Support for column families in TTL DB

Summary:
This will enable people using TTL DB to do so with multiple column families. They can also specify different TTLs for each one.

TODO: Implement CreateColumnFamily() in TTL world.

Test Plan: Added a very simple sanity test.

Reviewers: dhruba, haobo, ljin, sdong, yhchiang

Reviewed By: haobo

CC: leveldb, alberts

Differential Revision: https://reviews.facebook.net/D17859

include/rocksdb/write_batch.h

@@ -65,9 +65,7 @@ class WriteBatch {
 
   // If the database contains a mapping for "key", erase it.  Else do nothing.
   void Delete(ColumnFamilyHandle* column_family, const Slice& key);
-  void Delete(const Slice& key) {
-    Delete(nullptr, key);
-  }
+  void Delete(const Slice& key) { Delete(nullptr, key); }
 
   // Append a blob of arbitrary size to the records in this batch. The blob will
   // be stored in the transaction log but not in any other file. In particular,

include/utilities/utility_db.h

@@ -2,9 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
-#ifndef ROCKSDB_LITE
 #pragma once
-#include "stackable_db.h"
+#ifndef ROCKSDB_LITE
+#include <vector>
+#include <string>
+
+#include "utilities/stackable_db.h"
+#include "rocksdb/db.h"
 
 namespace rocksdb {
 
@@ -46,6 +50,13 @@ class UtilityDB {
                             StackableDB** dbptr,
                             int32_t ttl = 0,
                             bool read_only = false);
+
+    // OpenTtlDB with column family support
+    static Status OpenTtlDB(
+        const DBOptions& db_options, const std::string& name,
+        const std::vector<ColumnFamilyDescriptor>& column_families,
+        std::vector<ColumnFamilyHandle*>* handles, StackableDB** dbptr,
+        std::vector<int32_t> ttls, bool read_only = false);
 };
 
 } //  namespace rocksdb