/// <summary>
/// receive date stream through socket
/// </summary>
/// <param name="control"></param>
private void __threadListen(ThreadControl control)
{
logger.Debug($"{nameof(__threadListen)}() on duty.");
var count = 1; // the actual received count of bytes by socket
var lenBuff = new byte[sizeof(uint)]; // store the message length number in byte format
var slot = new byte[slotSize]; // reception slot, it could maintain the integral data of a message
int k = 0, l = 0; // pointer for slot, pointer for lenBuff
uint msgLen = 0, verifyLen = 0; // message header, check code
var rbuffer = new byte[bufferSize]; // reception buffer
var slotBackup = slot; // switch back to the primal slot after using super slot
socket.SendBufferSize = this.bufferSize;
while (!control.SafelyTerminating)
{
/*******************************
* receive bytes through socket
* *****************************/
rwlsSocket.EnterReadLock();
try
{
var result = socket.BeginReceive(rbuffer, 0, rbuffer.Length, SocketFlags.None, x => x = null, null); // async reception，to realize 'SafelyTermination'
while (!control.SafelyTerminating && !result.IsCompleted) // wait for completion
{
Thread.Sleep(1);
}
if (control.SafelyTerminating || !socket.Connected)
{
break; // termination signal detected, stop listening
}
count = socket.EndReceive(result);
}
catch (SocketException se)
{
logger.Error($"{se.Message}");
break;
}
catch (Exception ex)
{
logger.Fatal("fatal error occurred in __threadListen.", ex);
Catch(new EOCException(ex));
break;
}
finally
{
rwlsSocket.ExitReadLock();
}
/*****************************
* process the received bytes
* ***************************/
for (var j = 0; j < count;) // deal with the bytes received in rbuffer
{
if (msgLen == 0)
{
lenBuff[l] = rbuffer[j];
++j; // point to the 1st byte of content
if (++l == lenBuff.Length)
{
l = 0;
msgLen = BitConverter.ToUInt32(lenBuff, 0);
if (verifyLen != 0) // need validation
{
if (verifyLen == msgLen) // validatin OK
{
watchDog = 0; // feed local dog, reset the timer
if (msgLen == 1) // system command code
{
if (slot[0] == DOG_FOOD_FLAG) // dog food
{
// pass
}
}
else
{
var msg = EMessage.FromBytes(slot, 0, k);
ThreadPool.QueueUserWorkItem(_processInMessage, msg);
}
msgLen = 0;
}
else
{
Catch(new EOCException("transmission error, please reconnect!"));
}
verifyLen = 0;
if (slot.Length != slotSize)
{
slot = slotBackup;
}
}
else
{
if (msgLen > slotSize)
{
slot = new byte[msgLen]; // super slot
}
}
k = 0;
}
}
else
{
int n = (int)(msgLen - k);
if (n + j > count)
{
n = count - j;
}
Array.Copy(rbuffer, j, slot, k, n);
k += n;
j += n;
if (k == msgLen)
{
verifyLen = msgLen;
msgLen = 0;
}
}
}
}
control.SetAbortedFlags();
OnThreadListenAborted();
logger.Debug($"{nameof(__threadListen)}() aborted.");
}
/// <summary>
/// watch dog has the highest authority in agent, it performs some light weight operations, such as update 'TCounters'
/// </summary>
private void __threadWatchdog(ThreadControl control)
{
logger.Debug($"{nameof(__threadWatchdog)}() on duty.");
var feedCycle = Math.Min(1000, this.timeout >> 1); // the cycle of dog feeding, unit: ms
var feedTCounter = 0;
var msg = new EMessage(0);
var foodBag = new[] { DOG_FOOD_FLAG };
var threadInterval = 1; // watch dog scan cycle, ms
while (!control.SafelyTerminating)
{
Thread.Sleep(threadInterval);
// -1 denote that the dog is dead，only __threadListen can set it back to '0' to rebirth the dog
if (watchDog == -1)
{
continue; // no more actions when dog has died
}
/*******************
* update TCounters
* *****************/
KeyValuePair <uint, TCounter>[] msgIdAndTCounterPairs;
lock (dictMsgId2TC) msgIdAndTCounterPairs = dictMsgId2TC.ToArray();
foreach (var kv in msgIdAndTCounterPairs)
{
if (kv.Value.Decrease(threadInterval) || !this.IsConnected) // request timeout
{
kv.Value.CountDown = 0; // set countdown to 'timeout'
RemoveWaitFlag(kv.Key);
ThreadPool.QueueUserWorkItem(_processTimeoutMessage, kv.Value.RequestMsg);
}
}
/************
* watch dog
* **********/
if (IsConnected)
{
// check local dog
watchDog += threadInterval;
if (watchDog >= timeout)
{
watchDog = -1; // time out flag
GetControl(ThreadType.Listen).SafeAbort();
OnConnectionTimeout();
logger.Error($"{this} connection timeout.");
}
// feed remote dog
feedTCounter += threadInterval;
if (feedTCounter >= feedCycle)
{
feedTCounter = 0; // reset
try
{
SendBytes(foodBag, 0, foodBag.Length);
}
catch
{
// pass, ignore all errors
}
}
}
}
control.SetAbortedFlags();
logger.Debug($"{nameof(__threadWatchdog)}() aborted.");
this.Destroy();
this.Phase = ConnectionPhase.P0Start;
}
