Make WaitForFlushMemTable public (#125)

Move `WaitForFlushMemTable` API to public. It is needed for hotfix of tikv/titan#93

Signed-off-by: Yi Wu <yiwu@pingcap.com>

db/db_impl.h

@@ -746,6 +746,25 @@ class DBImpl : public DB {
  static Status CreateAndNewDirectory(Env* env, const std::string& dirname,
  std::unique_ptr<Directory>* directory);
 
+ // Wait for memtable flushed.
+ // If flush_memtable_id is non-null, wait until the memtable with the ID
+ // gets flush. Otherwise, wait until the column family don't have any
+ // memtable pending flush.
+ // resuming_from_bg_err indicates whether the caller is attempting to resume
+ // from background error.
+ Status WaitForFlushMemTable(ColumnFamilyData* cfd,
+ const uint64_t* flush_memtable_id = nullptr,
+ bool resuming_from_bg_err = false) {
+ return WaitForFlushMemTables({cfd}, {flush_memtable_id},
+ resuming_from_bg_err);
+ }
+ // Wait for memtables to be flushed for multiple column families.
+ Status WaitForFlushMemTables(
+ const autovector<ColumnFamilyData*>& cfds,
+ const autovector<const uint64_t*>& flush_memtable_ids,
+ bool resuming_from_bg_err);
+
+
  protected:
  Env* const env_;
  const std::string dbname_;
@@ -1026,24 +1045,6 @@ class DBImpl : public DB {
  Status WaitUntilFlushWouldNotStallWrites(ColumnFamilyData* cfd,
  bool* flush_needed);
 
- // Wait for memtable flushed.
- // If flush_memtable_id is non-null, wait until the memtable with the ID
- // gets flush. Otherwise, wait until the column family don't have any
- // memtable pending flush.
- // resuming_from_bg_err indicates whether the caller is attempting to resume
- // from background error.
- Status WaitForFlushMemTable(ColumnFamilyData* cfd,
- const uint64_t* flush_memtable_id = nullptr,
- bool resuming_from_bg_err = false) {
- return WaitForFlushMemTables({cfd}, {flush_memtable_id},
- resuming_from_bg_err);
- }
- // Wait for memtables to be flushed for multiple column families.
- Status WaitForFlushMemTables(
- const autovector<ColumnFamilyData*>& cfds,
- const autovector<const uint64_t*>& flush_memtable_ids,
- bool resuming_from_bg_err);
-
  // REQUIRES: mutex locked and in write thread.
  void AssignAtomicFlushSeq(const autovector<ColumnFamilyData*>& cfds);