Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/src/rocksdb/db/flush_scheduler.h b/src/rocksdb/db/flush_scheduler.h
new file mode 100644
index 000000000..eb03f3e11
--- /dev/null
+++ b/src/rocksdb/db/flush_scheduler.h
@@ -0,0 +1,55 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <atomic>
+#include <cstdint>
+#include <mutex>
+#include <set>
+
+#include "util/autovector.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class ColumnFamilyData;
+
+// FlushScheduler keeps track of all column families whose memtable may
+// be full and require flushing. Unless otherwise noted, all methods on
+// FlushScheduler should be called only with the DB mutex held or from
+// a single-threaded recovery context.
+class FlushScheduler {
+ public:
+  FlushScheduler() : head_(nullptr) {}
+
+  // May be called from multiple threads at once, but not concurrent with
+  // any other method calls on this instance
+  void ScheduleWork(ColumnFamilyData* cfd);
+
+  // Removes and returns Ref()-ed column family. Client needs to Unref().
+  // Filters column families that have been dropped.
+  ColumnFamilyData* TakeNextColumnFamily();
+
+  // This can be called concurrently with ScheduleWork but it would miss all
+  // the scheduled flushes after the last synchronization. This would result
+  // into less precise enforcement of memtable sizes but should not matter much.
+  bool Empty();
+
+  void Clear();
+
+ private:
+  struct Node {
+    ColumnFamilyData* column_family;
+    Node* next;
+  };
+
+  std::atomic<Node*> head_;
+#ifndef NDEBUG
+  std::mutex checking_mutex_;
+  std::set<ColumnFamilyData*> checking_set_;
+#endif  // NDEBUG
+};
+
+}  // namespace ROCKSDB_NAMESPACE