1 // Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
2 //  This source code is licensed under both the GPLv2 (found in the
3 //  COPYING file in the root directory) and Apache 2.0 License
4 //  (found in the LICENSE.Apache file in the root directory).
5 
6 package org.rocksdb;
7 
8 import java.util.Arrays;
9 import java.util.Objects;
10 
11 /**
12  * ColumnFamilyHandle class to hold handles to underlying rocksdb
13  * ColumnFamily Pointers.
14  */
15 public class ColumnFamilyHandle extends RocksObject {
ColumnFamilyHandle(final RocksDB rocksDB, final long nativeHandle)16   ColumnFamilyHandle(final RocksDB rocksDB,
17       final long nativeHandle) {
18     super(nativeHandle);
19     // rocksDB must point to a valid RocksDB instance;
20     assert(rocksDB != null);
21     // ColumnFamilyHandle must hold a reference to the related RocksDB instance
22     // to guarantee that while a GC cycle starts ColumnFamilyHandle instances
23     // are freed prior to RocksDB instances.
24     this.rocksDB_ = rocksDB;
25   }
26 
27   /**
28    * Gets the name of the Column Family.
29    *
30    * @return The name of the Column Family.
31    *
32    * @throws RocksDBException if an error occurs whilst retrieving the name.
33    */
getName()34   public byte[] getName() throws RocksDBException {
35     return getName(nativeHandle_);
36   }
37 
38   /**
39    * Gets the ID of the Column Family.
40    *
41    * @return the ID of the Column Family.
42    */
getID()43   public int getID() {
44     return getID(nativeHandle_);
45   }
46 
47   /**
48    * Gets the up-to-date descriptor of the column family
49    * associated with this handle. Since it fills "*desc" with the up-to-date
50    * information, this call might internally lock and release DB mutex to
51    * access the up-to-date CF options. In addition, all the pointer-typed
52    * options cannot be referenced any longer than the original options exist.
53    *
54    * Note that this function is not supported in RocksDBLite.
55    *
56    * @return the up-to-date descriptor.
57    *
58    * @throws RocksDBException if an error occurs whilst retrieving the
59    *     descriptor.
60    */
getDescriptor()61   public ColumnFamilyDescriptor getDescriptor() throws RocksDBException {
62     assert(isOwningHandle());
63     return getDescriptor(nativeHandle_);
64   }
65 
66   @Override
equals(final Object o)67   public boolean equals(final Object o) {
68     if (this == o) {
69       return true;
70     }
71     if (o == null || getClass() != o.getClass()) {
72       return false;
73     }
74 
75     final ColumnFamilyHandle that = (ColumnFamilyHandle) o;
76     try {
77       return rocksDB_.nativeHandle_ == that.rocksDB_.nativeHandle_ &&
78           getID() == that.getID() &&
79           Arrays.equals(getName(), that.getName());
80     } catch (RocksDBException e) {
81       throw new RuntimeException("Cannot compare column family handles", e);
82     }
83   }
84 
85   @Override
hashCode()86   public int hashCode() {
87     try {
88       return Objects.hash(getName(), getID(), rocksDB_.nativeHandle_);
89     } catch (RocksDBException e) {
90       throw new RuntimeException("Cannot calculate hash code of column family handle", e);
91     }
92   }
93 
94   /**
95    * <p>Deletes underlying C++ iterator pointer.</p>
96    *
97    * <p>Note: the underlying handle can only be safely deleted if the RocksDB
98    * instance related to a certain ColumnFamilyHandle is still valid and
99    * initialized. Therefore {@code disposeInternal()} checks if the RocksDB is
100    * initialized before freeing the native handle.</p>
101    */
102   @Override
disposeInternal()103   protected void disposeInternal() {
104     if(rocksDB_.isOwningHandle()) {
105       disposeInternal(nativeHandle_);
106     }
107   }
108 
getName(final long handle)109   private native byte[] getName(final long handle) throws RocksDBException;
getID(final long handle)110   private native int getID(final long handle);
getDescriptor(final long handle)111   private native ColumnFamilyDescriptor getDescriptor(final long handle) throws RocksDBException;
disposeInternal(final long handle)112   @Override protected final native void disposeInternal(final long handle);
113 
114   private final RocksDB rocksDB_;
115 }
116