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/* @file dbhelpers.h
db helpers are helper functions and classes that let us easily manipulate the local
database instance in-proc.
* Copyright (C) 2008 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
* 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 <>.
#pragma once
#include "../pch.h"
#include "client.h"
#include "db.h"
namespace mongo {
const BSONObj reverseNaturalObj = BSON( "$natural" << -1 );
class Cursor;
class CoveredIndexMatcher;
all helpers assume locking is handled above them
struct Helpers {
/* ensure the specified index exists.
@param keyPattern key pattern, e.g., { ts : 1 }
@param name index name, e.g., "name_1"
This method can be a little (not much) cpu-slow, so you may wish to use
OCCASIONALLY ensureIndex(...);
Note: use ensureHaveIdIndex() for the _id index: it is faster.
Note: does nothing if collection does not yet exist.
static void ensureIndex(const char *ns, BSONObj keyPattern, bool unique, const char *name);
/* fetch a single object from collection ns that matches query.
set your db SavedContext first.
@param query - the query to perform. note this is the low level portion of query so "orderby : ..."
won't work.
@param requireIndex if true, complain if no index for the query. a way to guard against
writing a slow query.
@return true if object found
static bool findOne(const char *ns, const BSONObj &query, BSONObj& result, bool requireIndex = false);
static DiskLoc findOne(const char *ns, const BSONObj &query, bool requireIndex);
* @param foundIndex if passed in will be set to 1 if ns and index found
* @return true if object found
static bool findById(Client&, const char *ns, BSONObj query, BSONObj& result ,
bool * nsFound = 0 , bool * indexFound = 0 );
/* uasserts if no _id index.
@return null loc if not found */
static DiskLoc findById(NamespaceDetails *d, BSONObj query);
/** Get/put the first (or last) object from a collection. Generally only useful if the collection
only ever has a single object -- which is a "singleton collection".
You do not need to set the database (Context) before calling.
@return true if object exists.
static bool getSingleton(const char *ns, BSONObj& result);
static void putSingleton(const char *ns, BSONObj obj);
static void putSingletonGod(const char *ns, BSONObj obj, bool logTheOp);
static bool getFirst(const char *ns, BSONObj& result) { return getSingleton(ns, result); }
static bool getLast(const char *ns, BSONObj& result); // get last object int he collection; e.g. {$natural : -1}
* you have to lock
* you do not have to have Context set
* o has to have an _id field or will assert
static void upsert( const string& ns , const BSONObj& o );
/** You do not need to set the database before calling.
@return true if collection is empty.
static bool isEmpty(const char *ns, bool doAuth=true);
// TODO: this should be somewhere else probably
static BSONObj toKeyFormat( const BSONObj& o , BSONObj& key );
class RemoveCallback {
virtual ~RemoveCallback() {}
virtual void goingToDelete( const BSONObj& o ) = 0;
/* removeRange: operation is oplog'd */
static long long removeRange( const string& ns , const BSONObj& min , const BSONObj& max , bool yield = false , bool maxInclusive = false , RemoveCallback * callback = 0 );
/* Remove all objects from a collection.
You do not need to set the database before calling.
static void emptyCollection(const char *ns);
class Database;
// manage a set using collection backed storage
class DbSet {
DbSet( const string &name = "", const BSONObj &key = BSONObj() ) :
name_( name ),
key_( key.getOwned() ) {
void reset( const string &name = "", const BSONObj &key = BSONObj() );
bool get( const BSONObj &obj ) const;
void set( const BSONObj &obj, bool val );
string name_;
BSONObj key_;
* user for saving deletd bson objects to a flat file
class RemoveSaver : public Helpers::RemoveCallback , boost::noncopyable {
RemoveSaver( const string& type , const string& ns , const string& why);
void goingToDelete( const BSONObj& o );
path _root;
path _file;
ofstream* _out;
} // namespace mongo
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