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Improves Lazy WAL transaction log compaction performance.

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This commit is contained in:
Ahmed Yasin Koculu
2022-08-16 00:07:08 +02:00
parent 59b26e6a54
commit 59dfaf5aec
1 changed files with 44 additions and 24 deletions
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src/ZoneTree/WAL/LazyFileSystemWriteAheadLog.cs
+44 -24
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@@ -40,8 +40,12 @@ public sealed class LazyFileSystemWriteAheadLog<TKey, TValue> : IWriteAheadLog<T
}
}
readonly object AppendLock = new();
volatile bool isRunning = false;
volatile bool isWriterCancelled = false;
volatile Task WriteTask;
public string FilePath { get; }
@@ -88,6 +92,14 @@ public sealed class LazyFileSystemWriteAheadLog<TKey, TValue> : IWriteAheadLog<T
ConsumeQueue();
}
void CancelWriter()
{
lock (AppendLock)
{
isWriterCancelled = true;
}
}
void ConsumeQueue()
{
lock (this)
@@ -114,10 +126,9 @@ public sealed class LazyFileSystemWriteAheadLog<TKey, TValue> : IWriteAheadLog<T
var valueBytes = ValueSerializer.Serialize(q.Value);
AppendLogEntry(keyBytes, valueBytes, q.OpIndex);
}
catch (Exception e)
catch (Exception)
{
// todo log the exception.
//Console.WriteLine(e.Message);
}
}
if (isRunning && Queue.IsEmpty)
@@ -126,11 +137,12 @@ public sealed class LazyFileSystemWriteAheadLog<TKey, TValue> : IWriteAheadLog<T
{
FileStream.WriteTail();
}
catch(Exception e)
catch(Exception)
{
// todo log the exception.
// Console.WriteLine(e.Message);
}
if (!isRunning)
break;
if (EmptyQueuePollInterval == 0)
Thread.Yield();
else
@@ -184,26 +196,31 @@ public sealed class LazyFileSystemWriteAheadLog<TKey, TValue> : IWriteAheadLog<T
void AppendLogEntry(byte[] keyBytes, byte[] valueBytes, long opIndex)
{
var entry = new LogEntry
lock (AppendLock)
{
OpIndex = opIndex,
KeyLength = keyBytes.Length,
ValueLength = valueBytes.Length,
Key = keyBytes,
Value = valueBytes
};
entry.Checksum = entry.CreateChecksum();
if (isWriterCancelled)
return;
var entry = new LogEntry
{
OpIndex = opIndex,
KeyLength = keyBytes.Length,
ValueLength = valueBytes.Length,
Key = keyBytes,
Value = valueBytes
};
entry.Checksum = entry.CreateChecksum();
var binaryWriter = new BinaryWriter(FileStream, Encoding.UTF8, true);
binaryWriter.Write(entry.OpIndex);
binaryWriter.Write(entry.KeyLength);
binaryWriter.Write(entry.ValueLength);
if (entry.Key != null)
binaryWriter.Write(entry.Key);
if (entry.Value != null)
binaryWriter.Write(entry.Value);
binaryWriter.Write(entry.Checksum);
binaryWriter.Flush();
var binaryWriter = BinaryWriter;
binaryWriter.Write(entry.OpIndex);
binaryWriter.Write(entry.KeyLength);
binaryWriter.Write(entry.ValueLength);
if (entry.Key != null)
binaryWriter.Write(entry.Key);
if (entry.Value != null)
binaryWriter.Write(entry.Value);
binaryWriter.Write(entry.Checksum);
binaryWriter.Flush();
}
}
static void ReadLogEntry(BinaryReader reader, ref LogEntry entry)
@@ -262,15 +279,18 @@ public sealed class LazyFileSystemWriteAheadLog<TKey, TValue> : IWriteAheadLog<T
}
else
{
StopWriter(false);
Queue.Clear();
CancelWriter();
}
// Replacement crash recovery is not required here,
// because the lazy write ahead log is not durable.
// implementing crash recovery here does not make it durable.
var existingLength = FileStream.Length;
FileStream.SetLength(0);
StartWriter();
if (isWriterCancelled)
isWriterCancelled = false;
else
StartWriter();
var len = keys.Length;
for (var i = 0; i < len; ++i)
{