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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#ifndef OS_INDEXMANAGER_H
#define OS_INDEXMANAGER_H
#include <tr1/memory>
#include <map>
#include "common/Mutex.h"
#include "common/Cond.h"
#include "common/config.h"
#include "common/debug.h"
#include "CollectionIndex.h"
#include "HashIndex.h"
#include "FlatIndex.h"
/// Public type for Index
typedef std::tr1::shared_ptr<CollectionIndex> Index;
/**
* Encapsulates mutual exclusion for CollectionIndexes.
*
* Allowing a modification (removal or addition of an object) to occur
* while a read is occuring (lookup of an object's path and use of
* that path) may result in the path becoming invalid. Thus, during
* the lifetime of a CollectionIndex object and any paths returned
* by it, no other concurrent accesses may be allowed.
*
* This is enforced using shared_ptr. A shared_ptr<CollectionIndex>
* is returned from get_index. Any paths generated using that object
* carry a reference to the parrent index. Once all
* shared_ptr<CollectionIndex> references have expired, the destructor
* removes the weak_ptr from col_indices and wakes waiters.
*/
class IndexManager {
Mutex lock; ///< Lock for Index Manager
Cond cond; ///< Cond for waiters on col_indices
bool upgrade;
/// Currently in use CollectionIndices
map<coll_t,std::tr1::weak_ptr<CollectionIndex> > col_indices;
/// Cleans up state for c @see RemoveOnDelete
void put_index(
coll_t c ///< Put the index for c
);
/// Callback for shared_ptr release @see get_index
class RemoveOnDelete {
public:
coll_t c;
IndexManager *manager;
RemoveOnDelete(coll_t c, IndexManager *manager) :
c(c), manager(manager) {}
void operator()(CollectionIndex *index) {
manager->put_index(c);
delete index;
}
};
/**
* Index factory
*
* Encapsulates logic for handling legacy FileStore
* layouts
*
* @param [in] c Collection for which to get index
* @param [in] path Path to collection
* @param [out] index Index for c
* @return error code
*/
int build_index(coll_t c, const char *path, Index *index);
public:
/// Constructor
IndexManager(bool upgrade) : lock("IndexManager lock"),
upgrade(upgrade) {}
/**
* Reserve and return index for c
*
* @param [in] c Collection for which to get index
* @param [in] path Path to collection
* @param [out] index Index for c
* @return error code
*/
int get_index(coll_t c, const char *path, Index *index);
/**
* Initialize index for collection c at path
*
* @param [in] c Collection for which to init Index
* @param [in] path Path to collection
* @param [in] filestore_version version of containing FileStore
* @return error code
*/
int init_index(coll_t c, const char *path, uint32_t filestore_version);
};
#endif
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