fix open failure with empty wal

Summary: Closes https://github.com/facebook/rocksdb/pull/1490

Differential Revision: D4158821

Pulled By: IslamAbdelRahman

fbshipit-source-id: 59b73f4

db/column_family_test.cc

@@ -941,6 +941,12 @@ TEST_F(ColumnFamilyTest, CrashAfterFlush) {
   db_options_.env = env_;
 }
 
+TEST_F(ColumnFamilyTest, OpenNonexistentColumnFamily) {
+  ASSERT_OK(TryOpen({"default"}));
+  Close();
+  ASSERT_TRUE(TryOpen({"default", "dne"}).IsInvalidArgument());
+}
+
 #ifndef ROCKSDB_LITE  // WaitForFlush() is not supported
 // Makes sure that obsolete log files get deleted
 TEST_F(ColumnFamilyTest, DifferentWriteBufferSizes) {

db/db_impl.cc

@@ -1688,6 +1688,9 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& log_numbers,
     }
   }
 
+  // True if there's any data in the WALs; if not, we can skip re-processing
+  // them later
+  bool data_seen = false;
   if (!read_only) {
     // no need to refcount since client still doesn't have access
     // to the DB and can not drop column families while we iterate
@@ -1723,6 +1726,7 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& log_numbers,
           cfd->CreateNewMemtable(*cfd->GetLatestMutableCFOptions(),
                                  versions_->LastSequence());
         }
+        data_seen = true;
       }
 
       // write MANIFEST with update
@@ -1748,7 +1752,7 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& log_numbers,
     }
   }
 
-  if (!flushed) {
+  if (data_seen && !flushed) {
     // Mark these as alive so they'll be considered for deletion later by
     // FindObsoleteFiles()
     for (auto log_number : log_numbers) {