private void ProcessSingleStageTransactionRequest(TransactionRequest transactionRequest, IClient client)
{
var typesToPut = transactionRequest.ItemsToPut.Select(i => i.FullTypeName).Distinct().ToList();
var typesToDelete = transactionRequest.ItemsToDelete.Select(i => i.FullTypeName).Distinct().ToList();
var types = typesToPut.Union(typesToDelete).Distinct();
try
{
foreach (var type in types)
{
if (!DataStores[type].Lock.TryEnterWriteLock(Constants.DelayForLock))
{
throw new CacheException("Failed to acquire write locks for single-stage transaction",
ExceptionType.FailedToAcquireLock);
}
}
Dbg.Trace($"S: fallback to single stage for transaction {transactionRequest.TransactionId}");
// check the conditions (in case of conditional update)
int index = 0;
foreach (var condition in transactionRequest.Conditions)
{
if (!condition.IsEmpty())
{
var ds = DataStores[condition.TypeName];
ds.CheckCondition(transactionRequest.ItemsToPut[index].PrimaryKey, condition);
}
index++;
}
PersistenceEngine?.NewTransaction(new MixedTransaction
{
ItemsToDelete = transactionRequest.ItemsToDelete,
ItemsToPut = transactionRequest.ItemsToPut
}
);
// update the data in memory
var dataRequests = transactionRequest.SplitByType();
foreach (var dataRequest in dataRequests)
{
if (!DataStores.ContainsKey(dataRequest.FullTypeName))
{
throw new NotSupportedException($"The type {dataRequest.FullTypeName} is not registered");
}
DataStores[dataRequest.FullTypeName].ProcessRequest(dataRequest, client, null);
}
client.SendResponse(new NullResponse());
Dbg.Trace($"S: end writing delayed transaction {transactionRequest.TransactionId}");
}
catch (CacheException e)
{
client.SendResponse(new ExceptionResponse(e, e.ExceptionType));
}
catch (Exception e)
{
Dbg.Trace($"error writing delayed transaction:{e.Message}");
client.SendResponse(new ExceptionResponse(e));
// failed to write a durable transaction so stop here
}
finally
{
// release acquired locks
foreach (var type in types)
{
if (DataStores[type].Lock.IsWriteLockHeld)
{
DataStores[type].Lock.ExitWriteLock();
}
}
}
}
private void ProcessTransactionRequest(TransactionRequest transactionRequest, IClient client)
{
// First try to acquire a write lock on all concerned data stores
var typesToPut = transactionRequest.ItemsToPut.Select(i => i.FullTypeName).Distinct().ToList();
var typesToDelete = transactionRequest.ItemsToDelete.Select(i => i.FullTypeName).Distinct().ToList();
var types = typesToPut.Union(typesToDelete).Distinct().ToList();
if (types.Any(t => !DataStores.ContainsKey(t)))
{
throw new NotSupportedException("Type not registered");
}
// do not work too hard if it's single stage
if (transactionRequest.IsSingleStage)
{
ProcessSingleStageTransactionRequest(transactionRequest, client);
return;
}
if (!AcquireWriteLock(client, types, transactionRequest.TransactionId))
{
return;
}
Dbg.Trace($"S: lock acquired by all clients for transaction {transactionRequest.TransactionId}");
// Second register a durable delayed transaction. It can be cancelled later
try
{
// check the conditions (in case of conditional update)
int index = 0;
foreach (var condition in transactionRequest.Conditions)
{
if (!condition.IsEmpty())
{
var ds = DataStores[condition.TypeName];
ds.CheckCondition(transactionRequest.ItemsToPut[index].PrimaryKey, condition);
}
index++;
}
Dbg.Trace($"S: begin writing delayed transaction {transactionRequest.TransactionId}");
PersistenceEngine?.NewTransaction(new MixedTransaction
{
ItemsToDelete = transactionRequest.ItemsToDelete,
ItemsToPut = transactionRequest.ItemsToPut
},
true
);
client.SendResponse(new ReadyResponse());
Dbg.Trace($"S: end writing delayed transaction {transactionRequest.TransactionId}");
}
catch (CacheException e)
{
Dbg.Trace($"error in first stage:{e.Message} server {ShardIndex}");
client.SendResponse(new ExceptionResponse(e, e.ExceptionType));
// failed to write a durable transaction so stop here
// unlock
foreach (var type in types)
{
if (DataStores[type].Lock.IsWriteLockHeld)
{
DataStores[type].Lock.ExitWriteLock();
}
}
return;
}
catch (Exception e)
{
Dbg.Trace($"error in first stage:{e.Message} server {ShardIndex}");
client.SendResponse(new ExceptionResponse(e));
// failed to write a durable transaction so stop here
// unlock
foreach (var type in types)
{
if (DataStores[type].Lock.IsWriteLockHeld)
{
DataStores[type].Lock.ExitWriteLock();
}
}
return;
}
try
{
Dbg.Trace($"S: begin waiting for client go {transactionRequest.TransactionId}");
var answer = client.ShouldContinue();
Dbg.Trace($"S: end waiting for client go answer = {answer}");
if (answer.HasValue) // the client has answered
{
if (answer.Value)
{
// update the data in memory
var dataRequests = transactionRequest.SplitByType();
foreach (var dataRequest in dataRequests)
{
if (!DataStores.ContainsKey(dataRequest.FullTypeName))
{
throw new NotSupportedException(
$"The type {dataRequest.FullTypeName} is not registered");
}
DataStores[dataRequest.FullTypeName].ProcessRequest(dataRequest, client, null);
}
ServerLog.LogInfo(
$"S: two stage transaction committed successfully on server {ShardIndex} {transactionRequest.TransactionId}");
}
else
{
ServerLog.LogWarning(
$"S: two stage transaction cancelled by client on server {ShardIndex} {transactionRequest.TransactionId}");
// cancel the delayed transaction
PersistenceEngine?.CancelDelayedTransaction();
}
}
else // the client failed to answer in a reasonable delay (which is less than the delay to commit a delayed transaction )
{
PersistenceEngine?.CancelDelayedTransaction();
}
}
catch (Exception e)
{
ServerLog.LogInfo($"error in the second stage of a transaction:{e.Message}");
}
// unlock
foreach (var type in types)
{
if (DataStores[type].Lock.IsWriteLockHeld)
{
DataStores[type].Lock.ExitWriteLock();
}
}
}