chrome/browser/sync/glue/tab_node_pool.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_SYNC_GLUE_TAB_NODE_POOL_H_
   6 #define CHROME_BROWSER_SYNC_GLUE_TAB_NODE_POOL_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12
  13 class ProfileSyncService;
  14
  15 namespace browser_sync {
  16
  17 // A pool for managing free/used tab sync nodes. Performs lazy creation
  18 // of sync nodes when necessary.
  19 class TabNodePool {
  20  public:
  21   explicit TabNodePool(ProfileSyncService* sync_service);
  22   ~TabNodePool();
  23
  24   // Build a sync tag from tab_node_id.
  25   static std::string TabIdToTag(const std::string machine_tag,
  26                                 size_t tab_node_id);
  27
  28   // Add a previously allocated tab sync node to our pool. Increases the size
  29   // of tab_syncid_pool_ by one and marks the new tab node as free.
  30   // Note: this should only be called when we discover tab sync nodes from
  31   // previous sessions, not for freeing tab nodes we created through
  32   // GetFreeTabNode (use FreeTabNode below for that).
  33   void AddTabNode(int64 sync_id);
  34
  35   // Returns the sync_id for the next free tab node. If none are available,
  36   // creates a new tab node.
  37   // Note: We make use of the following "id's"
  38   // - a sync_id: an int64 used in |syncer::InitByIdLookup|
  39   // - a tab_id: created by session service, unique to this client
  40   // - a tab_node_id: the id for a particular sync tab node. This is used
  41   //   to generate the sync tab node tag through:
  42   //       tab_tag = StringPrintf("%s_%ui", local_session_tag, tab_node_id);
  43   // tab_node_id and sync_id are both unique to a particular sync node. The
  44   // difference is that tab_node_id is controlled by the model associator and
  45   // is used when creating a new sync node, which returns the sync_id, created
  46   // by the sync db.
  47   int64 GetFreeTabNode();
  48
  49   // Return a tab node to our free pool.
  50   // Note: the difference between FreeTabNode and AddTabNode is that
  51   // FreeTabNode does not modify the size of |tab_syncid_pool_|, while
  52   // AddTabNode increases it by one. In the case of FreeTabNode, the size of
  53   // the |tab_syncid_pool_| should always be equal to the amount of tab nodes
  54   // associated with this machine.
  55   void FreeTabNode(int64 sync_id);
  56
  57   // Clear tab pool.
  58   void clear() {
  59     tab_syncid_pool_.clear();
  60     tab_pool_fp_ = -1;
  61   }
  62
  63   // Return the number of tab nodes this client currently has allocated
  64   // (including both free and used nodes)
  65   size_t capacity() const { return tab_syncid_pool_.size(); }
  66
  67   // Return empty status (all tab nodes are in use).
  68   bool empty() const { return tab_pool_fp_ == -1; }
  69
  70   // Return full status (no tab nodes are in use).
  71   bool full() {
  72     return tab_pool_fp_ == static_cast<int64>(tab_syncid_pool_.size())-1;
  73   }
  74
  75   void set_machine_tag(const std::string& machine_tag) {
  76     machine_tag_ = machine_tag;
  77   }
  78
  79  private:
  80   // Pool of all available syncid's for tab's we have created.
  81   std::vector<int64> tab_syncid_pool_;
  82
  83   // Free pointer for tab pool. Only those node id's, up to and including the
  84   // one indexed by the free pointer, are valid and free. The rest of the
  85   // |tab_syncid_pool_| is invalid because the nodes are in use.
  86   // To get the next free node, use tab_syncid_pool_[tab_pool_fp_--].
  87   int64 tab_pool_fp_;
  88
  89   // The machiine tag associated with this tab pool. Used in the title of new
  90   // sync nodes.
  91   std::string machine_tag_;
  92
  93   // Our sync service profile (for making changes to the sync db)
  94   ProfileSyncService* sync_service_;
  95
  96   DISALLOW_COPY_AND_ASSIGN(TabNodePool);
  97 };
  98
  99 }  // namespace browser_sync
 100
 101 #endif  // CHROME_BROWSER_SYNC_GLUE_TAB_NODE_POOL_H_