbuff.append(chunkSize[i]);
}
sbuff.append("] totalNelems=").append(totalNelems);
sbuff.append(" elemSize=").append(elemSize);
return sbuff.toString();
}
static public interface DataChunkIterator {
public boolean hasNext();
public DataChunk next() throws IOException;
}
static public class DataChunk {
public int[] offset; // offset index of this chunk, reletive to entire array
public long filePos; // filePos of a single raw data chunk
public DataChunk(int[] offset, long filePos) {
this.offset = offset;
this.filePos = filePos;
}
}
}