Make WaitForFlushMemTable public (#126)

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

Signed-off-by: Yi Wu <yiwu@pingcap.com>
Signed-off-by: tabokie <xy.tao@outlook.com>

db/db_impl/db_impl.h

@@ -954,6 +954,24 @@ class DBImpl : public DB {
 
  VersionSet* GetVersionSet() const { return versions_.get(); }
 
+ // 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);
+
 #ifndef NDEBUG
  // Compact any files in the named level that overlap [*begin, *end]
  Status TEST_CompactRange(int level, const Slice* begin, const Slice* end,
@@ -1678,24 +1696,6 @@ 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);
-
  inline void WaitForPendingWrites() {
  mutex_.AssertHeld();
  TEST_SYNC_POINT("DBImpl::WaitForPendingWrites:BeforeBlock");