Squashed 'src/rocksdb/' content from commit 224932d

git-subtree-dir: src/rocksdb
git-subtree-split: 224932d4d0b561712107d747c662df181c39644d

table/two_level_iterator.h

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+//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+#include "rocksdb/iterator.h"
+#include "rocksdb/env.h"
+#include "table/iterator_wrapper.h"
+
+namespace rocksdb {
+
+struct ReadOptions;
+class InternalKeyComparator;
+class Arena;
+
+struct TwoLevelIteratorState {
+  explicit TwoLevelIteratorState(bool check_prefix_may_match)
+    : check_prefix_may_match(check_prefix_may_match) {}
+
+  virtual ~TwoLevelIteratorState() {}
+  virtual Iterator* NewSecondaryIterator(const Slice& handle) = 0;
+  virtual bool PrefixMayMatch(const Slice& internal_key) = 0;
+
+  // If call PrefixMayMatch()
+  bool check_prefix_may_match;
+};
+
+
+// Return a new two level iterator.  A two-level iterator contains an
+// index iterator whose values point to a sequence of blocks where
+// each block is itself a sequence of key,value pairs.  The returned
+// two-level iterator yields the concatenation of all key/value pairs
+// in the sequence of blocks.  Takes ownership of "index_iter" and
+// will delete it when no longer needed.
+//
+// Uses a supplied function to convert an index_iter value into
+// an iterator over the contents of the corresponding block.
+// arena: If not null, the arena is used to allocate the Iterator.
+//        When destroying the iterator, the destructor will destroy
+//        all the states but those allocated in arena.
+extern Iterator* NewTwoLevelIterator(TwoLevelIteratorState* state,
+                                     Iterator* first_level_iter,
+                                     Arena* arena = nullptr);
+
+}  // namespace rocksdb