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/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/diskloc.h"
#include "mongo/db/index/index_cursor.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/jsobj.h"
namespace mongo {
class UpdateTicket;
struct InsertDeleteOptions;
/**
* An IndexAccessMethod is the interface through which all the mutation, lookup, and
* traversal of index entries is done. The class is designed so that the underlying index
* data structure is opaque to the caller.
*
* IndexAccessMethods for existing indices are obtained through the system catalog.
*
* We assume the caller has whatever locks required. This interface is not thread safe.
*
*/
class IndexAccessMethod {
public:
virtual ~IndexAccessMethod() { }
//
// Lookup, traversal, and mutation support
//
/**
* Internally generate the keys {k1, ..., kn} for 'obj'. For each key k, insert (k ->
* 'loc') into the index. 'obj' is the object at the location 'loc'. If not NULL,
* 'numInserted' will be set to the number of keys added to the index for the document. If
* there is more than one key for 'obj', either all keys will be inserted or none will.
*
* The behavior of the insertion can be specified through 'options'.
*/
virtual Status insert(const BSONObj& obj,
const DiskLoc& loc,
const InsertDeleteOptions& options,
int64_t* numInserted) = 0;
/**
* Analogous to above, but remove the records instead of inserting them. If not NULL,
* numDeleted will be set to the number of keys removed from the index for the document.
*/
virtual Status remove(const BSONObj& obj,
const DiskLoc& loc,
const InsertDeleteOptions& options,
int64_t* numDeleted) = 0;
/**
* Checks whether the index entries for the document 'from', which is placed at location
* 'loc' on disk, can be changed to the index entries for the doc 'to'. Provides a ticket
* for actually performing the update.
*
* Returns an error if the update is invalid. The ticket will also be marked as invalid.
* Returns OK if the update should proceed without error. The ticket is marked as valid.
*
* There is no obligation to perform the update after performing validation.
*/
virtual Status validateUpdate(const BSONObj& from,
const BSONObj& to,
const DiskLoc& loc,
const InsertDeleteOptions& options,
UpdateTicket* ticket) = 0;
/**
* Perform a validated update. The keys for the 'from' object will be removed, and the keys
* for the object 'to' will be added. Returns OK if the update succeeded, failure if it did
* not. If an update does not succeed, the index will be unmodified, and the keys for
* 'from' will remain. Assumes that the index has not changed since validateUpdate was
* called. If the index was changed, we may return an error, as our ticket may have been
* invalidated.
*/
virtual Status update(const UpdateTicket& ticket, int64_t* numUpdated) = 0;
/**
* Fills in '*out' with an IndexCursor. Return a status indicating success or reason of
* failure. If the latter, '*out' contains NULL. See index_cursor.h for IndexCursor usage.
*/
virtual Status newCursor(IndexCursor **out) const = 0;
// ------ index level operations ------
/**
* initializes this index
* only called once for the lifetime of the index
* if called multiple times, is an error
*/
virtual Status initializeAsEmpty() = 0;
/**
* Try to page-in the pages that contain the keys generated from 'obj'.
* This can be used to speed up future accesses to an index by trying to ensure the
* appropriate pages are not swapped out.
* See prefetch.cpp.
*/
virtual Status touch(const BSONObj& obj) = 0;
/**
* Walk the entire index, checking the internal structure for consistency.
* Set numKeys to the number of keys in the index.
*
* Return OK if the index is valid.
*
* Currently wasserts that the index is invalid. This could/should be changed in
* the future to return a Status.
*/
virtual Status validate(int64_t* numKeys) = 0;
//
// Bulk operations support
//
/**
* Starts a bulk operation.
* You work on the returned IndexAccessMethod and then call commitBulk.
* This can return NULL, meaning bulk mode is not available.
*
* Long term, you'll eventually be able to mix/match bulk, not bulk,
* have as many as you want, etc..
*
* For now (1/8/14) you can only do bulk when the index is empty
* it will fail if you try other times.
*/
virtual IndexAccessMethod* initiateBulk() = 0;
/**
* Call this when you are ready to finish your bulk work.
* Pass in the IndexAccessMethod gotten from initiateBulk.
* After this method is called, the bulk index access method is invalid
* and should not be used.
* @param bulk - something created from initiateBulk
* @param mayInterrupt - is this commit interruptable (will cancel)
* @param dups - if NULL, error out on dups if not allowed
* if not NULL, put the bad DiskLocs there
*/
virtual Status commitBulk( IndexAccessMethod* bulk,
bool mayInterrupt,
std::set<DiskLoc>* dups ) = 0;
};
/**
* Updates are two steps: verify that it's a valid update, and perform it.
* validateUpdate fills out the UpdateStatus and update actually applies it.
*/
class UpdateTicket {
public:
UpdateTicket() : _isValid(false) { }
protected:
// These friends are the classes that actually fill out an UpdateStatus.
friend class BtreeBasedAccessMethod;
class PrivateUpdateData;
bool _isValid;
// This is meant to be filled out only by the friends above.
scoped_ptr<PrivateUpdateData> _indexSpecificUpdateData;
};
class UpdateTicket::PrivateUpdateData {
public:
virtual ~PrivateUpdateData() { }
};
/**
* Flags we can set for inserts and deletes (and updates, which are kind of both).
*/
struct InsertDeleteOptions {
InsertDeleteOptions() : logIfError(false), dupsAllowed(false) { }
// If there's an error, log() it.
bool logIfError;
// Are duplicate keys allowed in the index?
bool dupsAllowed;
};
} // namespace mongo
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