Use unique_ptr for rocksdb::DB to prevent memory leak if StateMachine throws in constructor

CHANGELOG.md

@@ -12,6 +12,9 @@ All notable changes to this project will be documented in this file.
   From now on, a node which has been vetoed will abstain from starting election
   rounds until it has received fresh heartbeats since receiving that veto.
 
+### Fixed
+- A couple of minor memory leaks.
+
 ## 0.3.1 (2018-08-03)
 ### Added
 - Command `hclone` for creating identical copies of entire hashes.

src/StateMachine.cc

@@ -139,9 +139,11 @@ StateMachine::StateMachine(const std::string &f, bool write_ahead_log, bool bulk
     options.allow_concurrent_memtable_write = false;
   }
 
-  rocksdb::Status status = rocksdb::DB::Open(options, filename, &db);
+  rocksdb::DB *tmpdb = nullptr;
+  rocksdb::Status status = rocksdb::DB::Open(options, filename, &tmpdb);
   if(!status.ok()) qdb_throw("Cannot open " << quotes(filename) << ":" << status.ToString());
 
+  db.reset(tmpdb);
   ensureCompatibleFormat(!dirExists);
   ensureBulkloadSanity(!dirExists);
   ensureClockSanity(!dirExists);
@@ -182,8 +184,7 @@ StateMachine::~StateMachine() {
 
   if(db) {
     qdb_info("Closing state machine " << quotes(filename));
-    delete db;
-    db = nullptr;
+    db.reset();
   }
 }
 
@@ -594,7 +595,7 @@ rocksdb::Status StateMachine::lhlen(StagingArea &stagingArea, const std::string
 }
 
 rocksdb::Status StateMachine::rawGetAllVersions(const std::string &key, std::vector<rocksdb::KeyVersion> &versions) {
-  return rocksdb::GetAllKeyVersions(db, key, key, &versions);
+  return rocksdb::GetAllKeyVersions(db.get(), key, key, &versions);
 }
 
 rocksdb::Status StateMachine::rawScan(StagingArea &stagingArea, const std::string &key, size_t count, std::vector<std::string> &elements) {
@@ -1470,7 +1471,7 @@ rocksdb::Status StateMachine::flushall(StagingArea &stagingArea) {
 
 rocksdb::Status StateMachine::checkpoint(const std::string &path) {
   rocksdb::Checkpoint *checkpoint = nullptr;
-  RETURN_ON_ERROR(rocksdb::Checkpoint::Create(db, &checkpoint));
+  RETURN_ON_ERROR(rocksdb::Checkpoint::Create(db.get(), &checkpoint));
 
   rocksdb::Status st = checkpoint->CreateCheckpoint(path);
   delete checkpoint;

src/StateMachine.hh

@@ -295,7 +295,7 @@ private:
   std::mutex lastAppliedMtx;
 
   std::mutex writeMtx;
-  rocksdb::DB* db = nullptr;
+  std::unique_ptr<rocksdb::DB> db;
 
   std::unique_ptr<ConsistencyScanner> consistencyScanner;
 

src/storage/StagingArea.hh

@@ -49,7 +49,7 @@ public:
 
     if(readOnly) {
       // Acquire snapshot.
-      snapshot.reset(new StateMachine::Snapshot(sm.db));
+      snapshot.reset(new StateMachine::Snapshot(sm.db.get()));
     }
   }
 
@@ -65,7 +65,8 @@ public:
       return rocksdb::Status::NotFound();
     }
 
-    return writeBatchWithIndex.GetFromBatchAndDB(stateMachine.db, rocksdb::ReadOptions(), slice, &value);
+    return writeBatchWithIndex.GetFromBatchAndDB(stateMachine.db.get(),
+      rocksdb::ReadOptions(), slice, &value);
   }
 
   rocksdb::Status exists(const rocksdb::Slice &slice) {
@@ -80,7 +81,7 @@ public:
     }
 
     rocksdb::PinnableSlice ignored;
-    return writeBatchWithIndex.GetFromBatchAndDB(stateMachine.db, rocksdb::ReadOptions(), slice, &ignored);
+    return writeBatchWithIndex.GetFromBatchAndDB(stateMachine.db.get(), rocksdb::ReadOptions(), slice, &ignored);
   }
 
   rocksdb::Status get(const rocksdb::Slice &slice, std::string &value) {
@@ -92,7 +93,7 @@ public:
       return stateMachine.db->Get(snapshot->opts(), slice, &value);
     }
 
-    return writeBatchWithIndex.GetFromBatchAndDB(stateMachine.db, rocksdb::ReadOptions(), slice, &value);
+    return writeBatchWithIndex.GetFromBatchAndDB(stateMachine.db.get(), rocksdb::ReadOptions(), slice, &value);
   }
 
   void put(const rocksdb::Slice &slice, const rocksdb::Slice &value) {