Mantis#1903. Thank you kindly, CMickeyb for a patch that:
patch attached replaces the tree walk algorithm used to build the folder hierarchy with a single database query. That is, we replace 1 database query per folder with 1 query for the root folder's properties and 1 query to retrieve the entire collection of folders for a user.0.6.0-stable
Charles Krinke
parent
a9f1561380
commit
54af3b4f4d
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@ -704,13 +704,116 @@ namespace OpenSim.Data.MySQL
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/// <returns></returns>
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public List<InventoryFolderBase> getFolderHierarchy(LLUUID parentID)
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{
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List<InventoryFolderBase> folders = new List<InventoryFolderBase>();
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getInventoryFolders(ref folders, parentID);
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/* Note: There are subtle changes between this implementation of getFolderHierarchy and the previous one
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* - We will only need to hit the database twice instead of n times.
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* - We assume the database is well-formed - no stranded/dangling folders, all folders in heirarchy owned
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* by the same person, each user only has 1 inventory heirarchy
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* - The returned list is not ordered, instead of breadth-first ordered
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There are basically 2 usage cases for getFolderHeirarchy:
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1) Getting the user's entire inventory heirarchy when they log in
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2) Finding a subfolder heirarchy to delete when emptying the trash.
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This implementation will pull all inventory folders from the database, and then prune away any folder that
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is not part of the requested sub-heirarchy. The theory is that it is cheaper to make 1 request from the
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database than to make n requests. This pays off only if requested heirarchy is large.
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By making this choice, we are making the worst case better at the cost of making the best case worse.
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This way is generally better because we don't have to rebuild the connection/sql query per subfolder,
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even if we end up getting more data from the SQL server than we need.
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- Francis
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*/
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try
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{
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List<InventoryFolderBase> folders = new List<InventoryFolderBase>();
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Dictionary<LLUUID, List<InventoryFolderBase>> hashtable
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= new Dictionary<LLUUID, List<InventoryFolderBase>>(); ;
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List<InventoryFolderBase> parentFolder = new List<InventoryFolderBase>();
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lock (database)
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{
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MySqlCommand result;
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MySqlDataReader reader;
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bool buildResultsFromHashTable = false;
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for (int i = 0; i < folders.Count; i++)
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getInventoryFolders(ref folders, folders[i].ID);
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database.CheckConnection();
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return folders;
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/* Fetch the parent folder from the database to determine the agent ID, and if
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* we're querying the root of the inventory folder tree */
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result = new MySqlCommand("SELECT * FROM inventoryfolders WHERE folderID = ?uuid",
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database.Connection);
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result.Parameters.AddWithValue("?uuid", parentID.ToString());
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reader = result.ExecuteReader();
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while (reader.Read()) // Should be at most 1 result
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parentFolder.Add(readInventoryFolder(reader));
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reader.Close();
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result.Dispose();
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if (parentFolder.Count >= 1) // No result means parent folder does not exist
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{
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if (parentFolder[0].ParentID == LLUUID.Zero) // We are querying the root folder
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{
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/* Get all of the agent's folders from the database, put them in a list and return it */
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result = new MySqlCommand("SELECT * FROM inventoryfolders WHERE agentID = ?uuid",
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database.Connection);
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result.Parameters.AddWithValue("?uuid", parentFolder[0].Owner.ToString());
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reader = result.ExecuteReader();
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while (reader.Read())
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{
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InventoryFolderBase curFolder = readInventoryFolder(reader);
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if (curFolder.ID != parentID) // Do not need to add the root node of the tree to the list
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folders.Add(curFolder);
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}
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reader.Close();
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result.Dispose();
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} // if we are querying the root folder
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else // else we are querying a subtree of the inventory folder tree
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{
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/* Get all of the agent's folders from the database, put them all in a hash table
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* indexed by their parent ID */
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result = new MySqlCommand("SELECT * FROM inventoryfolders WHERE agentID = ?uuid",
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database.Connection);
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result.Parameters.AddWithValue("?uuid", parentFolder[0].Owner.ToString());
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reader = result.ExecuteReader();
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while (reader.Read())
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{
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InventoryFolderBase curFolder = readInventoryFolder(reader);
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if (hashtable.ContainsKey(curFolder.ParentID)) // Current folder already has a sibling
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hashtable[curFolder.ParentID].Add(curFolder); // append to sibling list
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else // else current folder has no known (yet) siblings
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{
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List<InventoryFolderBase> siblingList = new List<InventoryFolderBase>();
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siblingList.Add(curFolder);
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// Current folder has no known (yet) siblings
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hashtable.Add(curFolder.ParentID, siblingList);
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}
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} // while more items to read from the database
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reader.Close();
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result.Dispose();
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// Set flag so we know we need to build the results from the hash table after
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// we unlock the database
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buildResultsFromHashTable = true;
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} // else we are querying a subtree of the inventory folder tree
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} // if folder parentID exists
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if (buildResultsFromHashTable)
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{
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/* We have all of the user's folders stored in a hash table indexed by their parent ID
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* and we need to return the requested subtree. We will build the requested subtree
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* by performing a breadth-first-search on the hash table */
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if (hashtable.ContainsKey(parentID))
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folders.AddRange(hashtable[parentID]);
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for (int i = 0; i < folders.Count; i++) // **Note: folders.Count is *not* static
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if (hashtable.ContainsKey(folders[i].ID))
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folders.AddRange(hashtable[folders[i].ID]);
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}
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} // lock(database)
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return folders;
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}
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catch (Exception e)
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{
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database.Reconnect();
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m_log.Error(e.ToString());
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return null;
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}
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}
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/// <summary>
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@ -392,6 +392,7 @@ namespace OpenSim.Data.SQLite
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{
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folders.Add(buildFolder(row));
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}
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}
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}
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@ -414,12 +415,100 @@ namespace OpenSim.Data.SQLite
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/// <returns></returns>
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public List<InventoryFolderBase> getFolderHierarchy(LLUUID parentID)
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{
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/* Note: There are subtle changes between this implementation of getFolderHierarchy and the previous one
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* - We will only need to hit the database twice instead of n times.
