Adding iterator JNI binding

java/RocksDBSample.java

@@ -3,8 +3,7 @@
 // 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.
 
-import java.util.*;
-import java.lang.*;
+import java.util.Arrays;
 import org.rocksdb.*;
 import org.rocksdb.util.SizeUnit;
 import java.io.IOException;
@@ -142,6 +141,11 @@ public class RocksDBSample {
         System.out.println("Failed in call to geHistogramData()");
         assert(false); //Should never reach here.
       }
+      
+      Iterator iterator = db.iterator();
+      iterator.seekToFirst();
+      assert(iterator.isValid());
+      iterator.close();      
     } catch (RocksDBException e) {
       System.err.println(e);
     }

java/org/rocksdb/Iterator.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;
+
+public class Iterator {
+  private long nativeHandle_;
+  
+  public Iterator(long nativeHandle) {
+    nativeHandle_ = nativeHandle;
+  }
+  
+  public boolean isValid() {
+    assert(isInitialized());
+    return isValid0(nativeHandle_);
+  }
+  
+  public void seekToFirst() {
+    assert(isInitialized());
+    seekToFirst0(nativeHandle_);
+  }
+  
+  public synchronized void close() {
+    if(nativeHandle_ != 0) {
+      close0(nativeHandle_);
+    }
+  }
+  
+  @Override protected void finalize() {
+    close();
+  }
+  
+  private boolean isInitialized() {
+    return (nativeHandle_ != 0);
+  }
+  
+  private native boolean isValid0(long handle);
+  private native void close0(long handle);
+  private native void seekToFirst0(long handle);
+}
\ No newline at end of file

java/org/rocksdb/RocksDB.java

@@ -5,7 +5,6 @@
 
 package org.rocksdb;
 
-import java.util.*;
 import java.io.Closeable;
 import java.io.IOException;
 
@@ -136,6 +135,10 @@ public class RocksDB {
       throws RocksDBException {
     remove(nativeHandle_, writeOpt.nativeHandle_, key, key.length);
   }
+  
+  public Iterator iterator() {
+    return new Iterator(iterator0(nativeHandle_));
+  }
 
   @Override protected void finalize() {
     close();
@@ -170,6 +173,7 @@ public class RocksDB {
   protected native void remove(
       long handle, long writeOptHandle,
       byte[] key, int keyLen) throws RocksDBException;
+  protected native long iterator0(long optHandle);
   protected native void close0();
 
   protected long nativeHandle_;

java/rocksjni/iterator.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++ and enables
+// calling c++ rocksdb::Iterator methods from Java side.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <jni.h>
+
+#include "include/org_rocksdb_Iterator.h"
+#include "rocksjni/portal.h"
+#include "rocksdb/iterator.h"
+
+jboolean Java_org_rocksdb_Iterator_isValid0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  return st->Valid();
+}
+
+void Java_org_rocksdb_Iterator_seekToFirst0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  st->SeekToFirst();
+}
+
+void Java_org_rocksdb_Iterator_close0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  delete st;
+  
+  rocksdb::IteratorJni::setHandle(env, jobj, nullptr);
+}
\ No newline at end of file

java/rocksjni/portal.h

@@ -213,5 +213,38 @@ class BackupableDBOptionsJni {
         reinterpret_cast<jlong>(op));
   }
 };
+
+class IteratorJni {
+ public:
+  // Get the java class id of org.rocksdb.Iteartor.
+  static jclass getJClass(JNIEnv* env) {
+    static jclass jclazz = env->FindClass("org/rocksdb/Iterator");
+    assert(jclazz != nullptr);
+    return jclazz;
+  }
+
+  // Get the field id of the member variable of org.rocksdb.Iterator
+  // 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::Iterator
+  static rocksdb::Iterator* getHandle(JNIEnv* env, jobject jobj) {
+    return reinterpret_cast<rocksdb::Iterator*>(
+        env->GetLongField(jobj, getHandleFieldID(env)));
+  }
+
+  // Pass the rocksdb::Iterator pointer to the java side.
+  static void setHandle(
+      JNIEnv* env, jobject jobj, rocksdb::Iterator* op) {
+    env->SetLongField(
+        jobj, getHandleFieldID(env),
+        reinterpret_cast<jlong>(op));
+  }
+};
 }  // namespace rocksdb
 #endif  // JAVA_ROCKSJNI_PORTAL_H_

java/rocksjni/rocksjni.cc

@@ -296,3 +296,10 @@ void Java_org_rocksdb_RocksDB_close0(
 
   rocksdb::RocksDBJni::setHandle(env, java_db, nullptr);
 }
+
+jlong Java_org_rocksdb_RocksDB_iterator0(
+    JNIEnv* env, jobject jdb, jlong db_handle) {
+  auto db = reinterpret_cast<rocksdb::DB*>(db_handle);
+  rocksdb::Iterator* iterator = db->NewIterator(rocksdb::ReadOptions());
+  return reinterpret_cast<jlong>(iterator);
+}
\ No newline at end of file

java/rocksjni/statistics.cc

@@ -13,7 +13,6 @@
 #include "include/org_rocksdb_Statistics.h"
 #include "rocksjni/portal.h"
 #include "rocksdb/statistics.h"
-#include <iostream>
 
 /*
  * Class:     org_rocksdb_Statistics