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Abstractions for common iterator behaviour

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This commit is contained in:
Adam Retter 2015-01-03 15:08:10 +00:00
parent e01acb3a04
commit de678b288e
3 changed files with 160 additions and 122 deletions
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105
java/org/rocksdb/AbstractRocksIterator.java Normal file
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@ -0,0 +1,105 @@
// 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;
/**
* Base class implementation for Rocks Iterators
* in the Java API
* <p/>
* <p>Multiple threads can invoke const methods on an RocksIterator without
* external synchronization, but if any of the threads may call a
* non-const method, all threads accessing the same RocksIterator must use
* external synchronization.</p>
*
* @param P The type of the Parent Object from which the Rocks Iterator was
* created. This is used by disposeInternal to avoid double-free
* issues with the underlying C++ object.
* @see org.rocksdb.RocksObject
*/
public abstract class AbstractRocksIterator<P extends RocksObject>
extends RocksObject implements RocksIteratorInterface {
final P parent_;
protected AbstractRocksIterator(P parent, long nativeHandle) {
super();
nativeHandle_ = nativeHandle;
// parent must point to a valid RocksDB instance.
assert (parent != null);
// RocksIterator must hold a reference to the related parent instance
// to guarantee that while a GC cycle starts RocksIterator instances
// are freed prior to parent instances.
parent_ = parent;
}
@Override
public boolean isValid() {
assert (isInitialized());
return isValid0(nativeHandle_);
}
@Override
public void seekToFirst() {
assert (isInitialized());
seekToFirst0(nativeHandle_);
}
@Override
public void seekToLast() {
assert (isInitialized());
seekToLast0(nativeHandle_);
}
@Override
public void seek(byte[] target) {
assert (isInitialized());
seek0(nativeHandle_, target, target.length);
}
@Override
public void next() {
assert (isInitialized());
next0(nativeHandle_);
}
@Override
public void prev() {
assert (isInitialized());
prev0(nativeHandle_);
}
@Override
public void status() throws RocksDBException {
assert (isInitialized());
status0(nativeHandle_);
}
/**
* <p>Deletes underlying C++ iterator pointer.</p>
* <p/>
* <p>Note: the underlying handle can only be safely deleted if the parent
* instance related to a certain RocksIterator is still valid and initialized.
* Therefore {@code disposeInternal()} checks if the parent is initialized
* before freeing the native handle.</p>
*/
@Override
protected void disposeInternal() {
synchronized (parent_) {
assert (isInitialized());
if (parent_.isInitialized()) {
disposeInternal(nativeHandle_);
}
}
}
abstract void disposeInternal(long handle);
abstract boolean isValid0(long handle);
abstract void seekToFirst0(long handle);
abstract void seekToLast0(long handle);
abstract void next0(long handle);
abstract void prev0(long handle);
abstract void seek0(long handle, byte[] target, int targetLen);
abstract void status0(long handle) throws RocksDBException;
}

89
java/org/rocksdb/RocksIterator.java
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@ -18,58 +18,9 @@ package org.rocksdb;
*
* @see org.rocksdb.RocksObject
*/
public class RocksIterator extends RocksObject implements RocksIteratorInterface {
public RocksIterator(RocksDB rocksDB, long nativeHandle) {
super();
nativeHandle_ = nativeHandle;
// rocksDB must point to a valid RocksDB instance.
assert(rocksDB != null);
// RocksIterator must hold a reference to the related RocksDB instance
// to guarantee that while a GC cycle starts RocksDBIterator instances
// are freed prior to RocksDB instances.
rocksDB_ = rocksDB;
}
@Override
public boolean isValid() {
assert(isInitialized());
return isValid0(nativeHandle_);
}
@Override
public void seekToFirst() {
assert(isInitialized());
seekToFirst0(nativeHandle_);
}
@Override
public void seekToLast() {
assert(isInitialized());
seekToLast0(nativeHandle_);
}
@Override
public void seek(byte[] target) {
assert(isInitialized());
seek0(nativeHandle_, target, target.length);
}
@Override
public void next() {
assert(isInitialized());
next0(nativeHandle_);
}
@Override
public void prev() {
assert(isInitialized());
prev0(nativeHandle_);
}
@Override
public void status() throws RocksDBException {
assert(isInitialized());
status0(nativeHandle_);
public class RocksIterator extends AbstractRocksIterator<RocksDB> {
protected RocksIterator(RocksDB rocksDB, long nativeHandle) {
super(rocksDB, nativeHandle);
}
/**
@ -99,33 +50,15 @@ public class RocksIterator extends RocksObject implements RocksIteratorInterface
return value0(nativeHandle_);
}
/**
* <p>Deletes underlying C++ iterator pointer.</p>
*
* <p>Note: the underlying handle can only be safely deleted if the RocksDB
* instance related to a certain RocksIterator is still valid and initialized.
* Therefore {@code disposeInternal()} checks if the RocksDB is initialized
* before freeing the native handle.</p>
*/
@Override protected void disposeInternal() {
synchronized (rocksDB_) {
assert (isInitialized());
if (rocksDB_.isInitialized()) {
disposeInternal(nativeHandle_);
}
}
}
@Override final native void disposeInternal(long handle);
@Override final native boolean isValid0(long handle);
@Override final native void seekToFirst0(long handle);
@Override final native void seekToLast0(long handle);
@Override final native void next0(long handle);
@Override final native void prev0(long handle);
@Override final native void seek0(long handle, byte[] target, int targetLen);
@Override final native void status0(long handle) throws RocksDBException;
private native boolean isValid0(long handle);
private native void disposeInternal(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);
final RocksDB rocksDB_;
}

