Merge pull request #124 from ankgup87/master

[Java] Add iterator JNI bindings

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

@@ -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 +141,41 @@ public class RocksDBSample {
         System.out.println("Failed in call to geHistogramData()");
         assert(false); //Should never reach here.
       }
+
+      Iterator iterator = db.newIterator();
+
+      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();
+      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

@@ -0,0 +1,146 @@
+// 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;
+
+/**
+ * An iterator yields a sequence of key/value pairs from a source.
+ * The following class defines the interface.  Multiple implementations
+ * are provided by this library.  In particular, iterators are provided
+ * to access the contents of a Table or a DB.
+ *
+ * Multiple threads can invoke const methods on an Iterator without
+ * external synchronization, but if any of the threads may call a
+ * non-const method, all threads accessing the same Iterator must use
+ * external synchronization.
+ */
+public class Iterator {
+  private long nativeHandle_;
+
+  public Iterator(long nativeHandle) {
+    nativeHandle_ = nativeHandle;
+  }
+
+  /**
+   * An iterator is either positioned at a key/value pair, or
+   * not valid.  This method returns true iff the iterator is valid.
+   * @return true if iterator is valid.
+   */
+  public boolean isValid() {
+    assert(isInitialized());
+    return isValid0(nativeHandle_);
+  }
+
+  /**
+   * Position at the first key in the source.  The iterator is Valid()
+   * after this call iff the source is not empty.
+   */
+  public void seekToFirst() {
+    assert(isInitialized());
+    seekToFirst0(nativeHandle_);
+  }
+
+  /**
+   * Position at the last key in the source.  The iterator is
+   * Valid() after this call iff the source is not empty.
+   */
+  public void seekToLast() {
+    assert(isInitialized());
+    seekToLast0(nativeHandle_);
+  }
+
+  /**
+   * Moves to the next entry in the source.  After this call, Valid() is
+   * true iff the iterator was not positioned at the last entry in the source.
+   * REQUIRES: Valid()
+   */
+  public void next() {
+    assert(isInitialized());
+    next0(nativeHandle_);
+  }
+
+  /**
+   * Moves to the previous entry in the source.  After this call, Valid() is
+   * true iff the iterator was not positioned at the first entry in source.
+   * REQUIRES: Valid()
+   */
+  public void prev() {
+    assert(isInitialized());
+    prev0(nativeHandle_);
+  }
+
+  /**
+   * Return the key for the current entry.  The underlying storage for
+   * the returned slice is valid only until the next modification of
+   * the iterator.
+   * REQUIRES: Valid()
+   * @return key for the current entry.
+   */
+  public byte[] key() {
+    assert(isInitialized());
+    return key0(nativeHandle_);
+  }
+
+  /**
+   * Return the value for the current entry.  The underlying storage for
+   * the returned slice is valid only until the next modification of
+   * the iterator.
+   * REQUIRES: !AtEnd() && !AtStart()
+   * @return value for the current entry.
+   */
+  public byte[] value() {
+    assert(isInitialized());
+    return value0(nativeHandle_);
+  }
+
+  /**
+   * Position at the first key in the source that at or past target
+   * The iterator is Valid() after this call iff the source contains
+   * an entry that comes at or past target.
+   */
+  public void seek(byte[] target) {
+    assert(isInitialized());
+    seek0(nativeHandle_, target, target.length);
+  }
+
+  /**
+   * If an error has occurred, return it.  Else return an ok status.
+   * If non-blocking IO is requested and this operation cannot be
+   * satisfied without doing some IO, then this returns Status::Incomplete().
+   *
+   */
+  public void status() throws RocksDBException {
+    assert(isInitialized());
+    status0(nativeHandle_);
+  }
+
+  /**
+   * Deletes underlying C++ iterator pointer.
+   */
+  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);
+  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/org/rocksdb/Options.java

@@ -508,7 +508,7 @@ public class Options {
     return maxBackgroundCompactions(nativeHandle_);
   }
 
-  /** 
+  /**
    * Creates statistics object which collects metrics about database operations.
      Statistics objects should not be shared between DB instances as
      it does not use any locks to prevent concurrent updates.

