From 5fe176d8f61ded795a9d26f94f25c65f274dd220 Mon Sep 17 00:00:00 2001
From: Bob Potter <bobby.potter@gmail.com>
Date: Tue, 20 May 2014 18:52:27 -0500
Subject: [PATCH 1/2] Java Bindings: prevent segfault from double delete

Give BackupableDB sole responsibility of the native
object to prevent RocksDB from also trying to delete
it.
---
 java/org/rocksdb/BackupableDB.java |  4 ++++
 java/org/rocksdb/RocksDB.java      | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/java/org/rocksdb/BackupableDB.java b/java/org/rocksdb/BackupableDB.java
index 91607d4df..b85f792fc 100644
--- a/java/org/rocksdb/BackupableDB.java
+++ b/java/org/rocksdb/BackupableDB.java
@@ -31,6 +31,10 @@ public class BackupableDB extends RocksDB {
     BackupableDB bdb = new BackupableDB(RocksDB.open(opt, db_path));
     bdb.open(bdb.db_.nativeHandle_, bopt.nativeHandle_);
 
+    // Prevent the RocksDB object from attempting to delete
+    // the underly C++ DB object.
+    bdb.db_.disOwnNativeObject();
+
     return bdb;
   }
 
diff --git a/java/org/rocksdb/RocksDB.java b/java/org/rocksdb/RocksDB.java
index 23dad1dc4..bc0390d9f 100644
--- a/java/org/rocksdb/RocksDB.java
+++ b/java/org/rocksdb/RocksDB.java
@@ -337,6 +337,18 @@ public class RocksDB extends RocksObject {
     opt.filter_ = null;
   }
 
+  /**
+   * Revoke ownership of the native object.
+   *
+   * This will prevent the object from attempting to delete the underlying
+   * native object in its finalizer. This must be used when another object
+   * (e.g. BackupableDB) takes over ownership of the native object or both
+   * will attempt to delete the underlying object when garbage collected.
+   */
+  protected void disOwnNativeObject() {
+    nativeHandle_ = 0;
+  }
+
   // native methods
   protected native void open(
       long optionsHandle, long cacheSize, String path) throws RocksDBException;

From 05dd018353aeb9448ccd02fb954389cb28090086 Mon Sep 17 00:00:00 2001
From: Bob Potter <bobby.potter@gmail.com>
Date: Tue, 27 May 2014 13:54:02 -0500
Subject: [PATCH 2/2] BackupableDB: don't keep a reference to the RocksDB
 object now that we have disOwnNativeObject

---
 java/org/rocksdb/BackupableDB.java | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/java/org/rocksdb/BackupableDB.java b/java/org/rocksdb/BackupableDB.java
index b85f792fc..f57d47df1 100644
--- a/java/org/rocksdb/BackupableDB.java
+++ b/java/org/rocksdb/BackupableDB.java
@@ -25,15 +25,14 @@ public class BackupableDB extends RocksDB {
   public static BackupableDB open(
       Options opt, BackupableDBOptions bopt, String db_path)
       throws RocksDBException {
-    // since BackupableDB c++ will handle the life cycle of
-    // the returned RocksDB of RocksDB.open(), here we store
-    // it as a BackupableDB member variable to avoid GC.
-    BackupableDB bdb = new BackupableDB(RocksDB.open(opt, db_path));
-    bdb.open(bdb.db_.nativeHandle_, bopt.nativeHandle_);
+
+    RocksDB db = RocksDB.open(opt, db_path);
+    BackupableDB bdb = new BackupableDB();
+    bdb.open(db.nativeHandle_, bopt.nativeHandle_);
 
     // Prevent the RocksDB object from attempting to delete
     // the underly C++ DB object.
-    bdb.db_.disOwnNativeObject();
+    db.disOwnNativeObject();
 
     return bdb;
   }
@@ -68,9 +67,8 @@ public class BackupableDB extends RocksDB {
    * A protected construction that will be used in the static factory
    * method BackupableDB.open().
    */
-  protected BackupableDB(RocksDB db) {
+  protected BackupableDB() {
     super();
-    db_ = db;
   }
 
   @Override protected void finalize() {
@@ -79,6 +77,4 @@ public class BackupableDB extends RocksDB {
 
   protected native void open(long rocksDBHandle, long backupDBOptionsHandle);
   protected native void createNewBackup(long handle, boolean flag);
-
-  private final RocksDB db_;
 }