public User FirstUser(Predicate <User> p)
{
if (p == null)
{
return(null); // Done to conveniently handle system insertions
}
// Check if user is scheduled for removal
foreach (var entry in toRemove)
{
if (p(entry))
{
return(null);
}
}
// Check loaded users
foreach (var entry in loadedUsers)
{
if (p(entry))
{
return(entry);
}
}
// Check modified users
foreach (var entry in changeList)
{
if (p(entry))
{
if (!loadedUsers.Contains(entry))
{
loadedUsers.Add(entry);
}
return(entry);
}
}
// Read from database
using (var reader = XmlReader.Create(DatabaseName))
{
if (!Traverse(reader, MasterEntry))
{
return(null);
}
while ((reader.Name.Equals("User") && reader.NodeType != XmlNodeType.EndElement) || (reader.Read() && reader.NodeType != XmlNodeType.EndElement))
{
if (reader.Name.Equals("User"))
{
User n = FromEncoded(User.Parse(ReadEntry(reader), this));
if (n != null && p(n))
{
if (!loadedUsers.Contains(n))
{
loadedUsers.Add(n);
}
return(n);
}
}
}
}
return(null);
}
// Permissive (cache-dependent) flush
private void Flush(bool optional)
{
if (optional && (changeList.Count < 30 && toRemove.Count < 30))
{
return; // No need to flush
}
string temp = GenerateTempFileName("tmp_", ".xml");
using (var writer = XmlWriter.Create(temp))
{
using (var reader = XmlReader.Create(DatabaseName))
{
int masterDepth = 0;
bool trigger = false, wn = false, recent = false, justTriggered = false;
while (wn || reader.Read() || (reader.NodeType == XmlNodeType.None && justTriggered))
{
justTriggered = false;
wn = false;
if (trigger)
{
foreach (var user in changeList)
{
WriteUser(writer, user);
}
bool wroteNode = false;
while ((wroteNode || reader.Name.Equals("User") || reader.Read()) && reader.NodeType != XmlNodeType.EndElement && reader.NodeType != XmlNodeType.None)
{
wroteNode = false;
if (reader.Name.Equals("User"))
{
User u = FromEncoded(User.Parse(ReadEntry(reader), this));
if (u != null)
{
bool shouldWrite = true;
foreach (var toChange in changeList)
{
if (toChange.Name.Equals(u.Name))
{
shouldWrite = false;
break;
}
}
if (shouldWrite)
{
foreach (var remove in toRemove)
{
if (remove.Name.Equals(u.Name))
{
shouldWrite = false;
break;
}
}
}
if (shouldWrite)
{
WriteUser(writer, u);
}
}
}
else
{
wroteNode = true;
writer.WriteNode(reader, true);
}
}
trigger = false;
recent = true;
writer.WriteEndElement();
toRemove.Clear();
changeList.Clear();
}
if (masterDepth != MasterEntry.Length && reader.Name.Equals(MasterEntry[masterDepth]))
{
trigger = reader.NodeType == XmlNodeType.Element && ++masterDepth == MasterEntry.Length;
justTriggered = true;
reader.MoveToContent();
writer.WriteStartElement(MasterEntry[masterDepth - 1]);
}
else if (masterDepth == MasterEntry.Length && recent)
{
if (masterDepth != 1)
{
writer.WriteEndElement();
}
recent = false;
}
else
{
wn = true;
writer.WriteNode(reader, true);
}
}
}
writer.Flush();
}
File.Delete(DatabaseName);
File.Move(temp, DatabaseName);
}