01: /*
02: * <copyright>
03: *
04: * Copyright 1997-2004 BBNT Solutions, LLC
05: * under sponsorship of the Defense Advanced Research Projects
06: * Agency (DARPA).
07: *
08: * You can redistribute this software and/or modify it under the
09: * terms of the Cougaar Open Source License as published on the
10: * Cougaar Open Source Website (www.cougaar.org).
11: *
12: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
13: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
14: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
15: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
16: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
17: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
18: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
22: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: *
24: * </copyright>
25: */
26:
27: package org.cougaar.mts.base;
28:
29: import java.util.Iterator;
30: import org.cougaar.mts.std.AttributedMessage;
31:
32: /**
33: * A cost-based {@link LinkSelectionPolicy} that chooses the cheapest
34: * link. If no other poliy is loaded, this is the one that will be
35: * used.
36: */
37: public class MinCostLinkSelectionPolicy extends
38: AbstractLinkSelectionPolicy {
39:
40: // Example of using MTS services in a selection policy
41: //
42: // public void load() {
43: // super.load();
44: // System.out.println("ID=" +getRegistry().getIdentifier());
45: // }
46:
47: public DestinationLink selectLink(Iterator links,
48: AttributedMessage message, AttributedMessage failedMessage,
49: int retryCount, Exception lastException) {
50: int min_cost = -1;
51: DestinationLink cheapest = null;
52: while (links.hasNext()) {
53: DestinationLink link = (DestinationLink) links.next();
54: int cost = link.cost(message);
55:
56: // If a link reports 0 cost, use it. With proper
57: // ordering, this allows us to skip relatively expensive
58: // cost calculations (eg rmi) that can't be any better
59: // anyway.
60: if (cost == 0)
61: return link;
62:
63: // If a link reports MAX_VALUE, ignore it.
64: if (cost == Integer.MAX_VALUE)
65: continue;
66:
67: if (cheapest == null || cost < min_cost) {
68: cheapest = link;
69: min_cost = cost;
70: }
71: }
72: return cheapest;
73: }
74: }
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