Add RibbonFilter Java API

Author: mike-evolved

java/src/main/java/org/rocksdb/RibbonFilter.java

@@ -0,0 +1,86 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+package org.rocksdb;
+
+import java.util.Objects;
+
+public class RibbonFilter extends Filter {
+
+  private static final double DEFAULT_BITS_PER_KEY = 10.0;
+  private static final int DEFAULT_BLOOM_BEFORE_LEVEL = -1;
+
+  private final double bitsPerKey;
+  private final int bloomBeforeLevel;
+
+  /**
+   * Creates a new Ribbon filter with default bits per key (10.0).
+   */
+  public RibbonFilter() {
+    this(DEFAULT_BITS_PER_KEY);
+  }
+
+  /**
+   * Creates a new Ribbon filter with the specified bits per key.
+   *
+   * @param bitsPerKey the number of bits per key (typical: 8-12)
+   */
+  public RibbonFilter(final double bitsPerKey) {
+    this(createNewRibbonFilter(bitsPerKey, DEFAULT_BLOOM_BEFORE_LEVEL), bitsPerKey, DEFAULT_BLOOM_BEFORE_LEVEL);
+  }
+
+  /**
+   * Internal constructor for FilterPolicyType
+   *
+   * @param nativeHandle handle to existing ribbon filter at RocksDB C++ side
+   * @param bitsPerKey number of bits to use - recorded for comparison
+   */
+  RibbonFilter(final long nativeHandle, final double bitsPerKey) {
+    this(nativeHandle, bitsPerKey, DEFAULT_BLOOM_BEFORE_LEVEL);
+  }
+
+  /**
+   * Creates a new Ribbon filter with bits per key and bloom_before_level.
+   *
+   * @param bitsPerKey the number of bits per key (typical: 8-12)
+   * @param bloomBeforeLevel use Bloom filters for levels below this, Ribbon for levels at or above
+   *                         (-1 means always use Ribbon, 0 means use Bloom for L0, 
+   *                         1 means Bloom for L0-L1, etc.)
+   */
+  public RibbonFilter(final double bitsPerKey, final int bloomBeforeLevel) {
+    this(createNewRibbonFilter(bitsPerKey, bloomBeforeLevel), bitsPerKey, bloomBeforeLevel);
+  }
+
+  /**
+   * Internal constructor
+   *
+   * @param nativeHandle handle to existing ribbon filter at RocksDB C++ side
+   * @param bitsPerKey number of bits to use - recorded for comparison
+   * @param bloomBeforeLevel bloom before level setting - recorded for comparison
+   */
+  private RibbonFilter(final long nativeHandle, final double bitsPerKey, final int bloomBeforeLevel) {
+    super(nativeHandle);
+    this.bitsPerKey = bitsPerKey;
+    this.bloomBeforeLevel = bloomBeforeLevel;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o)
+      return true;
+    if (o == null || getClass() != o.getClass())
+      return false;
+    RibbonFilter that = (RibbonFilter) o;
+    return Double.compare(that.bitsPerKey, bitsPerKey) == 0 &&
+           bloomBeforeLevel == that.bloomBeforeLevel;
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(bitsPerKey, bloomBeforeLevel);
+  }
+
+  private static native long createNewRibbonFilter(final double bitsPerKey, final int bloomBeforeLevel);
+}