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* - We assume the database is well-formed - no stranded/dangling folders, all folders in heirarchy owned
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* by the same person, each user only has 1 inventory heirarchy
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* - The returned list is not ordered, instead of breadth-first ordered
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There are basically 2 usage cases for getFolderHeirarchy:
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1) Getting the user's entire inventory heirarchy when they log in
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2) Finding a subfolder heirarchy to delete when emptying the trash.
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This implementation will pull all inventory folders from the database, and then prune away any folder that
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is not part of the requested sub-heirarchy. The theory is that it is cheaper to make 1 request from the
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database than to make n requests. This pays off only if requested heirarchy is large.
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By making this choice, we are making the worst case better at the cost of making the best case worse
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- Francis
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*/
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List<InventoryFolderBase> folders = new List<InventoryFolderBase>();
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getInventoryFolders(ref folders, Util.ToRawUuidString(parentID));
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DataRow[] folderRows = null, parentRow;
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InventoryFolderBase parentFolder = null;
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lock (ds)
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{
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/* Fetch the parent folder from the database to determine the agent ID.
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* Then fetch all inventory folders for that agent from the agent ID.
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*/
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DataTable inventoryFolderTable = ds.Tables["inventoryfolders"];
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string selectExp = "UUID = '" + Util.ToRawUuidString(parentID) + "'";
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parentRow = inventoryFolderTable.Select(selectExp); // Assume at most 1 result
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if (parentRow.GetLength(0) >= 1) // No result means parent folder does not exist
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{
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parentFolder = buildFolder(parentRow[0]);
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LLUUID agentID = parentFolder.Owner;
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selectExp = "agentID = '" + Util.ToRawUuidString(agentID) + "'";
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folderRows = inventoryFolderTable.Select(selectExp);
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}
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for (int i = 0; i < folders.Count; i++)
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getInventoryFolders(ref folders, Util.ToRawUuidString(folders[i].ID));
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if ( folderRows!=null && folderRows.GetLength(0)>=1 ) // No result means parent folder does not exist
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{ // or has no children
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/* if we're querying the root folder, just return an unordered list of all folders in the user's
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* inventory
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*/
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if (parentFolder.ParentID == LLUUID.Zero)
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{
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foreach (DataRow row in folderRows)
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{
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InventoryFolderBase curFolder = buildFolder(row);
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if (curFolder.ID != parentID) // Return all folders except the parent folder of heirarchy
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folders.Add(buildFolder(row));
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}
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} // If requesting root folder
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/* else we are querying a non-root folder. We currently have a list of all of the user's folders,
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* we must construct a list of all folders in the heirarchy below parentID.
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* Our first step will be to construct a hash table of all folders, indexed by parent ID.
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* Once we have constructed the hash table, we will do a breadth-first traversal on the tree using the
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* hash table to find child folders.
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*/
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else
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{ // Querying a non-root folder
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// Build a hash table of all user's inventory folders, indexed by each folder's parent ID
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Dictionary<LLUUID, List<InventoryFolderBase>> hashtable =
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new Dictionary<LLUUID, List<InventoryFolderBase>>(folderRows.GetLength(0));
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foreach (DataRow row in folderRows)
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{
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InventoryFolderBase curFolder = buildFolder(row);
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if (curFolder.ParentID != LLUUID.Zero) // Discard root of tree - not needed
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{
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if ( hashtable.ContainsKey(curFolder.ParentID ) )
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{
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// Current folder already has a sibling - append to sibling list
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hashtable[curFolder.ParentID].Add( curFolder );
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}
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else {
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List<InventoryFolderBase> siblingList = new List<InventoryFolderBase>();
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siblingList.Add( curFolder );
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// Current folder has no known (yet) siblings
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hashtable.Add( curFolder.ParentID, siblingList );
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}
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}
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} // For all inventory folders
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// Note: Could release the ds lock here - we don't access folderRows or the database anymore.
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// This is somewhat of a moot point as the callers of this function usually lock db anyways.
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if ( hashtable.ContainsKey( parentID ) ) // if requested folder does have children
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folders.AddRange( hashtable[parentID] );
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// BreadthFirstSearch build inventory tree **Note: folders.Count is *not* static
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for ( int i = 0; i < folders.Count; i++ )
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if (hashtable.ContainsKey(folders[i].ID))
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folders.AddRange(hashtable[folders[i].ID]);
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} // if requesting a subfolder heirarchy
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} // if folder parentID exists and has children
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} // lock ds
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return folders;
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}
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