HADOOP-2479 Save on number of Text object creations

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git-svn-id: https://svn.apache.org/repos/asf/lucene/hadoop/trunk/src/contrib/hbase@606333 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/hadoop/hbase/io/TextSequence.java

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+/**
+ * Copyright 2007 The Apache Software Foundation
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.io;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.WritableComparator;
+
+/**
+ * As CharSequence is to String, so is TextSequence to {@link Text}
+ * (except a TextSequence is a Text whereas a String is a CharSequence). Use
+ * when you want to conserve on object creation.
+ * 
+ * <p>Use with care. If danger that the passed in {@link Text} instance can
+ * change during the life of this TextSequence, concretize this TextSequence
+ * by calling {@link #toText()}.
+ * 
+ * <p>Equals considers a Text equal if the TextSequence brackets the same bytes.
+ * 
+ * <p>TODO: Should this be an Interface as CharSequence is?
+ */
+public class TextSequence extends Text {
+  private Text delegatee;
+  private int start = 0;
+  private int end = -1;
+  
+  public TextSequence() {
+    super();
+    this.delegatee = new Text();
+  }
+  
+  public TextSequence(final Text d) {
+    this(d, 0);
+  }
+  
+  public TextSequence(final Text d, final int s) {
+    this(d, s, d.getLength());
+  }
+  
+  public TextSequence(final Text d, final int s, final int e) {
+    this.delegatee = d;
+    if (s < 0 || s >= d.getLength()) {
+      throw new IllegalArgumentException("Nonsensical start position " + s);
+    }
+    this.start = s;
+    if (e == -1) {
+      this.end = this.delegatee.getLength();
+    } else if (e <= 0 || e > d.getLength()) {
+      throw new IllegalArgumentException("Nonsensical start position " + s);
+    } else {
+      this.end = e;
+    }
+  }
+
+  public int charAt(int position) {
+    if (position + this.start > this.end ||
+        position + this.start < this.start) {
+      return -1;
+    }
+    return this.delegatee.charAt(start + position);
+  }
+
+  public int compareTo(Object o) {
+    if (o instanceof TextSequence) {
+      TextSequence that = (TextSequence)o;
+      if (this == that) {
+        return 0;
+      }
+      return WritableComparator.compareBytes(this.delegatee.getBytes(),
+        this.start, this.getLength(),
+        that.delegatee.getBytes(), that.start, that.getLength());
+    }
+    // Presume type is Text as super method does.
+    Text that = (Text)o;
+    return WritableComparator.compareBytes(this.delegatee.getBytes(),
+      this.start, this.getLength(), that.getBytes(), 0, that.getLength());
+  }
+
+  public boolean equals(Object o) {
+    return compareTo(o) == 0;
+  }
+
+  public int find(String what, int s) {
+    return this.delegatee.find(what, this.start + s) - this.start;
+  }
+
+  public int find(String what) {
+    return find(what, 0);
+  }
+
+  public byte[] getBytes() {
+    byte [] b  = new byte [getLength()];
+    System.arraycopy(this.delegatee.getBytes(), this.start, b, 0, getLength());
+    return b;
+  }
+  
+  /**
+   * @return A new Text instance made from the bytes this TextSequence covers.
+   */
+  public Text toText() {
+    return new Text(getBytes());
+  }
+
+  public int getLength() {
+    return this.end == -1? this.delegatee.getLength(): this.end - this.start;
+  }
+
+  public int hashCode() {
+    int hash = 1;
+    for (int i = this.start; i < getLength(); i++)
+      hash = (31 * hash) + this.delegatee.getBytes()[i];
+    return hash;
+  }
+
+  public void set(byte[] utf8, int start, int len) {
+    this.delegatee.set(utf8, start, len);
+  }
+
+  public void set(byte[] utf8) {
+    this.delegatee.set(utf8);
+  }
+
+  public void set(String string) {
+    this.delegatee.set(string);
+  }
+
+  public void set(Text other) {
+    this.delegatee.set(other);
+    this.start = 0;
+    this.end = other.getLength();
+  }
+
+  public String toString() {
+    return this.delegatee.toString().substring(this.start, this.end);
+  }
+
+
+  public void readFields(DataInput in) throws IOException {
+    this.start = in.readInt();
+    this.end = in.readInt();
+    this.delegatee.readFields(in);
+  }
+  
+  public void write(DataOutput out) throws IOException {
+    out.writeInt(this.start);
+    out.writeInt(this.end);
+    this.delegatee.write(out);
+  }
+}

src/test/org/apache/hadoop/hbase/io/TestTextSequence.java

@@ -0,0 +1,72 @@
+/**
+ * Copyright 2007 The Apache Software Foundation
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hbase.io;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+
+import org.apache.hadoop.hbase.HBaseTestCase;
+import org.apache.hadoop.io.Text;
+
+public class TestTextSequence extends HBaseTestCase {
+
+  protected void setUp() throws Exception {
+    super.setUp();
+  }
+
+  protected void tearDown() throws Exception {
+    super.tearDown();
+  }
+  
+  /**
+   * Test compares of TextSequences and of TextSequence to Text.
+   * @throws Exception
+   */
+  public void testCompare() throws Exception {
+    final Text a = new Text("abcdef");
+    final Text b = new Text("defghi");
+    TextSequence as = new TextSequence(a, 3);
+    TextSequence bs = new TextSequence(b, 0, 3);
+    assertTrue(as.compareTo(bs) == 0);
+    assertTrue(as.equals(bs));
+    // Test where one is a Text and other is a TextSequence
+    final Text family = new Text("abc:");
+    final Text column = new Text(family.toString() + "qualifier");
+    final TextSequence ts = new TextSequence(column, 0, family.getLength());
+    assertTrue(ts.compareTo(family) == 0);
+    assertTrue(ts.equals(family));
+  }
+  
+  public void testSerialize() throws Exception {
+    final Text t = new Text(getName());
+    final TextSequence ts = new TextSequence(t, 1, 3);
+    ByteArrayOutputStream baos = new ByteArrayOutputStream();
+    DataOutputStream dao = new DataOutputStream(baos);
+    ts.write(dao);
+    dao.close();
+    ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+    DataInputStream dis = new DataInputStream(bais);
+    TextSequence deserializeTs = new TextSequence();
+    deserializeTs.readFields(dis);
+    assertTrue(ts.equals(deserializeTs));
+  }
+}