source: src/main/java/geniusweb/runserver/PartyConnectionFactory.java@ 45

package geniusweb.runserver;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Date;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;

import geniusweb.protocol.partyconnection.ProtocolToPartyConn;
import geniusweb.protocol.partyconnection.ProtocolToPartyConnFactory;
import geniusweb.references.PartyRef;
import geniusweb.references.Reference;
import tudelft.utilities.logging.Reporter;
import tudelft.utilities.repository.NoResourcesNowException;

/**
 * Factory conform ConnectionWithPartyFactory based on HTTP calls and websockets
 * following the partiesserver protocols.
 */
class PartyConnectionFactory implements ProtocolToPartyConnFactory {
        private final Reporter log;

        /**
         * @param logger the logger used for all created connections as well as for
         *               failed attempts to connect.
         */
        public PartyConnectionFactory(Reporter logger) {
                this.log = logger;
        }

        @Override
        public WebSocketProtToPartyConn connect(Reference reference)
                        throws IOException, NoResourcesNowException {
                try {
                        return new WebSocketProtToPartyConn(reference, log).init();
                } catch (IOException e) {
                        Date date = getWaitingTime(e);
                        if (date == null)
                                throw e;
                        throw new NoResourcesNowException("No resources for " + reference,
                                        date);
                }
        }

        /**
         * This is a specific implementation that uses a simple modified Banker's
         * algorithm.
         * 
         * @throws NoResourcesNowException if one party can not be allocated,
         *                                 failing with a
         *                                 {@link NoResourcesNowException}. In this
         *                                 case all resources that were allocated
         *                                 while the attempt was done are freed up.
         */

        @Override
        public List<ProtocolToPartyConn> connect(List<Reference> references)
                        throws IOException, NoResourcesNowException {
                /*
                 * FIXME Check first. If request is impossible, we should throw a
                 * ProtocolException instead of keeping failing with
                 * NoResourcesNowException. This implementation will cause a life lock
                 * in a session or tournament with impossible settings (eg more parties
                 * than slots on the partiesserver).
                 */
                log.log(Level.INFO, "attempting to connect " + references);
                List<ProtocolToPartyConn> connections = new LinkedList<>();
                try {
                        for (Reference partyref : references) {
                                ProtocolToPartyConn conn = null;
                                while (conn == null) {
                                        try {
                                                conn = connect(partyref);
                                        } catch (IOException e) {
                                                throw new IOException(
                                                                "Failed to connect to " + partyref.toString(),
                                                                e);
                                        }
                                }
                                connections.add(conn);
                        }
                } catch (IOException | NoResourcesNowException e) {
                        // free all already created connections
                        for (ProtocolToPartyConn conn : connections) {
                                conn.close();
                        }
                        throw e;
                }
                log.log(Level.INFO, "succesfully connected " + references);
                return connections;
        }

        /**
         * Try to get a suggested wait time out of the IOException.
         * 
         * Sometiems the IOException itself contains already the text "please retry
         * later".
         * 
         * 
         * @param e the {@link IOException} that may contain extra information
         * @return a Date contained in the IOException
         */
        private Date getWaitingTime(IOException e) {
                String msg = e.getMessage();
                if (msg.contains("retry later")) {
                        long suggestedRetryTime = -1;
                        try {
                                String[] elements = msg.split(" ");
                                suggestedRetryTime = Long
                                                .parseLong(elements[elements.length - 1]);
                        } catch (NumberFormatException e1) {
                                // silent catch, we check the value and report errors below.
                        }
                        if (suggestedRetryTime < 0) {
                                log.log(Level.WARNING,
                                                "Server 503 message does not contain proper positive long as last value:"
                                                                + msg,
                                                e);
                                suggestedRetryTime = System.currentTimeMillis() + 5000;
                        }
                        return new Date(suggestedRetryTime);
                }
                return null;
        }

        private Map<URI, Set<Reference>> groupByServer(List<Reference> references) {
                Map<URI, Set<Reference>> map = new HashMap<>();
                for (Reference ref : references) {

                }
                return map;

        }

        /**
         * Get the base uri of a Reference (http://base./../..) from a ref like
         * http://base../run/<somepartyname>
         * 
         * @param ref the reference to extract base URI from
         * @return URI holding the base name of the server
         */
        private URI getBaseURI(PartyRef ref) {
                String str = ref.getURI().toString();
                try {
                        return new URI(str.substring(0, str.indexOf("/run/")));
                } catch (URISyntaxException e) {
                        e.printStackTrace(); // straight bug
                        return null;
                }
        }
}