Fix db_stress when GetLiveFiles() flushes dropped CF (#6805)

Summary:
Current impl. of db_stress will abort verification and report failure if
GetLiveFiles() causes a dropped column family to be flushed. This is not
desired.
To fix, this PR makes the following change:
In GetLiveFiles, if flush is triggered and returns
Status::IsColumnFamilyDropped(), then set status to Status::OK().
This is OK because dropped column families will be skipped during the rest of
this function, and valid column families will have their live files returned to
caller.

Test plan (dev server):
make check
./db_stress -ops_per_thread=1000 -get_live_files_one_in=100 -clear_column_family_one_in=100
./db_stress -disable_wal=1 -reopen=0 -ops_per_thread=1000 -get_live_files_one_in=100 -clear_column_family_one_in=100
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6805

Reviewed By: ltamasi

Differential Revision: D21390044

Pulled By: riversand963

fbshipit-source-id: de67846b95a4f1b88aa0a30c3d70c43cc68625b9

HISTORY.md

@@ -15,6 +15,7 @@
 * Add a ConfigOptions argument to the APIs dealing with converting options to and from strings and files.  The ConfigOptions is meant to replace some of the options (such as input_strings_escaped and ignore_unknown_options) and allow for more parameters to be passed in the future without changing the function signature.
 * Add NewFileChecksumGenCrc32cFactory to the file checksum public API, such that the builtin Crc32c based file checksum generator factory can be used by applications.
 * Add IsDirectory to Env and FS to indicate if a path is a directory.
+* Flush(..., column_family) may return Status::ColumnFamilyDropped() instead of Status::InvalidArgument() if column_family is dropped while processing the flush request.
 
 ### New Features
 * Added support for pipelined & parallel compression optimization for `BlockBasedTableBuilder`. This optimization makes block building, block compression and block appending a pipeline, and uses multiple threads to accelerate block compression. Users can set `CompressionOptions::parallel_threads` greater than 1 to enable compression parallelism. This feature is experimental for now.

db/db_filesnapshot.cc

@@ -90,6 +90,9 @@ Status DBImpl::GetLiveFiles(std::vector<std::string>& ret,
       mutex_.Unlock();
       status = AtomicFlushMemTables(cfds, FlushOptions(),
                                     FlushReason::kGetLiveFiles);
+      if (status.IsColumnFamilyDropped()) {
+        status = Status::OK();
+      }
       mutex_.Lock();
     } else {
       for (auto cfd : *versions_->GetColumnFamilySet()) {
@@ -103,8 +106,10 @@ Status DBImpl::GetLiveFiles(std::vector<std::string>& ret,
         TEST_SYNC_POINT("DBImpl::GetLiveFiles:2");
         mutex_.Lock();
         cfd->UnrefAndTryDelete();
-        if (!status.ok()) {
+        if (!status.ok() && !status.IsColumnFamilyDropped()) {
           break;
+        } else if (status.IsColumnFamilyDropped()) {
+          status = Status::OK();
         }
       }
     }

db/db_impl/db_impl_compaction_flush.cc

@@ -1906,7 +1906,7 @@ Status DBImpl::WaitForFlushMemTables(
       }
     }
     if (1 == num_dropped && 1 == num) {
-      return Status::InvalidArgument("Cannot flush a dropped CF");
+      return Status::ColumnFamilyDropped();
     }
     // Column families involved in this flush request have either been dropped
     // or finished flush. Then it's time to finish waiting.