ceph/src/os/filestore/IndexManager.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14 #ifndef OS_INDEXMANAGER_H
  15 #define OS_INDEXMANAGER_H
  16
  17 #include "include/memory.h"
  18 #include "include/unordered_map.h"
  19
  20 #include "common/Mutex.h"
  21 #include "common/Cond.h"
  22 #include "common/config.h"
  23 #include "common/debug.h"
  24
  25 #include "CollectionIndex.h"
  26 #include "HashIndex.h"
  27
  28
  29 /// Public type for Index
  30 struct Index {
  31   CollectionIndex *index;
  32
  33   Index() : index(NULL) {}
  34   explicit Index(CollectionIndex* index) : index(index) {}
  35
  36   CollectionIndex *operator->() { return index; }
  37   CollectionIndex &operator*() { return *index; }
  38 };
  39
  40
  41 /**
  42  * Encapsulates mutual exclusion for CollectionIndexes.
  43  *
  44  * Allowing a modification (removal or addition of an object) to occur
  45  * while a read is occuring (lookup of an object's path and use of
  46  * that path) may result in the path becoming invalid.  Thus, during
  47  * the lifetime of a CollectionIndex object and any paths returned
  48  * by it, no other concurrent accesses may be allowed.
  49  * This is enforced by using CollectionIndex::access_lock
  50  */
  51 class IndexManager {
  52   CephContext* cct;
  53   RWLock lock; ///< Lock for Index Manager
  54   bool upgrade;
  55   ceph::unordered_map<coll_t, CollectionIndex* > col_indices;
  56
  57   /**
  58    * Index factory
  59    *
  60    * Encapsulates logic for handling legacy FileStore
  61    * layouts
  62    *
  63    * @param [in] c Collection for which to get index
  64    * @param [in] path Path to collection
  65    * @param [out] index Index for c
  66    * @return error code
  67    */
  68   int build_index(coll_t c, const char *path, CollectionIndex **index);
  69   bool get_index_optimistic(coll_t c, Index *index);
  70 public:
  71   /// Constructor
  72   explicit IndexManager(CephContext* cct,
  73                         bool upgrade) : cct(cct),
  74                                         lock("IndexManager lock"),
  75                                         upgrade(upgrade) {}
  76
  77   ~IndexManager();
  78
  79   /**
  80    * Reserve and return index for c
  81    *
  82    * @param [in] c Collection for which to get index
  83    * @param [in] baseDir base directory of collections
  84    * @param [out] index Index for c
  85    * @return error code
  86    */
  87   int get_index(coll_t c, const string& baseDir, Index *index);
  88
  89   /**
  90    * Initialize index for collection c at path
  91    *
  92    * @param [in] c Collection for which to init Index
  93    * @param [in] path Path to collection
  94    * @param [in] filestore_version version of containing FileStore
  95    * @return error code
  96    */
  97   int init_index(coll_t c, const char *path, uint32_t filestore_version);
  98 };
  99
 100 #endif