Extract the interface for a RocksIterator

java/org/rocksdb/RocksIterator.java

@@ -6,9 +6,9 @@
 package org.rocksdb;
 
 /**
- * <p>An iterator yields a sequence of key/value pairs from a source.
- * The following class defines the interface. Multiple implementations
- * are provided by this library.  In particular, iterators are provided
+ * <p>An iterator that yields a sequence of key/value pairs from a source.
+ * Multiple implementations are provided by this library.
+ * In particular, iterators are provided
  * to access the contents of a Table or a DB.</p>
  *
  * <p>Multiple threads can invoke const methods on an RocksIterator without
@@ -18,7 +18,7 @@ package org.rocksdb;
  *
  * @see org.rocksdb.RocksObject
  */
-public class RocksIterator extends RocksObject {
+public class RocksIterator extends RocksObject implements RocksIteratorInterface {
   public RocksIterator(RocksDB rocksDB, long nativeHandle) {
     super();
     nativeHandle_ = nativeHandle;
@@ -30,57 +30,48 @@ public class RocksIterator extends RocksObject {
     rocksDB_ = rocksDB;
   }
 
-  /**
-   * An iterator is either positioned at a key/value pair, or
-   * not valid.  This method returns true iff the iterator is valid.
-   *
-   * @return true if iterator is valid.
-   */
+  @Override
   public boolean isValid() {
     assert(isInitialized());
     return isValid0(nativeHandle_);
   }
 
-  /**
-   * Position at the first key in the source.  The iterator is Valid()
-   * after this call iff the source is not empty.
-   */
+  @Override
   public void seekToFirst() {
     assert(isInitialized());
     seekToFirst0(nativeHandle_);
   }
 
-  /**
-   * Position at the last key in the source.  The iterator is
-   * valid after this call iff the source is not empty.
-   */
+  @Override
   public void seekToLast() {
     assert(isInitialized());
     seekToLast0(nativeHandle_);
   }
 
-  /**
-   * <p>Moves to the next entry in the source.  After this call, Valid() is
-   * true iff the iterator was not positioned at the last entry in the source.</p>
-   *
-   * <p>REQUIRES: {@link #isValid()}</p>
-   */
+  @Override
+  public void seek(byte[] target) {
+    assert(isInitialized());
+    seek0(nativeHandle_, target, target.length);
+  }
+
+  @Override
   public void next() {
     assert(isInitialized());
     next0(nativeHandle_);
   }
 
-  /**
-   * <p>Moves to the previous entry in the source.  After this call, Valid() is
-   * true iff the iterator was not positioned at the first entry in source.</p>
-   *
-   * <p>REQUIRES: {@link #isValid()}</p>
-   */
+  @Override
   public void prev() {
     assert(isInitialized());
     prev0(nativeHandle_);
   }
 
+  @Override
+  public void status() throws RocksDBException {
+    assert(isInitialized());
+    status0(nativeHandle_);
+  }
+
   /**
    * <p>Return the key for the current entry.  The underlying storage for
    * the returned slice is valid only until the next modification of
@@ -108,32 +99,6 @@ public class RocksIterator extends RocksObject {
     return value0(nativeHandle_);
   }
 
-  /**
-   * <p>Position at the first key in the source that at or past target
-   * The iterator is valid after this call iff the source contains
-   * an entry that comes at or past target.</p>
-   *
-   * @param target byte array describing a key or a
-   *     key prefix to seek for.
-   */
-  public void seek(byte[] target) {
-    assert(isInitialized());
-    seek0(nativeHandle_, target, target.length);
-  }
-
-  /**
-   * If an error has occurred, return it.  Else return an ok status.
-   * If non-blocking IO is requested and this operation cannot be
-   * satisfied without doing some IO, then this returns Status::Incomplete().
-   *
-   * @throws RocksDBException thrown if error happens in underlying
-   *    native library.
-   */
-  public void status() throws RocksDBException {
-    assert(isInitialized());
-    status0(nativeHandle_);
-  }
-
   /**
    * <p>Deletes underlying C++ iterator pointer.</p>
    *

java/org/rocksdb/RocksIteratorInterface.java

@@ -0,0 +1,80 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+package org.rocksdb;
+
+/**
+ * <p>Defines the interface for an Iterator which provides
+ * access to data one entry at a time. Multiple implementations
+ * are provided by this library.  In particular, iterators are provided
+ * to access the contents of a DB and Write Batch.</p>
+ * <p/>
+ * <p>Multiple threads can invoke const methods on an RocksIterator without
+ * external synchronization, but if any of the threads may call a
+ * non-const method, all threads accessing the same RocksIterator must use
+ * external synchronization.</p>
+ *
+ * @see org.rocksdb.RocksObject
+ */
+public interface RocksIteratorInterface {
+
+  /**
+   * <p>An iterator is either positioned at an entry, or
+   * not valid.  This method returns true if the iterator is valid.</p>
+   *
+   * @return true if iterator is valid.
+   */
+  public boolean isValid();
+
+  /**
+   * <p>Position at the first entry in the source.  The iterator is Valid()
+   * after this call if the source is not empty.</p>
+   */
+  public void seekToFirst();
+
+  /**
+   * <p>Position at the last entry in the source.  The iterator is
+   * valid after this call if the source is not empty.</p>
+   */
+  public void seekToLast();
+
+  /**
+   * <p>Position at the first entry in the source whose key is that or
+   * past target.</p>
+   * <p/>
+   * <p>The iterator is valid after this call if the source contains
+   * a key that comes at or past target.</p>
+   *
+   * @param target byte array describing a key or a
+   *               key prefix to seek for.
+   */
+  public void seek(byte[] target);
+
+  /**
+   * <p>Moves to the next entry in the source.  After this call, Valid() is
+   * true if the iterator was not positioned at the last entry in the source.</p>
+   * <p/>
+   * <p>REQUIRES: {@link #isValid()}</p>
+   */
+  public void next();
+
+  /**
+   * <p>Moves to the previous entry in the source.  After this call, Valid() is
+   * true if the iterator was not positioned at the first entry in source.</p>
+   * <p/>
+   * <p>REQUIRES: {@link #isValid()}</p>
+   */
+  public void prev();
+
+  /**
+   * <pIf an error has occurred, return it.  Else return an ok status.
+   * If non-blocking IO is requested and this operation cannot be
+   * satisfied without doing some IO, then this returns Status::Incomplete().</p>
+   *
+   * @throws RocksDBException thrown if error happens in underlying
+   *                          native library.
+   */
+  public void status() throws RocksDBException;
+}