mirror of https://gitee.com/bigwinds/arangodb
206 lines
10 KiB
C++
206 lines
10 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Jan Steemann
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_STORAGE_ENGINE_STORAGE_ENGINE_H
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#define ARANGOD_STORAGE_ENGINE_STORAGE_ENGINE_H 1
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#include "Basics/Common.h"
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#include "ApplicationFeatures/ApplicationFeature.h"
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#include "VocBase/voc-types.h"
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#include <velocypack/Builder.h>
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#include <velocypack/Slice.h>
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struct TRI_vocbase_t;
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namespace arangodb {
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class StorageEngine : public application_features::ApplicationFeature {
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public:
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// create the storage engine
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StorageEngine(application_features::ApplicationServer* server, std::string const& name)
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: application_features::ApplicationFeature(server, name), _typeName(name) {
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// each specific storage engine feature is optional. the storage engine selection feature
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// will make sure that exactly one engine is selected at startup
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setOptional(true);
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// storage engines must not use elevated privileges for files etc
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requiresElevatedPrivileges(false);
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// TODO: determine more sensible startup order for storage engine
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startsAfter("DatabasePath");
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startsAfter("EngineSelector");
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startsAfter("FileDescriptors");
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startsAfter("Temp");
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}
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virtual void start() {}
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virtual void stop() {}
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virtual void recoveryDone(TRI_vocbase_t* vocbase) {}
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// status functionality
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// --------------------
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// return the name of the storage engine
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char const* typeName() const {
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return _typeName.c_str();
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}
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// inventory functionality
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// -----------------------
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// fill the Builder object with an array of databases that were detected
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// by the storage engine. this method must sort out databases that were not
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// fully created (see "createDatabase" below). called at server start only
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virtual void getDatabases(arangodb::velocypack::Builder& result) = 0;
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// fill the Builder object with an array of collections (and their corresponding
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// indexes) that were detected by the storage engine. called at server start only
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virtual void getCollectionsAndIndexes(arangodb::velocypack::Builder& result) = 0;
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// determine the maximum revision id previously handed out by the storage
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// engine. this value is used as a lower bound for further HLC values handed out by
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// the server. called at server start only, after getDatabases() and getCollectionsAndIndexes()
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virtual uint64_t getMaxRevision() = 0;
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virtual TRI_vocbase_t* openDatabase(arangodb::velocypack::Slice const& parameters, bool isUpgrade) = 0;
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// database, collection and index management
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// -----------------------------------------
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// asks the storage engine to create a database as specified in the VPack
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// Slice object and persist the creation info. It is guaranteed by the server that
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// no other active database with the same name and id exists when this function
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// is called. If this operation fails somewhere in the middle, the storage
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// engine is required to fully clean up the creation and throw only then,
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// so that subsequent database creation requests will not fail.
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// the WAL entry for the database creation will be written *after* the call
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// to "createDatabase" returns
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virtual TRI_vocbase_t* createDatabase(TRI_voc_tick_t id, arangodb::velocypack::Slice const& data) = 0;
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// asks the storage engine to drop the specified database and persist the
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// deletion info. Note that physical deletion of the database data must not
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// be carried out by this call, as there may
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// still be readers of the database's data. It is recommended that this operation
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// only sets a deletion flag for the database but let's an async task perform
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// the actual deletion. The async task can later call the callback function to
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// check whether the physical deletion of the database is possible.
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// the WAL entry for database deletion will be written *after* the call
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// to "dropDatabase" returns
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virtual int dropDatabase(TRI_vocbase_t* vocbase, bool waitForDeletion,
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std::function<bool()> const& canRemovePhysically) = 0;
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// asks the storage engine to create a collection as specified in the VPack
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// Slice object and persist the creation info. It is guaranteed by the server
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// that no other active collection with the same name and id exists in the same
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// database when this function is called. If this operation fails somewhere in
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// the middle, the storage engine is required to fully clean up the creation
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// and throw only then, so that subsequent collection creation requests will not fail.
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// the WAL entry for the collection creation will be written *after* the call
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// to "createCollection" returns
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virtual void createCollection(TRI_voc_tick_t databaseId, TRI_voc_cid_t id,
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arangodb::velocypack::Slice const& data) = 0;
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// asks the storage engine to drop the specified collection and persist the
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// deletion info. Note that physical deletion of the collection data must not
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// be carried out by this call, as there may
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// still be readers of the collection's data. It is recommended that this operation
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// only sets a deletion flag for the collection but let's an async task perform
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// the actual deletion.
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// the WAL entry for collection deletion will be written *after* the call
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// to "dropCollection" returns
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virtual void dropCollection(TRI_voc_tick_t databaseId, TRI_voc_cid_t id,
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std::function<bool()> const& canRemovePhysically) = 0;
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// asks the storage engine to rename the collection as specified in the VPack
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// Slice object and persist the renaming info. It is guaranteed by the server
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// that no other active collection with the same name and id exists in the same
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// database when this function is called. If this operation fails somewhere in
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// the middle, the storage engine is required to fully revert the rename operation
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// and throw only then, so that subsequent collection creation/rename requests will
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// not fail. the WAL entry for the rename will be written *after* the call
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// to "renameCollection" returns
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virtual void renameCollection(TRI_voc_tick_t databaseId, TRI_voc_cid_t id,
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arangodb::velocypack::Slice const& data) = 0;
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// asks the storage engine to change properties of the collection as specified in
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// the VPack Slice object and persist them. If this operation fails
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// somewhere in the middle, the storage engine is required to fully revert the
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// property changes and throw only then, so that subsequent operations will not fail.
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// the WAL entry for the propery change will be written *after* the call
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// to "changeCollection" returns
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virtual void changeCollection(TRI_voc_tick_t databaseId, TRI_voc_cid_t id,
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arangodb::velocypack::Slice const& data) = 0;
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// asks the storage engine to create an index as specified in the VPack
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// Slice object and persist the creation info. The database id, collection id
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// and index data are passed in the Slice object. Note that this function
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// is not responsible for inserting the individual documents into the index.
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// If this operation fails somewhere in the middle, the storage engine is required
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// to fully clean up the creation and throw only then, so that subsequent index
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// creation requests will not fail.
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// the WAL entry for the index creation will be written *after* the call
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// to "createIndex" returns
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virtual void createIndex(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
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TRI_idx_iid_t id, arangodb::velocypack::Slice const& data) = 0;
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// asks the storage engine to drop the specified index and persist the deletion
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// info. Note that physical deletion of the index must not be carried out by this call,
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// as there may still be users of the index. It is recommended that this operation
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// only sets a deletion flag for the index but let's an async task perform
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// the actual deletion.
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// the WAL entry for index deletion will be written *after* the call
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// to "dropIndex" returns
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virtual void dropIndex(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
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TRI_idx_iid_t id) = 0;
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// document operations
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// -------------------
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// iterate all documents of the underlying collection
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// this is called when a collection is openend, and all its documents need to be added to
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// indexes etc.
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virtual void iterateDocuments(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
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std::function<void(arangodb::velocypack::Slice const&)> const& cb) = 0;
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// adds a document to the storage engine
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// this will be called by the WAL collector when surviving documents are being moved
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// into the storage engine's realm
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virtual void addDocumentRevision(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
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arangodb::velocypack::Slice const& document) = 0;
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// removes a document from the storage engine
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// this will be called by the WAL collector when non-surviving documents are being removed
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// from the storage engine's realm
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virtual void removeDocumentRevision(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
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arangodb::velocypack::Slice const& document) = 0;
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private:
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std::string const _typeName;
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};
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}
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#endif
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