Change filter implementation

java/Makefile

-NATIVE_JAVA_CLASSES = org.rocksdb.RocksDB org.rocksdb.Options org.rocksdb.WriteBatch org.rocksdb.WriteBatchInternal org.rocksdb.WriteBatchTest org.rocksdb.WriteOptions org.rocksdb.BackupableDB org.rocksdb.BackupableDBOptions org.rocksdb.Statistics org.rocksdb.Iterator org.rocksdb.VectorMemTableConfig org.rocksdb.SkipListMemTableConfig org.rocksdb.HashLinkedListMemTableConfig org.rocksdb.HashSkipListMemTableConfig org.rocksdb.PlainTableConfig org.rocksdb.ReadOptions
+NATIVE_JAVA_CLASSES = org.rocksdb.RocksDB org.rocksdb.Options org.rocksdb.WriteBatch org.rocksdb.WriteBatchInternal org.rocksdb.WriteBatchTest org.rocksdb.WriteOptions org.rocksdb.BackupableDB org.rocksdb.BackupableDBOptions org.rocksdb.Statistics org.rocksdb.Iterator org.rocksdb.VectorMemTableConfig org.rocksdb.SkipListMemTableConfig org.rocksdb.HashLinkedListMemTableConfig org.rocksdb.HashSkipListMemTableConfig org.rocksdb.PlainTableConfig org.rocksdb.ReadOptions org.rocksdb.Filter
 NATIVE_INCLUDE = ./include
 ROCKSDB_JAR = rocksdbjni.jar
 

java/RocksDBSample.java

@@ -32,6 +32,7 @@ public class RocksDBSample {
       assert(db == null);
     }
 
+    Filter filter = new Filter(10);
     options.setCreateIfMissing(true)
         .createStatistics()
         .setWriteBufferSize(8 * SizeUnit.KB)
@@ -39,7 +40,7 @@ public class RocksDBSample {
         .setDisableSeekCompaction(true)
         .setBlockSize(64 * SizeUnit.KB)
         .setMaxBackgroundCompactions(10)
-        .createBloomFilter(10);
+        .setFilter(filter);
     Statistics stats = options.statisticsPtr();
 
     assert(options.createIfMissing() == true);
@@ -225,5 +226,6 @@ public class RocksDBSample {
     // be sure to dispose c++ pointers
     options.dispose();
     readOptions.dispose();
+    filter.dispose();
   }
 }

java/org/rocksdb/Filter.java

+// 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);
+}
\ No newline at end of file

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_;

java/rocksjni/filter.cc

+// 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.
+//
+// This file implements the "bridge" between Java and C++ for rocksdb::Filter.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <jni.h>
+#include <string>
+
+#include "include/org_rocksdb_Filter.h"
+#include "rocksjni/portal.h"
+#include "rocksdb/filter_policy.h"
+
+/*
+ * Class:     org_rocksdb_Filter
+ * Method:    newFilter
+ * Signature: (I)V
+ */
+void Java_org_rocksdb_Filter_newFilter(
+    JNIEnv* env, jobject jobj, jint bits_per_key) {
+  const rocksdb::FilterPolicy* fp = rocksdb::NewBloomFilterPolicy(bits_per_key);
+  rocksdb::FilterJni::setHandle(env, jobj, fp);
+}
+
+/*
+ * Class:     org_rocksdb_Filter
+ * Method:    dispose0
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_Filter_dispose0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto fp = reinterpret_cast<rocksdb::FilterPolicy*>(handle);
+  delete fp;
+
+  rocksdb::FilterJni::setHandle(env, jobj, nullptr);
+}
\ No newline at end of file

java/rocksjni/options.cc

@@ -122,19 +122,13 @@ jlong Java_org_rocksdb_Options_statisticsPtr(
 
 /*
  * Class:     org_rocksdb_Options
- * Method:    createBloomFilter0
- * Signature: (JI)V
+ * Method:    setFilter0
+ * Signature: (JJ)V
  */
-void Java_org_rocksdb_Options_createBloomFilter0(
-    JNIEnv* env, jobject jobj, jlong jhandle, jint jbits_per_key) {
-  rocksdb::Options* opt = reinterpret_cast<rocksdb::Options*>(jhandle);
-
-  // Delete previously allocated pointer
-  if(opt->filter_policy) {
-    delete opt->filter_policy;
-  }
-
-  opt->filter_policy = rocksdb::NewBloomFilterPolicy(jbits_per_key);
+void Java_org_rocksdb_Options_setFilter0(
+    JNIEnv* env, jobject jobj, jlong jopt_handle, jlong jfp_handle) {
+  reinterpret_cast<rocksdb::Options*>(jopt_handle)->filter_policy =
+      reinterpret_cast<rocksdb::FilterPolicy*>(jfp_handle);
 }
 
 /*

java/rocksjni/portal.h

@@ -12,6 +12,7 @@
 
 #include <jni.h>
 #include "rocksdb/db.h"
+#include "rocksdb/filter_policy.h"
 #include "utilities/backupable_db.h"
 
 namespace rocksdb {
@@ -281,5 +282,38 @@ class IteratorJni {
         reinterpret_cast<jlong>(op));
   }
 };
+
+class FilterJni {
+ public:
+  // Get the java class id of org.rocksdb.Filter.
+  static jclass getJClass(JNIEnv* env) {
+    static jclass jclazz = env->FindClass("org/rocksdb/Filter");
+    assert(jclazz != nullptr);
+    return jclazz;
+  }
+
+  // Get the field id of the member variable of org.rocksdb.Filter
+  // that stores the pointer to rocksdb::Iterator.
+  static jfieldID getHandleFieldID(JNIEnv* env) {
+    static jfieldID fid = env->GetFieldID(
+        getJClass(env), "nativeHandle_", "J");
+    assert(fid != nullptr);
+    return fid;
+  }
+
+  // Get the pointer to rocksdb::Filter.
+  static rocksdb::FilterPolicy* getHandle(JNIEnv* env, jobject jobj) {
+    return reinterpret_cast<rocksdb::FilterPolicy*>(
+        env->GetLongField(jobj, getHandleFieldID(env)));
+  }
+
+  // Pass the rocksdb::Filter pointer to the java side.
+  static void setHandle(
+      JNIEnv* env, jobject jobj, const rocksdb::FilterPolicy* op) {
+    env->SetLongField(
+        jobj, getHandleFieldID(env),
+        reinterpret_cast<jlong>(op));
+  }
+};
 }  // namespace rocksdb
 #endif  // JAVA_ROCKSJNI_PORTAL_H_