/**
* <summary>
* Creates a connected facade and returns it. Called either from constructor or inside
* a write lock.</summary>
*
* <param name="srvs">List of server addresses that this method will try to connect to.</param>
* <returns>Connected client facade.</returns>
* <exception cref="GridClientServerUnreachableException">If none of the servers can be reached.</exception>
*/
private C connect(ICollection <IPEndPoint> srvs)
{
Dbg.Assert(guard.IsReaderLockHeld);
if (srvs.Count == 0)
{
throw new GridClientServerUnreachableException("Failed to establish connection to the grid node (address " +
"list is empty).");
}
IOException cause = null;
foreach (IPEndPoint srv in srvs)
{
try {
C cnn = connect(srv);
Dbg.WriteLine("Connection successfully opened: " + srv);
return(cnn);
}
catch (IOException e) {
Dbg.WriteLine("Unable to connect to grid node [srvAddr=" + srv + ", msg=" + e.Message + ']');
cause = e;
}
}
A.NotNull(cause, "cause");
throw new GridClientServerUnreachableException("Failed to connect to any of the servers in list: "
+ String.Join <IPEndPoint>(",", srvs), cause);
}
/**
* <summary>
* AND predicate. Passes if and only if both provided filters accept the node.
* This filter uses short-term condition evaluation, i.e. second filter would not
* be invoked if first filter returned <c>false</c>.</summary>
*
* <param name="first">First filter to check.</param>
* <param name="second">Second filter to check.</param>
* <returns>Conjunction predicate.</returns>
*/
public static Predicate <T> And <T>(Predicate <T> first, Predicate <T> second)
{
A.NotNull(first, "first");
A.NotNull(second, "second");
return(delegate(T t) {
return first(t) && second(t);
});
}
/**
* <summary>
* Applies filter and returns filtered collection of nodes.</summary>
*
* <param name="elements">Nodes to be filtered.</param>
* <param name="filter">Filter to apply</param>
* <returns>Filtered collection.</returns>
*/
public static IList <T> ApplyFilter <T>(IEnumerable <T> elements, Predicate <T> filter) where T : class
{
A.NotNull(filter, "filter");
IList <T> res = new List <T>();
foreach (T e in elements)
{
if (filter(e))
{
res.Add(e);
}
}
return(res);
}
/**
* <summary>
* Gets active communication facade.</summary>
*
* <param name="srvs">Remote nodes to which connection should be established.</param>
* <returns>Communication facade.</returns>
* <exception cref="GridClientServerUnreachableException">If none of the servers can be reached after the exception.</exception>
* <exception cref="GridClientClosedException">If client was closed manually.</exception>
*/
public C connection(ICollection <IPEndPoint> srvs)
{
guard.AcquireReaderLock(Timeout.Infinite);
try {
checkClosed();
if (srvs.Count == 0)
{
throw new GridClientServerUnreachableException("Failed to establish connection to the grid" +
" (address list is empty).");
}
C conn;
/* Search for existent connection. */
foreach (IPEndPoint endPoint in srvs)
{
if (!conns.TryGetValue(endPoint, out conn))
{
continue;
}
A.NotNull(conn, "connection");
/* Ignore closed connections. */
if (conn.CloseIfIdle(DefaultIdleTimeout))
{
closeIdle(DefaultIdleTimeout);
continue;
}
return(conn);
}
/* Create new connection. */
conn = connect(srvs);
var cookie = guard.UpgradeToWriterLock(Timeout.Infinite);
try {
var endPoint = conn.ServerAddress;
if (conns.ContainsKey(endPoint))
{
/* Destroy new connection. */
conn.Close(false);
/* Recover connection from the cache. */
conns.TryGetValue(endPoint, out conn);
}
else
{
/* Save connection in cache. */
conns.Add(conn.ServerAddress, conn);
}
}
finally {
guard.DowngradeFromWriterLock(ref cookie);
}
return(conn);
}
finally {
guard.ReleaseReaderLock();
}
}