performance hack: use a hash cache for all hashes that are computed by a

byte array. If this hash is used in a HashMap (which is very often the
case) then this hack eliminates a lot of re-computations of the same
hash.

source/net/yacy/kelondro/data/citation/CitationReference.java

@@ -133,9 +133,14 @@ public class CitationReference implements Reference, Serializable {
         return false;
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.urlhash());
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.urlhash());
+        }
+        return this.hashCache;
     }
 
     @Override

source/net/yacy/kelondro/data/image/ImageReferenceRow.java

@@ -200,18 +200,21 @@ public final class ImageReferenceRow extends AbstractReference implements /*Imag
     @Override
     public ImageReferenceRow clone() {
         final byte[] b = new byte[urlEntryRow.objectsize];
-        System.arraycopy(entry.bytes(), 0, b, 0, urlEntryRow.objectsize);
+        System.arraycopy(this.entry.bytes(), 0, b, 0, urlEntryRow.objectsize);
         return new ImageReferenceRow(b);
     }
 
+    @Override
     public String toPropertyForm() {
-        return entry.toPropertyForm('=', true, true, false, false);
+        return this.entry.toPropertyForm('=', true, true, false, false);
     }
 
+    @Override
     public Entry toKelondroEntry() {
         return this.entry;
     }
 
+    @Override
     public byte[] urlhash() {
         return this.entry.getColBytes(col_urlhash, true);
     }
@@ -220,6 +223,7 @@ public final class ImageReferenceRow extends AbstractReference implements /*Imag
         return (int) this.entry.getColLong(col_lastModified);  // this is the time in MicoDateDays format
     }
 
+    @Override
     public long lastModified() {
         return MicroDate.reverseMicroDateDays((int) this.entry.getColLong(col_lastModified));
     }
@@ -232,6 +236,7 @@ public final class ImageReferenceRow extends AbstractReference implements /*Imag
         return (int) this.entry.getColLong(col_hitcount);
     }
 
+    @Override
     public Collection<Integer> positions() {
         return new ArrayList<Integer>(0);
     }
@@ -271,17 +276,24 @@ public final class ImageReferenceRow extends AbstractReference implements /*Imag
         return toPropertyForm();
     }
 
+    @Override
     public boolean isOlder(final Reference other) {
         if (other == null) return false;
         if (this.lastModified() < other.lastModified()) return true;
         return false;
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.urlhash());
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.urlhash());
+        }
+        return this.hashCache;
     }
 
+    @Override
     public void join(Reference oe) {
         throw new UnsupportedOperationException("");
 

source/net/yacy/kelondro/data/image/ImageReferenceVars.java

@@ -381,9 +381,14 @@ public class ImageReferenceVars extends AbstractReference implements ImageRefere
         this.wordsintext = this.wordsintext + oe.wordsintext();
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.urlHash);
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.urlHash);
+        }
+        return this.hashCache;
     }
 
     public void addPosition(int position) {

source/net/yacy/kelondro/data/meta/DigestURI.java

@@ -160,12 +160,14 @@ public class DigestURI extends MultiProtocolURI implements Serializable {
         this.hash = null;
     }
 
-    /* (non-Javadoc)
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
-     * @see java.lang.Object#hashCode()
+
-     */
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(hash());
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(hash());
+        }
+        return this.hashCache;
     }
 
     public static final int flagTypeID(final String hash) {

source/net/yacy/kelondro/data/word/WordReferenceRow.java

@@ -215,6 +215,7 @@ public final class WordReferenceRow extends AbstractReference implements WordRef
             this.out = new LinkedBlockingQueue<WordReferenceRow>();
             for (int i = 0; i < concurrency; i++) {
                 this.worker[i] = new Thread() {
+                    @Override
                     public void run() {
                         String s;
                         try {
@@ -290,22 +291,27 @@ public final class WordReferenceRow extends AbstractReference implements WordRef
         return new WordReferenceRow(b);
     }
 
+    @Override
     public String toPropertyForm() {
         return this.entry.toPropertyForm('=', true, true, false, false);
     }
 
+    @Override
     public Entry toKelondroEntry() {
         return this.entry;
     }
 
+    @Override
     public byte[] urlhash() {
         return this.entry.getColBytes(col_urlhash, true);
     }
 
+    @Override
     public int virtualAge() {
         return (int) this.entry.getColLong(col_lastModified);  // this is the time in MicoDateDays format
     }
 
+    @Override
     public long lastModified() {
         return MicroDate.reverseMicroDateDays((int) this.entry.getColLong(col_lastModified));
     }
@@ -314,10 +320,12 @@ public final class WordReferenceRow extends AbstractReference implements WordRef
         return MicroDate.reverseMicroDateDays((int) this.entry.getColLong(col_freshUntil));
     }
 
+    @Override
     public int hitcount() {
         return (0xff & this.entry.getColByte(col_hitcount));
     }
 
+    @Override
     public Collection<Integer> positions() {
         return new ArrayList<Integer>(0);
     }
@@ -327,54 +335,67 @@ public final class WordReferenceRow extends AbstractReference implements WordRef
         return (int) this.entry.getColLong(col_posintext);
     }
 
+    @Override
     public int posinphrase() {
         return (0xff & this.entry.getColByte(col_posinphrase));
     }
 
+    @Override
     public int posofphrase() {
         return (0xff & this.entry.getColByte(col_posofphrase));
     }
 
+    @Override
     public int wordsintext() {
         return (int) this.entry.getColLong(col_wordsInText);
     }
 
