com.bigdata.rdf.spo.JustificationRemover Maven / Gradle / Ivy
package com.bigdata.rdf.spo;
import java.util.Arrays;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.log4j.Logger;
import com.bigdata.btree.IIndex;
import com.bigdata.btree.IRangeQuery;
import com.bigdata.btree.ITupleIterator;
import com.bigdata.btree.keys.IKeyBuilder;
import com.bigdata.btree.keys.KeyBuilder;
import com.bigdata.btree.keys.SuccessorUtil;
import com.bigdata.rdf.inf.Justification;
import com.bigdata.util.Bytes;
/**
* Class writes on the justification index, removing all {@link Justification}s
* for each statement specified by the caller.
*
* Note: There is only one index for {@link Justification}s. The keys all use
* the {s,p,o} of the entailed statement as their prefix, so given a statement
* it is trivial to do a range scan for its justifications.
*
* @todo Since this task accepts a "chunk" of statements, it should flood range
* delete requests for each of the statements to the justifications index
* using the {@link ExecutorService} , but only if the triple store
* provides concurrency control for writers on the same index.
*
* @author Bryan Thompson
* @version $Id$
*/
public class JustificationRemover implements Callable {
protected static final Logger log = Logger
.getLogger(JustificationRemover.class);
/**
* True iff the {@link #log} level is INFO or less.
*/
final static protected boolean INFO = log.isInfoEnabled();
/**
* True iff the {@link #log} level is DEBUG or less.
*/
final static protected boolean DEBUG = log.isDebugEnabled();
final SPORelation db;
final ISPO[] a;
final int numStmts;
final AtomicLong sortTime;
final AtomicLong writeTime;
public JustificationRemover(SPORelation db, ISPO[] stmts, int numStmts,
boolean clone, AtomicLong sortTime, AtomicLong writeTime) {
if (db == null)
throw new IllegalArgumentException();
this.db = db;
if (clone) {
this.a = new ISPO[numStmts];
System.arraycopy(stmts, 0, a, 0, numStmts);
} else {
this.a = stmts;
}
this.numStmts = numStmts;
this.sortTime = sortTime;
this.writeTime = writeTime;
}
public Long call() throws Exception {
final long begin = System.currentTimeMillis();
final IIndex ndx = db.getJustificationIndex();
/*
* Place statements in index order (SPO since all justifications begin
* with the SPO of the entailed statement.
*/
Arrays.sort(a, 0, numStmts, SPOKeyOrder.SPO.getComparator());
final long beginWrite = System.currentTimeMillis();
sortTime.addAndGet(beginWrite - begin);
// thread-local key builder.
final IKeyBuilder keyBuilder = KeyBuilder.newInstance(db.getKeyArity()*Bytes.SIZEOF_LONG);
// remove statements from the index.
for (int i = 0; i < numStmts; i++) {
final ISPO spo = a[i];
keyBuilder.reset();
spo.s().encode(keyBuilder);
spo.p().encode(keyBuilder);
spo.o().encode(keyBuilder);
/*
* Form an iterator that will range scan the justifications having
* that statement as their 'head'. The iterator uses the REMOVEALL
* flag to have the justifications deleted on the server and does
* not actually send back the keys or vals to the client.
*/
final byte[] fromKey = keyBuilder.getKey();
final byte[] toKey = SuccessorUtil.successor(fromKey.clone());
final ITupleIterator itr = ndx.rangeIterator(fromKey, toKey,
0/* capacity */, IRangeQuery.REMOVEALL, null/* filter */);
// FullyBufferedJustificationIterator itr = new
// FullyBufferedJustificationIterator(
// db, spo);
long n = 0;
while (itr.hasNext()) {
itr.next();
// itr.remove();
n++;
}
if (DEBUG) {
log.debug("Removed " + n + " justifications for "
+ spo.toString(/* db */));
}
}
final long endWrite = System.currentTimeMillis();
writeTime.addAndGet(endWrite - beginWrite);
return endWrite - begin;
}
}