/// <summary>
/// Creates a new transaction log manager.
/// </summary>
/// <param name="engineId">The engine this transaction log manager is used for. Only used for logging purposes.</param>
/// <param name="keyValueStore">The key/value store to write transaction logs to.</param>
/// <param name="policy">The serialization policy to use when serializing objects.</param>
public TransactionLogManager(Uri engineId, IKeyValueStore keyValueStore, ISerializationPolicy policy)
{
_engineId = engineId;
_keyValueStore = keyValueStore;
_policy = policy;
_lock = new AsyncLock();
_versionedLogs = new Queue <ITransactionLog>();
_metadataTable = new SerializingKeyValueTable <string>(
_keyValueStore.GetTable(MetadataTableName),
(str, s) =>
{
using var writer = new BinaryWriter(s);
writer.Write(str);
},
s =>
{
using var reader = new BinaryReader(s);
return(reader.ReadString());
}
);
using (var t = _keyValueStore.CreateTransaction())
{
var tx = _metadataTable.Enter(t);
if (!tx.Contains(ActiveCountKey))
{
Invariant.Assert(!tx.Contains(LatestKey) && !tx.Contains(HeldCountKey), "Transaction log versioning keys are only partially populated.");
_activeCount = _heldCount = _latest = 0;
}
else
{
Invariant.Assert(tx.Contains(LatestKey) && tx.Contains(HeldCountKey), "Transaction log versioning keys are only partially populated.");
_activeCount = long.Parse(tx[ActiveCountKey], CultureInfo.InvariantCulture);
_heldCount = long.Parse(tx[HeldCountKey], CultureInfo.InvariantCulture);
_latest = long.Parse(tx[LatestKey], CultureInfo.InvariantCulture);
}
}
Tracing.Transaction_Log_Initialization(null, _engineId, _latest, _activeCount, _heldCount);
for (var i = _latest - _heldCount + 1; i <= _latest; i++)
{
_versionedLogs.Enqueue(new TransactionLog(_keyValueStore, _policy, i));
}
}
/// <summary>
/// Creates a new serializing key value table using the specified underlying table and the specified serialization and deserialization functions.
/// </summary>
/// <param name="table">The underlying table, storing values of type <c>byte[]</c>.</param>
/// <param name="serialize">The function to serialize a value of type <typeparamref name="TValue"/>.</param>
/// <param name="deserialize">The function to deserialize a value of type <typeparamref name="TValue"/>.</param>
public SerializingKeyValueTable(IKeyValueTable <string, byte[]> table, Action <TValue, Stream> serialize, Func <Stream, TValue> deserialize)
{
_table = table;
_serialize = serialize;
_deserialize = deserialize;
}