Fix memory leak for probableWALfiles in db_impl.cc

Summary: using unique_ptr to have automatic delete for probableWALfiles in db_impl.cc

Test Plan: make

Reviewers: sheki, dhruba

Reviewed By: sheki

CC: leveldb

Differential Revision: https://reviews.facebook.net/D10083

db/db_impl.cc

@@ -894,8 +894,9 @@ Status DBImpl::GetUpdatesSince(SequenceNumber seq,
   }
   //  std::shared_ptr would have been useful here.
 
-  std::vector<LogFile>* probableWALFiles = new std::vector<LogFile>();
-  s = FindProbableWALFiles(&walFiles, probableWALFiles, seq);
+  std::unique_ptr<std::vector<LogFile>> probableWALFiles(
+    new std::vector<LogFile>());
+  s = FindProbableWALFiles(&walFiles, probableWALFiles.get(), seq);
   if (!s.ok()) {
     return s;
   }
@@ -904,7 +905,7 @@ Status DBImpl::GetUpdatesSince(SequenceNumber seq,
                                    &options_,
                                    storage_options_,
                                    seq,
-                                   probableWALFiles,
+                                   std::move(probableWALFiles),
                                    &last_flushed_sequence_));
   iter->get()->Next();
   return iter->get()->status();

db/transaction_log_iterator_impl.cc

@@ -9,18 +9,18 @@ TransactionLogIteratorImpl::TransactionLogIteratorImpl(
                            const Options* options,
                            const StorageOptions& soptions,
                            SequenceNumber& seq,
-                           std::vector<LogFile>* files,
+                           std::unique_ptr<std::vector<LogFile>> files,
                            SequenceNumber const * const lastFlushedSequence) :
   dbname_(dbname),
   options_(options),
   soptions_(soptions),
   startingSequenceNumber_(seq),
-  files_(files),
+  files_(std::move(files)),
   started_(false),
   isValid_(false),
   currentFileIndex_(0),
   lastFlushedSequence_(lastFlushedSequence) {
-  assert(files_ != nullptr);
+  assert(files_.get() != nullptr);
   assert(lastFlushedSequence_);
 }
 
@@ -73,7 +73,7 @@ bool TransactionLogIteratorImpl::Valid() {
 }
 
 void TransactionLogIteratorImpl::Next() {
-  LogFile currentLogFile = files_->at(currentFileIndex_);
+  LogFile currentLogFile = files_.get()->at(currentFileIndex_);
   LogReporter reporter = NewLogReporter(currentLogFile.logNumber);
 
 //  First seek to the given seqNo. in the current file.
@@ -134,9 +134,9 @@ void TransactionLogIteratorImpl::Next() {
     }
 
     if (openNextFile) {
-      if (currentFileIndex_ < files_->size() - 1) {
+      if (currentFileIndex_ < files_.get()->size() - 1) {
         ++currentFileIndex_;
-        Status status = OpenLogReader(files_->at(currentFileIndex_));
+        Status status = OpenLogReader(files_.get()->at(currentFileIndex_));
         if (!status.ok()) {
           isValid_ = false;
           currentStatus_ = status;

db/transaction_log_iterator_impl.h

@@ -30,14 +30,9 @@ class TransactionLogIteratorImpl : public TransactionLogIterator {
                              const Options* options,
                              const StorageOptions& soptions,
                              SequenceNumber& seqNum,
-                             std::vector<LogFile>* files,
+                             std::unique_ptr<std::vector<LogFile>> files,
                              SequenceNumber const * const lastFlushedSequence);
 
-  virtual ~TransactionLogIteratorImpl() {
-    //  TODO move to cc file.
-    delete files_;
-  }
-
   virtual bool Valid();
 
   virtual void Next();
@@ -51,7 +46,7 @@ class TransactionLogIteratorImpl : public TransactionLogIterator {
   const Options* options_;
   const StorageOptions& soptions_;
   const uint64_t startingSequenceNumber_;
-  const std::vector<LogFile>* files_;
+  std::unique_ptr<std::vector<LogFile>> files_;
   bool started_;
   bool isValid_;  // not valid when it starts of.
   Status currentStatus_;