java/org/rocksdb/RocksDB.java

@@ -5,7 +5,6 @@
 
 package org.rocksdb;
 
-import java.util.*;
 import java.io.Closeable;
 import java.io.IOException;
 
@@ -137,6 +136,20 @@ public class RocksDB {
     remove(nativeHandle_, writeOpt.nativeHandle_, key, key.length);
   }
 
+  /**
+   * Return a heap-allocated iterator over the contents of the database.
+   * The result of newIterator() is initially invalid (caller must
+   * call one of the Seek methods on the iterator before using it).
+   *
+   * Caller should close the iterator when it is no longer needed.
+   * The returned iterator should be closed before this db is closed.
+   *
+   * @return instance of iterator object.
+   */
+  public Iterator newIterator() {
+    return new Iterator(iterator0(nativeHandle_));
+  }
+
   @Override protected void finalize() {
     close();
   }
@@ -170,6 +183,7 @@ 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

@@ -0,0 +1,147 @@
+// 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"
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    isValid0
+ * Signature: (J)Z
+ */
+jboolean Java_org_rocksdb_Iterator_isValid0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  return reinterpret_cast<rocksdb::Iterator*>(handle)->Valid();
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    close0
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_Iterator_seekToFirst0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  reinterpret_cast<rocksdb::Iterator*>(handle)->SeekToFirst();
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    seekToFirst0
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_Iterator_seekToLast0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  reinterpret_cast<rocksdb::Iterator*>(handle)->SeekToLast();
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    seekToLast0
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_Iterator_next0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  reinterpret_cast<rocksdb::Iterator*>(handle)->Next();
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    next0
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_Iterator_prev0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  reinterpret_cast<rocksdb::Iterator*>(handle)->Prev();
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    prev0
+ * Signature: (J)V
+ */
+jbyteArray Java_org_rocksdb_Iterator_key0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
+  rocksdb::Slice key_slice = it->key();
+
+  jbyteArray jkey = env->NewByteArray(key_slice.size());
+  env->SetByteArrayRegion(
+      jkey, 0, key_slice.size(),
+      reinterpret_cast<const jbyte*>(key_slice.data()));
+  return jkey;
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    key0
+ * Signature: (J)[B
+ */
+jbyteArray Java_org_rocksdb_Iterator_value0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
+  rocksdb::Slice value_slice = it->value();
+
+  jbyteArray jvalue = env->NewByteArray(value_slice.size());
+  env->SetByteArrayRegion(
+      jvalue, 0, value_slice.size(),
+      reinterpret_cast<const jbyte*>(value_slice.data()));
+  return jvalue;
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    value0
+ * Signature: (J)[B
+ */
+void Java_org_rocksdb_Iterator_seek0(
+    JNIEnv* env, jobject jobj, jlong handle,
+    jbyteArray jtarget, jint jtarget_len) {
+  auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
+  jbyte* target = env->GetByteArrayElements(jtarget, 0);
+  rocksdb::Slice target_slice(
+      reinterpret_cast<char*>(target), jtarget_len);
+
+  it->Seek(target_slice);
+
+  env->ReleaseByteArrayElements(jtarget, target, JNI_ABORT);
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    seek0
+ * Signature: (J[BI)V
+ */
+void Java_org_rocksdb_Iterator_status0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
+  rocksdb::Status s = it->status();
+
+  if (s.ok()) {
+    return;
+  }
+
+  rocksdb::RocksDBExceptionJni::ThrowNew(env, s);
+}
+
+/*
+ * Class:     org_rocksdb_Iterator
+ * Method:    status0
+ * Signature: (J)V
+ */
+void Java_org_rocksdb_Iterator_close0(
+    JNIEnv* env, jobject jobj, jlong handle) {
+  auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
+  delete it;
+
+  rocksdb::IteratorJni::setHandle(env, jobj, nullptr);
+}

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 +296,15 @@ void Java_org_rocksdb_RocksDB_close0(
 
   rocksdb::RocksDBJni::setHandle(env, java_db, nullptr);
 }
+
+/*
+ * Class:     org_rocksdb_RocksDB
+ * Method:    iterator0
+ * Signature: (J)J
+ */
+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);
+}

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