Componentize tab_node_pool to sync_driver

chrome/browser/sync/sessions/tab_node_pool.cc

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "chrome/browser/sync/sessions/tab_node_pool.h"
-
-#include "base/format_macros.h"
-#include "base/logging.h"
-#include "base/strings/stringprintf.h"
-#include "sync/api/sync_change.h"
-#include "sync/api/sync_data.h"
-#include "sync/internal_api/public/base/model_type.h"
-#include "sync/protocol/session_specifics.pb.h"
-#include "sync/protocol/sync.pb.h"
-
-namespace browser_sync {
-
-const size_t TabNodePool::kFreeNodesLowWatermark = 25;
-const size_t TabNodePool::kFreeNodesHighWatermark = 100;
-
-TabNodePool::TabNodePool()
-    : max_used_tab_node_id_(kInvalidTabNodeID) {}
-
-// static
-// We start vending tab node IDs at 0.
-const int TabNodePool::kInvalidTabNodeID = -1;
-
-TabNodePool::~TabNodePool() {}
-
-// Static
-std::string TabNodePool::TabIdToTag(
-    const std::string machine_tag, int tab_node_id) {
-  return base::StringPrintf("%s %d", machine_tag.c_str(), tab_node_id);
-}
-
-void TabNodePool::AddTabNode(int tab_node_id) {
-  DCHECK_GT(tab_node_id, kInvalidTabNodeID);
-  DCHECK(nodeid_tabid_map_.find(tab_node_id) == nodeid_tabid_map_.end());
-  unassociated_nodes_.insert(tab_node_id);
-  if (max_used_tab_node_id_ < tab_node_id)
-    max_used_tab_node_id_ = tab_node_id;
-}
-
-void TabNodePool::AssociateTabNode(int tab_node_id,
-                                    SessionID::id_type tab_id) {
-  DCHECK_GT(tab_node_id, kInvalidTabNodeID);
-  // Remove sync node if it is in unassociated nodes pool.
-  std::set<int>::iterator u_it = unassociated_nodes_.find(tab_node_id);
-  if (u_it != unassociated_nodes_.end()) {
-    unassociated_nodes_.erase(u_it);
-  } else {
-    // This is a new node association, the sync node should be free.
-    // Remove node from free node pool and then associate it with the tab.
-    std::set<int>::iterator it = free_nodes_pool_.find(tab_node_id);
-    DCHECK(it != free_nodes_pool_.end());
-    free_nodes_pool_.erase(it);
-  }
-  DCHECK(nodeid_tabid_map_.find(tab_node_id) == nodeid_tabid_map_.end());
-  nodeid_tabid_map_[tab_node_id] = tab_id;
-}
-
-int TabNodePool::GetFreeTabNode(syncer::SyncChangeList* append_changes) {
-  DCHECK_GT(machine_tag_.length(), 0U);
-  DCHECK(append_changes);
-  if (free_nodes_pool_.empty()) {
-    // Tab pool has no free nodes, allocate new one.
-    int tab_node_id = ++max_used_tab_node_id_;
-    std::string tab_node_tag = TabIdToTag(machine_tag_, tab_node_id);
-
-    // We fill the new node with just enough data so that in case of a crash/bug
-    // we can identify the node as our own on re-association and reuse it.
-    sync_pb::EntitySpecifics entity;
-    sync_pb::SessionSpecifics* specifics = entity.mutable_session();
-    specifics->set_session_tag(machine_tag_);
-    specifics->set_tab_node_id(tab_node_id);
-    append_changes->push_back(syncer::SyncChange(
-        FROM_HERE,
-        syncer::SyncChange::ACTION_ADD,
-        syncer::SyncData::CreateLocalData(tab_node_tag,
-                                          tab_node_tag,
-                                          entity)));
-
-    // Grow the pool by 1 since we created a new node.
-    DVLOG(1) << "Adding sync node " << tab_node_id
-             << " to tab node id pool";
-    free_nodes_pool_.insert(tab_node_id);
-    return tab_node_id;
-  } else {
-    // Return the next free node.
