ceph/src/rocksdb/db/flush_scheduler.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 <stdint.h>
   9 #include <atomic>
  10 #include <mutex>
  11 #include <set>
  12 #include "util/autovector.h"
  13
  14 namespace ROCKSDB_NAMESPACE {
  15
  16 class ColumnFamilyData;
  17
  18 // FlushScheduler keeps track of all column families whose memtable may
  19 // be full and require flushing. Unless otherwise noted, all methods on
  20 // FlushScheduler should be called only with the DB mutex held or from
  21 // a single-threaded recovery context.
  22 class FlushScheduler {
  23  public:
  24   FlushScheduler() : head_(nullptr) {}
  25
  26   // May be called from multiple threads at once, but not concurrent with
  27   // any other method calls on this instance
  28   void ScheduleWork(ColumnFamilyData* cfd);
  29
  30   // Removes and returns Ref()-ed column family. Client needs to Unref().
  31   // Filters column families that have been dropped.
  32   ColumnFamilyData* TakeNextColumnFamily();
  33
  34   // This can be called concurrently with ScheduleWork but it would miss all
  35   // the scheduled flushes after the last synchronization. This would result
  36   // into less precise enforcement of memtable sizes but should not matter much.
  37   bool Empty();
  38
  39   void Clear();
  40
  41  private:
  42   struct Node {
  43     ColumnFamilyData* column_family;
  44     Node* next;
  45   };
  46
  47   std::atomic<Node*> head_;
  48 #ifndef NDEBUG
  49   std::mutex checking_mutex_;
  50   std::set<ColumnFamilyData*> checking_set_;
  51 #endif  // NDEBUG
  52 };
  53
  54 }  // namespace ROCKSDB_NAMESPACE