Add more iterator JNI bindings

Author: Ankit Gupta

java/Makefile

@@ -1,4 +1,4 @@
-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
+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
 NATIVE_INCLUDE = ./include
 ROCKSDB_JAR = rocksdbjni.jar
 

java/RocksDBSample.java

@@ -143,12 +143,39 @@ public static void main(String[] args) {
       }
 
       Iterator iterator = db.iterator();
+      
+      boolean seekToFirstPassed = false;
+      for (iterator.seekToFirst(); iterator.isValid(); iterator.next()) {
+        iterator.status();
+        assert(iterator.key() != null);
+        assert(iterator.value() != null);
+        seekToFirstPassed = true;
+      }
+      if(seekToFirstPassed) {
+        System.out.println("iterator seekToFirst tests passed.");
+      }
+      
+      boolean seekToLastPassed = false;
+      for (iterator.seekToLast(); iterator.isValid(); iterator.prev()) {
+        iterator.status();
+        assert(iterator.key() != null);
+        assert(iterator.value() != null);
+        seekToLastPassed = true;
+      }
+      
+      if(seekToLastPassed) {
+        System.out.println("iterator seekToLastPassed tests passed.");
+      }
+      
       iterator.seekToFirst();
-      assert(iterator.isValid());
-      iterator.next();
-      iterator.seekToLast();
-      iterator.prev();
-      iterator.close();      
+      iterator.seek(iterator.key());
+      assert(iterator.key() != null);
+      assert(iterator.value() != null);
+      
+      System.out.println("iterator seek test passed.");
+      
+      iterator.close();
+      System.out.println("iterator tests passed.");
     } catch (RocksDBException e) {
       System.err.println(e);
     }

java/org/rocksdb/Iterator.java

@@ -37,6 +37,26 @@ public void prev() {
     prev0(nativeHandle_);
   }
 
+  public byte[] key() {
+    assert(isInitialized());
+    return key0(nativeHandle_);
+  }
+  
+  public byte[] value() {
+    assert(isInitialized());
+    return value0(nativeHandle_);
+  }
+  
+  public void seek(byte[] target) {
+    assert(isInitialized());
+    seek0(nativeHandle_, target, target.length);
+  }
+  
+  public void status(){
+    assert(isInitialized());
+    status0(nativeHandle_);
+  }
+  
   public synchronized void close() {
     if(nativeHandle_ != 0) {
       close0(nativeHandle_);
@@ -57,4 +77,8 @@ private boolean isInitialized() {
   private native void seekToLast0(long handle);
   private native void next0(long handle);
   private native void prev0(long handle);
+  private native byte[] key0(long handle);
+  private native byte[] value0(long handle);
+  private native void seek0(long handle, byte[] target, int targetLen);
+  private native void status0(long handle);
 }

java/rocksjni/iterator.cc

@@ -54,6 +54,63 @@ void Java_org_rocksdb_Iterator_prev0(
   st->Prev();
 }
 
+jbyteArray Java_org_rocksdb_Iterator_key0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  rocksdb::Slice key_slice = st->key();
+  
+  jbyteArray jkey = env->NewByteArray(key_slice.size());
+    env->SetByteArrayRegion(
+        jkey, 0, key_slice.size(),
+        reinterpret_cast<const jbyte*>(key_slice.data()));
+  return jkey;
+}
+
+jbyteArray Java_org_rocksdb_Iterator_value0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  rocksdb::Slice value_slice = st->value();
+  
+  jbyteArray jvalue = env->NewByteArray(value_slice.size());
+    env->SetByteArrayRegion(
+        jvalue, 0, value_slice.size(),
+        reinterpret_cast<const jbyte*>(value_slice.data()));
+  return jvalue;
+}
+
+void Java_org_rocksdb_Iterator_seek0(
+    JNIEnv* env, jobject jobj, jlong handle,
+    jbyteArray jtarget, jint jtarget_len) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  jbyte* target = env->GetByteArrayElements(jtarget, 0);
+  rocksdb::Slice target_slice(
+      reinterpret_cast<char*>(target), jtarget_len);
+  
+  st->Seek(target_slice);
+  
+  env->ReleaseByteArrayElements(jtarget, target, JNI_ABORT);
+}
+
+void Java_org_rocksdb_Iterator_status0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto st = reinterpret_cast<rocksdb::Iterator*>(handle);
+  assert(st != nullptr);
+  
+  rocksdb::Status s = st->status();
+  
+  if (s.ok()) {
+    return;
+  }
+  
+  rocksdb::RocksDBExceptionJni::ThrowNew(env, s);
+}
+
 void Java_org_rocksdb_Iterator_close0(
     JNIEnv* env, jobject jobj, jlong handle) {
   auto st = reinterpret_cast<rocksdb::Iterator*>(handle);