public Editor Edit(string key, long expectedSequenceNumber = AnySequenceNumber)
{
CheckNotClosed();
ValidateKey(key);
lruEntries.TryGetValue(key, out var entry);
if (expectedSequenceNumber != AnySequenceNumber &&
(null == entry || entry.UnsafeSequenceNumber != expectedSequenceNumber))
{
return(null); // Snapshot is stale.
}
if (null == entry)
{
entry = new UnsafeEntry(key, Directory, ValueCount);
lruEntries[key] = entry;
}
else if (null != entry.UnsafeCurrentEditor)
{
return(null); // Another edit is in progress.
}
var editor = new Editor(entry, this);
entry.UnsafeCurrentEditor = editor;
// Flush the journal before creating files to prevent file leaks.
journalWriter.WriteLine($"{DirtyFlag} {key}");
journalWriter.Flush();
return(editor);
}
public Editor(UnsafeEntry entry, DiskLruCache parent)
{
this.parent = parent;
Entry = entry;
written = entry.UnsafeReadable ? null : new bool[parent.ValueCount];
}
private void ReadJournalLine(string line)
{
if (null == line)
{
throw new EndOfStreamException();
}
var firstSpace = line.IndexOf(' ');
if (firstSpace == -1)
{
throw new IOException($"unexpected journal line: {line}");
}
var keyBegin = firstSpace + 1;
var secondSpace = line.IndexOf(' ', keyBegin);
string key;
if (secondSpace == -1)
{
key = line.Substring(keyBegin);
if (firstSpace == RemoveFlag.Length && line.StartsWith(RemoveFlag))
{
lruEntries.Remove(key);
return;
}
}
else
{
var length = secondSpace - keyBegin;
key = line.Substring(keyBegin, length);
}
lruEntries.TryGetValue(key, out var entry);
if (null == entry)
{
entry = new UnsafeEntry(key, Directory, ValueCount);
lruEntries[key] = entry;
}
if (secondSpace != -1 && firstSpace == CleanFlag.Length && line.StartsWith(CleanFlag))
{
var parts = line.Substring(secondSpace + 1).Split(' ');
entry.UnsafeReadable = true;
entry.UnsafeCurrentEditor = null;
entry.SetLengths(parts);
}
else if (secondSpace == -1 && firstSpace == DirtyFlag.Length && line.StartsWith(DirtyFlag))
{
entry.UnsafeCurrentEditor = new Editor(entry, this);
}
else if (secondSpace == -1 && firstSpace == ReadFlag.Length && line.StartsWith(ReadFlag))
{
// This work was already done by calling lruEntries.get().
}
else
{
throw new IOException($"unexpected journal line: {line}");
}
}