ceph/src/rocksdb/db/pre_release_callback.h

   1 // Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #pragma once
   7
   8 #include "rocksdb/status.h"
   9
  10 namespace rocksdb {
  11
  12 class DB;
  13
  14 class PreReleaseCallback {
  15  public:
  16   virtual ~PreReleaseCallback() {}
  17
  18   // Will be called while on the write thread after the write and before the
  19   // release of the sequence number. This is useful if any operation needs to be
  20   // done before the write gets visible to the readers, or if we want to reduce
  21   // the overhead of locking by updating something sequentially while we are on
  22   // the write thread. If the callback fails, this function returns a non-OK
  23   // status, the sequence number will not be released, and same status will be
  24   // propagated to all the writers in the write group.
  25   // seq is the sequence number that is used for this write and will be
  26   // released.
  27   // is_mem_disabled is currently used for debugging purposes to assert that
  28   // the callback is done from the right write queue.
  29   virtual Status Callback(SequenceNumber seq, bool is_mem_disabled) = 0;
  30 };
  31
  32 }  //  namespace rocksdb