public void ProcessTransactionRequest(TransactionRequest transactionRequest, IClient client,
SafeDictionary <string, DataStore> dataStores)
{
if (transactionRequest.TransactionId == default)
{
client.SendResponse(new ExceptionResponse(
new CacheException(
"Transaction request received without transaction id")));
return;
}
// First try to acquire a write lock on all concerned data stores
var types = transactionRequest.AllCollections;
var keys = dataStores.Keys;
if (types.Any(t => !keys.Contains(t)))
{
throw new NotSupportedException("Type not registered");
}
var transactionId = transactionRequest.TransactionId;
// do not work too hard if it's single stage
if (transactionRequest.IsSingleStage)
{
ProcessSingleStageTransactionRequest(transactionRequest, client, dataStores);
return;
}
var lockAcquired = _lockManager.TryAcquireWriteLock(transactionId, Constants.DelayForLockInMilliseconds, types.ToArray());
if (lockAcquired)
{
var answer = client.ShouldContinue();
if (answer.HasValue && answer.Value)
{
}
else
{
_lockManager.CloseSession(transactionId);
return;
}
}
else
{
client.SendResponse(new ExceptionResponse(
new CacheException(
$"can not acquire write lock on server for transaction {transactionRequest.TransactionId}"),
ExceptionType.FailedToAcquireLock));
return;
}
Dbg.Trace($"S: lock acquired by all clients for transaction {transactionRequest.TransactionId}");
// Second register a durable delayed transaction. It can be cancelled later
try
{
CheckConditions(transactionRequest, dataStores);
// if we reach here the condition check has passed
SaveDurableTransaction(transactionRequest, dataStores);
client.SendResponse(new ReadyResponse());
Dbg.Trace($"S: end writing delayed transaction {transactionRequest.TransactionId}");
}
catch (CacheException e)
{
Dbg.Trace($"error in first stage:{e.Message} ");
client.SendResponse(new ExceptionResponse(e, e.ExceptionType));
// failed to write a durable transaction so stop here
// unlock
_lockManager.CloseSession(transactionRequest.TransactionId);
return;
}
catch (Exception e)
{
Dbg.Trace($"error in first stage:{e.Message} ");
client.SendResponse(new ExceptionResponse(e));
// failed to write a durable transaction so stop here
// unlock
_lockManager.CloseSession(transactionRequest.TransactionId);
return;
}
try
{
Dbg.Trace($"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
ExecuteInMemory(transactionRequest, dataStores);
ServerLog.LogInfo(
$"S: two stage transaction committed successfully {transactionRequest.TransactionId}");
}
else
{
ServerLog.LogWarning(
$"S: two stage transaction cancelled by client on server {transactionRequest.TransactionId}");
// cancel the delayed transaction
_transactionLog?.CancelDelayedTransaction();
}
}
else // the client failed to answer in a reasonable delay (which is less than the delay to commit a delayed transaction )
{
_transactionLog?.CancelDelayedTransaction();
}
}
catch (Exception e)
{
ServerLog.LogInfo($"error in the second stage of a transaction:{e.Message}");
}
// unlock
_lockManager.CloseSession(transactionRequest.TransactionId);
}