88
java/rocksjni/iterator.cc
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@ -14,6 +14,17 @@
#include "rocksjni/portal.h"
#include "rocksdb/iterator.h"
/*
* Class: org_rocksdb_RocksIterator
* Method: disposeInternal
* Signature: (J)V
*/
void Java_org_rocksdb_RocksIterator_disposeInternal(
JNIEnv* env, jobject jobj, jlong handle) {
auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
delete it;
}
/*
* Class: org_rocksdb_RocksIterator
* Method: isValid0
@ -36,7 +47,7 @@ void Java_org_rocksdb_RocksIterator_seekToFirst0(
/*
* Class: org_rocksdb_RocksIterator
* Method: seekToFirst0
* Method: seekToLast0
* Signature: (J)V
*/
void Java_org_rocksdb_RocksIterator_seekToLast0(
@ -46,7 +57,7 @@ void Java_org_rocksdb_RocksIterator_seekToLast0(
/*
* Class: org_rocksdb_RocksIterator
* Method: seekToLast0
* Method: next0
* Signature: (J)V
*/
void Java_org_rocksdb_RocksIterator_next0(
@ -56,7 +67,7 @@ void Java_org_rocksdb_RocksIterator_next0(
/*
* Class: org_rocksdb_RocksIterator
* Method: next0
* Method: prev0
* Signature: (J)V
*/
void Java_org_rocksdb_RocksIterator_prev0(
@ -66,41 +77,8 @@ void Java_org_rocksdb_RocksIterator_prev0(
/*
* Class: org_rocksdb_RocksIterator
* Method: prev0
* Signature: (J)V
*/
jbyteArray Java_org_rocksdb_RocksIterator_key0(
JNIEnv* env, jobject jobj, jlong handle) {
auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
rocksdb::Slice key_slice = it->key();
jbyteArray jkey = env->NewByteArray(static_cast<jsize>(key_slice.size()));
env->SetByteArrayRegion(jkey, 0, static_cast<jsize>(key_slice.size()),
reinterpret_cast<const jbyte*>(key_slice.data()));
return jkey;
}
/*
* Class: org_rocksdb_RocksIterator
* Method: key0
* Signature: (J)[B
*/
jbyteArray Java_org_rocksdb_RocksIterator_value0(
JNIEnv* env, jobject jobj, jlong handle) {
auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
rocksdb::Slice value_slice = it->value();
jbyteArray jkeyValue =
env->NewByteArray(static_cast<jsize>(value_slice.size()));
env->SetByteArrayRegion(jkeyValue, 0, static_cast<jsize>(value_slice.size()),
reinterpret_cast<const jbyte*>(value_slice.data()));
return jkeyValue;
}
/*
* Class: org_rocksdb_RocksIterator
* Method: value0
* Signature: (J)[B
* Method: seek0
* Signature: (J[BI)V
*/
void Java_org_rocksdb_RocksIterator_seek0(
JNIEnv* env, jobject jobj, jlong handle,
@ -117,8 +95,8 @@ void Java_org_rocksdb_RocksIterator_seek0(
/*
* Class: org_rocksdb_RocksIterator
* Method: seek0
* Signature: (J[BI)V
* Method: status0
* Signature: (J)V
*/
void Java_org_rocksdb_RocksIterator_status0(
JNIEnv* env, jobject jobj, jlong handle) {
@ -134,11 +112,33 @@ void Java_org_rocksdb_RocksIterator_status0(
/*
* Class: org_rocksdb_RocksIterator
* Method: disposeInternal
* Signature: (J)V
* Method: key0
* Signature: (J)[B
*/
void Java_org_rocksdb_RocksIterator_disposeInternal(
jbyteArray Java_org_rocksdb_RocksIterator_key0(
JNIEnv* env, jobject jobj, jlong handle) {
auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
delete it;
rocksdb::Slice key_slice = it->key();
jbyteArray jkey = env->NewByteArray(static_cast<jsize>(key_slice.size()));
env->SetByteArrayRegion(jkey, 0, static_cast<jsize>(key_slice.size()),
reinterpret_cast<const jbyte*>(key_slice.data()));
return jkey;
}
/*
* Class: org_rocksdb_RocksIterator
* Method: value0
* Signature: (J)[B
*/
jbyteArray Java_org_rocksdb_RocksIterator_value0(
JNIEnv* env, jobject jobj, jlong handle) {
auto it = reinterpret_cast<rocksdb::Iterator*>(handle);
rocksdb::Slice value_slice = it->value();
jbyteArray jkeyValue =
env->NewByteArray(static_cast<jsize>(value_slice.size()));
env->SetByteArrayRegion(jkeyValue, 0, static_cast<jsize>(value_slice.size()),
reinterpret_cast<const jbyte*>(value_slice.data()));
return jkeyValue;
}