/// <summary>
/// Called to find(or create if one is not found) the appropriate OutboundSessionDriver for a given partition.
/// This method will ensure that we have a one(targetPartition)-to-one(outBoundSessionDriver) relationship.
///
/// TODO: this layer must catch all exceptions and decide what to do with them -- lower layer functions like ResolveAndNormalizeTargetPartition
/// will throw in case of unrecoverable errors like FabricObjectClosedException
/// </summary>
/// <param name="targetPartition">Find or Create OutBoundSessionDriver for this Partition</param>
/// <param name="streamManager">Stream manager that manages the reference to the driver</param>
/// <param name="sessionConnectionManager">Use this session connection manager to create a new session if one if not found</param>
/// <param name="timeout">Timeout</param>
/// <returns>Returns OutboundSessionDriver if successfull, null otherwise</returns>
internal static async Task <OutboundSessionDriver> FindOrCreateDriverAsync(
PartitionKey targetPartition,
StreamManager streamManager,
SessionConnectionManager sessionConnectionManager,
TimeSpan timeout)
{
OutboundSessionDriver streamOutboundSessionDriver = null;
// Complete the call within this time.
var remainingTimeout = timeout;
try
{
FabricEvents.Events.FindOrCreateOutboundSessionDriver("Start@" + streamManager.TraceType, targetPartition.ToString());
var beforeResolve = DateTime.UtcNow;
// The sync point pattern is used here because lock() pattern is not compatible with await pattern
var normalizedPartitionKey = await streamManager.SessionConnectionManager.ResolveAndNormalizeTargetPartition(targetPartition, remainingTimeout);
Diagnostics.Assert(
null != normalizedPartitionKey,
"normalizedPartitionKey is not expected to be null in OutboundSessionDriver.FindOrCreateDriverAsync().");
// Update remaining time for timeout
var afterResolve = DateTime.UtcNow;
remainingTimeout = TimeoutHandler.UpdateTimeout(remainingTimeout, beforeResolve, afterResolve);
var syncPoint
= new SyncPoint <PartitionKey>(
streamManager,
normalizedPartitionKey,
streamManager.RuntimeResources.OutboundSessionDriverSyncpoints);
try
{
// this is entering an await compatible critical section -- syncPoint.Dispose will leave it
await syncPoint.EnterAsync(remainingTimeout);
var afterEnter = DateTime.UtcNow;
remainingTimeout = TimeoutHandler.UpdateTimeout(remainingTimeout, afterResolve, afterEnter);
// Check if the driver already exists
var exists = streamManager.RuntimeResources.OutboundSessionDrivers.TryGetValue(normalizedPartitionKey, out streamOutboundSessionDriver);
// TODO: should we refcount how many streams depend on this session?
// create a new driver if if it does not exist already
if (!exists)
{
FabricEvents.Events.FindOrCreateOutboundSessionDriver("Creating@" + streamManager.TraceType, normalizedPartitionKey.ToString());
// we are actually the first stream attaching to this partition on start or recovery or all previous ones closed
// Find or create a new reliable messaging session
var session = await sessionConnectionManager.FindOrCreateOutboundSessionAsync(normalizedPartitionKey, remainingTimeout);
Diagnostics.Assert(null != session, "Session is not expected to be null in OutboundSessionDriver.FindOrCreateDriverAsync().");
// Create a new outbound session driver
streamOutboundSessionDriver = new OutboundSessionDriver(normalizedPartitionKey, streamManager, sessionConnectionManager, session);
Diagnostics.Assert(
null != streamOutboundSessionDriver,
"Stream OutboundSessionDriver is not expected to be null in OutboundSessionDriver.FindOrCreateDriverAsync().");
// Add ref. to stream manager active runtime resources
var addSuccess = streamManager.RuntimeResources.OutboundSessionDrivers.TryAdd(normalizedPartitionKey, streamOutboundSessionDriver);
Diagnostics.Assert(
addSuccess,
"{0} Unexpected failure to add newSessionDriver in OutboundSessionDriver.FindOrCreateDriverAsync",
streamManager.Tracer);
}
else
{
FabricEvents.Events.FindOrCreateOutboundSessionDriver("Found@" + streamManager.TraceType, normalizedPartitionKey.ToString());
}
}
finally
{
syncPoint.Dispose();
}
FabricEvents.Events.FindOrCreateOutboundSessionDriver("Finish@" + streamManager.TraceType, normalizedPartitionKey.ToString());
}
catch (TimeoutException)
{
FabricEvents.Events.FindOrCreateOutboundSessionDriver("Timeout@" + streamManager.TraceType, targetPartition.ToString());
throw;
}
catch (Exception e)
{
Tracing.WriteExceptionAsWarning("FindOrCreateDriverAsync.Failure", e, "{0}", streamManager.Tracer);
throw;
}
return(streamOutboundSessionDriver);
}