Add possibility to change ttl on open DB

Summary:
We have seen cases where it could be good to change TTL on already open DB.
Change ttl in TtlCompactionFilterFactory on open db.
Next time a filter is created, it will filter accroding to the set TTL.

Is this something that could be useful for others?
Any downsides?
Closes https://github.com/facebook/rocksdb/pull/3292

Differential Revision: D6731993

Pulled By: miasantreble

fbshipit-source-id: 73b94d69237b11e8730734389052429d621a6b1e

include/rocksdb/utilities/db_ttl.h

@@ -60,6 +60,10 @@ class DBWithTTL : public StackableDB {
                      DBWithTTL** dbptr, std::vector<int32_t> ttls,
                      bool read_only = false);
 
+ virtual void SetTtl(int32_t ttl) = 0;
+
+ virtual void SetTtl(ColumnFamilyHandle *h, int32_t ttl) = 0;
+
  protected:
   explicit DBWithTTL(DB* db) : StackableDB(db) {}
 };

utilities/ttl/db_ttl_impl.cc

@@ -309,5 +309,16 @@ Iterator* DBWithTTLImpl::NewIterator(const ReadOptions& opts,
   return new TtlIterator(db_->NewIterator(opts, column_family));
 }
 
+void DBWithTTLImpl::SetTtl(ColumnFamilyHandle *h, int32_t ttl) {
+  std::shared_ptr<TtlCompactionFilterFactory> filter;
+  Options opts;
+  opts = GetOptions(h);
+  filter = std::static_pointer_cast<TtlCompactionFilterFactory>(
+                                       opts.compaction_filter_factory);
+  if (!filter)
+    return;
+  filter->SetTtl(ttl);
+}
+
 }  // namespace rocksdb
 #endif  // ROCKSDB_LITE

utilities/ttl/db_ttl_impl.h

@@ -94,6 +94,10 @@ class DBWithTTLImpl : public DBWithTTL {
   static const int32_t kMinTimestamp = 1368146402;  // 05/09/2013:5:40PM GMT-8
 
   static const int32_t kMaxTimestamp = 2147483647;  // 01/18/2038:7:14PM GMT-8
+
+  void SetTtl(int32_t ttl) override { SetTtl(DefaultColumnFamily(), ttl); }
+
+  void SetTtl(ColumnFamilyHandle *h, int32_t ttl) override;
 };
 
 class TtlIterator : public Iterator {
@@ -209,6 +213,10 @@ class TtlCompactionFilterFactory : public CompactionFilterFactory {
         ttl_, env_, nullptr, std::move(user_comp_filter_from_factory)));
   }
 
+  void SetTtl(int32_t ttl) {
+    ttl_ = ttl;
+  }
+
   virtual const char* Name() const override {
     return "TtlCompactionFilterFactory";
   }

utilities/ttl/ttl_test.cc

@@ -283,6 +283,12 @@ class TtlTest : public testing::Test {
     delete dbiter;
   }
 
+  // Set ttl on open db
+  void SetTtl(int32_t ttl, ColumnFamilyHandle* cf = nullptr) {
+    ASSERT_TRUE(db_ttl_);
+    cf == nullptr ? db_ttl_->SetTtl(ttl) : db_ttl_->SetTtl(cf, ttl);
+  }
+
   class TestFilter : public CompactionFilter {
    public:
     TestFilter(const int64_t kSampleSize, const std::string& kNewValue)
@@ -626,6 +632,17 @@ TEST_F(TtlTest, ColumnFamiliesTest) {
   db_ttl_ = nullptr;
 }
 
+// Puts a set of values and checks its absence using Get after ttl
+TEST_F(TtlTest, ChangeTtlOnOpenDb) {
+  MakeKVMap(kSampleSize_);
+
+  OpenTtl(1);                                  // T=0:Open the db with ttl = 2
+  SetTtl(3);
+  PutValues(0, kSampleSize_);		       // T=0:Insert Set1. Delete at t=2
+  SleepCompactCheck(2, 0, kSampleSize_, true); // T=2:Set1 should be there
+  CloseTtl();
+}
+
 } //  namespace rocksdb
 
 // A black-box test for the ttl wrapper around rocksdb