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arangodb/arangod/StorageEngine/StorageEngine.h

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////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_STORAGE_ENGINE_STORAGE_ENGINE_H
#define ARANGOD_STORAGE_ENGINE_STORAGE_ENGINE_H 1
#include "Basics/Common.h"
#include "ApplicationFeatures/ApplicationFeature.h"
#include "MMFiles/MMFilesCollectorCache.h"
#include "VocBase/voc-types.h"
#include "VocBase/vocbase.h"
#include <velocypack/Builder.h>
#include <velocypack/Slice.h>
namespace arangodb {
class LogicalCollection;
class PhysicalCollection;
// @brief This token is handed out by Indexes and
// is used by StorageEngines to return a document
// Only specializations of this token can be created.
struct DocumentIdentifierToken {
public:
// TODO Replace by Engine::InvalidToken
constexpr DocumentIdentifierToken() : _data(0) {}
~DocumentIdentifierToken() {}
inline bool operator==(DocumentIdentifierToken const& other) const { return _data == other._data; }
inline bool operator==(uint64_t const& other) const { return _data == other; }
inline bool operator!=(DocumentIdentifierToken const& other) const { return !(operator==(other)); }
inline bool operator!=(uint64_t const& other) const { return !(operator==(other)); }
protected:
explicit DocumentIdentifierToken(uint64_t data) : _data(data) {}
public:
uint64_t _data;
};
class StorageEngine : public application_features::ApplicationFeature {
public:
// create the storage engine
StorageEngine(application_features::ApplicationServer* server, std::string const& engineName, std::string const& featureName)
: application_features::ApplicationFeature(server, featureName), _typeName(engineName) {
// each specific storage engine feature is optional. the storage engine selection feature
// will make sure that exactly one engine is selected at startup
setOptional(true);
// storage engines must not use elevated privileges for files etc
requiresElevatedPrivileges(false);
startsAfter("DatabasePath");
startsAfter("EngineSelector");
startsAfter("FileDescriptors");
startsAfter("Temp");
}
virtual void start() {}
virtual void stop() {}
virtual void recoveryDone(TRI_vocbase_t* vocbase) {}
// create storage-engine specific collection
virtual PhysicalCollection* createPhysicalCollection(LogicalCollection*) = 0;
// status functionality
// --------------------
// return the name of the storage engine
char const* typeName() const { return _typeName.c_str(); }
// inventory functionality
// -----------------------
// fill the Builder object with an array of databases that were detected
// by the storage engine. this method must sort out databases that were not
// fully created (see "createDatabase" below). called at server start only
virtual void getDatabases(arangodb::velocypack::Builder& result) = 0;
// fills the provided builder with information about the collection
virtual void getCollectionInfo(TRI_vocbase_t* vocbase, TRI_voc_cid_t cid,
arangodb::velocypack::Builder& result,
bool includeIndexes, TRI_voc_tick_t maxTick) = 0;
// fill the Builder object with an array of collections (and their corresponding
// indexes) that were detected by the storage engine. called at server start separately
// for each database
virtual int getCollectionsAndIndexes(TRI_vocbase_t* vocbase, arangodb::velocypack::Builder& result,
bool wasCleanShutdown, bool isUpgrade) = 0;
// return the path for a database
virtual std::string databasePath(TRI_vocbase_t const* vocbase) const = 0;
// return the path for a collection
virtual std::string collectionPath(TRI_vocbase_t const* vocbase, TRI_voc_cid_t id) const = 0;
virtual TRI_vocbase_t* openDatabase(arangodb::velocypack::Slice const& parameters, bool isUpgrade) = 0;
// database, collection and index management
// -----------------------------------------
// asks the storage engine to create a database as specified in the VPack
// Slice object and persist the creation info. It is guaranteed by the server that
// no other active database with the same name and id exists when this function
// is called. If this operation fails somewhere in the middle, the storage
// engine is required to fully clean up the creation and throw only then,
// so that subsequent database creation requests will not fail.
// the WAL entry for the database creation will be written *after* the call
// to "createDatabase" returns
virtual TRI_vocbase_t* createDatabase(TRI_voc_tick_t id, arangodb::velocypack::Slice const& data) = 0;
// asks the storage engine to drop the specified database and persist the
// deletion info. Note that physical deletion of the database data must not
// be carried out by this call, as there may still be readers of the database's data.
// It is recommended that this operation only sets a deletion flag for the database
// but let's an async task perform the actual deletion.
// the WAL entry for database deletion will be written *after* the call
// to "prepareDropDatabase" returns
virtual int prepareDropDatabase(TRI_vocbase_t* vocbase) = 0;
// perform a physical deletion of the database
virtual int dropDatabase(TRI_vocbase_t* vocbase) = 0;
/// @brief wait until a database directory disappears
virtual int waitUntilDeletion(TRI_voc_tick_t id, bool force) = 0;
// asks the storage engine to create a collection as specified in the VPack
// Slice object and persist the creation info. It is guaranteed by the server
// that no other active collection with the same name and id exists in the same
// database when this function is called. If this operation fails somewhere in
// the middle, the storage engine is required to fully clean up the creation
// and throw only then, so that subsequent collection creation requests will not fail.
