Change filter implementation

java/org/rocksdb/Filter.java

@@ -0,0 +1,50 @@
+// 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;
+
+/**
+ * Filters are stored in rocksdb and are consulted automatically
+ * by rocksdb to decide whether or not to read some
+ * information from disk. In many cases, a filter can cut down the
+ * number of disk seeks form a handful to a single disk seek per
+ * DB::Get() call.
+ *
+ * This function a new filter policy that uses a bloom filter
+ * with approximately the specified number of bits per key.
+ * A good value for bitsPerKey is 10, which yields a filter
+ * with ~ 1% false positive rate. 
+ */
+public class Filter {
+  private long nativeHandle_;
+    
+  public Filter(int bitsPerKey) {
+    newFilter(bitsPerKey);
+  }
+  
+  public long getNativeHandle() {
+    return nativeHandle_;
+  }
+  
+  /**
+   * Deletes underlying C++ filter pointer.
+   */
+  public synchronized void dispose() {
+    if(nativeHandle_ != 0) {
+      dispose0(nativeHandle_);
+    }
+  }
+
+  @Override protected void finalize() {
+    dispose();
+  }
+
+  private boolean isInitialized() {
+    return (nativeHandle_ != 0);
+  }
+  
+  private native void newFilter(int bitsPerKey);
+  private native void dispose0(long handle);
+}

java/org/rocksdb/Options.java

@@ -145,24 +145,14 @@ public class Options {
   }
 
   /**
-   * Filters are stored in rocksdb and are consulted automatically
-   * by rocksdb to decide whether or not to read some
-   * information from disk. In many cases, a filter can cut down the
-   * number of disk seeks form a handful to a single disk seek per
-   * DB::Get() call.
-   *
-   * This function a new filter policy that uses a bloom filter
-   * with approximately the specified number of bits per key.
-   * A good value for bitsPerKey is 10, which yields a filter
-   * with ~ 1% false positive rate.
-   *
-   * @param Bits per key for bloom filter.
+   * Use the specified filter policy to reduce disk reads.
+   * @param Filter policy java instance.
    * @return the instance of the current Options.
    * @see RocksDB.open()
    */
-  public Options createBloomFilter(int bitsPerKey) {
+  public Options setFilter(Filter filter) {
     assert(isInitialized());
-    createBloomFilter0(nativeHandle_, bitsPerKey);
+    setFilter0(nativeHandle_, filter.getNativeHandle());
     return this;
   }
 
@@ -1260,7 +1250,7 @@ public class Options {
   private native void useFixedLengthPrefixExtractor(
       long handle, int prefixLength);
 
-  private native void createBloomFilter0(long handle, int bitsPerKey);
+  private native void setFilter0(long optHandle, long fpHandle);
 
   long nativeHandle_;
   long cacheSize_;