fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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79 lines
2.5 KiB
79 lines
2.5 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// An iterator yields a sequence of key/value pairs from a source.
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// The following class defines the interface. Multiple implementations
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// are provided by this library. In particular, iterators are provided
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// to access the contents of a Table or a DB.
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//
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// Multiple threads can invoke const methods on an Iterator without
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// external synchronization, but if any of the threads may call a
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// non-const method, all threads accessing the same Iterator must use
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// external synchronization.
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#pragma once
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namespace rocksdb {
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class Cleanable {
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public:
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Cleanable();
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// No copy constructor and copy assignment allowed.
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Cleanable(Cleanable&) = delete;
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Cleanable& operator=(Cleanable&) = delete;
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~Cleanable();
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// Move constructor and move assignment is allowed.
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Cleanable(Cleanable&&);
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Cleanable& operator=(Cleanable&&);
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// Clients are allowed to register function/arg1/arg2 triples that
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// will be invoked when this iterator is destroyed.
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//
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// Note that unlike all of the preceding methods, this method is
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// not abstract and therefore clients should not override it.
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typedef void (*CleanupFunction)(void* arg1, void* arg2);
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void RegisterCleanup(CleanupFunction function, void* arg1, void* arg2);
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void DelegateCleanupsTo(Cleanable* other);
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// DoCleanup and also resets the pointers for reuse
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inline void Reset() {
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DoCleanup();
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cleanup_.function = nullptr;
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cleanup_.next = nullptr;
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}
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protected:
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struct Cleanup {
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CleanupFunction function;
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void* arg1;
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void* arg2;
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Cleanup* next;
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};
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Cleanup cleanup_;
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// It also becomes the owner of c
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void RegisterCleanup(Cleanup* c);
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private:
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// Performs all the cleanups. It does not reset the pointers. Making it
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// private
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// to prevent misuse
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inline void DoCleanup() {
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if (cleanup_.function != nullptr) {
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(*cleanup_.function)(cleanup_.arg1, cleanup_.arg2);
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for (Cleanup* c = cleanup_.next; c != nullptr;) {
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(*c->function)(c->arg1, c->arg2);
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Cleanup* next = c->next;
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delete c;
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c = next;
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}
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}
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}
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};
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} // namespace rocksdb
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