MultiGet for DBWithTTL

Summary: This is a feature request from rocksdb's user. I didn't even realize we don't support multigets on TTL DB :)

Test Plan: added a unit test

Reviewers: yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30561

utilities/ttl/db_ttl_impl.cc

@@ -202,8 +202,18 @@ std::vector<Status> DBWithTTLImpl::MultiGet(
     const ReadOptions& options,
     const std::vector<ColumnFamilyHandle*>& column_family,
     const std::vector<Slice>& keys, std::vector<std::string>* values) {
-  return std::vector<Status>(
+  auto statuses = db_->MultiGet(options, column_family, keys, values);
-      keys.size(), Status::NotSupported("MultiGet not supported with TTL"));
+  for (size_t i = 0; i < keys.size(); ++i) {
+    if (!statuses[i].ok()) {
+      continue;
+    }
+    statuses[i] = SanityCheckTimestamp((*values)[i]);
+    if (!statuses[i].ok()) {
+      continue;
+    }
+    statuses[i] = StripTS(&(*values)[i]);
+  }
+  return statuses;
 }
 
 bool DBWithTTLImpl::KeyMayExist(const ReadOptions& options,

utilities/ttl/ttl_test.cc

@@ -194,6 +194,25 @@ class TtlTest {
     }
   }
 
+  // checks the whole kvmap_ to return correct values using MultiGet
+  void SimpleMultiGetTest() {
+    static ReadOptions ropts;
+    std::vector<Slice> keys;
+    std::vector<std::string> values;
+
+    for (auto& kv : kvmap_) {
+      keys.emplace_back(kv.first);
+    }
+
+    auto statuses = db_ttl_->MultiGet(ropts, keys, &values);
+    size_t i = 0;
+    for (auto& kv : kvmap_) {
+      ASSERT_OK(statuses[i]);
+      ASSERT_EQ(values[i], kv.second);
+      ++i;
+    }
+  }
+
   // Sleeps for slp_tim then runs a manual compaction
   // Checks span starting from st_pos from kvmap_ in the db and
   // Gets should return true if check is true and false otherwise
@@ -533,6 +552,17 @@ TEST(TtlTest, KeyMayExist) {
   CloseTtl();
 }
 
+TEST(TtlTest, MultiGetTest) {
+  MakeKVMap(kSampleSize_);
+
+  OpenTtl();
+  PutValues(0, kSampleSize_, false);
+
+  SimpleMultiGetTest();
+
+  CloseTtl();
+}
+
 TEST(TtlTest, ColumnFamiliesTest) {
   DB* db;
   Options options;