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removed overhead of Entry object allocation during OpenIntToDoubleHashMap iteration 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@726490 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Luc Maisonobe 2008-12-14 16:31:58 +00:00
parent 11d8f0ec5f
commit da40b8373a
3 changed files with 74 additions and 67 deletions
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16
src/java/org/apache/commons/math/linear/SparseRealMatrix.java
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@ -104,10 +104,10 @@ public class SparseRealMatrix extends AbstractRealMatrix {
final RealMatrix out = new SparseRealMatrix(this);
for (OpenIntToDoubleHashMap.Iterator iterator = m.entries.iterator(); iterator.hasNext();) {
final OpenIntToDoubleHashMap.Entry entry = iterator.next();
final int row = entry.key() / columnDimension;
final int col = entry.key() - row * columnDimension;
out.setEntry(row, col, getEntry(row, col) + entry.value());
iterator.advance();
final int row = iterator.key() / columnDimension;
final int col = iterator.key() - row * columnDimension;
out.setEntry(row, col, getEntry(row, col) + iterator.value());
}
return out;
@ -138,10 +138,10 @@ public class SparseRealMatrix extends AbstractRealMatrix {
final RealMatrix out = new SparseRealMatrix(this);
for (OpenIntToDoubleHashMap.Iterator iterator = m.entries.iterator(); iterator.hasNext();) {
final OpenIntToDoubleHashMap.Entry entry = iterator.next();
final int row = entry.key() / columnDimension;
final int col = entry.key() - row * columnDimension;
out.setEntry(row, col, getEntry(row, col) - entry.value());
iterator.advance();
final int row = iterator.key() / columnDimension;
final int col = iterator.key() - row * columnDimension;
out.setEntry(row, col, getEntry(row, col) - iterator.value());
}
return out;

114
src/java/org/apache/commons/math/util/OpenIntToDoubleHashMap.java
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@ -456,16 +456,28 @@ public class OpenIntToDoubleHashMap implements Serializable {
/** Reference modification count. */
final int referenceCount;
/** Index of curent element. */
private int current;
/** Index of next element. */
private int index;
private int next;
/**
* Simple constructor.
*/
private Iterator() {
// preserve the modification count of the map to detect concurrent modifications later
referenceCount = count;
index = -1;
goToNext();
// initialize current index
next = -1;
try {
advance();
} catch (NoSuchElementException nsee) {
// ignored
}
}
/**
@ -473,81 +485,73 @@ public class OpenIntToDoubleHashMap implements Serializable {
* @return true if there is a next element
*/
public boolean hasNext() {
return index >= 0;
return next >= 0;
}
/**
* Get the next entry.
* @return next entry
* Get the key of current entry.
* @return key of current entry
* @exception ConcurrentModificationException if the map is modified during iteration
* @exception NoSuchElementException if there is no element left in the map
*/
public Entry next()
public int key()
throws ConcurrentModificationException, NoSuchElementException {
if (referenceCount != count) {
throw MathRuntimeException.createConcurrentModificationException("map has been modified while iterating",
null);
}
if (index < 0) {
if (current < 0) {
throw MathRuntimeException.createNoSuchElementException("iterator exhausted", null);
}
final Entry entry = new Entry(keys[index], values[index]);
goToNext();
return entry;
return keys[current];
}
/**
* Find next index.
* Get the value of current entry.
* @return value of current entry
* @exception ConcurrentModificationException if the map is modified during iteration
* @exception NoSuchElementException if there is no element left in the map
*/
private void goToNext() {
public double value()
throws ConcurrentModificationException, NoSuchElementException {
if (referenceCount != count) {
throw MathRuntimeException.createConcurrentModificationException("map has been modified while iterating",
null);
}
if (current < 0) {
throw MathRuntimeException.createNoSuchElementException("iterator exhausted", null);
}
return values[current];
}
/**
* Advance iterator one step further.
* @exception ConcurrentModificationException if the map is modified during iteration
* @exception NoSuchElementException if there is no element left in the map
*/
public void advance()
throws ConcurrentModificationException, NoSuchElementException {
if (referenceCount != count) {
throw MathRuntimeException.createConcurrentModificationException("map has been modified while iterating",
null);
}
// advance on step
current = next;
// prepare next step
try {
while (states[++index] != FULL) {
while (states[++next] != FULL) {
// nothing to do
}
} catch (ArrayIndexOutOfBoundsException e) {
index = -1;
next = -2;
if (current < 0) {
throw MathRuntimeException.createNoSuchElementException("iterator exhausted", null);
}
}
}
}
/** Entry class for the map.
* <p>Entry elements are built on the fly only during iteration,
* copying values. So changes in the map are <strong>not</strong>
* reflected on already built entries.</p>
*/
public static class Entry {
/** Key. */
private final int key;
/** Value. */
private final double value;
/**
* Simple constructor.
* @param key entry key
* @param value entry value
*/
private Entry(final int key, final double value) {
this.key = key;
this.value = value;
}
/**
* Get the key.
* @return entry key
*/
public int key() {
return key;
}
/**
* Get the value.
* @return entry value
*/
public double value() {
return value;
}
}

11
src/test/org/apache/commons/math/util/OpenIntToDoubleHashMapTest.java
View File

@ -228,15 +228,17 @@ public class OpenIntToDoubleHashMapTest extends TestCase {
OpenIntToDoubleHashMap.Iterator iterator = map.iterator();
for (int i = 0; i < map.size(); ++i) {
assertTrue(iterator.hasNext());
OpenIntToDoubleHashMap.Entry entry = iterator.next();
int key = entry.key();
iterator.advance();
int key = iterator.key();
assertTrue(map.containsKey(key));
assertEquals(javaMap.get(key), map.get(key), 0);
assertEquals(javaMap.get(key), iterator.value(), 0);
assertTrue(javaMap.containsKey(key));
}
assertFalse(iterator.hasNext());
try {
iterator.next();
iterator.advance();
fail("an exception should have been thrown");
} catch (NoSuchElementException nsee) {
// expected
}
@ -247,7 +249,8 @@ public class OpenIntToDoubleHashMapTest extends TestCase {
OpenIntToDoubleHashMap.Iterator iterator = map.iterator();
map.put(3, 3);
try {
iterator.next();
iterator.advance();
fail("an exception should have been thrown");
} catch (ConcurrentModificationException cme) {
// expected
}