// the WAL entry for the collection creation will be written *after* the call
// to "createCollection" returns
virtual std::string createCollection(TRI_vocbase_t* vocbase, TRI_voc_cid_t id,
arangodb::LogicalCollection const* parameters) = 0;
// asks the storage engine to drop the specified collection and persist the
// deletion info. Note that physical deletion of the collection data must not
// be carried out by this call, as there may
// still be readers of the collection's data. It is recommended that this operation
// only sets a deletion flag for the collection but let's an async task perform
// the actual deletion.
// the WAL entry for collection deletion will be written *after* the call
// to "dropCollection" returns
virtual void prepareDropCollection(TRI_vocbase_t* vocbase, arangodb::LogicalCollection* collection) = 0;
// perform a physical deletion of the collection
virtual void dropCollection(TRI_vocbase_t* vocbase, arangodb::LogicalCollection* collection) = 0;
// asks the storage engine to change properties of the collection as specified in
// the VPack Slice object and persist them. If this operation fails
// somewhere in the middle, the storage engine is required to fully revert the
// property changes and throw only then, so that subsequent operations will not fail.
// the WAL entry for the propery change will be written *after* the call
// to "changeCollection" returns
virtual void changeCollection(TRI_vocbase_t* vocbase, TRI_voc_cid_t id,
arangodb::LogicalCollection const* parameters,
bool doSync) = 0;
// asks the storage engine to create an index as specified in the VPack
// Slice object and persist the creation info. The database id, collection id
// and index data are passed in the Slice object. Note that this function
// is not responsible for inserting the individual documents into the index.
// If this operation fails somewhere in the middle, the storage engine is required
// to fully clean up the creation and throw only then, so that subsequent index
// creation requests will not fail.
// the WAL entry for the index creation will be written *after* the call
// to "createIndex" returns
virtual void createIndex(TRI_vocbase_t* vocbase, TRI_voc_cid_t collectionId,
TRI_idx_iid_t id, arangodb::velocypack::Slice const& data) = 0;
// asks the storage engine to drop the specified index and persist the deletion
// info. Note that physical deletion of the index must not be carried out by this call,
// as there may still be users of the index. It is recommended that this operation
// only sets a deletion flag for the index but let's an async task perform
// the actual deletion.
// the WAL entry for index deletion will be written *after* the call
// to "dropIndex" returns
virtual void dropIndex(TRI_vocbase_t* vocbase, TRI_voc_cid_t collectionId,
TRI_idx_iid_t id) = 0;
virtual void unloadCollection(TRI_vocbase_t* vocbase, TRI_voc_cid_t collectionId) = 0;
virtual void signalCleanup(TRI_vocbase_t* vocbase) = 0;
// document operations
// -------------------
// iterate all documents of the underlying collection
// this is called when a collection is openend, and all its documents need to be added to
// indexes etc.
virtual void iterateDocuments(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
std::function<void(arangodb::velocypack::Slice const&)> const& cb) = 0;
// adds a document to the storage engine
// this will be called by the WAL collector when surviving documents are being moved
// into the storage engine's realm
virtual void addDocumentRevision(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
arangodb::velocypack::Slice const& document) = 0;
// removes a document from the storage engine
// this will be called by the WAL collector when non-surviving documents are being removed
// from the storage engine's realm
virtual void removeDocumentRevision(TRI_voc_tick_t databaseId, TRI_voc_cid_t collectionId,
arangodb::velocypack::Slice const& document) = 0;
/// @brief remove data of expired compaction blockers
virtual bool cleanupCompactionBlockers(TRI_vocbase_t* vocbase) = 0;
/// @brief insert a compaction blocker
virtual int insertCompactionBlocker(TRI_vocbase_t* vocbase, double ttl, TRI_voc_tick_t& id) = 0;
/// @brief touch an existing compaction blocker
virtual int extendCompactionBlocker(TRI_vocbase_t* vocbase, TRI_voc_tick_t id, double ttl) = 0;
/// @brief remove an existing compaction blocker
virtual int removeCompactionBlocker(TRI_vocbase_t* vocbase, TRI_voc_tick_t id) = 0;
/// @brief a callback function that is run while it is guaranteed that there is no compaction ongoing
virtual void preventCompaction(TRI_vocbase_t* vocbase,
std::function<void(TRI_vocbase_t*)> const& callback) = 0;
/// @brief a callback function that is run there is no compaction ongoing
virtual bool tryPreventCompaction(TRI_vocbase_t* vocbase,
std::function<void(TRI_vocbase_t*)> const& callback,
bool checkForActiveBlockers) = 0;
virtual int shutdownDatabase(TRI_vocbase_t* vocbase) = 0;
virtual int openCollection(TRI_vocbase_t* vocbase, LogicalCollection* collection, bool ignoreErrors) = 0;
/// @brief transfer markers into a collection
virtual int transferMarkers(LogicalCollection* collection, MMFilesCollectorCache*,
MMFilesOperationsType const&) = 0;
protected:
arangodb::LogicalCollection* registerCollection(
TRI_vocbase_t* vocbase, arangodb::velocypack::Slice params) {
return vocbase->registerCollection(true, params);
}
private:
std::string const _typeName;
};
}
namespace std {
template <>
struct hash<arangodb::DocumentIdentifierToken> {
inline size_t operator()(arangodb::DocumentIdentifierToken const& token) const noexcept {
return token._data;
}
};
template <>
struct equal_to<arangodb::DocumentIdentifierToken> {
bool operator()(arangodb::DocumentIdentifierToken const& lhs,
arangodb::DocumentIdentifierToken const& rhs) const {
return lhs == rhs;
}
};
}
#endif