/// <summary>
/// Compact the log until specified address, moving active records to the tail of the log.
/// </summary>
/// <param name="functions">Functions used to manage key-values during compaction</param>
/// <param name="cf">User provided compaction functions (see <see cref="ICompactionFunctions{Key, Value}"/>).</param>
/// <param name="untilAddress">Compact log until this address</param>
/// <param name="shiftBeginAddress">Whether to shift begin address to untilAddress after compaction. To avoid
/// data loss on failure, set this to false, and shift begin address only after taking a checkpoint. This
/// ensures that records written to the tail during compaction are first made stable.</param>
/// <returns>Address until which compaction was done</returns>
public long Compact <Input, Output, Context, Functions, CompactionFunctions>(Functions functions, CompactionFunctions cf, long untilAddress, bool shiftBeginAddress)
where Functions : IFunctions <Key, Value, Input, Output, Context>
where CompactionFunctions : ICompactionFunctions <Key, Value>
{
if (untilAddress > fht.Log.SafeReadOnlyAddress)
{
throw new FasterException("Can compact only until Log.SafeReadOnlyAddress");
}
var originalUntilAddress = untilAddress;
var lf = new LogCompactionFunctions <Key, Value, Input, Output, Context, Functions>(functions);
using var fhtSession = fht.For(lf).NewSession <LogCompactionFunctions <Key, Value, Input, Output, Context, Functions> >();
VariableLengthStructSettings <Key, Value> variableLengthStructSettings = null;
if (allocator is VariableLengthBlittableAllocator <Key, Value> varLen)
{
variableLengthStructSettings = new VariableLengthStructSettings <Key, Value>
{
keyLength = varLen.KeyLength,
valueLength = varLen.ValueLength,
};
}
using (var tempKv = new FasterKV <Key, Value>(fht.IndexSize, new LogSettings {
LogDevice = new NullDevice(), ObjectLogDevice = new NullDevice()
}, comparer: fht.Comparer, variableLengthStructSettings: variableLengthStructSettings))
using (var tempKvSession = tempKv.NewSession <Input, Output, Context, Functions>(functions))
{
using (var iter1 = fht.Log.Scan(fht.Log.BeginAddress, untilAddress))
{
while (iter1.GetNext(out var recordInfo))
{
ref var key = ref iter1.GetKey();
ref var value = ref iter1.GetValue();
if (recordInfo.Tombstone || cf.IsDeleted(key, value))
{
tempKvSession.Delete(ref key, default, 0);
