realtimetraffic/realtimetrafficd/hub.go

/*
* Copyright (C) 2014 struktur AG
* http://www.strukturag.com
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is baeed on ideas from the chat example of gorilla/websocket.
* Copyright 2013 Gary Burd. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
*  Redistributions of source code must retain the above copyright notice, this
*  list of conditions and the following disclaimer.
*
*  Redistributions in binary form must reproduce the above copyright notice, this
*  list of conditions and the following disclaimer in the documentation and/or
*  other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package main

type hub struct {
	grabbers    map[string]*grabber
	connections map[*connection]bool
	broadcast   chan *interfacedata
	register    chan *connection
	unregister  chan *connection
}

var h = hub{
	broadcast:   make(chan *interfacedata),
	register:    make(chan *connection),
	unregister:  make(chan *connection),
	connections: make(map[*connection]bool),
	grabbers:    make(map[string]*grabber),
}

func (h *hub) run() {

	var eg *grabber
	var ok bool

	for {
		select {
		case c := <-h.register:
			h.connections[c] = true
			if eg, ok = h.grabbers[c.iface]; !ok {
				eg = newGrabber(c.iface)
				h.grabbers[c.iface] = eg
			}
			eg.start()
		case c := <-h.unregister:
			delete(h.connections, c)
			close(c.send)
			if eg, ok = h.grabbers[c.iface]; ok {
				eg.stop()
			}
		case d := <-h.broadcast:
			for c := range h.connections {
				if c.iface == d.iface {
					if m, err := d.encode(); err == nil {
						select {
						case c.send <- m:
						default:
							close(c.send)
							delete(h.connections, c)
						}
					}
				}
			}
		}
	}
}