+    @Override
     public int phrasesintext() {
         return (int) this.entry.getColLong(col_phrasesInText);
     }
 
+    @Override
     public byte[] getLanguage() {
         return this.entry.getColBytes(col_language, true);
     }
 
+    @Override
     public char getType() {
         return (char) this.entry.getColByte(col_doctype);
     }
 
+    @Override
     public int wordsintitle() {
         return (0xff & this.entry.getColByte(col_wordsInTitle));
     }
 
+    @Override
     public int llocal() {
         return (0xff & this.entry.getColByte(col_llocal));
     }
 
+    @Override
     public int lother() {
         return (0xff & this.entry.getColByte(col_lother));
     }
 
+    @Override
     public int urllength() {
         return (0xff & this.entry.getColByte(col_urlLength));
     }
 
+    @Override
     public int urlcomps() {
         return (0xff & this.entry.getColByte(col_urlComps));
     }
 
+    @Override
     public Bitfield flags() {
         return new Bitfield(this.entry.getColBytes(col_flags, false));
     }
 
+    @Override
     public double termFrequency() {
         return (((double) hitcount()) / ((double) (wordsintext() + wordsintitle() + 1)));
     }
@@ -393,11 +414,17 @@ public final class WordReferenceRow extends AbstractReference implements WordRef
         return Base64Order.enhancedCoder.equal(urlhash(), other.urlhash());
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(urlhash());
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(urlhash());
+        }
+        return this.hashCache;
     }
 
+    @Override
     public void join(final Reference oe) {
         throw new UnsupportedOperationException("");
 

source/net/yacy/kelondro/data/word/WordReferenceVars.java

@@ -31,7 +31,6 @@ import java.util.Comparator;
 import java.util.Queue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
-import java.util.concurrent.Semaphore;
 
 import net.yacy.cora.document.ASCII;
 import net.yacy.cora.document.UTF8;
@@ -394,9 +393,14 @@ public class WordReferenceVars extends AbstractReference implements WordReferenc
         return Base64Order.enhancedCoder.equal(this.urlHash, other.urlHash);
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.urlHash);
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.urlHash);
+        }
+        return this.hashCache;
     }
 
     @Override

source/net/yacy/kelondro/util/ByteArray.java

@@ -44,7 +44,7 @@ import net.yacy.cora.order.ByteOrder;
 public class ByteArray {
 
     private final byte[] buffer;
-    private int hash;
+    private final int hash;
 
 
     public ByteArray(final byte[] bb) {
@@ -53,7 +53,7 @@ public class ByteArray {
     }
 
     public int length() {
-        return buffer.length;
+        return this.buffer.length;
     }
 
     public byte[] asBytes() {
@@ -61,7 +61,7 @@ public class ByteArray {
     }
 
     public byte readByte(final int pos) {
-        return buffer[pos];
+        return this.buffer[pos];
     }
 
     public static boolean startsWith(final byte[] buffer, final byte[] pattern) {
@@ -83,11 +83,14 @@ public class ByteArray {
         return order.compare(this.buffer, aoffset, b.buffer, boffset, blength);
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        if (this.hash != 0) return this.hash;        
+        if (this.hashCache == Integer.MIN_VALUE) {
-        this.hash = hashCode(this.buffer);
+            this.hashCache = ByteArray.hashCode(this.buffer);
-        return this.hash;
+        }
+        return this.hashCache;
     }
 
     /**
@@ -104,8 +107,8 @@ public class ByteArray {
     @Override
     public boolean equals(Object other) {
         ByteArray b = (ByteArray) other;
-        if (buffer == null && b == null) return true;
+        if (this.buffer == null && b == null) return true;
-        if (buffer == null || b == null) return false;
+        if (this.buffer == null || b == null) return false;
         if (this.buffer.length != b.buffer.length) return false;
         int l = this.buffer.length;
         while (--l >= 0) if (this.buffer[l] != b.buffer[l]) return false;

source/net/yacy/search/snippet/MediaSnippet.java

@@ -100,9 +100,14 @@ public class MediaSnippet implements Comparable<MediaSnippet>, Comparator<MediaS
         if ((this.attr == null) || (this.attr.length() == 0)) this.attr = "_";
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.href.hash());
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.href.hash());
+        }
+        return this.hashCache;
     }
 
     @Override

source/net/yacy/search/snippet/ResultEntry.java

@@ -103,9 +103,13 @@ public class ResultEntry implements Comparable<ResultEntry>, Comparator<ResultEn
             if ((p = this.alternative_urlname.indexOf('?')) > 0) this.alternative_urlname = this.alternative_urlname.substring(0, p);
         }
     }
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.urlentry.hash());
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.urlentry.hash());
+        }
+        return this.hashCache;
     }
     @Override
     public boolean equals(final Object obj) {

source/net/yacy/search/snippet/TextSnippet.java

@@ -400,9 +400,14 @@ public class TextSnippet implements Comparable<TextSnippet>, Comparator<TextSnip
         return o1.compareTo(o2);
     }
 
+    private int hashCache = Integer.MIN_VALUE; // if this is used in a compare method many times, a cache is useful
+
     @Override
     public int hashCode() {
-        return ByteArray.hashCode(this.urlhash);
+        if (this.hashCache == Integer.MIN_VALUE) {
+            this.hashCache = ByteArray.hashCode(this.urlhash);
+        }
+        return this.hashCache;
     }
 
     @Override