public static byte[] GetValue(string key, Client currentClient)
{
//
// Read a value from the store. If the value has lived past its TTL, we'll expire it.
//
Value value;
using(TimeLock.Acquire(_values)) {
bool foundValue = _values.TryGetValue(key, out value);
if (!foundValue || value == null) {
return null;
}
if (value.TTL > 0) {
//
// Honour expiry TTL on object if any
//
if (value.TimeAdded.AddSeconds(value.TTL).CompareTo(DateTime.Now) <= 0) {
RemoveValue(key);
return null;
}
}
//
//Do some book-keeping with the value
//
value.LastAccessed = DateTime.Now;
Interlocked.Increment(ref value.NumAccesses);
return value.Data;
}
}
//
// Async callback for socket accept event
//
public void AcceptCallback(IAsyncResult ar)
{
//
// Free up the listen loop to go churn out more sockets
//
_acceptEvent.Set();
//
// Get client request socket and finish accept
//
byte[] buffer = new byte[Client.BufferSize];
Socket listenSocket = (Socket)ar.AsyncState;
Socket handler = null;
try {
handler = listenSocket.EndAccept(ar);
} catch (SocketException ex) {
handler.Shutdown(SocketShutdown.Both);
Log.LogMessage(" AcceptCallback " + ex.ToString());
return;
}
//
// We have a new client. Create a new client object and kick off the state machine
//
ConfigureClientSocket(handler);
Client currentClient = new Client {
WorkSocket = handler,
State = SocketState.ReadCommand,
UniqueId = DateTime.Now.Ticks.ToString(),
ClientNetworkHelper = new NetworkHelper(handler, buffer),
Buffer = buffer
};
Log.LogMessage("Connected to client from " + handler.RemoteEndPoint.ToString() + " \n");
StateMachine(currentClient);
}
private void StateMachine(Client currentClient)
{
try {
switch (currentClient.State) {
case SocketState.ReadCommand:
currentClient.ClientNetworkHelper.BeginReadLine( ReadCommandCallback , currentClient);
break;
case SocketState.ReadValue:
currentClient.ClientNetworkHelper.BeginReadValue(currentClient.ValueTotalBytes,ReadValueCallback, currentClient);
break;
default:
Debug.Assert(false);
Log.LogError("Server.StateMachine: Invalid state");
break;
}
} catch (Exception ex) {
//
// Something bad happened.
//
Log.LogError("Exception in state machine (client will be disconnected!: " + ex.ToString());
currentClient.Dispose();
}
}
private void ExecCommand(Client currentClient)
{
if (currentClient.CurrentCommand.Action == CommandType.GET) {
//
// Read value from the store and send it to the client if found. If we don't,
// find it, send a NOT_FOUND message to the client. We then clean up the state machine
// and wait for the next command from the client
//
byte[] data = Store.GetValue(currentClient.CurrentCommand.Key, currentClient);
PerfCounters.LogGet(data != null);
if (data != null) {
currentClient.ClientNetworkHelper.SendValue(data , currentClient.CurrentCommand.Key);
} else {
currentClient.ClientNetworkHelper.SendMessage( "NOT_FOUND");
}
return;
}
if (currentClient.CurrentCommand.Action == CommandType.DELETE) {
//
// Delete the specified value from the store.
// TODO: Send an error if the value wasnt found in the store
//
if (Store.RemoveValue(currentClient.CurrentCommand.Key)) {
currentClient.ClientNetworkHelper.SendMessage("DELETED");
} else {
currentClient.ClientNetworkHelper.SendMessage("NOT_FOUND");
}
PerfCounters.LogDelete();
return;
}
if (currentClient.CurrentCommand.Action == CommandType.SET) {
//
// Read the header for a SET/UPDATE command.
//
if (currentClient.CurrentCommand.Size > Global.MAX_CACHE_MEMORY) {
currentClient.ClientNetworkHelper.SendError( "Item too large");
return;
}
currentClient.ValueTotalBytes = currentClient.CurrentCommand.Size;
currentClient.State = SocketState.ReadValue;
return;
}
}
