private static IChordEndpoint findBootstrapNode()
{
const int timeout = 10000;
// expect all chord nodes to use the same port
// expect something like an exclusive LAN for chord nodes
// get network id and broadcast address
var networkId = IpSettingUtils.GetIpv4NetworkId();
var broadcast = IpSettingUtils.GetIpv4Broadcast();
var chordPort = IpSettingUtils.GetChordPort();
// TODO: think of using ASP.NET helper functions instead
// determine the first and last address in the address space
var firstIp = new BigInteger(networkId.GetAddressBytes()) + 1;
var lastIp = new BigInteger(broadcast.GetAddressBytes()) - 1;
// loop through all possible node addresses in the network
for (BigInteger addr = firstIp; addr <= lastIp; addr++)
{
// define the chord endpoint to be tried out
var targetEndpoint = new ChordEndpoint()
{
NodeId = -1,
IpAddress = new IPAddress(addr.ToByteArray()).ToString(),
Port = chordPort.ToString()
};
// send chord health check requests
var cancelCallback = new CancellationTokenSource();
var requestTask = Task.Run(() => sendRequest(
new ChordRequestMessage()
{
Type = ChordRequestType.HealthCheck,
RequesterId = -1
},
targetEndpoint
), cancelCallback.Token
);
// time out the request after several seconds
var timeoutTask = Task.Delay(timeout);
var first = Task.WhenAny(requestTask, timeoutTask);
bool bootstrapFound = first != timeoutTask;
// cancel the request after a timeout and try another IP
if (!bootstrapFound)
{
cancelCallback.Cancel(); continue;
}
// a bootstrapper was found
return(requestTask.Result.Responder);
}
return(null);
}
static ChordController()
{
// determine the local chord endpoint's IP address and port
string localIp = IpSettingUtils.GetChordIpv4Address().ToString();
string localPort = IpSettingUtils.GetChordPort().ToString();
// define a function callback for finding bootstrap nodes
Func <Task <IChordEndpoint> > bootstrapFunc =
() => { return(Task.Run(() => findBootstrapNode())); };
// join the chord network using a bootstrap node
node = new ChordNode(sendRequest, localIp, localPort);
node.JoinNetwork(bootstrapFunc).Wait();
}
