More optimizations

src/main/java/com/teragrep/blf_01/ConcatenatedToken.java

@@ -46,28 +46,40 @@
 
 package com.teragrep.blf_01;
 
+import java.nio.ByteBuffer;
 import java.util.ArrayList;
 
 public class ConcatenatedToken {
 
-    ArrayList<Token> tokens;
-    public ConcatenatedToken(ArrayList<Token> tokens) {
-        this.tokens = tokens;
+    private ByteBuffer concatenatedBuffer;
+
+    public ConcatenatedToken() {
+        this.concatenatedBuffer = ByteBuffer.allocateDirect(256*1024);
     }
 
-    byte[] concatenate() {
-        int size = 0;
+    byte[] concatenate(ArrayList<Token> tokens) {
+        concatenatedBuffer.clear();
         for (Token token : tokens) {
-            size = size + token.bytes.length;
+            if (concatenatedBuffer.position() + token.bytes.length >= concatenatedBuffer.capacity()) {
+                int size = 0;
+                for (Token tokenForSize : tokens) {
+                    size = size + tokenForSize.bytes.length;
+                }
+                concatenatedBuffer = extendBuffer(concatenatedBuffer, size);
+            }
+            concatenatedBuffer.put(token.bytes);
         }
-        byte[] bytes = new byte[size];
 
-        int pos = 0;
-        for (Token token : tokens) {
-            System.arraycopy(token.bytes, 0, bytes, pos, token.bytes.length);
-            pos = pos + token.bytes.length;
-        }
+        concatenatedBuffer.flip();
+        byte[] rv = new byte[concatenatedBuffer.remaining()];
+        concatenatedBuffer.get(rv);
+        return rv;
+    }
 
-        return bytes;
+    private ByteBuffer extendBuffer(ByteBuffer byteBuffer, int size) {
+        ByteBuffer newBuffer = ByteBuffer.allocateDirect(byteBuffer.capacity() + size);
+        byteBuffer.flip();
+        newBuffer.put(byteBuffer);
+        return newBuffer;
     }
 }

src/main/java/com/teragrep/blf_01/Entanglement.java

@@ -55,11 +55,13 @@ public class Entanglement {
     private final ArrayList<Token> allTokens;
     private final ArrayList<Token> forwardScanTokens;
     private final ArrayList<Token> backwardsScanTokens;
+    private final ConcatenatedToken concatenatedToken;
     public Entanglement() {
         this.endWindowScanTokens = new ArrayList<>(512);
         this.allTokens = new ArrayList<>(512);
         this.forwardScanTokens = new ArrayList<>(512);
         this.backwardsScanTokens = new ArrayList<>(512);
+        this.concatenatedToken = new ConcatenatedToken();
     }
 
     public ArrayList<Token> entangle(ArrayList<Token> tokens) {
@@ -86,7 +88,7 @@ private ArrayList<Token> startWindowScan(ArrayList<Token> tokenList)  {
             // +++++ subtask endWindowScan
             allTokens.addAll(endWindowScan(forwardScanTokens));
             // -----
-            Token concatenated = new Token(new ConcatenatedToken(forwardScanTokens).concatenate());
+            Token concatenated = new Token(concatenatedToken.concatenate(forwardScanTokens));
             allTokens.add(concatenated);
             // -----
         }
@@ -108,7 +110,7 @@ private ArrayList<Token> endWindowScan(ArrayList<Token> tokenList) {
             while (backwardIterator.hasPrevious()) {
                 backwardsScanTokens.add(0, backwardIterator.previous());
             }
-            endWindowScanTokens.add(new Token(new ConcatenatedToken(backwardsScanTokens).concatenate()));
+            endWindowScanTokens.add(new Token(concatenatedToken.concatenate(backwardsScanTokens)));
             // ----- task
         }
 

src/test/java/com/teragrep/blf_01/ConcatenatedTokenTest.java

@@ -64,9 +64,9 @@ public void testConcatenation() {
         Token token3 = new Token("cd");
         tokenList.add(token3);
 
-        ConcatenatedToken concatenatedToken = new ConcatenatedToken(tokenList);
+        ConcatenatedToken concatenatedToken = new ConcatenatedToken();
 
         byte[] expected = "ab.cd".getBytes(StandardCharsets.UTF_8);
-        Assertions.assertArrayEquals(expected,concatenatedToken.concatenate());
+        Assertions.assertArrayEquals(expected,concatenatedToken.concatenate(tokenList));
     }
 }