-    return *free_nodes_pool_.begin();
-  }
-}
-
-void TabNodePool::FreeTabNode(int tab_node_id,
-                               syncer::SyncChangeList* append_changes) {
-  DCHECK(append_changes);
-  TabNodeIDToTabIDMap::iterator it = nodeid_tabid_map_.find(tab_node_id);
-  DCHECK(it != nodeid_tabid_map_.end());
-  nodeid_tabid_map_.erase(it);
-  FreeTabNodeInternal(tab_node_id, append_changes);
-}
-
-void TabNodePool::FreeTabNodeInternal(
-    int tab_node_id,
-    syncer::SyncChangeList* append_changes) {
-  DCHECK(free_nodes_pool_.find(tab_node_id) == free_nodes_pool_.end());
-  DCHECK(append_changes);
-  free_nodes_pool_.insert(tab_node_id);
-
-  // If number of free nodes exceed kFreeNodesHighWatermark,
-  // delete sync nodes till number reaches kFreeNodesLowWatermark.
-  // Note: This logic is to mitigate temporary disassociation issues with old
-  // clients: http://crbug.com/259918. Newer versions do not need this.
-  if (free_nodes_pool_.size() > kFreeNodesHighWatermark) {
-    for (std::set<int>::iterator free_it = free_nodes_pool_.begin();
-         free_it != free_nodes_pool_.end();) {
-      const std::string tab_node_tag = TabIdToTag(machine_tag_, *free_it);
-      append_changes->push_back(syncer::SyncChange(
-          FROM_HERE,
-          syncer::SyncChange::ACTION_DELETE,
-          syncer::SyncData::CreateLocalDelete(tab_node_tag,
-                                              syncer::SESSIONS)));
-      free_nodes_pool_.erase(free_it++);
-      if (free_nodes_pool_.size() <= kFreeNodesLowWatermark) {
-        return;
-      }
-    }
-  }
-}
-
-bool TabNodePool::IsUnassociatedTabNode(int tab_node_id) {
-  return unassociated_nodes_.find(tab_node_id) != unassociated_nodes_.end();
-}
-
-void TabNodePool::ReassociateTabNode(int tab_node_id,
-                                      SessionID::id_type tab_id) {
-  // Remove from list of unassociated sync_nodes if present.
-  std::set<int>::iterator it = unassociated_nodes_.find(tab_node_id);
-  if (it != unassociated_nodes_.end()) {
-    unassociated_nodes_.erase(it);
-  } else {
-    // tab_node_id must be an already associated node.
-    DCHECK(nodeid_tabid_map_.find(tab_node_id) != nodeid_tabid_map_.end());
-  }
-  nodeid_tabid_map_[tab_node_id] = tab_id;
-}
-
-SessionID::id_type TabNodePool::GetTabIdFromTabNodeId(
-    int tab_node_id) const {
-  TabNodeIDToTabIDMap::const_iterator it = nodeid_tabid_map_.find(tab_node_id);
-  if (it != nodeid_tabid_map_.end()) {
-    return it->second;
-  }
-  return kInvalidTabID;
-}
-
-void TabNodePool::DeleteUnassociatedTabNodes(
-    syncer::SyncChangeList* append_changes) {
-  for (std::set<int>::iterator it = unassociated_nodes_.begin();
-       it != unassociated_nodes_.end();) {
-    FreeTabNodeInternal(*it, append_changes);
-    unassociated_nodes_.erase(it++);
-  }
-  DCHECK(unassociated_nodes_.empty());
-}
-
-// Clear tab pool.
-void TabNodePool::Clear() {
-  unassociated_nodes_.clear();
-  free_nodes_pool_.clear();
-  nodeid_tabid_map_.clear();
-  max_used_tab_node_id_ = kInvalidTabNodeID;
-}
-
-size_t TabNodePool::Capacity() const {
-  return nodeid_tabid_map_.size() + unassociated_nodes_.size() +
-         free_nodes_pool_.size();
-}
-
-bool TabNodePool::Empty() const { return free_nodes_pool_.empty(); }
-
-bool TabNodePool::Full() { return nodeid_tabid_map_.empty(); }
-
-void TabNodePool::SetMachineTag(const std::string& machine_tag) {
-  machine_tag_ = machine_tag;
-}
-
-}  // namespace browser_sync