Close on TTLDB causes segfault when destructing

[adamretter]

The following simple code will cause a segfault. ttl_db-test.cc:

#include <string>
#include "rocksdb/db.h"
#include "rocksdb/options.h"
#include "rocksdb/utilities/db_ttl.h"

using namespace rocksdb;

int main() {
  Options options;
  options.create_if_missing = true;
  
  DBWithTTL* ttl_db;
  Status s = DBWithTTL::Open(options, "test-ttl-db", &ttl_db);
  assert(s.ok());

  //TODO comment-out line below to avoid SIGSEGV
  ttl_db->Close();

  delete ttl_db;
}

Compile the above file inside a rocksdb git clone with:

$ DEBUG_LEVEL=2  make -j4 shared_lib
$ clang++ -std=c++11 -stdlib=libc++ -fpic -I include/ -o ttl_db-test librocksdb.dylib ttl_db-test.cc

Running the code above (./ttl_db-test) shows a segfault. The lldb trace is:

Process 50972 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
    frame #0: 0x000000010014df6a librocksdb.5.18.dylib`rocksdb::DBImpl::GetOptions(this=0x0000000100cb7000, column_family=0x0000000100cbf480) const at db_impl.cc:2006 [opt]
   2003	  InstrumentedMutexLock l(&mutex_);
   2004	  auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
   2005	  return Options(BuildDBOptions(immutable_db_options_, mutable_db_options_),
-> 2006	                 cfh->cfd()->GetLatestCFOptions());
   2007	}
   2008
   2009	DBOptions DBImpl::GetDBOptions() const {
Target 0: (ttl_db-test) stopped.

The lldb backtrace is:

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
  * frame #0: 0x000000010014df6a librocksdb.5.18.dylib`rocksdb::DBImpl::GetOptions(this=0x0000000100cb7000, column_family=0x0000000100cbf480) const at db_impl.cc:2006 [opt]
    frame #1: 0x0000000100330ef6 librocksdb.5.18.dylib`rocksdb::StackableDB::GetOptions(this=<unavailable>, column_family=<unavailable>) const at stackable_db.h:269 [opt]
    frame #2: 0x000000010011901f librocksdb.5.18.dylib`rocksdb::DB::GetOptions(this=0x0000000100cbf620) const at db.h:904 [opt]
    frame #3: 0x00000001003b94dc librocksdb.5.18.dylib`rocksdb::DBWithTTLImpl::~DBWithTTLImpl(this=0x0000000100cbf620) at db_ttl_impl.cc:41 [opt]
    frame #4: 0x00000001003b95ae librocksdb.5.18.dylib`rocksdb::DBWithTTLImpl::~DBWithTTLImpl() [inlined] rocksdb::DBWithTTLImpl::~DBWithTTLImpl(this=0x0000000100cbf620) at db_ttl_impl.cc:38 [opt]
    frame #5: 0x00000001003b95a9 librocksdb.5.18.dylib`rocksdb::DBWithTTLImpl::~DBWithTTLImpl(this=0x0000000100cbf620) at db_ttl_impl.cc:38 [opt]
    frame #6: 0x000000010000135c ttl_db-test`main + 508
    frame #7: 0x00007fff59c6508d libdyld.dylib`start + 1

[adamretter]

The problem seems to be that calling Close removes the options from the db, however the destructor of TTLDB wants to try and access the options. I am open to discussing how best to fix this...